Cycling Performance Tips
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Cycling Performance Tips Cycling Performance Tips Document Transcript

  • CYCLING PERFORMANCE TIPS Training vs Genetics It’s interesting to speculate whether genetics or training/attitude determine a world class cyclist. I put the following question (from one of this websire’s readers) to an online coaching forum and will summarize the answers below. "I am a 20 year old competitive middle distance track runner, but I am considering the possibility of becoming a cyclist. I have biomechanical problems of the feet that I feel will make it impossible for me to compete at the very highest level as a runner. My question is what sort of physiological/anatomical characteristics does it take to be a world class cylcist, and how do I tell if I have those features? I have a good aerobic system with a H.R that does not rise easily in training, plus I have good short distance sprinting speed. Could these be transferred effectively into cycling? Also is it necessary to have naturally large quad musculature to be an elite cyclists?" There was a general consensus that almost anyone, of normal stature and physiology, could become a world class cyclist if they were willing to make the physical and mental commitment necessary AND they choose their event (sprint versus endurance) wisely based upon their physiological characteristics. In that regard, cycling is a sport in which people of all sizes and builds can participate and be very competitive. And although genetic factors may come into play and have a significant affect at the very highest level of competition, most people are so far from those limits it's more an excuse than anything else to quote "genetics" as an excuse for poor performance. The biggest single thing that affects performance and potential is ATTITUDE with TRAINING close behind. Any benefits of gentics would pertain mostly to true sprinters and much less to those requiring endurance. Basicall y genetics brings predisposition, but an athlete's environment (training, diet/nutrition, attitude, etc.) dictate outcome. The one measure often quoted as a measure of a world class ability endurance cyclist (ie the Tour De France) is a VO2 max of at least 80ml/O2/kg/min. Sprinters tend to be just under the 80 mark. But there was general agreement that VO2 max testing is like IQ testing, there is not much correlation between it and anything else besides taking the test. If VO2 max testing has any utility it is in identifying athletes that may have more potential than has been recognized through other means. Low VO2 max testing, however, does not make it impossible to develop a high level of performance. How much can VO2max be improved with training? A few thought that a 10% increment might be the most that could be trained. While others, based on personal experience, felt that over the years maximal oxygen uptake could increase significantly more than 10%. Finally, there was consesus that training not only increases the VO2max, but improves technique. And the effective translation of the VO2 into useful work is the result of that training. Which is why someone with slightly lower VO2 can beat those who "test" higher. DEVELOPING A TRAINING PROGRAM (Background) Designing a training program for any particular activity needs to be tailored to the duration and intensity (power, sprint, endurance) as well as the specific muscle groups being used (running, cycling, lifting, etc.) in the event. A general aerobic training program, for example, will not maximize your performance for that time trial coming up in a few weeks.
  • Brief power activities lasting for 30 to 60 seconds or repetitive sprint events rely on energy stored in the muscles as ATP and creatine phosphate (CP). Weight lifters and sprinters will gear their training towards improving those energy systems. As duration extends beyond one minute, energy is provided by anaerobic glycogen dependent pathways which produce lactic acid as a byproduct. And finally, after several minutes, aerobic pathways take on increasing significance with well over 90% of the energy in endurance events coming from these oxygen dependent metabolic systems. A successful training program focuses on developing the energy system specific for your particular event. The muscle groups needed for your event should also be factored into training program development. When 60 college aged men, equal as far as their level of aerobic conditioning, were divided into three groups - one training on a treadmill, one on a bicycle trainer at an equivalent %VO2max, and a third used as a non training control, the exercise specific benefits of training were clearly demonstrated. Both training groups improved their VO2max equally when tested on their training device, however, while the treadmill group improved 7% in VO2max when tested on either the treadmill or bicycle ergometer, the group training on the bicycle trainer improved 8% when tested on the bicycle ergometer, but only 3% when tested on the treadmill - proof of the failure of crosstraining to maximize performance across all aerobic events. The investigators speculated that changes in metabolic and circulatory factors in the muscles being trained, or adaptations related to the total muscle mass used during training, were responsible for these differences. Thus a successful training program also needs to focus on the specific activity and muscle groups to be used in the event. PRINCIPLES OF TRAINING All training programs adhere to basic, common principles. They include: I. EXERCISE OVERLOAD - the training event must increase the frequency, intensity, or duration of the specific exercise activity being trained for to be able to promote physiologic improvement and achieve a training response. II. SPECIFICITY OF TRAINING - adaptations in metabolic pathways and muscle fibers are dependent on applying the types of metabolic stress (aerobic versus anaerobic) to be used in the final event to the specific muscle groups to be used for that activity. III. SPECIFICITY OF VO2MAX - To achieve the optimum improvement in VO2max for any activity, the cardiovascular system needs to be stressed by that specific activity. As demonstrated above, there are general benefits to the heart and vascular system from any aerobic exercise, but if one wants to maximize VO2max, one needs to use the specific activity in training (a bicycle trainer will not maximize performance on a treadmill). IV. SPECIFICITY OF LOCAL MUSCLE CHANGES - there are local improvements in the muscle trained for a specific activity that will not generalize to other muscle fibers in that limb, or to the same muscle used in other exercises. Changes in ATP levels and other metabolic parameters in the vastus lateralis (a thigh muscle) are greater in cyclists (who use this muscle to a greater degree) than in runners training at the same VO2max). V. INDIVIDUAL DIFFERENCES - Not all individuals will respond to an equivalent training stimulus to the same degree or at the same rate. We are all different genetically and training programs need to be individualized. VI. REVERSIBILITY OF TRAINING - Deconditioning can occur rapidly when training ceases. At bed rest for 20 days, there is a decrease in VO2max of about 1% per day. Maintaining some level of conditioning during the off season minimizes deconditioning. And a reconditioning program should be part of every athletes schedule before the next season’s competition begins. PHYSIOLOGIC CHANGES OF TRAINING Anaerobic pathway changes (sprint and power activities) - • increases in ATP and creatine phosphate
  • • increase in enzymes involved in anaerobic glycogen breakdown • increase in lactic acid levels - probably secondary to increased production and an increase in tolerance to the discomfort produced from lactic acid in the muscles • increase in fast twitch fiber size Aerobic pathway changes - • mitochondria (where aerobic metabolism occurs) are larger and • increases in number • increased enzyme levels that generate ATP aerobically (without producing lactic acid) • increase in enzymes that facilitate lipid metabolism (an alternative route of energy production) • greater capacity to metabolize glycogen (partly related to increase in mitochondria and intracellular enzyme levels • increase in slow twitch muscle fiber size Cardiovascular changes - • increase in heart size • increase in blood volume (plasma) • decrease in heart rate • increase in volume of blood pumped per heart beat (stroke volume) • increase in amount of blood pumped per minute (cardiac output = rate x stroke volume) • increase in oxygen extraction at the muscle capillary interface • less blood flow needed to the muscle for a set level of exercise (from increased efficiency of oxygen extraction) • reduction in systolic and diastolic blood pressure • increase in volume of respirations (each breath, tidal volume) and breathing frequency with exercise TECHNICAL MONITORS With all the gizmos and gadgets that are available, it is tempting to focus on the technical aspects of training at the expense of the basics. It is important to listen to your body and be patient waiting for results, Avoid the temptation of constantly measuring yourself against data produced by other athletes. As it is difficult to know HOW to use comparative data from others, you should focus on comparing your current performance to previous efforts as the best measure of progress, leaving the data of others out of the mix. It's basically hard, repetitive work, and there are no short cuts to your personal best. TRAINING OPTIONS A focused training program can increase your VO2max by 15 to 30% over a 3 month period and up to 50% over 2 years. And the converse is true as ell. There is a drop off in metabolic adaptations within a few weeks of stopping training although changes in numbers of muscle capillaries and skeletal and cardiac muscle fiber size probably occur more slowly (see detraining below). Metabolic adaptations facilitate lactic acid removal allowing you to perform exercise at a higher level of %VO2max for longer periods of time, and changes in lipid metabolism which will provide extra Calories from fat to supplement those from glycogen and glucose metabolism for any
  • specified level of activity (%VO2max). The result is an increase in maximal performance and the ability to maintain a high level of performance for a longer time interval (endurance). Training also improves the muscle's tolerance for the stresses of prolonged exertion. These include strengthening of the connective tissue between muscle fibers to minimize the microtrauma (and post exercise discomfort) that occur with with physical exertion. Not every training session (in your program) needs to stress the cardiovascular system. In fact a successful program needs to be balanced with at least two days per week at less than maximal cardiovascular intensity to allow for mental and physical recovery. And it has been demonstrated that your performance in a competitive event is better if you taper your training program in the week prior. TRAINING INTENSITY Is more better? Not necessarily. The exact optimum for training intensity varies by a few percent between individuals (that's why coaches can help find that extra few % of a performance advantage for an elite athlete. It is generally accepted that maximum aerobic improvement occurs at 85% VO2max (approximately 90% of your max. heart rate), and REGULAR training above this level will increase the potential for injury without a corresponding benefit in cardiovascular (or musculoskeletal) adaptation. Lower levels of exercise - 60% maximum heart rate for 45 minutes or 70% maximum heart rate for 20 minutes - will modestly improve (or at least maintain) general cardiovascular conditioning but the use of the "long slow distance" approach where your maximum heart rate is always kept at 60 to 80% VO2max will not optimize your personal performance for high level aerobic events. For example, a West Virginia U. study assigned 15 women to either a low intensity (132 beats per minute) or high intensity (163 bpm) group exercising for 45 minutes, 4 times a week. There was an increase in VO2max for members of the high intensity group, but not the low intensity one. TRAINING DURATION The optimum duration for a training session depends on the intensity. Ten minutes of 70% maximum heart rate will be of some benefit, but 30 to 40 minutes are even better. Does going 60 minutes give you a proportionally greater benefit? Maybe not as there is some point at which the negative effects of exercise on breaking down and injuring muscle tissue outweight the cardiovascular benefits. Does 30 minutes of 80% MHR equate to 40 minutes at 70% i.e. increase the intensity to compensate for decreasing the duration? For endurance perhaps, but certainly not for improving your VO2max. As proof that there is an upper limit for the benefits of aerobic training, a group of swimmers training 1.5 hours per day was compared to a group training with two equivalent 1.5 hour sessions. There was no difference in the final performance, power, or endurance between the two groups. For aerobic training (continuous, not intervals) at less than 90% maximum heart rate it makes the most sense to look at the duration of the planned event, and train • at the same level of anticipated performance (%VO2max) • for a duration (distance) equal to 110 - 120% of the event TRAINING FREQUENCY It appears that maximum aerobic conditioning (increasing VO2max) occurs with 3 workout days per week. So unless one is trying to burn Calories to lose weight, or is working on increasing mileage to get the musculoskeletal system (back, shoulders) in shape for a long endurance event on the bike, it is better to take off 2 to 3 days per week to allow for muscle and ligament repair and decrease the risk of cumulative stress resulting in an increase in training injuries. And
  • interestingly, it appears that these 3 days per week will maximize aerobic conditioning equally in any combination - i.e. 3 days in a row with 4 off, alternating days of exercise, etc. DETRAINING Studies on maintaining the benefits of aerobic training revealed that a 2/3 reduction in training frequency i.e. going from 6 days a week to 2 days a week (keeping the same maximal intensity for each individual workout) maintained the gains. You can cut a 60 minute, 6 per week program to 60 minutes, 2 times a week and maintain your aerobic fitness level, BUT you CANNOT maintain a similar fitness level by cutting the intensity of the 60 minute session and keeping it at 6 times per week. If intensity is held constant, the frequency and duration of exercise required to maintain fitness are much less than the effort needed to attain that fitness level in the first place. METHODS OF TRAINING Training needs to be structured for the intensity and duration of the planned sporting event. Anaerobic (oxygen independent) exercise is generally brief (less than 60 seconds in duration) and is fueled by the anaerobic energy pathways in the cell (ATP, creatine phosphate). The classic anaerobic sport is weightlifting. Sprint activities also use anaerobic pathways. If the sprint lasts more than 5 or 10 seconds, lactic acid production (and clearance) also becomes an issue because of the negative effects of lactic acid on muscle performance. Training focused on anaerobic activities will enhance the ATP and CP energy transfer pathways in the cell as well as improving the tolerance for and clearance of lactic acid. Aerobic training (more important for cycling and other sporting events lasting more than 60 seconds) on the other hand provides its benefits by improving the cardiovascular and oxygen delivery systems to the muscle cell. These include improvements in both cardiac output (amount of blood pumped by the heart per minute) and at the muscle fiber level where there is an increase in the removal or extraction of oxygen from the blood cells in the capillaries. In addition, there is an improvement in the efficiency of the cellular metabolic pathways which convert glucose into ATP. As the level of exertion (measured by %VO2max) increases, there is a slow transition towards anaerobic metabolism in the muscle. There are always areas of relatively lesser perfusion within the muscle that are functioning anaerobically. So even at 50 to 60% VO2max some anaerobic conditioning is occuring. But at 85% VO2max (the "anaerobic threshhold" for most individuals) there is an abrupt increase in anaerobic metabolism throughout the entire muscle. So even though some cross training of the anaerobic systems takes place during exercise at 60 to 80% VO2max, a training program for sprint performance needs to include several exercise sessions per week above 85%VO2max. Long slow distance may be good training for aerobic, endurance events, but it will not improve your sprint performance. Both aerobic and anaerobic exercise sessions need to be included in a training program, but it is the balance of the amount of each type of exercise (aerobic vs anaerobic; interval training, continuous training, and fartlek training) in the overall program which determines its suitability for the competitive event for which you are training. INTERVAL TRAINING Doing intervals refers to sandwiching periods of intense physical activity between periods of recovery to allow longer periods of training time at your peak performance levels. One study in runners demonstrated that continuous, maximal performance levels could be sustained for only 0.8 miles before exhaustion occurred, while a similar level of peak exertion could be maintained for a cumulative distance (duration) of over 4 miles when intervals were used. If one is training for sprints of up to 20 seconds in duration (which do not involve significant lactic acid buildup and basically are training the ATP and CP systems), it is recommended that the
  • duration of the training interval should be increased by 1 to 5 seconds over the usual best time for that sprint distance with exercise intensity or maximum effort being unchanged,. For example, if one is training for a 100 yard dash, and has a personal best of 12 seconds, the training interval should be a 13 or 14 seconds sprint at the same pace (ignoring the total distance being covered in the 13 or 14 seconds). And a relief period 3 times longer than the training interval is recommended for recovery - 42 seconds in this example. Training for longer intervals (up to several minutes) produces significant lactic acid along with stressing the anaerobic metabolic pathways. To train for these longer distances (several minutes of maximum output), it is suggested that the distance being trained for be subdivided, and the training interval effort focused on that shorter distance. For example, if one is training for a personal best mile ride on the bike, and the best time for the entire mile is 3 minutes on the bike with the best 1/4 mile segment being 30 seconds and the best 1/2 mile segment being 80 seconds, the training interval could be set at either 1/4 or 1/2 mile and the time for this training interval set at your personal best minus 3 to 5 seconds. In this example the training interval might be chosen as 1/4 mile with a goal of a 25 second time. And the rest interval should be 2 times the training interval (as lactic acid clearance does not require the same recovery time as recharging the intracellular metabolic machinery). But training program drop out rates can double when intervals are used, so they should be used judiciously. Don't use them all year round, consider a twice a week program during your peak season, and separate each session by at least 48 hours to allow adequate recovery. If your long ride is on the weekend, Tuesday and Thursday make the most sense. The goal should be 10 to 20 minutes of hard pedaling per training interval session, not counting warm up, recovery, or cool down. A good place to start is with 5 minutes of peak effort. One approach is to use one day a week for short intervals (i.e. five 60 second and five 90 second intervals) and a second for longer intervals (two 3 minute and two 5 minute intervals). Allow 3 to 5 minutes for recovery between intervals and don't forget a 20 to 30 minute warm up and a 15 minute cool down. It has been shown that as few as a half dozen 5 minute intervals (separated by one minute recoveries) during a 300 km training week will improve both time trial and peak performance. If you have a heart rate monitor, an alternative is to key intervals to your maximum heart rate. Ride your intervals at 80 to 90% of your maximum heart rate and spin easily until your heart rate drops to 60 to 65% of maximum. CONTINUOUS TRAINING (LSD) Continuous training refers to aerobic activity performed at 60 to 90% VO2max for an hour or more. When done at the lower end of this range, it is often referred to as long, slow distance (LSD) training. This level of training is ideal for those starting off an exercise program, those wishing to maximize Caloric expenditure for weight loss purposes, and as an option for an active "rest" day in a weekly aerobic training program. This level of exertion can be maintained for hours at slightly less intensity than used in personal competitive events in the past, and is particularly suited for endurance event training. It is thought to have a preferential beneficial effect on the slow twitch muscle fibers (as opposed to the fast twitch fibers used in sprint interval training). It is suggested that a distance of 2 to 5 times the actual competitive event be chosen for this daily segment of the weekly training program. FARTLEK TRAINING This form of training is a combination of interval and LSD training. It is not as structured as an interval program being based on the personal perception of exertion rather than specific time or distance intervals. It mimics the "sprint to the line" that is part of many road races. While there is little scientific proof of its benefits it makes sense physiologically, and psychologically it adds a
  • feeling of freedom to those long slow days. How many sprints, and for how long?? The choice is up to you, but the intervals are probably in the neighborhood of those used for interval training. KEY POINTS FOR AN AEROBIC TRAINING PROGRAM • Training needs to be structured for the intensity and duration of the planned sporting event. • Long slow distance training is important at the beginning of the training season and for very long endurance events. • Maximum aerobic improvement occurs at 85% VO2max (90% max. heart rate). • Maximum aerobic conditioning (increasing VO2max) occurs with 3 workout days per week at or above 85% VO2max. Additional training days should be at a slower pace to allow recovery and build musculoskeletal strength. • Intervals can be ridden for one or two of these days. • Exercising at less than 85% VO2max will improve general cardiovascular conditioning and overall musculoskeletal tolerance. It is suggested that one day a week be alloted to a long slow training ride equal to a distance of 2 to 5 times the actual competitive event. • In training for endurance events (less than 90% maximum heart rate), train at the level of anticipated performance (%VO2max, %MHR)) and with a long training ride equal to that of the event + 10 to 20%. (see also USING A HEART RATE MONITOR) PUTTING THIS ALL TOGETHER, a good weekly training program: • is built on a good training base at the beginning of the season. • 3 days of high level cardiovascular activity (2 of which may be intervals) • 1 day training ride equal to the duration of the event and at a similar intensity • 1 day LONG slow recovery ride • the other 2 days should be spent off the bike or used for a short slow ride to "loosen up" PERCEIVED EFFORT How hard am I working? Am I pushing myself and getting the maximum from my training efforts? These are common questions for those of us focused on a high quality workout. Although Heart Rate Monitors are touted as THE only way to know the exact intensity level of your cardiovascular workout, there is a cheaper, easier alternative - the Rating of Perceived Exertion (RPE) scale {below} proposed by G. A. Borg in 1982 (Med Sci in Sports Exer. 14(5):377-81, 1982). The RPE scale ranges from 6 to 20, and includes a literal description for each level of exercise intensity. It was designed so adding a 0 to the level of exertion would give a rough estimate of your heart rate i.e. if you were resting (a 6 on the scale) your heart rate would be in the neighborhood of 60. Although RPE isn’t accurate enough for detailed physiologic studies, research has demonstrated an amazingly high correlation for any individual from day to day. In other words if you felt you were exercising at a 13 (somewhat hard) on two different days, and checked your heart rate, it would be quite similar. How can you use the RPE scale? First familiarize yourself with the levels. Then, using a treadmill or wind trainer, rate your own level of exertion BEFORE you check your pulse rate. With a little practice you will find that you will be amazingly accurate in predicting your heart rate. At that point you can use your own RPE instead of a heart rate monitor to monitor the intensity of the day’s workout. RPE can change as fitness improves (a higher heart rate for any level of perceived exertion) and with factors such as hydration, carbohydrate status, and ambient temperature. So recalibrate your own RPE scale regularly during the season if you are using this tool in your training.
  • RPE scale • 6 - resting • 7 - very, very light • 9 - very light • 11 - fairly light • 13 - somewhat hard • 15 - hard • 17 - very hard • 19 - very, very hard Fatigue Overtraining, Overreaching, and Chronic Fatigue Fatigue with trining refers to the tiredness one feels after riding. It is part of the training process in that physiologic over load with exercise, or gradually increasing work load, is the stimulus which leads to adaptation and performance improvement. Fatigue lets us know that we are pushing our physical limits. However, in certain circumstances, fatigue can be a warning that we are pushing too hard (that there is an imbalance between exercise and recovery), and indicate the need to back off or risk an actual deterioration in our performance. This is a common dilemma in a personal training program: Hard work makes us faster, but how much is too much? Let's be alittle more specific and talk about 5 types of fatigue. • The bonk (fatigue resulting from muscle glycogen depletion) usually develops 1 to 2 hours into a ride. It is a particular problem if "on the bike" glucose supplements are not used to extend internal muscle glycogen stores. • Post ride fatigue is a normal response to several hours of vigorous exercise and indicates we are pushing our training limits. It leads to improved performance the next time out. • Overreaching is the next step up - the fatigue we feel at the end of a particularly hard week of riding. It blends with #2, and will, with recovery, make us faster and stronger. It is also a warning that we are flirting with overtraining. • Overtraining is the debilitating and often long term (lasting weeks to months) fatigue which limits rather than stimulates improvement in performance. • Pathologic fatigue related to illness A regular rider needs to routinely assess his or her level of post ride fatigue, trying to walk the fine line separating post exercise fatigue (necessary if one is pushing themself) and overtraining (which can only hinder future performance). This is made even more complicated in that: • inadequate sleep • international travel • personal life stresses can all increase the level of your fatigue with exercise or training. Although it may seem paradoxical, structured rest is a key component of all training programs and may be one of the toughest training choices you'll have to make. To minimize the risk of
  • overtraining, you should include at least one and occasionally two rest days per week along with a day of easy spinning. Over reaching is a normal part of the training cycle. It may require several extra (and unplanned) recovery days. But if you find that your performance is not improving with several extra recovery days, it's time to take a break from riding and switch to alternative aerobic activities (at 70% maximum heart rate to maintain your cardiovascular fitness). To push ahead is to risk a level of overtraining which may require a month or two off the bike to recover. Be particularly sensitive to overtraining as your signal of pushing too hard if you have made a sudden or dramatic change in: • your training intensity • your training frequency • your training duration (the hours per week) • decreased the recovery time between sessions BACKGROUND/PHYSIOLOGY Fiercer competition between athletes and a wider knowledge of optimal training regimens have dramatically influenced current training methods. A single training bout per day was previously considered sufficient, whereas today’s athletes regularly train twice a day or more. Consequently, the number of athletes who are overtraining and have insufficient rest is increasing. The positive result of training in any sport is adaptation and improved performance: the supercompensation principle - which includes the breakdown process (training) followed by the recovery process (rest). Overtraining results from an imbalance between training and recovery, exercise and exercise capacity, stress and stress tolerance. Elite sports require large numbers of training hours per week. It is assumed that the relationship between training and improved performance is an inverted U-shape. Overreaching (short term overtraining) is most likely associated with insufficient recovery in the muscle with a decline in ATP levels. Overtraining is a more complicated physiologic problem, perhaps related to failure of the hypothalamus to cope with the total amount of stress. Overreaching lasts from a few days to 2 weeks and is associated with fatigue, reduction of maximum performance capacity, and a brief interval of decreased personal performance. Recovery is achieved with a reduction in training or a few extra days of rest. Overtraining (overtraining syndrome, staleness, systemic overtraining) is the result of many weeks of exceeding the athlete’s physiologic limits and can result in weeks or months of diminished performance - symptoms normally resolve in 6-12 weeks but may continue much longer or recur if athletes return to hard training too soon. It involves mood disturbances, muscle soreness/stiffness, and changes in blood chemistry values, hormone levels, and nocturnal urinary catecholamine excretion. Stress factors such as the monotony of a training program and an acute increase in training program intensity lasting more than a few days increase the risk of development of overtraining. On the other hand, heavy training loads appear to be tolerated for extensive periods of time if athletes take a rest day every week, and alternate hard and easy days of training. Pathologic fatigue is deined as fatigue and tiredness that cannot be explained by the volume of training. These are generally medical conditions such as infection, neoplasia, disorders of the blood, cardiovascular, or endocrine systems, and psychologic/psychiatric disorders. Included in this grouping are the side effects of medications and "chronic fatigue syndrome" - an ill defined medical condition. A recent article has muddied the water even further by describing muscle changes from years of high volume exercise training that may be related to this entity. For those of you interested in the basic physiology of overtraining, the underlying pathology is speculated to be related to an autonomic nervous system imbalance and/or a problem with the endocrine system. Several findings support this thesis. During heavy endurance training or overreaching periods, the majority of studies indicate a reduced adrenal responsiveness to ACTH which is compensated by an increased pituitary ACTH release. In early overtraining syndrome, despite increased pituitary ACTH release, adrenal responsiveness continues and serum cortisol
  • levels fall. In advanced stages of overtraining, pituitary ACTH release falls as well. In this stage, there is additional evidence of decreased intrinsic sympathetic activity and sensitivity of target organs to catecholamines - indicated by decreased catecholamine excretion during night rest, decreased beta-adrenoreceptor density, decreased beta-adrenoreceptor-mediated responses, and increased resting and exercise induced plasma norepinephrine levels. There is also a psychological toll from overtraining. For the most part, the competitive athlete is a well-adjusted individual who demonstrates less depression, anxiety, and fatigue than nonathletic counterparts. The well-trained athlete, however, may also have a personality that is somewhat rigid, strongly goal oriented, and perfectionist. It is not unrealistic to expect that when confronted with diminished performance or success, such an athlete may be compelled to drive himself or herself harder to succeed. This can express itself in the form of depression and accompanying chronic fatigue. Listed below are some of the physiologic and performance changes that have been documented with overtraining. A common thread is the inability to attain maximum energy output (aerobically as well as anaerobically) and the psychological consequences that go along with failing to do your best. • a decrease in scores on a self assessment of well-being; mood swings noted by others • sustained fatigue • a failure to progress in a training program • a decrease in the level of personal performance following a several day recovery period • an increase in mild illnesses recorded in a training diary • increased sleeping heart rate • a decrease in maximal physical performance • a decrease in maximal exercise induced heart rate • a decrease in the ratio of blood lactate concentration to ratings of perceived exertion at maximal work loads • a decrease in the clearance of blood lactic acid from min. 3 to min. 12 post maximal anaerobic activity • a decreased intramuscular utilization of carbohydrates at maximal exercise levels • a decrease in blood glucose, lactate, ammonia, glycerol, free fatty acids, albumin, LDL, VLDL cholesterol, hemoglobin level (transient), leukocytes • absence of an increase of serum cortisol normally induced by 30 min. of acute exercise • lowering of VO2max • nocturnal catecholamine excretion decreased markedly contrary to exercise-related plasma catecholamine responses which increased more than expected. • resting and exercise-related cortisol and aldosterone levels decreased. Several studies have suggested that overtraining may be associated with health issues above and beyond the immediate deterioration in physical performance. One study of Harvard alumni found a lower death rate (mortality) among men expending as few as 200 Calories per week in exercise versus those leading sedentary lifestyles, but when they regularly spent over 4000 Calories on exercise per week the death rate began to rise again. And two different studies have suggested a decrease in immune system competence with intense training (cycling 300 miles per week for 6 months or 2 intensive sessions of running per day for 6 days). But before you throw in the towel, there is overwhelming evidence that a moderate cycling program will actually stimulate and improve your immune system. The challenge for your personal training program is in finding your own limits, and avoiding that transition from overreaching to overtraining. WHO IS PRONE TO THE RISKS OF OVERTRAINING? Cyclists are one of the few groups of athletes capable of reaching the over trained level associated with prolonged fatigue. It has been speculated that this is due to the way cycling stresses the body with muscle activity concentrated in a single muscle group - the quadriceps. And it isn't necessary to undertake an extensive training program to be at risk. Even those working out sporadically (and with light training schedules) are at risk. While a professional cyclist
  • might consider a 50 mile ride as part of a light recovery week, your 20 mile ride could produce all the symptoms of overtraining. CLUES TO OVERTRAINING How do YOU know when you are in danger of OT? The following are clues which might suggest that an extra day or two of rest is in order. Personality/Disposition - While your personal demeanor is difficult to quantify, it appears to be the most sensitive and earliest indicator of overtraining. Anger, depression, and a decrease in your sense of well being and vigor have all been reported as signs of OT. You won't need a psychologist to help you with this one. Your family and significant others are usually the first to point these symptoms out to you. Resting heart rate - A resting pulse rate is taken on awakening in the morning before getting out of bed. An increase of 10% or 10 beats per minute for several days in a row is accepted by most coaches as a sign to slow down. Remember, it is the trend of your resting heart rate, taken over a period of days, that is important, not a single day's reading. Performance - A short, standardized time trial every week is another helpful monitoring tool, and the changes will usually be in minutes, not seconds. If you see a deterioration, take some time off or consider switching to another aerobic activity (being careful to keep your exercising heart rate below 70% of maximum). A drop of 10 beats per minute in your time trial maximum heart rate has also been used as an indicator of overtraining. General fatigue - Ongoing daily lethargy is a clue that it's time to slow down. General physical complaints - Sore throat, sore muscles, and chronic diarrhea all may indicate the chronic stress of overtraining. An increase in minor illnesses has been reported as well. Disruption of the normal sleep cycle - Falling asleep easily, awakening abruptly, and then feeling like you need a nap at 10 AM can reflect a change in your normal sleep cycle associated with overtraining. Biochemical parameters - And of course there are a myriad of biochemical parameters that have been used by coaches to identify early overtraining. These include resting and exercise cortisol levels, norepinephrine levels, and lactic acid clearing after maximal exercise. But when it comes right down to it, you are how you feel, so to speak. Your sense of well being, sense of fatigue throughout the day, and sense of perceived effort as you take that weekly ride over your regular route all appear to be more sensitive than the most sophisticated laboratory study in identifying early overtraining. WHAT CAN YOU DO? In a nutshell, overtraining is the result of "doing too much, too quickly". The body likes regular, moderate changes, not upheaval, in a training program. So don't increase your mileage or training time by more than 10% per week. The most important aspect of preventing OT is realizing you are almost there. And a good training diary is the single most important tool you have at your immediate disposal to alert you to the risk. In addition to the usual training facts such as mileage and times, it should include a daily notation on: • resting heart rate before getting out of bed • mood self assessment • self assessment of level of fatigue throughout the prior day ("heavy legs") • minor illnesses - i.e. GI upset, diarrhea, sore throat, and runny nose • performance (time) on a weekly standardized ride done at your perceived maximum. More scientific would be measurement of oxygen consumption (down), heart rate (up), and blood lactate levels (down). For professional coaches, there are some intriguing additional tools and literature available. • J C Puffer and J M Shane in Clin Sports Med 1992 Apr. 11(2):327-38 reviewed the issue of chronic fatigue as it related to overtraining versus other medical diagnoses, and presented a diagnostic framework to assist in the assessment of the athlete who presents with such complaints.
  • • W Derman et al Journal of Sports Sciences 1997 15:341-351 also review the clinical approach to sorting out chronic fatigue in the athlete. • G Kenatta and P Hassmen in Sports Med 1998 Jul 26(1):1-16 describe a methodology they call refer to as the total quality recovery (TQR) process. By using a TQR scale, structured around the scale developed for ratings of perceived exertion (RPE), they suggest that the recovery process can be monitored and matched against the breakdown (training) process (TQR versus RPE). The TQR scale emphasizes both the athlete's perception of recovery and the importance of active measures to improve the recovery process. Directing attention to psychophysiological cues serves the same purpose as in RPE, i.e. increasing self-awareness. They suggest that using this tool o differentiates between the types of stress affecting an athlete's performance o identifies factors influencing an athlete's ability to adapt to physical training o structures the recovery process. • From the laboratory or biochemical perspective, A C Snyder et al in Int J Sports Med 1993 Jan 14(1):29-32 proposed monitoring the ratio of blood lactate concentration to ratings of perceived exertion. They performed an incremental exercise test to maximal effort monitoring blood lactate concentration (HLa) and ratings of perceived exertion (RPE) for each workload. They found that at maximal workload all seven subjects had HLa:RPE ratios of less than 100 when over-reached and concluded that the ease and speed at which the HLa:RPE ratio can be determined may make it useful for coaches and athletes in monitoring intensive exercise training and recovery. • P Pelayo et al in Eur J Appl Physiol 1996;74(1-2):107-13 reviewed measurements of blood lactate concentration both during and after a maximal anaerobic lactic test (MANLT). The percentage of mean blood lactate decrease (% [La-]recovery) between min. 3 and min. 12 of the passive recovery post-MANLT increased from week 2 to 10 with aerobic training and decreased from week 10 to 21. The lowest % [La-]recovery coincided with signs of OT, such as bad temper and increased sleeping heart rate. They concluded that the % [La-]recovery could be an efficient marker for avoiding OT in elite athletes. IN SUMMARY Overtraining refers to prolonged fatigue and reduced performance despite increased training. Its roots include muscle damage, cytokine actions, the acute phase response, improper nutrition, mood disturbances, and diverse consequences of stress hormone responses. The clinical features are varied, non-specific, anecdotal and legion. No single test is diagnostic. The best treatment is prevention, which means • balancing training and rest • monitoring mood, fatigue, symptoms and performance • ensuring optimal nutrition, especially total energy and carbohydrate intake. Over reaching is a normal part of the training/recovery cycle, but if your performance is not improving after a few days of recovery, it's time to switch to other aerobic activities which will keep you at 70% of your maximum heart rate (to maintain your level of fitness) or risk entering the zone of OT which may take a month or two to recover. How long do you need to rest? If you have made a significant increase in your training schedule, and have been at it for 3 weeks or more, the chances are that you are entering that gray zone of overreaching. If so, recovery (and again this means keeping your general level of aerobic activity at 70% max. heart rate, not complete inactivity) takes at least 3 days and often up to several weeks as opposed to the normal recovery cycle of less than 3 days. The implication in that situation is that you may need more than 1 or 2 days of rest before a big event to perform at your personal best.
  • In addition, you can structure your training program to decrease the risk of overtraining. It should include at least one (and sometimes two) rest days per week as well as a day or two of easy spinning. This reflects the practical experience of coaches who have had to deal with the results of pushing too hard for too long. Increasing variation (decreasing monotony) both in your training routine from week to week (long rides, intervals) as well within individual rides has been proven to minimize training stress and decrease the risk of OT. As in all aspects of personal training programs there is individual variability, so it is up to you to decide where to draw your own line. But remember that rest is a key part of any training program and may be the toughest training choice you'll have to make.And finally, don't forget to pay particular attention to post exercise carbohydrate replacement. Part of the fatigue of overtraining may be related to chronically inadequate muscle glycogen stores from poor post training ride dietary habits. EXERCISE INDUCED MUSCLE PAIN, SORENESS, AND CRAMPS There are three types of muscle pain related to exercise. • pain occurring during or immediately after exercise • delayed onset muscle pain • muscle cramps MUSCLE PAIN DURING EXERCISE Exercise requiring significant effort, either from high energy demands (low resistance, rapid contraction rate) or substantial muscle effort (high resistance, low contraction rate) is often associated with muscle pain or discomfort. No study has identified a single cause for this discomfort, although the fact that it occurs more quickly in a muscle with a limited blood supply suggests that the culprit is a product of muscle metabolism. In addition, as the ingestion of sodium bicarbonate will delay the onset of pain for any level of exercise, it is thought that the substance is acidic in character. Lactic acid is considered the likeliest candidate although other metabolites such as pyruvic acid and ammonia have also been suggested. Based on the differing results in various papers in the literature, it is most likely that pain in the actively contracting muscle is multifactorial (ie related to a combination of substances) including the build up of acidic intermediate metabolites, ionic shifts at the cell membrane level (K, magnesium), and actual changes in the muscle cell proteins themselves. The fact that training will increase the level of activity at which discomfort first occurs indicates that the muscle cell can adapt to these factors. It is interesting that the body also has a mechanism to deal with this discomfort. Endorphins, opiate like substances produced internally, are secreted into the central nervous system during endurance exercise and will alter the perception of pain during prolonged high intensity exercise. Thus we have a mechanism to warn of muscle overuse, and also one to suppress pain during prolonged exercise which may be beneficial in fleeing from dangerous situations. Although conventional wisdom holds that taking aspirin before a ride will cut down on muscle pain during exercise, a study at the University of Georgia recently concluded that even at large doses (20 mg per kg or 4 standard aspirin for the average rider), aspirin did not delay the onset of muscle pain during exercise or reduce the perceived intensity when it occured. DELAYED ONSET MUSCLE SORENESS (DOMS) This is the soreness (stiffness) that begins 24 to 48 hours after exercise and peaking by 48 to 72 hours. It is most evident after "eccentric" muscle actions which involve actively resisting lengthening of the muscle as occurs in raising or lowering a weight, and indicate a high tension on muscle fibers and connective tissue as opposed to isometric or static tension activity. It is accompanied by a decrease in muscle strength, a reduced range of motion, and leakage of muscle cell proteins (creatine kinase, myoglobin) into the blood. These three findings indicate muscle damage (most likely related to minute tears and physical damage) as opposed to the
  • buildup of metabolic byproducts during exercise, and muscle biopsies demonstrate muscle contractile fiber damage and an inflammatory response. Generally DOMS is noted after unaccustomed eccentric exercise. And it does not appear that soreness from previous exercise increases the chance of further muscle damage. In fact the adaptive process of healing, even from microscopic injury with minimal pain, appears to have a significant protective effect on the development of muscle damage and soreness from subsequent exercise - the reason one should use a gradually progressive exercise training program. In 1997, a small group of elite athletes with a combination of chronic fatigue and delayed onset muscle soreness were described. Muscle biopsies were abnormal and the authors speculated on the possibility of cummulative chronic injury which might interfere with performance. MUSCLE CRAMPS It's not unusual to hear the following story: "I entered my first mountain bike race (18 miles) and at mile 14, my thighs and right calve cramped up. This has happened before on long rides. I thought I trained enough, hydrated enough, and ate enough bananas, but I still cramped up and had to go real slow for the last 4 miles. It was sooooo frustrating. I have another race coming up next month but its only 12 miles but has steeper hills. What should I do? Do tights help reduce cramps? When I get them (cramps) should I massage the cramped area? Should I train the amount of miles of the race?" Cramps are most common when you use your muscles beyond their accustomed limit (either for a longer than normal duration or at a higher than normal level of activity) - which explains why cramps are more common at the end of a long or particularly strenuous ride or after a particularly vigorous sprint. In fact cramps are among the most frequent complaint in marathon participants (18% in one study). In another study of cyclists competing in a 100 mile race, 70% of male participants experienced cramps (women, interestingly, had a rate less than half as frequent at 30%). The pain is brought on by an intense, active contraction of the muscle cells themselves. Although cramps may occasionally be the result of fluid and electrolyte (sodium) imbalance from sweating, that is not universally the case as individuals involved in activities requiring chronic use of a muscle without sweating (musicians for example) will also experience cramps. In one study of marathon runners, there were no differences in sodium or hydration levels between the 15 participants who developed cramps and the 67 who didn't. And although a low magnesium level can cause severe muscle cramping, another study of magnesium supplements in triathletes failed to show any benefits as far as cramping. However, as is often the case when there is no consensus on etiology (probably related to the fact there are multiple potential causes), you will find conflicting opinions. Bill Misner, PhD starts off noting that "the etiology of a common exertional muscle cramp during the heat of summer is not agreed upon by research because of a multiple of biochemical aberrations that may result in neurophysiological failure", then reviews the convoluted physiology of muscle contraction, and concludes that "the single cause of muscle cramps is inconclusive to date." Unfortunately he then proceeds to give us a specific electrolyte formula to prevent cramps (unsupported by any controlled studies other than in exceptional circumstances). There are 4 issues to be considered in the prevention of muscle cramps: • training - as with the two other forms of activity related muscle pain, training to the level of the anticipated activity will decrease the possibility of cramps. • hydration - dehydration is the second most common cause of muscle cramps after exerting beyond your training. • electrolyte replacement - sweat contains approximately 2 grams sodium/liter, 1 gram chloride/liter,0.2 gram potssium /liter, and 0.1 gram magnesium/liter - and if you are acclimated, these concentrations are even lower. Except in extreme circumstances, dietary intake will replace these losses, but if you are going to be exercising in excessively hot or humid conditions, most trainers would suggest paying close attention to salt intake and even adding 1/2 tsp of salt (1150 mg of sodium) per day to your food. Don't worry about elevating your blood pressure as we are talking about a short term
  • supplement and the sodium effect on blood pressure happens over months to years. A sports drink might help, but it is likely that maintaining adequate hydration is more important than the small amount of electrolytes they contain - and water is still a lot less expensive. The role of other micronutients and vitamins are completely unproven. • muscle glycogen reserves - replenishment of ATP is important for proper muscle cell functioning with adequate Caloric intake needed to achieve optimal physical performance. However the role of adequate glycogen reserves in preventing muscle cramps is speculative and requires further investigtion. What's the answer? Everyone's physiology is different, and thus the answer to preventing cramps almost certainly varies from person to person as well. Maintaining adequate fluid replacement and nutrition is essential for optimal physical performance above and beyond the benefits in preventing muscle cramps. From there it becomes a trial and error approach to see what might help you. If you suffer from muscle cramps, try manipulating supplements - potassium, magnesium, calcium. Try one of the commercial brands. But for the vast majority who only rarely suffer from cramps it will be training, fluids and carbs that are the key. And for them supplements are just an added expense without any clear benefit. If cramps do occur, gently stretching the affected muscle will give relief, and some authorities feel that stretching used prophyllactically will prevent cramps. Calf cramps can be relieved by standing on the bike and dropping your heel, while anterior thigh cramps can be stretched out by unclipping and moving your thigh backwards towards your buttocks. Although a number of medications have been suggested as treatments for muscle cramps (vitamin E, verapamil, and nifedipine to name a few) only quinine has been shown to be effective in scientifically controlled studies. But the high incidence of side effects limit its usefulness as a routine treatment. My recommendations for those suffering from frequent muscle cramps? • #1 is an adequate training program designed for the event being considered • a close second is maintaining good hydration • a sports drink containing electrolytes for severe conditions of heat and humidity • a regular program of stetching before, during, and after exercise. Pushing beyond your training is a sure fire way to get them. Remember to " train to the ride" i.e. push yourself to the level of your competitive ride once a week. Here's a great example of the role training plays in prevention of cramps - even though it relates to the question of cramps in a non cycling event. The answer was provided by an associate at my clinic. Q:I started cycling about 6 months ago and trained really hard this summer for a double century. In all the training and the race itself I rarely suffer from any muscle spasms. However since I started cycling I (may just be coincidence) get EXTREME spasms when I hike down hill. Hiking uphill doesn't bother me, but my quads and calfs literally freeze up after only 5-10 minutes of down hill hiking. It becomes so painful I can barely bend my leg. Last time I only hiked 1/2 mile and I thought they were going to have to carry me out. I've tried stretching before and it doesn't help. Within hours the spasms are nearly gone and by morning I feel fine. This probably sounds crazy, but I can't figure out how I can bike 200 miles and can't hike 1/2 mile. A: Here's the somewhat technical answer: The ankle plantar flexors and quads act concentrically in cycling - that is they generate tension (fire) while shortening. Through the down stroke the ankle plantar flexes and the knee extends under the influence of the gastrocs, soleus and quads. At the bottom of the stroke and through the up stroke, the hamstrings are shortening too. In walking down hill the opposite is true. Your friend is repeatedly letting himself down hill under the eccentric firing of the quads, plantar flexors and hamstrings. To keep from falling forward the hamstrings fire to keep the pelvis from rotating forwards. During stance phase the ankle dorsiflexes over the planted foot lengthening the plantar flexors and the knee flexes lengtheing the quadriceps muscles. A pack will change the equation in that it will greatly amplify the intramuscular tension and therefore the work performed by the muscle. Work that these muscles
  • are not trained (training meaning the physiologic and anatomic adaptations to repeated work) to do. And the short version: In terms of improving the situation the answer is really cross training - his muscles are well equipped for steady state aerobic concentric work at 90 to 110 rpm but not the greater intensity, near anaerobic threshold eccentric work of hiking down hill. I would bet that eight weeks of running including 20% speed/interval work will turn the problem around. Post Ride Recovery and Your Training Program Ask a cyclist about their training program and you will hear about mileage, intervals, and nutritional secrets. Only recently has post ride recovery made it onto the list of priorities. Yet successful cyclists know that preparation for the next ride begins even as the current one is being completed. POST EXERCISE FATIGUE A cyclist may experience 4 distinct types of fatigue. • The bonk (fatigue resulting from muscle glycogen depletion) usually develops 1 to 2 hours into a ride. It is a particular problem if "on the bike" glucose supplements are not used to extend internal muscle glycogen stores. • Post ride fatigue is a normal response to several hours of vigorous exercise and indicates we are pushing our training limits. It leads to improved performance the next time out. • Overreaching is the next step up - the fatigue we feel at the end of a particularly hard week of riding. It is really just an extension of #2, and will, with recovery, make us faster and stronger. • Overtraining is the debilitating and often long term (lasting weeks to months) fatigue which limits rather than stimulates improvement in performance. A regular rider needs to routinely assess his or her level of post ride fatigue, trying to walk the fine line separating post exercise fatigue (necessary if one is pushing themself) and overtraining (which can only hinder future performance). Although it may seem paradoxical, structured rest is a key component of all training programs and may actually be one of the toughest training choices you'll have to make. To minimize the risk of overtraining, you should include at least one and occasionally two rest days per week along with a day of easy spinning. Over reaching is a normal part of the training cycle. It may require several extra (and unplanned) recovery days. But if you find that your performance is not improving with several extra recovery days, it's time to take a break from riding and switch to alternative aerobic activities (at 70% maximum heart rate to maintain your cardiovascular fitness). To push ahead is to risk a level of overtraining which may require a month or two off the bike to recover. NUTRITION Carbohydrates are the primary energy source for all cyclists who push themselves, while fats are more important in slower, endurance events. Protein is not an energy source, but maintains and repairs cells and tissue. The "bonk" occurs when the body's stores of carbohydrate (glycogen in the liver and muscles) is depleted and the exercising muscle shifts to fat metabolism as its primary source of energy. Occasionally overtraining may be the result of failing to adequately replace the muscle glycogen depleted as a result of daily training with the onset of what might be considered a chronic bonk type situation - or at least bonking much earlier in a ride than ususal. this is particularly a risk at the elite athlete level where there may be multiple training seesions (or competitions) per day, and limited time to eat. To minimize the risk of early bonking and chronic glycogen depletion as a possible cause of overtraining, it is important to maximize your body glycogen stores by using dietary carbohydrates to your advantage before, during, and after a ride:
  • • eating a high carbohydrate diet in the days and hours before your ride • using carbohydrate supplements while riding • using the immediate post ride recovery interval to begin rebuilding carbohydrate stores. For the pre ride period, the traditional carbohydrate loading program (which traditionally includes a carbohydrate depletion phase for several days followed by forcing carbohydrates for the 3 days immediately prior to the event)to maximize glycogen stores is not essential. A high carbohydrate diet alone (without a preceding carbohydrate depletion phase) will provide 90% of the benefits of the full program while avoiding the digestive turmoil that can occur during the carbohydrate depletion phase. {NOTE: Although any increase in glycogen stores WILL increase the DURATION of exercise to fatigue, they WILL NOT increase MAXIMUM PERFORMANCE (VO2max)} Maximizing carbohydrate replacement while riding is important for events of more than 2 hours. At least 1 to 2 grams of carbohydrate per minute can be absorbed and metabolized to supplement pre ride body glycogen stores. This additional carbohydrate fuel will prolong the time to the bonk. In extreme events such as the Tour de France, as much as 50% of the daily energy expenditures can be provided by supplements taken while on the bike. Finally, take advantage of the glycogen repletion window that is open in the 4 hours immediately following vigorous exercise. During this time, any carbohydrates you eat will be converted into muscle glycogen at 3 times the normal rate - and some data suggests there is a 50% fall in this super charged repletion rate by 2 hours with a return to a normal repletion rate by 4 hours. (Ivy JL et al,J Appl Physiol 1988 Apr;64(4):1480-5). The slowing rate of glycogen storage occurs even when plasma glucose and insulin levels remain elevated with oral supplements. After this initial 4 hours, muscle glycogen stores are replenished at a rate of approximately 5% per hour. And while it may require up to 48 hours for complete muscle glycogen replacement following a 2 hour ride, for all practical purposes glycogen stores are almost completely rebuilt in the first 24 hours post event. But for the athlete who is on a daily training schedule, or is in a multiday event, the glycogen window can be used to get a jump on the normal repletion process and minimize the chance of gradually developing chronic glycogen depletion (and the fatigue that goes along with it). • How much glucose is enough during this 4 hour interval? Most studies have suggested that you can incorporate 3 grams of carbohydrate per kg of body weight during this 4 hours and up to 10 grams per kg over the post ride 24 hour period. • Is more better? Although the rate of CHO incorporation begins to fall at 2 hours, taking all the CHO in the first few hours may not be the answer as there appears to be a maximum repletion rate in the neighborhood of 1.5 grams of CHO per kg body weight per 2 hour period. • Is the type of carbohydrate important? Glucose and sucrose appear to be of equal value while there is some evidence that fructose is less beneficial. • Will a carbohydrate/protein drink enhance glycogen repletion during this glycogen window as compared to a pure glucose drink alone? Only if inadequate carbohydrate is being eaten. Although it had been originally been suggested in 1992 that the addition of protein to a carbohydrate supplement would enhance the rate of muscle glycogen resynthesis after endurance exercise (Zawadzki et al., J. Appl.Physiol. 72: 1854-1859, 1992), Roy et al (J Appl Physiol 1998 Mar;84(3):890-6) proved that the difference was not protein per se, but the fact that the two drinks were not Calorically equal. Van Hall (J Appl Physiol 2000 May;88(5):1631-6) also supported that hypothesis when they demonstrated the failure of the coingestion of carbohydrate and protein, compared with ingestion of carbohydrate alone, to increase leg glucose uptake or glycogen resynthesis rate further when carbohydrate was ingested in sufficient amounts every 15 min to induce an optimal rate of glycogen resynthesis. • Does it make a difference how one eats in the 24 hour post exercise period? Burke LM et al could not show a difference in postexercise glycogen storage over 24 h when a high-
  • carbohydrate diet was fed as small frequent snacks or as large meals. However there did appear to be some advantage of eating carbohydrates with a high glycemic index. So what does all this mean? Aim to drink or eat 3 grams of carbohydrate per kg of body weight over the four hours after exercise - but use some common sense in spreading it over the full four hours - at most 1.0 gm of carbohydrate per kg body weight per hour (at 4 Calories per gram, this would be approximately 200 Calories per hour for the average rider). A recovery drink (especially one that contains complex corbohydrate to maximize the Caloric density of the drink) may help in that first hour if you have trouble eating after exercising. And if you can't find those liquid carbs at the end of the ride? Don't worry, you can catch up on your mucscle glycogen repletion by eating a high carbohydrate diet over the next 24 hours. And it doesn't have to be pure carbs either. Burke LM et al (J Appl Physiol 1995 Jun;78(6):2187- 92) decided to investigate whether the addition of fat and protein to carbohydrate feedings in the 24 hour post exercise period affects muscle glycogen storage. Eight well-trained triathletes undertook an exercise trial (2 h at 75% peak O2 consumption, followed by four 30-s sprints) on three occasions, each 1 wk apart. For 24 h after each trial, the subjects rested and were assigned to the following diets in randomized order: control(C) diet (CHO = 7g/kg1/day), added fat and protein (FP) diet (C diet + 1.6 g/kg/day fat + 1.2 g/kg/day protein), and matched-energy diet [C diet + 4.8g/kg/day additional CHO (Polycose) to match the additional energy in the FP diet]. Meals were eaten at t = 0, 4, 8, and 21 h of recovery. There were no differences between trials in muscle glycogen storage over 24 h in equal Caloric diets of carbohydrate alone (approx 10 grams of CHO per kg body wt per 24 hours (sic)) vs. CHO/Pro/fat. (C 85.8, FP 80.5, matched-energy, 87.9 mmol/kg wet wt). SPECIFIC POST RIDE (RECOVERY) DIETARY RECOMMENDATIONS: • take in 3 to 4 gm carbohydrate/kg BW in the 4 hours post ride - start immediately • don't push beyond 1.5 grams CHO per kg body wt per hour as an upper limit • consider using a high Caloric density glucose polymer sports drink in the first few hours • aim for 8 to 10 grams of CHO per kg body weight over the next 24 hours to maximize repletion of muscle and liver glycogen. HOW MUCH SHOULD YOU EAT? Estimating your Caloric replacement needs is always a challenge. And as CHANGE IN WEIGHT (IN LBS) = (CALORIES BURNED - CALORIES CONSUMED)/3500 you will see the results reflected in the bathroom scales. Regular physical exercise will help to protect your muscles (at the expense of fat) during periods of negative Caloric balance so you will not lose significant muscle mass even if you underestimate your Calorie needs. However, if you overshoot on the Calorie replacement, and especially if you have been exercising at a slow pace (which will preferentially burn fat Calories while maintaining muscle glycogen stores), any post ride carbohydrate loading may find muscle glycogen stores already "filled" and any additional carbohydrate Calories will be converted directly into fat. THE BOTTOM LINE Eat a high carbohydrate diet(60 to 70% carbohydrate, low in fat), the diet that is best for endurance performance . Do weight training to maintain upper body muscle mass. And keep an eye on the bathroom scale to determine if you have estimated replacement needs correctly. With a regular exercise program, a modest weight gain should be in muscle mass and any weight loss from fat. FLUIDS Although water does not provide Caloric energy, adequate hydration is at least as important to good athletic performance as the food you eat. One of the biggest mistakes of many competitive athletes is failing to replace fluid losses associated with exercise. This is especially the case in cycling as rapid skin evaporation decreases the sense of perspiring and imparts a false sense of only minimal fluid loss when sweat production and loss through the lungs can easily exceed 2 quarts per hour. For a successful ride, it is essential that you start off adequately hydrated, begin
  • fluid replacement early, and drink regularly during the ride. In fact, a South African report on two groups of cyclists, one consciously rehydrating, the other no, exercising at 90% of their maximum demonstrated a measurable difference in physical performance as early as 15 minutes into the study. Total body fluid losses during exercise lead to a diminished plasma volume (the fluid actually circulating within the blood vessels) as well as a lowered muscle water content. As fluid loss progresses, there is a direct effect on physiologic function and athletic performance. An unreplaced water loss equla to 2% of base line body weight will impact heat regulation, at 3% there is a measurable effect on muscle cell contraction times, and when fluid loss reaches 4% of body weight there is a measurable 5% to 10% drop in performance. In addition, one study demonstrated that this performance effect can persist for 4 hours after rehydration takes place - emphasizing the need to anticipate and regularly replace fluid losses. Maintaining plasma volume is one of the hidden keys to optimal physical performance. So make it a point to weigh yourself both before and after the ride - most of your weight loss will be fluid, and 2 pounds is equal to 1 quart. A drop of a pound or two won't impair performance, but a greater drop indicates the need to reassess your on the bike program. And use the post ride period to begin replacement of any excess losses. If you do so, you will be well rewarded the next time out. But as a word of warning to those who practice the philosophy of "if a little is good, a lot is better", there are also risks with overcorrecting the water losses of exercise. There have been reports of hyponatremia (low blood sodium concentration) with seizures in marathon runners who have over replaced sweat losses (salt and water) with pure water. And this risk increases for longer events more than 5 hours). Weighing yourself regularly on long rides will help you tailor YOUR OWN PERSONAL replacement program. A weight gain of more that 1 or 2 pounds will indicate that you are overcorrecting your water losses and may be placing yourself at risk for this unusual metabolic condition. Altitude • Physiology • Altitude as a training aid • Competition at altitude • The recreational rider going to altitude PHYSIOLOGY As altitude increases above sea level, atmospheric (or barometric) pressure drops with a parallel decrease in the amount of oxygen available at the blood/air interface in the lung alveolus. Hypoxia (a low blood oxygen level) occurs and results in a decrease in the amount of oxygen delivered to the cell to do physical work. Although the heart rate (and thus the cardiac output) increases to deliver more blood (with less oxygen per ml) to the cell, complete compensation does not occur and the maximal aerobic ability (VO2 max.) is reduced by approximately 1% for every 100 meters (~ 300 feet) above 4500 feet in recreational athletes and can be detected in highly trained athletes at altitudes as low as 1500 feet above sea level. Other adaptive changes (acclimatization) include a higher ventilation (respiratory or breathing) rate and a higher blood lactate level for any level of submaximal exercise, both of which increase the sensation of dyspnea (shortness of breath) and fatigue. Some acclimatization responses occur immediately while others may take 4 to 6 weeks. In addition to decreases in maximal aerobic capacity, acute mountain sickness (AMS) affects, to varying degrees, all travelers to high altitudes (elevations greater than 5280 feet). In a small percentage of patients, AMS can lead to high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE). Symptoms of AMS range from a combination of headache, insomnia,
  • anorexia, nausea, and dizziness,to more serious manifestations, such as vomiting, dyspnea, muscle weakness, oliguria, peripheral edema, and retinal hemorrhage. Although the primary cause of these symptoms is related to the reduced oxygen content and humidity of the ambient air at high altitudes, the physiologic pathway relating hypoxemia to AMS and its sequelae remains unclear. Tips on self-diagnosis and symptom recognition are critical elements to be included in educating patients who are contemplating a trip to high altitudes. Short term physiologic responses to altitude The most immediate response to altitude is the hyperventilation that occurs in response to a decrease in arterial oxygen levels above 2000 meters. And this increased respiratory rate can remain elevated for up to a year at altitude. The hyperventilation response varies from individual to individual. Those with a strong hypoxic drive will perform exercise tasks better at altitude than those with a blunted ventilatory response. There is also an increase in the resting heart rate and cardiac output. The increase in blood flow compensates for the decreased blood oxygen concentration and leaves the total amount of oxygen delivered to the muscles unchanged. However, the fact that there is always less oxygen available means that even with the compensatory increase in heart rate and blood flow, the level of exercise at which oxygen demands are unmet and metabolism becomes anaerobic (VO2 max.) will always be less than at sea level. Long term adjustments to altitude Hyperventilation and the increased cardiac output provide an immediate response to limit the effects of altitude on physical performance. With time, a change in the body’s acid-base balance counters the effects of a chronically lower blood CO2 from hyperventilation (respiratory alkalosis), but does not affect physical performance to any significant degree. An increase in the blood hemoglobin (hematocrit) level increases the oxygen carrying capacity of the blood and is the most important performance adaptation to altitude. The result is that every milliliter of blood that moves through the muscle capillaries will be able to deliver an increased amount of oxygen compared to the same volume of blood with a sea level hematocrit. Finally, there are cellular changes that favor oxygen delivery to the muscle cell. The capillary concentration in skeletal muscle is increased in animals living at altitude compared to those at sea level, and muscle biopsies in acclimatized men have demonstrated an increase in myoglobin, mitochondria, and metabolic enzymes necessary for aerobic energy transfer. These changes should improve the efficiency of oxygen delivery and extraction at the muscle cell level. Together these adaptations are sufficient to restore exercise capacity to NEAR sea level values at altitudes up to 2500 meters (7500 feet). At higher elevations, acclimatization is not sufficient to restore VO2 max. to normal. But not all the changes that occur with acclimatization are favorable to improve athletic performance in the face of a decrease in available oxygen. One notable negative is the loss of lean body mass and body fat that occurs with long term exposure to high altitudes. The result is a decreased maximum potential for athletic performance because of decreased muscle mass. The time course of acclimitization As mentioned, the ventilatory response begins immediately upon climbing to altitude from sea level and continue over several days at altitude. Hyperventilation changes the blood acid base balance (with a respiratory alkalosis) which in turn stimulates the kidneys to excrete bicarbonate to compensate. This renal compensatory response takes about a week. The sympathetic nervous system is activated almost immediately with an increase in both sympathetic nerve activity and an increase in blood epinephrine levels - resulting in an increase in heart rate and cardiac output to maintain tissue oxygen delivery at near sea level values. By two to three weeks, blood flow returns toward sea level values as oxygenation improves as a result of the other compensatory mechanisms. The hematocrit level increases within 24 to 48 hours because of a reduction in plasma volume, not an increase in red cell mass. Erythropoietin levels increase within hours, peak at about 48 hours, and remain elevated for 1 to 2 weeks. The red cell mass increases slowly and may take several years to reach levels equal to natives living permanently at these altitudes. The vast majority of these metabolic changes are complete by 3 to 4 weeks at altitude, but the structural changes (capillary density, mitochondrial number) take weeks to months to complete.
  • ALTITUDE AS A TRAINING AID Do the adaptive mechanisms described above compensate for the decrease in oxygen available at altitude. The answer is NO. Even with acclimatization, the proportion of the energy supplied by anaerobic metabolism for any level of activity (rather than by oxygen supported or aerobic pathways) increases and performance suffers. Does hypoxic exercise at altitude provide a training benefit? This is controversial, but controlled studies in trained athletes have not been confirmed any benefit for hypoxic exercise WITHOUT CONCOMITANT ACCLIMATIZATION. And the direct effects of interval training to stress and improve an athlete's maximum aerobic capacity (VO2 max.) definitely deteriorate with training at elevation as a result of the inability to maintain a VO2 max. comparable to sea level when training in a hypoxic environment. During interval work outs, speed, oxygen uptake, heart rate, and lactate levels are all lower than those from lower altitudes suggesting that interval training is best performed as near sea level as possible. Does exercise training at altitude improve sea level performance? Many scientists, athletes, and coaches have been intrigued by the similarities of altitude acclimatization and training effects. Does living and training at altitude (with the associated changes in red cell mass and cellular changes in mitochondria, etc.) lead to an increase in the maximal aerobic exercise capacity (VO2 max.) upon return to sea level? The answer is "it depends". It is the net balance between the benefits of the acclimatization effects and the negatives of a reduction in training intensity and deconditioning from hypoxia that are the ultimate determinate of the outcome of altitude training in endurance athletes. Controlled studies have NOT shown any advantage of TRAINING at altitude compared to a similar TRAINING program (the same absolute VO2 max. being achieved at both altitudes) at sea level. Are there any strategies that can use altitude to benefit a training program? The answer to this question is YES. But it requires balancing the acclimatization benefits of an increased red cell mass from living at altitude (one must be at altitude for more than 12 hours a day to maintain an increase erythropoietin level) while maintaining a VO2 max. in training equivalent to that possible at sea level. How high must one live to maximize acclimatization? An altitude of 2500 to 2800 meters maintains a balance between stimulating erythropoietin and minimizing the effects of acute mountain sickness that occur with increasing frequency at higher elevations. How long should one live at altitude to maximize benefits?? At least 3 to 4 weeks. How long will the acclimatization effects last? Based on actual performance studies, 2 to 3 weeks at most before they begin to reverse. And the optimal training altitude? Although this should be individualized as some athletes do quite well maintaining a high VO2 max training at high altitudes, the general rule is to train as close to sea level as possible, preferably below 1500 meters. So it is the balance between acclimatization and deconditioning that gives the personalized answer for each individual athlete. A few can maintain a high training VO2 max. even while training at altitude enabling them to live at altitude and train there as well. But the vast majority need to descend to train several times a week or face a competitive disadvantage from deconditioning. THE BOTTOM LINE Altitude can be used to improve sea level performance. But it needs to be used correctly. Its advantages are related to acclimatization effects i.e. an increase in the red cell mass from 2 to 3 weeks at altitude. The same benefits could be gained from using injections of erythropoietin if it were not a banned substances (and one with some health risks as well from overzealous use and exceedingly high hematocrits). Blood doping has the same effects. And it has been suggested that living (or sleeping for more than 12 hours a day) in a high altitude chamber or using nitrogen houses as the Scandinavians have proposed (and utilized) may have the same beneficial effect. But to maximize the benefits of the altitude effect, training (i.e. absolute VO2 max.) needs to be maintained at sea level values. Some athletes can train at altitude and pull this off, but the majority need will need to do interval training at least twice a week at sea level oxygen levels to avoid the offsetting disadvantages of deconditioning.
  • Altitude effects on performance are a complex issue, but are best summarized in the simple phrase: LIVE HIGH, TRAIN LOW. Is there any way to avoid the hassles of traveling to a lower elevation to train - gaining the advantages of the hypoxia of altitude to acclimatize during the majority of your day (and while sleeping at night) while maintaining a high level training program? The scandinavians reportedly live in a "nitrogen" house which lowers the ambient oxygen level during sleep and the portion of the day they spend there (and training is as easy as stepping out the door), while others have suggested sleeping in an altitude chamber. Another option that seemed to make sense to the author was living at altitude and using supplemental oxygen while training to raise the amount of oxygen available to the alveoli in the lung. This question was addressed to Dr. Ben Levine who has done the majority of the work leading up to the high-low theory of training. His response: Dear Dr. Rafoth, Thanks for your note. You are absolutely right that an alternative to travel for high-low is training high with supplemental O2. In fact, this is exactly the tack taken by US Cycling and US Swimming at Colorado Springs. It is a bit cumbersome, but as long as the workouts can be reproduced, will work fine. Ben Levine COMPETITION AT ALTITUDE What should an athlete do to prepare for competiton at altitude ? For endurance events, adequate time should be allowed to complete acclimatization - 2 to 3 weeks. The longer one waits, the more deconditioning of the VO2 max. that occurs. Returning to sea level to do interval training several times a week would be a definite advantage but is usually impractical. For sprints (400 meters or less) most of the energy for muscular activity is oxygen independent and acclimatization will not be of any benefit. And the lower air resistance at altitude will increase race times - that is why the 400 meter events were very fast in Mexico City in 1968 but the longer 1500 meter results were slower than at sea level. THE RECREATIONAL RIDER GOING TO ALTITUDE The major concern for this individual is Acute Mountain Sickness. The rider needs to accept that there will be an inevitable decrease in VO2max (see above) and no special training program that will blunt this effect of altitude on performance. Preventive strategies include allowing 2 days of acclimatization before engaging in strenuous exercise at high altitudes, avoiding alcohol, and increasing fluid intake. A high-carbohydrate, low- fat, low-salt diet can also aid in preventing the onset of AMS. Although slow ascent is the preferred approach to avoiding AMS, there are times when this is impractical (plane connections to the start of a ride, emergency situations). In those cases, there are medications available that can decrease the chances of developing AMS. Acetazolamide (250 mg twice daily or 500 mg slow release once daily), taken before and during, ascent is recommended by many physicians although dexamethasone (4 mg, 4 times daily) has been shown to be of equal effectiveness. And in one study, those on acetazolamide actually had more symptoms of nausea at low altitudes (where AMS was not an issue) than a placebo group.Nausea was not a problem for those using dexamethasone, and indeed a mild euphoria was often reported. The usual recommendation for both medications is to start 24 hours before going to altitude and then continuing for 48 hours after starting the ascent. By that time, normal adaptive mechanisms should have had time to take over. As dexamethasone is faster acting than acetazolamide, some authorities suggest taking the dexamethasone along, but starting it only when and if symptoms develop. As severe AMS is uncommon, this eliminates the inconvenience (and possible drug allergy or intolerance) of a medication that might not be needed.
  • Aging and Physical Performance There are two approaches to the relationship of aging and physical performance. Most athletes are concerned with the effects of aging on their own abilities to perform and compete. But for the nonathlete, the question is often whether physical activity can counteract or blunt the aging process itself. From that perspective, the answer is yes it can, and it has been estimated that 30% of all deaths from heart disease, diabetes, and colon cancer are related to inadequate physical activity. One study indicated that no more than 20% (and more likely less than 10%) of adults in the US obtain sufficient regular physical activity to have a measurable impact on their health and fitness levels. Is it safe to exercise as you age? If one uses common sense, the long term health benefits far outweigh any potential cardiac complications. One should avoid the extremes such as exercising above and beyond the level you have trained for, environmental extremes of temperature and humidity, and exercising when not feeling well. But even orthopedic injuries, which might be expected to be more common in the older athlete, do not appear to be increased with activities of moderate intensity and duration. EFFECTS OF AGING ON PHYSIOLOGIC FUNCTION Physiologic and performance measures peak in the late teens and 20s, and then decline with age. However they do not all decline at the same rate, and the rates of deterioration vary according to lifestyle (the old use it or lose it philosophy). Bones (osteoporosis) Aging is accompanied by a loss of bone mineral content. Aside from using calcium supplements to minimize bone loss, there is no support for a role of diet in preventing this natural process. On the other hand, there is excellent evidence on the benefits of regular physical activity to maintain muscle and bone structure. Muscular strength Strength levels for men and women are at their peak between the ages of 20 and 30. Without a regular exercise program, there is then a decrease in muscle mass from muscle fiber atrophy hat becomes particularly apparent at age 60 . However, this is a combination of aging effects on the muscle/ nerve unit AND a decrease in daily muscle loading. One study of men between the ages of 60 and 72 years, training with standard muscle resistance exercises, demonstrated an improvement rate equal to young adults. Another group of 70 year olds who had regularly trained from age 50, had a muscle cross sectional area equivalent to a group of 28 year old students. Neural function Reflexes do slow with age, but as with muscular strength, activity minimizes the effects. Active men in their 70s had reaction times equivalent to inactive men in their 20s. Pulmonary function Once again, there is a decrease in lung function with age that can be blunted with regular activity. These studies indicate that a lifetime of regular physical activity may retard the decline in pulmonary function associated with aging. Cardiovascular function • aerobic capacity declines twice as fast in sedentary individuals and may even plateau with a regular training program. • the maximum heart rate does decline with age • cardiac output also falls with age - partially related to heart rate, but also from a decrease in stroke volume But a group of active 45 year olds on a regular endurance exercise program, followed for 10 years were found to have maintained a stable blood pressure, body mass, and VO2 max. during the ten year period. HEALTH BENEFITS
  • Ben Franklin once said that the only constants in this world were death and taxes. The negative effects of aging on physical performance should probably be added to this list. However numerous studies have demonstrated the dramatic effect a regular exercise program (riding three to four times a week) can have on blunting the inevitable changes. • 41% less likele to die from heart disease • 58% less likely to develop diabetes And the training effect is so effective that the aging process may be held at bay for up to a decade or more. In fact, for any age group regular riders are 150% less like to die from all causes. NUTRITION AND THE OLDER ATHLETE Although there is a trend towards an increased percentage of body fat after age 30, there is good evidence that a resistance training program will minimize the loss of muscle mass, and good eating habits and self awareness will prevent weight gain. There are no special dietary needs for older athletes. However there is less "physiologic forgiveness" or latitude to skip the pre-event carbohydrate meal, and an increased sensitivity to major fluid shifts from sweating and inadequate replacement, but aside from this decreased tolerance for physiologic abuse, the principles of nutrition are exactly the same for all age groups. This includes vitamin, mineral, and electrolyte replacement as well as the use of ergogenic aids such as diet supplements and unusual food products. Breathing for Highly Trained Athletes Air from your surroundings is brought into the lungs during pulmonary ventilation. After being adequately warmed and moistened in the upper ariways (nasal passages, trachea, and bronchii) it ultimately moves through the bronchioles and alveolar ducts to the alveoli where gas exchange occurs - oxygen diffusing across the alveolar lining nto the blood and carbon dioxide out into the alveoli. The diaphragm muscle makes an airtight separation between the abdominal and thoracic cavities. During inspiration it flattens, increasing the space (and negative pressure relative to the atmosphere) in the thoracic cavity while decreasing the volume of the abdominal cavity (unless the abdominal muscle relax to offset this effect). During exercise, the intercostal muscles and other thoracic wall muscles (the accessory muscles of respiration) contract to aid the expansion (and increase the negative pressure) in the thoracic cavity. During expiration the opposite occurs in the diaphragm and accessory respiratory muscles, the thoracic cavity decreases in size, and air flows out of the lungs. With exercise conditioning, you will increase the amount of air that is regularly brought into the lungs each minute, and thus the amount of oxygen that can be extracted and delivered by the heart and vascular system to the exercising muscles. Along with the changes in the capillaries at the muscle cell level, this training effect allows you to ride longer and stronger without becoming anaerobic in your metabolism. RESPIRATORY MUSCLE TRAINING Would specific respiratory muscle training help the performance of trained, elite athletes?? Let’s see what the literature has to say. So what can we conclude from these studies? • Inspiratory muscle fatigue does occur with prolonged high intensity exercise and can be delayed by specific inspiratory muscle training (IMT). • There is controversy as to whether a normal training regimen adequately trains respiratory muscles to meet the needs of the activity for which the athlete is training. This
  • includes meeting the oxygen and carbon dioxide exchange requirements of the endranece athlete’s cardiovascular system, by providing adequate ambient air to the alveoli, as well as by decreasing lactic acid production from the repiratory muscles themselves for the appropriate level of respiratory activity. • The muscular capacity for pulmonary ventilation MAY limit physical performance in the highly trained athletes. • Preliminary research has demonstrated that inspiratory muscle training improves performance in highly trained rowers by some 2% more than a placebo group. Further studies should help to clarify whether specific respiratory training may improve the performance of the elite endurance athlete. WHAT CAN YOU DO? First, practice taking a deep breath. Typically during a normal breath we use only 10 to 15% of our lungs. And during exercise, we increase the rate, not the depth of our breathing. Although deep breathing is more work and uses a bit more energy, the pay off can be that 1 - 2% edge in a competitive situation. Here's 4 ways to make it happen: • Exhale more completely. If you exhale more completely, it is easier to take a deep breath. The usual rhythm is exhale to a count of 3 followed by inhaling to a count of 2. • Belly breathe. As you concentrate on deep breathing, you will push your diaphragm down and thus the abdominal contents out. If you are doing it correctly, your abs will expand more than your chest. • Widen your hand postion. A 2 cm wider hand postion will open up your chest and decrease the difficulty of drawing in a deep breath. • Synchronize your breathing. Try to synchronize your respiratory rhythm to that of your pedal cadence. Remember the 3:2 ratio of exhale to inhale. However a variation of pursed lip breathing focuses on the rhythm of respiration. Ian Jackson has developed a program, BreathPlay, which teaches skills in controlling ones expiration (and as a result inspiration) of air. He notes that ", athletes discover that pushing air out is a much more efficient way of meeting oxygen demands than sucking air in. They also discover how the active outbreath can bring powerful precision to any movement. The BreathPlay paradigm advocates using the active outbreath to setup a spinal stretch which is then released with the passive inbreath." It taps into the power of both "focus" and "hypnotherapy" to achieve performance gains. PURSED LIP BREATHING Does pursed lip breathing provide an advantage by creating a back pressure to keep the collapsing airways open? According to Frand Day MD (fday@powercranks.com) "Back pressure to keep the airways open on exhalation is really only necessary in seriously diseased lungs (such as seen in intensive care units). This is not normally necessary in athletes whose lungs are functioning normally (asthma attacks aside, where purse lips breathing is of littlebenefit). Moving air in and out of the lungs is a simple matter of physics. The volume of air moved depends upon the anatomy of the airways and the delta P (pressure) between the alveoli and the outside. On inhalation the expanding chest tends to open the airways, somewhat reducing the delta p necessary to move the required amount of air but exhalation tends to close the airways, requiring a higher delta p, but pursing the lips does nothing to change the required delta p if the lungs have normal amounts of elastic supportive tissue that normally keeps the airways open. As stated before, this increased back pressure is most useful is seriously diseased lungs and I am not aware of any data to show it useful in normal athletes."
  • DECREASED LUNG CAPACITY WITH ENDURANCE EVENTS A recent report indicated that lung function tests of endurance athletes during "ultra" marathon sports events has indicated a progressive decrease in lung volume and expiration rates of between 5% and 20% ,commonly indicative of asthma related disease. These results were noted in various sports events including canoeing, running, skiing and cycling. It was postulated that these athletes exhibited symptoms of exercise induced asthma. Does exercise cause spasm in the lung airways in all athletes, not just asthmatics?? There is some evidence that endurance athletes may become sensitized to allergens (proteins that cam bring on an asthma attack) and other environmental toxins the longer they are involved in their sport. This may be why such a high percentage of elite athletes are on medications for "exercise induced asthma". But with exercise induced asthma (which is the same as any other asthma), vital capacity diminishes with even a few minutes of beginning easy exercise. In ultra endurance athletes, there is most likely another factor (something that would occur in everyone such as fatique or dehydration) causing lower lung volumes and muscular efficiency that slowly evolves as exercise continues. This still to be identified factor,not asthma, reduces vital capacity if the event was long enough and becomes the most logical reason why such a high percentage would show reduced lung capacity.
  • WEIGHT TRAINING Cycling regularly is great for lower body strength, but leaves a lot to be desired for the upper body muscle groups. And this can be a major liability - both for roadies who need that extra edge in road competitions and for mountain bikers who need this upper body strength to lift, jump, or just plain muscle heavier bikes over rough terrain and obstacles. A reasonable approach is to focus on building strength (not bulk) in the winter and maintaining it during the peak riding season. WHY "MUSCLE UP"? 1.The upper body, including abdominal muscles, is an integral part of the pedal stroke. A strong torso provides the rigidity to deliver maximum power from the quads to the pedal. On a level stretch, a strong rider will barely move their upper body while those who are tiring will rock their pelvis on the saddle. And watch a group of road riders in a sprint or a technical single track rider pulling and rocking their shoulders and handlebars. This motion actually levers the bike, adding to the power of their legs on the pedals. 2. Muscle strength in the quads and legs can mean the difference between walking and riding up a short (10 to 15 pedal stroke) hill. 3. A strong upper body gives additional protection for those falls that are part of the sport. 4. Muscle strength and endurance help prevent the fatigue of the constant jarring and correction that are part of a long descent - and in turn this freshness helps to maintain sharp reflexes and technical RECOMMENDED EXERCISE PLANS There are two approaches to resistance or weight training. The first is the "keep it simple" approach one can put together at home and on the bike, and the other is the more "traditional" using free weights. Both should be done 3 times a week (2 times at a minimum) to maximize benefits. Most coaches recommend a program of strength building (higher weights, fewer reps) in the winter and then a shift to lower weights (perhaps 50% max) and more reps (3 sets, 50% max.weight, 25 reps OR 2 sets, 25% max.weight, 50 reps) as the cycling season approaches to mimic the ways you use your muscles on the bike and to decrease the possibility of injuries. The following idea builds on the concept of transitioning from a pure muscle building program to one that mimics how you use those muscles on the bike. Do a 3 - 5 minute "muscle reeducation" on the spin cycle after lifting. This stresses the muscles and then uses a sport specific task to coordinate the firing patterns of the muscle cells. The same concept is being applied when a coach uses a medicine ball to encourage new firing patterns. KEEP IT SIMPLE (i.e. you don't have free weights available) • Shift down 2 cogs on your bike during a long endurance ride, and concentrate on pushing and pulling through the pedal stroke at 60 - 80 RPM for 30 seconds. Repeat 6 times. A second set can be done after a 5 minute rest. An alternative to squats. • Dips on the back of two sturdy chairs. • Crunchers for the abs and low back. • Push-ups. TRADITIONAL • Upright rowing - strengthen deltoid and shoulder for extra protection in a fall. • Pull up - reproduces the pulling up you use on a steep uphill. • Squats - upper thigh parallel to the ground-for that quad strength for steep climbs. • Bent over rowing - to stabilize the handlebars when pedaling hard. • Step ups on a platform with weight on shoulders - one leg at a time-for quad strength.
  • • Push ups - mimics the push on the handlebars used during technical rides through dips and on uneven terrain. COMMON WEIGHT TRAINING MYTHS 1) You have to lift extrememly heavy weights to increase muscle size. Not so. Competitive body builders, whose success depends on muscle size, work with only moderately heavy loads using multiple sets of up to 12 lifts per set. The chance of injury with extremely heavy weights outweighs their benefits. 2) You can sculpt your body by using multiple reps with light weights. Up to a point this is true. But anything more than 15 reps per set offers little benefit. 3) The up side of a lift is more important than the return side. The up side, when you actually lift a weight, is called the concentric phase. The return, when you allow the weight to return to its starting point,is the eccentric phase. While both are important, there is evidence that the eccentric phase may actually have more impact on developing muscle strength. It is recommended that you lift with a two count and return to the starting postion with a four count. 4) Abdominal crunches will build up your back muscles. While crunches will strenghten abdominal muscles and protect your back, back extensions are needed to strenghten the spinal erector muscles. 5) Weight lifting increases aerobic capacity. Although a rider that is in better shape might ride more efficiently and thus for longer periods at any speed, there is no evidence that weight training will increase your VO2max or AT/LT. That's not to say that you can't add aerobic work to a weight session however. Aside from the warm-up it can be helpful to incorporate two or three "spin-bike", ergometer or stair-master aerobic "breaks" between standard exercises. These aerobic sessions should be limited to 3 to 5 minutes each so as not to detract from the core exercises (squats, toe raises, leg extensions, ab work, etc). BUT WILL WEIGHTS INCREASE MY PERFORMANCE? Even though most coaches include weight training in their programs, there is controversy on this point - particularly as to the usefulness of weights during the cycling season. The following article suggests that any benefits are minimal, at least for endurance performance. BISHOP, D., D. G. JENKINS, L. T. MACKINNON, M. MCENIERY, and M. F. CAREY. The effects of strength training on endurance performance and muscle characteristics. Med. Sci. Sports Exerc., Vol. 31, No. 6, pp. 886-891, 1999 Purpose: The purpose of this study was to determine the effects of resistance training on endurance performance and selected muscle characteristics of female cyclists. Methods: Twenty-one endurance-trained, female cyclists, aged 18-42 yr, were randomly assigned to either a resistance training (RT; N = 14) or a control group (CON; N = 7). Resistance training (2 ‫·׳‬wk-1) consisted of five sets to failure (2-8 RM) of parallel squats for 12 wk. Before and immediately after the resistance-training period, all subjects completed an incremental cycle test to allow determination of both their lactate threshold (LT) and peak oxygen consumption V(dot)O2). In addition, endurance performance was assessed by average power output during a 1-h cycle test (OHT), and leg strength was measured by recording the subject's one repetition maximum (1 RM) concentric squat. Before and after the 12-wk training program, resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, and the activities of 2-oxoglutarate dehydrogenase and phosphofructokinase. Results: After the resistance training program, there was a significant increase in 1 RM concentric squat strength for RT (35.9%) but not for CON (3.7%) (P < 0.05). However, there were NO significant changes in OHT performance, LT, V(dot)O2, muscle fiber characteristics, or enzyme activities in either group (P > 0.05). Conclusion: The present data suggest that increased leg strength does not improve cycle ENDURANCE performance in endurance-trained, female cyclists. FURTHER INFORMATION For those of you interested in further leads in pursuing weight conditioning, I'd suggest the web site of The National Strength and Conditioning Association.
  • STATIONARY CYCLING Indoor riding on a stationary bicycle or rollers, although monotonous and close to the most boring activity imaginable to a roadie or mud loving mountain biker, has advantages above and beyond avoiding darkness and bad weather. Used correctly, indoor riding can be a key component of a broad based cycling training program, particulary during the winter months. It is a great way to maintain cardiovascular fitness, but should be combined with weight or other resistance training if you plan on increasing muscle strength. Some cyclists have noted that using a stationary trainer or rollers seems much more difficult, target heart rate being similar, than riding outdoors. Why is that? There is an old saying that goes: an hour on the trainer is worth two on the road. One possibility is that when you're on the road, you get "rests" when you're freewheeling down a hill,in a draft, or halfwheeling in a group. On the trainer, you're at a reasonably constant rpm, which is not your normal style. Another is that the absence of distractions such as traffic lights, changing scenery, traffic and road conditions result in more of a focus on your effort - and pain hurts more if you think about it! Another option is to use step intervals as described in the section on off season training. And if you have the time to make it to the gym, spin classes may offer the best of all worlds - aerobic training, using all your cycling specific muscles, without the boredom of that stationary trainer in the basement. PROS AND CONS Reasons to consider stationary training: • SAVING TIME - avoid the time necessary to get to a road suitable for your workout, and with a planned program get yourmaximum training benefit in 60 minutes. • MORE INTENSE - minimizes the distractions of road biking, allowing you the concentration and focus to maximize and maintain your heart rate for the session without worrying about cars, potholes, or other road hazards. In fact, using a stationary bike is an optimum tool to determine your maximum heart rate. After you have warmed up, increase your effort and cadence every minute for 5 to 10 minutes. When you feel you can't pedal any faster, SPRINT. This is your maximum heart rate. • MORE PRECISE - just an extension of the above. The elimination of distractions allow you to focus on your planned workout. • IMPROVE YOUR PEDAL STROKE - spinning with one leg will accentuate flaws in your personal technique and allow you to focus on a smooth and complete pedal cycle. • PROMOTES RECOVERY - at the end of a difficult day of riding, consider jumping on the trainer and doing 20 minutes of gentle spinning at 55% max heart rate. Personal testimonials sugggest this is superior to massage to speed lactic acid clearance from the muscle and cut down on post training stiffness and soreness. • AVOIDING DARKNESS AND BAD WEATHER The biggest drawback of stationary cycling is the monotony and boredom of sitting and sweating in one place for an hour. What are some techniques to make it a bit more palatable? Consider these: • GROUP RIDES - Have a buddy bring his trainer to your place or, if there's one available, have your group meet at a local gym equipped with multiple machines. • STRUCTURED WORKOUTS - Have a planned program, and concentrate on sticking to it. A heart rate monitor gives you immediate feedback on your efforts and is a great tool to give you something other than the boredom to concentrate on. • KEEP YOUR MIND OCCUPIED - heart rate monitor, viceo opponent on a Computrainer (if you have the $$ to afford one), using your favorite CD as a key for intervals, reading (if you're just lazing along), and watching television.
  • • USE A FAN - The movement of the air is distracting and keeps you cool and more comfortable at the same time. • DRINK - It's easy to forget, and with the increased sweating on a stationary bike in a warm room, it's easy to get dehydrated. And the general sense of unease that comes along with dehydration increases the fatigue and tedium of the session. • GET GOOD EQUIPMENT - Stability of the trainer is key if you plan on sprinting out of the saddle for a little variety during the session.(The new generation fluid trainers are not only quieter, but will give you progressive resistance as well to mimic your on the road experience more closely. The harder you pedal, the more the resistance, simulating true wind resistance.) ROLLERS Rollers are an alternative to a fixed, stationary bike. But they have an additional challenge - balance!! Here are a few tips if you decide that rollers (which allow you to train on your own bicycle) are for you. First thing is to set the rollers correctly. Put the bike on the rollers and set the height of the front wheel the same as the rear one with adjusters or blocks of wood. If this is not done you will be riding up hill and the ballance will be wrong causing untold damage to the perineum etc. The next thing to do is to set the length the same as your bike. A plumb bob from the front axle of your bike should pass as close as possible to the centre of the front roller. A centimetre either way is OK. After this check the level again. It helps to place the rollers in a doorway so you can hold onto the door frame to get started (an alternative is to have a buddy standing by to give you a hand). Place the bike in the middle of the rollers and start by holding the left of center of the handlebars. Put your right foot in the clips. Keep your head up to keep a focus straight ahead. Practice riding smoothly without bouncing. Try 15 second spurts until you are steady on the bike. Cadences above 140rpm or so can easily be maintained, reaching over 180 rpm in a sprint. TRAINING PLAN Remember that having a plan helps fight the boredom, and is a key to making this a positive part of your training program. There are many plans available, but most have common themes. But before you turn up that stereo, a study of untrained men and women demonstrated that they rode an average of 27% longer when they cycled in silence rather than listening to music. And another study of trained cyclists found that a poorer workout when they cranked up the decibels.What's not clear is whether the hard core riders preferred silence and suffering and made the difference or whether it was the distraction of the music that kept everyone from maxing out. Since you will monitor these sessions using your heart rate (a heart rate monitor is very helpful if you have one) review the section of this page on the use of a heart rate monitor. For the week, you will probably want a day or two at 65-72% VO2 max. as recovery days, a day or two at 84-90% VO2 max. to build your aerobic base, and one or two interval sessions: • INTERVAL SESSION LENGTH - 45 - 60 minutes • INTERVAL SESSION FREQUENCY - once or twice a week • EASY WARM UP PERIOD - 12 to 15 minutes • INTERVALS - 4 or 5 sets of 1 or 2 minutes of sustained effort (comfortable resistance, 100+ RPM) with a 2 or 3 minute recovery period OR using a heart rate monitor to set you aerobic target. • COOL DOWN - 10 to 15 minutes SPIN CLASSES You are pedaling in the Tour de France. The crowd is cheering as you push yourself up a steep hill. Your thighs are burning. Your breath is coming in gasps. Will you make it? "You've reached the top!" a voice commands. "Back off that tension!" You reach down and loosen the tension on your stationary bike, and come back to reality.
  • Spinning is one of the newest and hottest exercise classes. Instead of merely tooling along on your stationary bicycle as you thumb through a magazine or watch the latest headline news, you burn up the imaginary road with a roomful of other exercisers, with the lights turned off and the music loud. Like other exercise classes, spinning is led by an instructor, who barks out commands throughout the 40- to 60-minute session. And like most other exercise classes, spinning starts out with a warm-up and stretching. Then comes the ride, alternating intervals of "hill climbing" (increased tension on the bike) and "sprinting" (less tension). The classes conclude with a cool-down and stretching. What enthusiasts say they like about spinning is that the amount of tension on the bike is determined by each rider. You can make it as tough or easy a ride as you want to -- only you know for sure. And to help the riders concentrate and set the mood, the lights are usually switched off. So when it's raining or you get home late and the sun is setting, there are no more excuses. It's either time to head for the basement or the garage where you can catch the evening news, or take an hour at the gym to join in the cameraderie of a spin class. Whichever choice you make, you will have the satisfaction of knowing that you are going to get that edge on the rest of your cycling buds. Intervals Interval training involves repeated periods of intense physical activity (the exercise interval) alternating with periods of recovery (the relaxation interval). The relaxation interval avoids significant lactic acid build up and, as a result, allows longer training time at peak performance levels. One study (in runners) pointed out that continuous, maximal performance could be sustained for only 0.8 miles (to exhaustion) while a similar level of exertion totaled over 4 miles when the training session consisted of intervals. But the down side is that training program drop out rates double when intervals are used. Intervals are most effective when used twice a week during the peak training season, and when interval sessions are separated by at least 48 hours to allow adequate recovery. (For example, if your long ride is on the weekend, Tuesday and Thursday make good interval days.) And don't start an interval program until you have a solid aerobic base of 500 miles of steady pedaling or you increase the risk of injury from pushing too hard,too quickly. The intensity of training is the secret to the success of intervals. A study of cyclists training with intervals for 40 minutes, 6 times a week for 10 weeks divided the group into thirds. • One third maintained exercise intensity, but decreased the duration of the sessions by 66%. • The second third maintained exercise intensity, but decreased the frequency to 2 times a week. • And the third maintained the frequency and duration, but decreased the intensity of the sessions. The VO2max of the first two groups held constant, and the third decreased. The conclusion: intensity of training is more important than duration and frequency in maximizing the intensity of performance when using intervals. However, there were ramifications of decreasing exercise volumes (frequency & duration) including a parallel decrease in endurance capacity at 75% VO2max. This reinforces the concept that it is the combination of intensity of exercise (best achieved with intervals) and total time (or volume) of exercise (the long slow distance idea) that determines the athlete's overall performance. REVIEW OF THE PHYSIOLOGY
  • The conventional wisdom is cycling pain results when you go anaerobic and lactic acid builds up in your muscle tissue. But studies in subjects who, because of a genetic defect, do not produce lactic acid demonstrated a similar pain response to anaerobic exercise as normal riders. Rather than lactic acid, culprits may be nervous system input from muscle fiber nerves, a chemical mediator other than lactic acid, or some other cellular change in the muscle fibers. When you train to your maximum (pushing the muscle pain limit), changes occur which will allow you to push even farther into your anaerobic zone the next time out. • muscle metabolism changes to extract more oxygen from every millilter of blood flowing through the muscle capillaries • more capillaries develop in the muscles • your heart adapts to pump more blood for any specific time interval • you learn to mentally deal with the pain and exercise through it Fartlek training is a modification of interval training, using alternate periods of slow and fast riding to improve aerobic capacity. It is not as precise as interval training and is based on the perception of how the rider feels at the time. Its advantage is to allow more flexibility, freedom, and variety in workouts. High Intensity Training (HIT) is an interval program for athletes already at a high level of training. In many ways it is the "icing on the cake" which gives the elite athlete that final edge for their event. INTERVAL DURATION Short exercise intervals are 15 to 90 seconds while longer intervals may be 3 to 5 minutes. Once you decide on the duration for your intervals, pace your effort to exercise at your maximum throughout that period (if you can't make it through the entire interval, you need to cut back your effort a bit). The goal should be 10 to 20 minutes of hard pedalling (not counting warm up, recovery, or cool down). If you are just beginning an interval program, consider starting with 5 minutes of peak effort. The relaxation or recovery interval is generally active rest (easy spinning) and can range from a ratio of 1:3 (hard pedaling:spinning) for sprint intervals of 20 seconds or less (ie 10 seconds of sprinting to 30 seconds of spinning) to 1:1 or 1:1.5 for 60 to 90 second intervals. To get the maximum benefit from interval training, it is important to allow adequate recovery time between intervals. But subsequent intervals should start before your heart rate and oxygen uptake have returned entirely to normal. If you are using a heart rate monitor, wait for your heart rate to drop to 60 or 65% of your maximum heart rate. If you are using perceived extertion (i.e. how you feel) to decide, wait until your breathing has returned to it's normal depth and rate. • anaerobic (sprint) interval 1:2 or 1:3 (rest:recovery ie rest interval 2 to 3 x the time of the effort) • aerobic 1:1 (ie equal rest interval) Consider using one day a week for short, sprint intervals (ie five 60 second and five 90 second intervals) and a second for your longer intervals (two - 3 minute and two - 5 minute intervals). Allow adequate time for recovery between intervals (up to 3 to 5 minutes) and don't forget a 20 to 30 minute warm up and a 15 minute cool down at the beginning and end of your session. It has been shown that as few as a half dozen 5 minute intervals during a 300 km training week will improve both time trial and peak performance. HEART RATE INTERVALS If you have a heart rate monitor, you can key intervals to your maximum heart rate. Ride your intervals at 80 to 90% of your maximum heart rate and spin easily until your heart rate drops to 60 to 65% of maximum. Mountain Biking
  • Although riding techniques may differ, the principles of nutrition and exercise physiology as well as specific mileage and cardiovascular training programs are quite similar for mountain biking and road biking. The biggest difference between mountain biking and road biking is that the off road terrain is quite irregular with considerable variation in rider energy output from minute to minute as one covers repeated up and downhill pitches rather than the more predictable steady grades and level stretches found on most road rides. For that reason, the mountain biker will tend to emphasize interval training (the comments on training mileage are relevant, but with at least one and possibly two interval days per week). Substituting a hill for your "interval" instead of picking up the pace on the flats offers a more realistic simulation of what will happen off road and will help train your legs as well as your cardiovascular system. Using a heart rate monitor to avoid overtraining from underestimating true levels of exertion is also helpful. And if you are trying to determine your principles of nutrition are the same as for road biking, and specific dietary recommendations are outlined in the BASIC TRAINING RIDE, INTERVALS, and COMPETITIVE EVENT sections of the "Nutrition plans for 6 common types of rides". The remaining sections (myths, training tips and aids, etc.) are equally relevant for mountain and road biking. The only section unique to mountain biking is on infections due to the off trail and forested terrain. HEART RATE MONITORS CONTENTS • Basic cardiovascular physiology • Pros and cons of using a heart rate monitor • Definitions • Calculating your maximum heart rate • Heart rate training zones • Training tips using a heart rate monitor • Resting heart rate • An opposing opinion The Heart Rate Monitor (HRM) is touted by many cyclists and trainers as the most significant training advance in the last ten years. Although many coaches refuse to work with an athlete without the physiologic training information it provides, HRMs have their detractors. And that small backlash is slowly growing. An alternative to a HRM, not quite as technical and rigid, uses perceived effort as a measure of your level of exertion. BASIC CARDIOVASCULAR PHYSIOLOGY First, let's review the basic physiology of the circulatory system asking ourselves the question "What does the heart rate really indicate?" The components of the cardiovascular system are: • the heart (the pump) • the arteries (a distribution system) • the capillaries (the exchange system where gases, nutrients, and other chemical compounds move to and from surrounding tissue • the veins (which are the return circuit) With every heart beat (contraction of the heart pump), a certain amount of blood (stroke volume) is pushed through the system. The contraction frequency of the heart is the heart rate (HR). The
  • amount of blood moved to the cells of the body every minute is the product of the heart rate and stroke volume (HR x strove volume). With physical activity (exercise) more oxygen is required by the muscle cells, and the circulatory system responds by increasing the heart rate (and the cardiac output). With aerobic training, the actual amount of blood pumped per heart beat (stroke volume) increases and the efficiency of the exchange process at the capillary level improves. The result is a lower heart rate for any level of physical activity in the trained versus the untrained individual. Thus aerobic training benefits include: • a lower resting heart rate • a lower heart rate for a specific level of exertion • an increased exercise capacity at an individual's maximum heart rate. The training effect results when the heart muscle is "stressed" by an increase in cardiac output (just as muscles in the arms and legs respond to the stress of lifting free weights). As the cardiac output is directly proportional to the heart rate, a heart rate monitor (HRM) can be used to structure and monitor an aerobic training program. (For additional background see Basic Exercise Physiology - the cardiac system.) Let's look at the pros and cons on the use of a HRM. PROS AND CONS The ADVANTAGES of a HRM include its use: • as a motivational tool - like a coach ; brings objectivity to a training program. • to teach beginners to read their bodies and avoid anaerobic overtraining. • to aid in doling out energy during time trialing or climbing, saving some for the final effort. • to analyze race efforts and design a personalized training program. • to spot overtraining (heart rate 10% higher than normal on awakening for several consecutive days). The DISADVANTAGES of a HRM are: • its inconsistency - at the same heart rate you're not always putting out the same effort day to day. • the lack of scientific support - there is no evidence training with a HRM improve competitive performance. • too much data, esp with elaborate HRMs, with little agreement on how to use this information to improve training or performance. • the lag time in heart rate response to a change in exertion - 15 to 30 sec lag with 2 to 3 min to stabilize at the new level of exertion. • its incompatibility with group training. • it distracts from dangerous road hazards. DEFINITIONS Here are some definitions you'll encounter in the literature on heart rate monitors: • bpm - beats per minute • Max HR (MHR) - maximum heart rate (expressed in beats per minute) • target heart rate - the training heart rate (usually a range of values)
  • • anaerobic threshold (AT)* (synonomous with lactate threshold). Lactate production occurs with muscle cell activity and increases as activity becomes more vigorous. Lactic acid is metabolized by the muscle cells, but at some point they cannot eliminate (or oxidize) the lactate as fast as it is being produced and the blood lactate level begins to increase. In trained athletes, this threshold for lactate buildup occurs at a higher activity level or percentage of the athlete's MHR or aerobic capacity. For all practical purposes, the AT is the highest heart rate you can maintain for a race or hard ride lasting up to an hour. As the AT increases with aerobic conditioning, it is considered one of the standard measurements to track training. The AT is usually reached at 80-90% of your maximum heart rate, but in elite riders rises to 90-93% of their maximum heart rate.(See also Basic Exercise Physiology - measures of cardiovascular fitness.) • lactate threshold (LT). See anaerobic threshold. * Determining your actual Anaerobic Threshold (synonyms are lactate threshold, AT, LT, Concini test). Accurate laboratory determination of your anaerobic threshold requires frequent blood draws while pedaling an ergometer at steadily increasing workloads. But for training purposes, the following approach is an alternative. Using a single gear, start cycling at 35 kph. Slowly increase speed on a flat course by 1km/hr every 300 meters (1/5 mile). Chart heart rate vs speed. Anaerobic Threshold is the "breakpoint" where heart rate levels off relative to speed. Let's assume you have decided to use a heart rate monitor in your training program. The first step is calculating your MHR or maximum heart rate. CALCULATING YOUR MAXIMUM HEART RATE (MHR) Interest in the MHR is based on the fact that it is a readily available surrogate for VO2max, the gold standard for assessing exercise capacity and and designing training programs. Just as we all vary in height and body habitus, everyone has their own personal maximum heart rate genetically "hardwired". Our maximum heart rate also decreases approximately one bpm (beat per minute) per year. The average MHR of a teenager is 220 beats per minute, but this may vary +/- 11 beats from the average (209-231 bpm). For example, a 40 year old who would be expected to have a MHR of 180 (220-40) could vary from 169 to 191 for his or her own personal MHR. Another key point is maximum heart rates are "sport specific" i.e. they vary from one sport to another. For a given rate of oxygen consumption, weight bearing activities such as running raise the heart rate more than cycling (part of your weight is supported by the bike). So you cannot use your maximum heart rate from running to plan a cycling training program without risking overtraining. One of the following two approaches can be used to determine your MHR for cycling. The first is more accurate and the one I prefer. There can be marked discrepancies between the estimated MHR and real life results (up to 5% of the population can have heart rates 20 beats above or below the ESTIMATED figure). And if you are in shape, the typical decline of one beat per minute per year doesn't always hold. • Warm up thoroughly. On a long, steady hill increase effort every minute for at least 5 minutes until you can't go any faster. Then sprint for 15 seconds. Check your heart rate at its maximum for a full 30 seconds and double the number. Similar results can be obtained on a stationary trainer. • 220 minus your age in years. A rough figure and much less accurate than the on bike approach. The only limit to the length of time one can ride at 100% of their MHR is personal discomfort. This level of activity does not "strain" the heart muscle or have other harmful effects on the heart itself. Although this level of activity might be considered in a competitive race or event for a short sprint, maximizing the benefits of a training program is the result of a mixture of recovery and hard days
  • (see below). As the time you can hold 100% MHR is considerably shorter than the time you can ride at 84-90% MHR, the art of racing is finding the right mix to get you to the finish line first. Most competitive athletes train at their lactate threshhold (84-90% of their MHR). HEART RATE TRAINING ZONES There are 5 training "zones" or heart rate ranges. These are arbitrary divisions and can differ from article to article or coach to coach. They are based on the increase in heart rate (and cardiac output) as the oxygen consumption of the exercising muscle increases, and the concept of the benefits of variable stress in developing the exercising muscle (heart or skeletal). As one moves up the hierarchy of training zones, exercise intensity increases and there is a shift from the use of fat as an energy source for the muscle cell to carbohydrate (below 70% MHR fat is burned preferentially). And as the MHR is reached, there is a shift in the muscle cell towards anaerobic (without oxygen) metabolism with increased lactic acid production. The Heart Rate Intensity Zones are divided as follows: • Zone 1 65% of MHR (recovery rides) • Zone 2 65-72% of MHR (endurance events) • Zone 3 73-80% of MHR (high level aerobic activity) • Zone 4 84-90% of MHR (lactate threshold(LT,AT); time trialing) • Zone 5 91-100% of MHR (sprints and anaerobic training) If you always train at low heart rates, you will develop endurance with no top end speed. Conversely if you train hard most of the time, you'll never recover completely and chronic fatigue will poison your performance. The solution is to mix hard training with easy pedaling in the proper proportions. The best approach is to stay below 80% of maximum heart rate (zones 1 to 3) on your easy days to build an aerobic base while allowing day to day recovery, and then push above 85% when it's time to go hard to improve your high level performance. But avoid training in the no man's land or mediocre middle at 80-85% of MHR where it's too difficult to maintain the pace for the long rides needed to build endurance and allow some recovery time, but not hard enough to significantly improve your aerobic performance and increase your lactate threshold. Training programs should be individualized, but once a good base is developed early in the season with Zones 1 and 2 exertion, most programs contain the following elements. TRAINING TIPS USING A HEART RATE MONITOR Tips for a training week: (see also mileage tips and training options) • one long recovery ride - zone 1 or 2 • one long day (event distance + 10 to 20%) - maxhr = to that planned for the event • three high intensity days - zone 4 • one or two interval workout days which are counted as one of the three zone 4 days. For example: o warm up - zone 1 o 20 min - zone 3 o 5 min - zone 4 o 7 intervals - hit 90% max, recover to 60 - 65% max o 5 min - zone 4 o 20 min - zone 3 o warm down - zone 1
  • • the sixth and seventh days of the week can be rest days off the bike or slow recovery rides at zone 1 or 2 exertion to stretch out your muscles. RESTING HEART RATE Your resting heart rate (RHR) can also be used as an indicator of your degree of training. As you train, your resting heart rate will fall. This is a result of the increased efficiency of the circulatory system. The heart will increase the volume of blood pumped per beat, and the peripheral muscle cells will become more effective at extracting oxygen from the blood passing through their capillary networks. The RHR for an untrained individual is 60 to 80 beats per minute. With training, it is not uncommon to see the RHR fall into the high 40s or low 50s. And as mentioned above, regular monitoring of your resting heart rate in the mornings (before getting up and beginning your daily activities) can be used as a monitor for overtraining (heart rate on awakening and before getting out of bed 10% higher than your personal normal for several consecutive days). SLOW HEART RATE A slow heart rate is considered a sign of good health. As one conditions, the heart will beat more slowly for any specific level of activity - including at rest. That is why the resting heart rate is a good measure of cardiovascular conditioning. The two exceptions are hypothermia, where a slow heart rate is a reason for alarm, and the other is a heart rhythm disorder. The latter can indicate heart disease, generally comes on quite suddenly, and is occasionally associated with an irregularity of the pulse. AN OPPOSING OPINION But there are differences of opinion on the usefulness of a heart rate monitor for training and competing. So keep an open mind and don't consider the HRM as the only real key to success. The following is from an Aussie coach, Graham Fowler: "I have observed a number of different %max heart rates during time trials. My nephew once rode a junior nationals ITT at 100%MHR. He didnt win it needless to say however didnt crack either. Obviously he was very fit or his MHR was inaccurate. I advise riders to ride just above (1 to 5 beats per min) what they consider threshold. This is around 92%mhr. This mark needs to be derived in training. I am aware of race day anxiety causing the heart rate to elevate somewhat so the hr is not such a good measure with an anxious rider. I am more inclined in the future the train with heart rate to establish a perceved effort (pe), and then remove the heart rate meter during racing and ride on pe alone. The speedo is then the govener (sic)." THE BOTTOM LINE The following question reflects one that I often receive: Q:I am 48 years old and a new MTB biker. I am working to keep/improve my shape in a controlled way, so I am using a HR monitor on my MTB bike. Until now I used Max HR of 180, just because quite often I reached this figure. Last time after accelerating my HR for 15 minutes, on a mountain steep trail I reached (for more than a minute) a HR of 182 -185 (in total it was 3 minutes of 8.7% trail with avg. speed of 8 km/h, avg. HR of 178 and max of 185) and I could continue without a problem with the trail. My questions are: • Should I consider my Max HR as 185? or what should it be?
  • • As it is quite far from my theoretical Max HR, what does it mean: Am I in good shape? Not in good shape? Means nothing (just genetic)? A:My opinion: • Maximum heart rate is very individual and all the rules to "calculate" MHR are just approximations to get you into the ballpark for you. Your maximum heart rate is what you have actually measured for yourself (185 for you). • Maximum heart rate has nothing to do with what shape you are in. And yes, it is probably related more to your inherited physiology (genetics) - assuming you are healthy - than anything else. • Use your maximum heart rate (and %'s thereof - training zones) as general training guidelines, not absolutes. Which means a difference of MHR of 180 versus 185, really is not that big a deal. This is not engineering (which is precise and reproducible day to day), but a biologic system which can vary from day to day. That's why perceived effort - which takes into account day to day variation in your biology - as a training tool makes more sense to me. Miscellaneous Training Questions Shaving Q. A few years back I took a pretty bad spill and recieved a ragin' road rash the entire length of my leg which took a few months to really heal. I was suprised at how painful it was...I guess the 1st degree burn syndrome. These days I'm getting at least 75 - 100 miles in a week but have not bit the bullet and shaved my legs. Do riders shave their legs for performance sake (ie. less wind resistance -- does hair really make that big of a difference?), or from a preventative stand point (when you take a spill, the hair doesn't get ripped out of your leg, causing a bad case of road rash)? A. I doubt that shaving your legs makes a significant difference in wind resistance. Shaved legs are a plus IF you take a fall and have to clean out gravel and dirt - the hair gets matted into the "scab" and pulling on it while cleaning just hurts that much more. Here the question is "does shaving regularly offset the rare time one will fall and need to clean up road rash?" Each rider has to answer that one for themself. I suspect that the reason most riders shave is cultural i.e. everyone who is a "serious cyclist" does it, so to be part of the club, one has to adopt the traditions. Proper Pedaling Technique Q. I'm curious which muscles should I use when pedaling for sustained riding? I have pedal clips and I find myself using my quads mostly. When I start to tire, I consciously start using my calves more by rotating my ankles as I pedal. I'm wondering if I should make a conscious effort to get in the habit of always using my calves, or what the most efficient method is? A.My guess is that 80% plus of your cycling energy is applied by your quads. At the bottom of the stroke, there is often a "wiping mud off the foot" backward push (and a number of professionals swear they also pull up on the backside - probably using hamstrings a bit). Good bikers have well developed calves, so we know they use them to some degree in the cycling effort. One does need to avoid ankling, which can be harmful.
  • EXERCISE PHYSIOLOGY ENERGY PRODUCTION IN THE CELL • oxidation (releasing food energy) • ATP (transferring food energy to the muscle cell) • aerobic/anaerobic metabolism (oxygen requirements for energy production) • energy content of the food we eat Energy to power muscle contractions is released when oxygen combines with chemical compounds in the cell to produce Adenosine Triphosphate or ATP. This chemical reaction is called oxidation. The amount of energy produced is limited by the amount of oxygen available within the cell and the chemical compounds (carbohydrates, fats, and protein) available to be oxidized (the "fule"). The foods we eat provide the fuel for cell energy production. They contain three energy containing compounds: carbohydrates, fats, and protein. As you will learn, carbohydrates are the primary energy source for short, maximum performance events (sprints) and for the average cyclist. Fats can also serve as an energy source for the cell, but are more important in endurance events (usually performed at less than 50% VO2 max.) Proteins are generally used to maintain and repair body tissues, and are not normally used to power muscle activity. The cardiovascular system delivers the oxygen necessary for oxidation. The oxygen is extracted in the lungs and transported in the blood to the cells where it is utilized. The byproduct of energy production, carbon dioxide, is transported back to the lungs by the circulating blood and leaves the body in expired air. When there is adequate oxygen to support the energy needs of the cell, metabolism is said to be aerobic. When the demand for energy outstrips the ability of the cardiovascular system to provide oxygen for oxidation, a more inefficient form of metabolism, anaerobic metabolism, occurs. OXIDATION & ATP Food energy is released through a chemical reaction with oxygen in a process called oxidation. When this occurs outside the body - for example the burning of oil (a fat) in a lamp or the use of a flaming sugar cube (a carbohydrate) as a decoration in a dessert - this energy is released as heat and light. In the body however, food energy needs to be released more slowly and in a form that can be harnessed for basic cell functions and transformed into mechanical movement by the muscle cells. This is accomplished by "refining" the three basic food materials (carbohydrate, fat, and protein), converting them into a single common chemical compound adenosine triphosphate (ATP). It is this ATP, synthesized as the cell metabolizes (or breaks down) these three basic foods that transfers the energy content of all foods to muscle action. ATP is composed of a base (adenosine), a sugar (ribose) and three phosphate groups. The chemical bonds between the phosphate groups contain the energy which is stored in this molecule. And it is the breaking of these bonds (as ATP is converted into ADP or adenosine diphosphate) that provides the energy to power muscle contractions and other cellular functions. PRODUCTION OF ATP - THREE PATHWAYS There is a limited capacity to store ATP in the cell, and at maximum work levels this ATP stored in the muscle cells is depleted in several seconds. In order to sustain physical activity, the cells
  • need to continually replenish or resynthesize their ATP. There are three pathways to accomplish this, and which one is used by the cell depends on the level and duration of the physical activity. The first breaks down phosphocreatine - another high energy, phosphate bearing molecule found in all muscle cells - to directly resynthesize ATP. But it is also in limited supply and provides at most another 5 to 10 seconds of energy, limiting its usefulness to sprint type activities. At this point, the body must switch to either of two other biologic processes to regenerate ATP - one requiring oxygen (aerobic) and another that does not (anaerobic). Aerobic metabolism, which is oxygen dependent, is the name for several different chemical processes in the cell, and can produce ATP from all three food elements - carbohydrates, fats, and protein. Aerobic metabolism supplies the ATP needed for endurance activities. Glycolysis, also known as anaerobic metabolism, is limited to the breakdown of carbohydrates (glucose, glycogen). Anaerobic metabolism is limited by the buildup of lactic acid which begins within minutes and degrades athletic performance by impairing muscle cell contraction and producing actual physical discomfort or pain. Anaerobic glycolysis is the source of energy for short bursts of high level activity lasting several minutes at most (sprints). THE BALANCE OF AEROBIC AND ANAEROBIC METABOLISM As one begins to exercise, the anaerobic pathway provides ATP while the body increases breathing and heart rate to deliver adequate oxygen to the cell. As more oxygen becomes available, the aerobic pathways pick up the slack and anaerobic metabolism falls off. However, anaerobic pathways continue to provide a small amount of ATP energy, and small amounts of lactic acid are still being produced. However this small amount of lactic acid is readily metabolized by liver and muscle cells, and does not accumulate to the degree that occurs at with anaerobic ATP activity (as in a sprint, for example). Aerobic pathways are used preferentially by the muscle cells until VO2max. is reached. At this point, the cardiovascular system cannot provide adequate oxygen to the muscle cell to continue aaerobic ATP production, and either the phosphocreatine system, or anaerobic metabolism cover the extra energy needs. When the level of activity once again returns to aerobic levels (less than VO2max), oxygen is once again available to regenerate phosphocreatine and metabolize (clear) the excess lactic acid produced during the sprint type activity. With training, changes occur in the cardiovascular system and muscle cells that support higher levels and longer duration of physical activity before anaerobic pathways are needed, and also clear lactic acid more quickly leading to faster recovery from anaerobic sprints. ENERGY CONTENT OF CARBOHYDRATES, FATS, AND PROTEIN The energy contained in equal weights of carbohydrate, fat, and protein is not the same. Energy content is measured in Calories (note the capital C). Carbohydrates and protein both contain 4.1 Calories per gram (120 Calories per ounce) while the energy "density" of fat is more than double at 9 Calories per gram. The disadvantage of fat as a fuel for exercise is that it is metabolized through pathways that differ from carbohydrates and can only support an exercise level equivalent to 50% VO2 max. It is an ideal fuel for endurance events, but unacceptable for high level aerobic (or sprint) type activities. Carbohydrate metabolism is much more efficient than fat metabolism assuming adequate oxygen is available (ie aerobic metabolism). But once VO2max has been reached, and anaerobic metabolism takes over, the efficiency of carbohydrate metabolism drops off dramatically. Carbohydrate will produce 19 times as many units of ATP per gram when metabolized in the presence of adequate cell oxygen supplies (aerobic) as opposed to its metabolism in an oxygen deficient (anaerobic) environment. In the well fed and rested state, the human body contains approximately 1500 carbohydrate Calories (stored as glycogen) in the liver and muscle tissue, and over 100,000 Calories of energy stored as fat. The carbohydrate Calories are adequate energy for several hours of brisk cycling
  • (80 to 100 % VO2max), and if one slows the pace to 50 - 60 % VO2max where fat Calories can be utilized, there are enough energy stores to support cycling at this reduced speed for days. How can these facts help you in designing a program to maximize your performance?? If one does not supplement glucose stores in the body (snacking while riding), you will run out of carbohydrate stored in your muscle and liver cells after 2 hours of aerobic activity, and the bonk occurs. This term describes the fatigue resulting from muscle glycogen depletion. Without adequate carbohydrate to fuel continues high level muscle activity, it is impossible to maintain a high level of energy output and one has to slow to speeds of 50% VO2max where fat metabolism can provide the needed Calories. The bonk can be delayed by using oral glucose to supplement muscle glycogen stores. On a long ride, a rider that snacks will have more glucose available to fuel that final sprint. Two other strategies are to 1) minimize extremely energy inefficient anaerobic sprints earlier in the ride (remember they are very inefficient in terms of ATP production) and 2) whenever possible, ride closer to 50% VO2max to take advantage of supplemental Calories available from fat metabolism. In addition to eating while riding, these two strategies will help to save a few more grams of muscle glycogen for that final sprint to the line. THE CARDIOVASCULAR SYSTEM & CONDITIONING Delivering Oxygen to the Muscle cells • cardiac output (transporting oxygen to the cells) • VO2 (oxygen consumption with exercise) • measures of cardiovascular fitness • skeletal muscles • changes in CV physiology with age Regular exercise (walking, running, cycling, etc.) stimulates changes in the cardiovascular system, lungs, and muscle cells which improve work capacity - for both endurance and sprint activities. Added health benefits include a decrease in resting heart rate and a lowering of maximal blood pressure with submaximal exercise. These changes can be measured with an exercise program that elicits 60% of your maximum heart rate for 30 minutes, 4 times a week. Understanding the physiology behind this training effect will help you in developing your own training program. The cardiovascular (heart and blood vessels) and pulmonary (lungs) systems work together to deliver the oxygen necessary for efficient (aerobic) energy metabolism to the exercising muscle. Oxygen is extracted from air in the lungs and then transported in the blood to the cells where it is extracted and utilized. The byproduct of energy production, carbon dioxide, is then transported back to the lungs by the circulating blood and leaves the body in expired air. CARDIAC OUTPUT The major reason for an increase in exercise capacity with an aerobic training program is the rise in the maximal cardiac output (amount of blood pumped by the heart per minute). It plays a bigger role in increasing maximal exercise performance than does the increase in oxygen uptake and utilization by the skeletal muscle cells. Since our maximal heart rate does not change, and may even be lower, following exercise training, this increase in cardiac output is the result of a higher stroke volume (amount of blood pumped per heart beat). Cardiac output = stroke volume x heart rate. The increase in stroke volume is a result of both a hypertrophy (enlargement) of the left ventricle muscle (athlete’s heart) as well as an enhancement of the heart’s contractile state, probably mediated by the autonomic nervous system. THE LUNGS The lungs job is to exchange (extract) oxygen from air drawn into the microscopic air sacs (alveoli) for carbon dioxide, a waste product of metabolism. Normally a half liter of air is drawn
  • into the lungs with each breath (which for the average cyclist is about 3.4 to 4 liters per minute - respiratory rate x air exchanged per breath). A competitive cyclist can exchange an additional 2 liters (6 liters per minute) while the legend Miguel Indurain was reported to have a respiratory capacity of 8 liters per minute. Although our respiratory capacity is relatively fixed (as a result of inherited factors such as body habitus and the size of our thoracic cavity), you can, with practice, increase your lung capacity to some degree. OXYGEN CONSUMPTION (VO2) VO2 is the amount (expressed as a volume or V) of oxygen used by the muscles during a specified interval (usually 1 minute) for cell metabolism and energy production. Maximum oxygen consumption (VO2max) is the maximum volume of oxygen that can be used per minute, representing any individual’s upper limit of aerobic (or oxygen dependent) metabolism. It can be expressed as an absolute amout (again as a volume per minute) or as a % of each individual's personal maximum (%VO2max). VO2max. dpends on: • lung capacity (getting oxygen from the air we breath into the blood which is passing through the lungs • cardiac output (the amount of blood pumped through the lungs, and of course the muscles as well, per minute) • and the ability of the muscle cells to extract oxygen from the blood passing through them (the arterio-venous or A-V O2 difference) Each of these factors improves with aerobic training and results in an increase in VO2max. The arterio-venous (A-V) O2 difference results from oxygen being delivered and extracted form the blood being delivered to an organ (usually muscle), the arterial concentration, and the blood leaving, the venous concentration. Oxygen extraction) and thus the A-V O2 difference, increases with exertion (almost doubling at maximal exercise versus at rest) as well as with training (increasing for any set level of exertion). At levels of exertion greater than the VO2 max., the energy needs of the cells outstrip the ability of the cardiovascular system to deliver the oxygen required for aerobic metabolism, and oxygen independent or anaerobic energy production begins. Anaerobic metabolism is not only less efficient (less ATP is formed per gram of muscle glycogen metabolized) resulting in more rapid depletion of muscle glycogen stores, but also results in a build up of lactic acid and other metabolites which impair muscle cell performance (even when adequate glycogen stores remain). The build up of excess lactic acid will be ultimately be eliminated when exercise levels decrease to an aerobic level and adequate oxygen is again available to the muscle cell. The build up of lactic acid (and amount of oxygen which will ultimately be needed to eliminate it) during anaerobic metabolism is responsible for oxygen debt (the period of time required to remove the excess lactic acid) and recovery phase that follows anaerobic exercise. MEASURES OF CARDIOVASCULAR FITNESS VO2 max. or maximum oxygen uptake, is considered the gold standard of cardiovascular, pulmonary, and muscule cell fitness. It is usually standardized per body weight and expressed in milliliters of oxygen per kilogram of body weight per minute, and is the maximum amount of oxygen your body (basically your muscles) can utilize. The VO2 max for an elite cyclist can range from 70 to more than 80 ml/kg/minute. It is generally measured on a treadmill or bicycle ergometer at a sports medicine clinic with the appropriate equipment. Exertion at or beyond 100% VO2max can be sustained for a few minutes at most. With training, you will increase your VO2max. as well as the ability to ride for longer periods at any % of your VO2max. The following all indicate that an individual's VO2max has been reached: • VO2 plateau - no further increase in oxygen use per minute even with an increase in work performed • heart rate within 10 beats of the age predicted maximum heart rate -this is the basis for using your maximum heart rate as a surrogate for your VO2 max when designing your personal training program)
  • • plasma (blood) lactate levels > 7 mmol/liter For those of you interested in the mathematical expression of VO2max, it is the product of the arterio-venous oxygen difference (the oxygen content of blood leaving the heart minus that returning to the heart and thus the amount being extracted by the working skeletal muscles) and the maximal cardiac output (the maximal heart rate times the volume of blood pumped per beat). This is called the Fick equation. • Ranges of VO2max by age/sex • Calculating %VO2max based on your % of your MHR (Maximum Heart Rate). Anaerobic Threshold (AT; also known as lactate threshold)is the level of physical performance at which the muscles produce more lactic acid than can be removed (by the liver and muscle enzyme systems). It is expressed as a percentage of VO2 max - or as indicated above as a % of its surrogate or maximum heart rate. At levels of exertion appraoching VO2max, there is a rapid increase in blood lactate levels. Cr. Concimi, a physiologist, suggested that it can be identified as the pulse rate deflection point with increasing exrcise (see the Concini test below). Your AT limits your rate of maximal exertion (remember it can be exceeded for only a few minutes as you build up oxygen debt) and thus can be assumed to be reflected as the maximum physical effort you can maintain continuously for 30 to 60 minutes. The more you exceed your LT or AT, the more quickly lactic acid will accumulate and thus limit further increases in your performance. As most cyclists don’t have access to lab facilities, you can estimate your AT with a 30 minute (about 10 mile) time trial. The average heart rate you can maintain is a good approximation of your AT. An individual's AT will improve with training, and cyclists with a higher AT can work at a higher level of energy expenditure for longer periods, defeating opponents of equal (or even greater) physical strength but with lower ATs. This concept explains why interval training, which is generally anaerobic, will improve performance. Concini Test Another method of measuring your AT (and LT) is the Concini test. As a cyclist’s efforts increase, their heart rate generally increases in a direct relationship to the energy expended (a linear relationship). But at some point the heart rate begins to level off even as the speed (and energy expenditure) continues to increase. This is the anaerobic threshold, that point at which oxygen cannot reach the muscles fast enough, lactate accumulates, and performance suffers. After an appropriate warm up, using a single gear and a relatively high speed, the rider gradually increases his or her speed by 1 km per hour every 300 meters or so. Heart rate is graphed versus speed, and the break point on the graph is the AT. Lactate Threshhold Recent work has focused on the blood lactate threshold (LT) as a reflection of an individual's level of training. The lactate threshold is that % of VO2 max. at which the cardiovascular system can no longer provide adequate oxygen for all the exercising muscle cells and lactic acid starts to accumulate in those muscle cells (and subsequently in the blood as well). At high levels of activity (but below 100% VO@max), there are always a few muscle cells (not entire muscles, but a small number of cells within those muscles) that are relatively deficient in oxygen and thus producing lactic acid. But this lactic acid is quickly metabolized by other cells that are still operating on an aerobic level. At some point, however, the balance between production of lactic acid and its removal shifts towards accumulation. This point is the LT. It is usually slightly below 100% VO2 max., and will improve with training (move closer to 100% VO2max). Those with an increased LT not only experience less physical deterioration in muscle cell performance for any level of %VO2max, but also use less glycogen for ATP production at any level of performance. Thus an improvement in LT allows the individual to perform at maximal levels for a longer period of time before running out of adequate energy (glycogen) stores. Resting heart rate, your heart rate on awakening in the morning, is a simple but effective indicator of your level of training. It will fall as you train, but then begin to rise again with overtraining. Cardiac Stress Testing for asymptomatic coronary artery disease. THE SKELETAL MUSCLES
  • There are two types of fibers: type I, or slow twitch, and type II or fast twitch. The slow twitch fibers are more energy efficient and use both fats and carbohydrates as an energy source. They are the major muscle fiber in use at 70-80% VO2 max. Fast twitch fibers on the other hand are less efficient, use mainly glycogen as fuel, and are called into action for sprints as the athlete approaches 100% of maximum performance. Although the ratio of slow to fast twitch fibers is generally controlled by genetic (inherited) factors, this ratio does change (often over years) with an ongoing training program. Along with these visible changes in the muscle cells, there are microscopic and metabolic changes at the muscle cell level with training. These include an increase in the size and number of the muscle cell mitochondria, an increase in the activity of various metabolic enzymes in the muscle cells, and an increase in the number of capillaries in the muscle that supply blood to the individual muscle cells. The net result is an increase in the amount of oxygen extracted from the blood in a single pass through the muscle (the arterial - venous oxygen difference). SUBMAXIMAL EXERCISE Endurance training (usually defined as training at less than 60 - 70% VO2max) improves the overall efficiency of the cardiovascular system as reflected in a smaller increase in heart rate for any given exercise intensity, and is also thought to promote a shift towards the use of fat as an energy source (more efficient with 9 Cal per gram versus 4 Cal per gram with carbohydrates). This is suppoted by the observation of a smaller increase in the plasma free fatty acid levels (indicating enhanced fat oxidation) at these activity levels. CHANGES IN EXERCISE PHYSIOLOGY WITH AGE Aging results in a progressive decline in the functional capacity of various body systems, and is reflected in a 9 to 10% decrease in maximal aerobic exercise capacity in sedentary individuals. It is well documented, however, that endurance training can attenuate this age related decline to about 5% per decade, and can also improve exercise performance in older men and women.And if you are more than 40, it may be time to consider cardiac stress testing for asymptomatic coronary artery disease. SKELETAL MUSCLE Skeletal muscles makes up over 1/2 of the body weight in a lean individual. All muscles (quadriceps, biceps, etc.) are composed of thousands of muscle cells. And these individual muscle cells contain two proteins - actin and myosin - which chemically interact and shorten the cell (and along with it the muscle itself) when the muscle cells are stimulated by a nerve impulse. The interaction of the actin-myosin complex, which results in the shortening or contraction of the muscle cell, requires the energy in the form of ATP. TWO TYPES OF MUSCLE FIBERS The muscle cells contain two distinct types of muscle cells or fibers. Type I (slow twitch, SO fibers) - These muscle cells shorten at a relatively slow speed and generate energy from both fats and carbohydrates via aerobic metabolism . They are the major muscle fiber in use at 70-80% VO2max. Type I cell characteristics include: • high concentration of mitochondria for aerobic metabolism • increased intracellular myoglobin (which gives the muscle its characteristic red color) to store and transport O2 • low concentration of glycolytic enzymes used for anaerobic metabolism • relatively fatigue resistant Type II (fast twitch, FG fibers) - These muscle cells are less efficient than the slow twitch cells and are almost entirely dependent on glycogen as fuel. They are called into action for sprints
  • when the athlete approaches 100% of their maximum performance (and are working in the anaerobic range above 100% VO2max). Type II cell characteristics include: • low concentration of mitochondria • high concentration of ATP and glycolytic (ATPase) enzymes • a rate of shortening 3 to 5 times that of a type I muscle cell The relative proportion of type I and type II fibers within a muscle varies from person to person and is determined by genetics (ie inheritance from your parents). However, with limits, this ratio can be modified with exercise and training. Successful endurance athletes have a preponderance of slow twitch muscle fibers (up to 90% of the fibers in the calf in cross country skiiers) while sprinters have more fast twitch fibers. Short term studies in bicyclists (5 months) failed to show a change in the ratio of cell types (percentage of slow vs fast twitch fibers) in leg muscles, but a longer multi-year study has suggested that this ratio can change with time, continuing to change for at least 5 years with regular training. But even without a change in the ratio of cell types, there is no question that both slow and fast twitch fibers can markedly improve their metabolic capacity with training. (see also Principles of Training) But all training may not be positive for muscle cell adptation. A recent article (Derman et al, Journal of Sports Medicine, 15:341-351, 1997) described muscle cell biopsy changes in athletes that: • had a history of high volume exercise training for years (5 of 9 had performed at the national or international level) • presented with chronic fatigue • had a syndrome of excessive late onset muscle soreness and stiffness Muscle biopsies from the vastus lateralis demonstrated cell structure abnormalities. They specualted that repeated bouts of high volume trainig over years (with repeated microtrauma) might lead to chronic muscle structure changes and symtpoms. At this time there is not enough evidence to call this, but it may represent a unique subset of elite athletes that present with training problems. MEASUREMENT OF ENERGY OUTPUT (POWER) Energy output (or work) is expressed as power (the amount of work done during a specified unit of time). Power output can be measured as steady state power output (maintaining a steady speed for minutes to hours) or maximal power output - which require maximal activation of the ATP-CP energy system. The latter reflects the maximal muscle power of the athlete and is limited by the amount of ATP and CP available in the cell - about 6 seconds. Curt Austin has put together a nice calculator to estimate power output (in Watts - you enter your own parameters) on his website. Malcolm Firth also published some comparative numbers in an online coaching forum. (As the amount of ATP-CP available to the muscle cell is limited, Malcolm's maximum power output over several minutes would be lower than that achievable in a brief sprint lasting 5 to 5 seconds): "In February 1998 I did a small research project in which a group of 24 cyclists were asked to do two tests on a CompuTrainer (an electomegnetically braked turbo trainer made by RacerMate of Seattle, USA). The first of these was a step increased load test to voluntary exhaustion in which the load began at 100 watts and was increased at approx 20 watts per minute. After a break of at least three hours the cyclists then rode a simulated ten miles time trial on the CompuTrainer with the instruction to complete the distance as quickly as possible. Some of the data is summarised below:
  • • Average Age: 33.17yr (standard deviation 12.97, range 16yr-61yr) • Average Max Power for 1 min: 367.46 watts (st dev 62.74w, range 263w-487w) • Average Max Heart Rate: 187.29bpm (st dev 12.16bpm, range 163bpm-211bpm) • Average 10 mile Time: 25min 52sec (st dev 1min 50sec, range 29min 09sec - 23min 02sec) • Average 10 mile Power Output: 286.46 watts (st dev 49.88w, range 215w - 375w) • Average 10 mile Heart Rate: 177.08bpm (st dev 11.78bpm, range 145bpm-199bpm) The average 10 mile heart rate worked out at 94.5% of the mean max heart rate.(st dev 2.81%, range 88.41%-97.41%). If you go to my web site at http://www.msfirth.freeserve.co.uk you will find an article giving details on how to use the average ten miles heart rate to estimate heart rates for other training and racing intensities." ENERGY REQUIREMENTS OF BICYCLING The energy requirements for a ride are dependent on: • the weight of the cyclist and equipment • the distance • the terrain (flat versus hilly) • the speed of the ride • headwinds or tailwinds And the Calories to fuel the ride are supplied (via the intestinal tract)from food eaten just before or on the ride, or from the body's internal energy reserves (fat, glycogen) in the liver, fatty tissue, or in the muscle itself. ENERGY - POWER, CALORIES & WATTS Before we go any further, let's review the terms energy, force, power, Calories, and watts which are often used interchangeably. Energy is the ability to perform work. The presence of energy is revealed only when change takes place. Potential energy is stored energy (the energy which will let you roll down the hill on your bike, starting from a dead stop, without ever pedaling). Kinetic energy is the energy of motion (the energy contained in you - and your bike - when already rolling down that hill and evident if you run into someone while in motion). The measurement units for energy (either potential or released) are calories or Calories. Force is the ability of that energy to make a change - to change the state of rest or motion in matter. When force is actually applied, work (force applied over some distance) is done. The same amount of work is done if the task is accomplished in 5 seconds or 5 minutes. The rate at which the work is done is power - the more work per minute or second, the more powerful the force applied to do that work. And watts are the units used to measure power. The more force applied to accomplish the task in a shorter period of time, the more work done and the more power required to do it. Energy output can be expressed in absolute terms (time interval independent) or in as energy released over a specified or defined time interval (time interval dependent). The most common time independent energy unit used in the cycling literature is the Calorie. In the physical sciences (physics, chemistry), a calorie (small "c") is the quantity of energy required to raise the temperature of 1 gram of water 1 degree centigrade. As this unit is too small to easily express the energy needs of biologic systems, the Calorie (large "C"), which is equivalent to 1000 calories (small c again) or 1 kcal is often used. Unfortunately most nutitionists forget to capitalize the "C" when they are writing about "calories" (they really mean Calories), so don't get confused. If the energy released is measured over a set period of time, it is expressed in watts, and is a reflection of power. Approximately 60% of the Caloric energy from the food we eat is lost as heat during the fabrication of ATP (adenosine triphosphate), the high energy, intermediary molecule actually used
  • by the muscle cell to power muscle contraction. Additional energy, again reflected as heat production, is lost when ATP is metabolized in the actual mechanical work of muscle fiber contraction. The net result - only 25% of the Caloric energy in the food we eat is actually used to power the mechanical work of the muscle cells. The initial heat loss associated with the conversion of Calories in food into ATP occurs slowly over several hours and is easily compensated for by our body's temperature contol mechanisms, but the heat produced with the metabolism of ATP to power muscle contraction is concentrated over a shorter period of time and is why our body temperature rises (and we sweat to compensate) when we are exercising. Our bicycle, on the other hand, is very efficient in terms of energy loss. Over 95% of the muscle energy we use at the pedals is translated into forward motion and less than 5% is lost (again as heat) from the rolling resistance of the tires, bearing friction, etc. Some of the things we can do to increase the efficiency (decrease resistance losses) are: • keep bearings and chain well lubricated • use light oil in bearings and bottom bracket for time trials • use light greases - paraffin gives more resistance than grease • use tires with a small "footprint" • keep tires maximally inflated to decrease rolling resistance • use thinner, more flexible tires (less energy taken up in sidewall deformation) Curt Austin has put together a nice calculator to estimate power output (in Watts - you enter your own parameters) on his website. As energy used in Watts is directly proportional to Calories, this calulator will let you play with the numbers for weight, postion on the bicycle, road grade, and air resistance/wind which we will discuss below. WEIGHT The combined weight of the cyclist and equipment impact the energy requirements of a ride. This relationship is directly proportional i.e. a doubling of the weight on the bike doubles the number of Calories expended. And 2 pounds on a cyclist is just as much a problem as 2 pounds of equipment on the bike frame itself. Austin did a nice analysis on the effect of weight on performance. Here's his conclusion: I thought it would be interesting to see how weight would influence these curves. If I lost 10 lbs (about 5%), I would be able to go about 5% faster on the steepest hills, 0.4% faster on the level, and about 2% slower on the downhills. Over a simulated 20-mile closed-circuit ride with a variety of grades, a 10-lb difference produced a 33 second difference. This may or may not seem significant in the context of a time trial. On the other hand, there are two hills on this simulated route where the heavier rider falls back 14 seconds. That is, about 200 feet back and well-dropped. A two-lb difference that you can buy at a bike shop for $500 amounts to only 7 seconds on this circuit, but again, this could mean cresting a hill 50 feet behind your better-sponsored buddies. HORIZONTAL DISTANCE Horizontal distance. We all know that it takes more energy the further we carry any object. The same is true in cycling. On level terrain, the number of Calories expended is directly proportional to the distance and doubling the distance (weight remaining the same) will double the number of Calories required. VERTICAL DISTANCE (hills) Vertical distance, i.e. climbing a grade or hills requires additional energy energy as you overcoming gravity (essentially lifting the cycle/rider to a higher elevation). A common question is how speed on the flats compares to speed on an uphill slope. Using Austin's calculator, I first calculated the power output for a 170 poound cyclist & 22 poound bike on the flats at 20 mph. It was 210 watts. Keeping energy output steady (at 210 watts), I then calculated the speed on a 1% (17.25 mph), 2% (14.6), 3% (12.3) and 5% (9.0) grade. What about descents and hilly terrain? How does weight factor into these riding conditions? You may have noticed that a heavier rider descends a hill faster (energy expenditures being applied to the pedals being equal) than a lighter one. This seems to fly in the face of a fact you learned in physics class about all objects falling at the same speed independent of their weight. But when going biking down a hill, the slope factor needs to be taken into account. The final speed down a
  • long hill is the balance between the propulsive forces - total rider/bike weight x the sine {that's a trigonometric function} of the angle of the hill - and the resistive forces - wind resistance is the big one. And the heavier rider comes out ahead. If one does the exact calculations with twin brothers weighing 175 pounds, descending a medium slope hill, riding similar bikes, and in exactly the same aerodynamic positions, with one carrying 25 pounds of lead shot, the heavier one would go 26.73 mph while the lighter one would be slightly slower at 25 mph. And what about rolling terrain?? With climbing, the lighter rider has a definite advantage over the heavier one. And in rolling terrain with repeated ups and downs, the lighter rider comes out ahead. INERTIAL WEIGHT Finally, weight is a factor in sprints where inertia (the resistance to setting an object into motion - why it is harder to get up to speed on a bike than to maintain that speed) comes into play. It definitely takes more energy to accelerate a heavier rider/bike combination in a sprint. And extra weight in some bike components (rims for example) may require twice as much energy to accelerate as an equal weight in the frame. This is a result of the fact that with rotational speed you are accelerating these components much more quickly. (Note: this means you should upgrade your tires, rims, crankset, and shoes before you spend your extra $$ to decrease your frame weight an equal amount). The bottom line - the heavier you are, the greater the total energy requirements for your ride. And except for the special case of inertia, all weight is equal. So don't forget that tthe extra water bottle, the larger heavier tool set, and even that extra pancake you ate in the morning all require additional energy on the ride. And saving a few ounces by eating one less pancake will have as much impact on your performance as that expensive titanium item you've been saving to buy. AIR RESISTANCE, WIND, AND DRAFTING Along with the Calories needed to • counter the effects of gravity • over come the friction and rolling resistance in the bicycle you also have to overcome air resistance. That's the resistance produced as we cycle (from the air molecules all around us). Air resistance increases with your air speed (the velocity of our travel through that mass of air). Even with the best riding technique, a head wind will increase your energy expenditure per mile for any specific ground speed (the speed indicated on your bike computer). With the head wind, your air speed (and air resistance) is now GREATER than your computer indicates, the air resistance is higher than at a similar ground speed in calm conditions, and your energy needs are greater. Likewise a tailwind will decrease our air speed relative to your ground speed and make it easier to maintain any specific ground speed. And worst of all, this relationship is an "exponential" one which means that doubling our air speed MORE THAN doubles the Calories expended per mile traveled.(This graph visually demonstrates the fact.) A headwind on an out and back course always results in a slower total ride time than for the same course ridden in calm conditions as the time gained on the return trip with a tail wind doesn't make up for the loss from grinding into the wind on the way out. For a 12 mph wind, total time will rise by about 7%. Remember that the "speed" that determines your energy needs to overcome air resistance is your AIR speed, not the GROUND speed which is read from your computer. When you are calculating energy needs for a ride, it is the air speed that is used. A head wind should be added to your average ground speed to determine your air speed (and thus air resistance) while a tail wind should be subtracted from your ground speed. If you think about it, this makes sense - it is always easier to ride with a tail wind, ground speed staying the same. At cycling speeds greater than 15 mph, the energy needed to overcome AIR RESISTANCE greatly exceed those of the rolling and mechanical resistance in your bike. For example, in going from 7.5 mph to 20 mph: • mechanical resistance increases by 225%
  • • rolling resistance by 363% • air resistance by 1800%. This is why drafting (which cuts down air resistance) provides such an advantage in high speed events. At 20 mph, drafting a single rider reduced energy requirements (measured by VO2 needs) by 18% and at 25 mph by 27%. In order to benefit from drafting, you've got to be in the drafting bubble behind the cyclist immediately in front of you. And in a crosswind the bubble will NOT be directly behind the rider in front but will be some angle away from them. The effectiveness of this bubble decreases with the distance, being the greatest if you draft closely and falling off until there is minimal benefit at 5 or 6 feet. The important fact is that you will get some benefit 3, or even 4 feet, back - and it’s a lot safer than being directly on the rear wheel of the rider in front of you. The rider being drafted also gains a slight advantage. This is explained by the fact that the low pressure behind the lead rider is increased in a pace line, giving the leader a slight "nudge" due to the pressure differential between the high pressure ahead and the low pressure behind. This is why a NASCAR racing car will go 1-2 mph faster when being drafted. Since wind resistance plays such a great role in the overall resistance we get when riding, it makes excellent sense to draft. Better if closer, but that comes with practice and skill as well as trust in the front-rider's smoothness and consistency. Your frontal surface area affects your air resistance. Wind tunnel results show that eliminating the drag created by projecting 4.5 inches of a pencil into the airstream will provide a 158 foot finish line advantage to a cyclist in a 25 mile time trial. That baggy jersey or upright position may be costing you minutes. Let's review the factors in air resistance again: Air resistance =.5*(rho/g)*Area*Cd*V^2 • rho=air density • g=gravity • area= frontal area of the rider and bike (scrunch down, less area, faster ride) • Cd=coefficient of friction (smoother rider and helmet, and less protrusions from the bike, the lower the Cd. This also refers to the shape of the frame, wheels, etc. A tube, spoke, fork shaped like a wing has a lower Cd than round spokes, tubes,or forks.) • V=air speed - which is squared (ie going from V=7mph to 21mph is a 3x increase in speed which is then squared and the force required is now 9x) SHOCKS/SUSPENSION Shocks, both front and rear, will affect your riding over uneven terrain on a mountain bike. Front shocks decrease vibration transmitted to the shoulders and allow more concentration on the course (no energy issues here). The older rear suspended bikes without a rigid rear triangle could absorb some pedal/rear wheel energy, but this is less of an issue with the newer rear suspensions. One study did compare rigid frame (RIG), front shock (FS), and fully suspended (FSR) mountain bikes using the same riders and course. The front suspended bikes finished 80 seconds ahead of the RIG and FSR bikes over a 31 minute course! THE BOTTOM LINE - HOW MANY CALORIES DO YOU "BURN" WHILE CYCLING? To calculate the Caloric requirements of cycling, you need to include the Calories needed to maintain your basic life processes - the BMR - and these are needed even if you were not exercising, and the Calories used for the physical activity itself. A third component called the "thermic effect of food" refers to the energy expended in digesting, absorbing, and transporting food energy to the cells in the body. Thus your total Caloric needs can be expressed as: CALORIC NEED = CAL(bmr) + CAL(physical efforts) + CAL(thermic effect)
  • As a rule, the average American, pursuing the average recreational activities and chores of daily living (mowing the lawn, etc.), uses: 1. 23% of their Calories for physical activity 2. 10% of their daily Calories for the thermic effect 3. 67% of their Calories for the BMR THERMIC EFFECT This is a straight 10% of all the Calories you actually eat, so you can easily calculate it. (You add up CAL(bmr) and CAL(physical effort) that need to be replaced and add another 10% to cover the energy needs of digestion and absorption.) ENERGY REQUIREMENTS IN A COLD ENVIRONMENT It was mentioned that a cold environment does NOT increase the BMR but requires the expenditure of additional Calories to maintain a constant body temperature. While riding there will be some "waste" energy (from the inefficiency of converting eaten of stored Calories into power at the pedal) but the wind chill effect from riding will accentuate any heat loss. How many additional Calories are needed ? At rest, roughly 16 Calories per day for every degree F below 98.6. Although one can argue about exact BMRs and find different formulae to calculate basal Caloric requirements, the only formula I am aware of that corrects for the ambient temperature is: Cal requirements/day = 4660-(15.9 x tempurature in degrees F) Again, this was for an individual exposed for long periods to the ambient tempurature, not just a several hour ride. Unfortunately the level of activity was not defined and for cycling, wind chill may decrease the effective tempurature even further. Does exercising in the cold markedly increase Caloric needs? Probably not by a big factor for most of us, but it again demonstrates the multitude of variables we need to consider as we try to estimate the Caloric needs of exercise and cycling. Formula for the Energy Requirements of Cycling From Bicycling Science by Frank Whitt and David Wilson, p.157 W = Cv [K1 + {K2(Cv+Cw)(Cv+Cw)} + {10.32Em(s/100 + 1.01a/g)}] Where: • W = power in watts o 1 W = 1 joule/sec o 69.78W = 1000 calories/min = 1 kilocal/min = 1 Calorie/min o 1 Calorie = 4186 joules • Cv = speed of cyclist in meters/sec o 1 mph = .447 meters/sec o 1 mph = 1.609 kilometeres/hr • K1 and K2 are constants (see table below) • Cw = headwind in meters/sec • Em = mass of cyclist and bicycle in kg o 1 pound = .4536 kg • s = slope or grade in % • a = acceleration of the bicycle in meters/(sec)(sec) • g = gravitational accel = 9.806 m/sec-sec at sea level CONSTANTS K1 &K2: ASSUMPTIONS MTN BIKE ROAD BIKE
  • BICYCLE WT 15 kg 10 kg RIDER + GEAR 80 kg 75 kg K1 7.845 3.509 K2 0.3872 0.2581 Assuming: • a level road • no head wind • constant speed i.e no acceleration or deceleration • ideal road or mtn. bike and rider the formula can be simplified to: W = Cv* [(K1**) + (K2**)(Cv*)(Cv*)] *Cv is your AIR speed (ie the resistance you are pedalling against is the resistance of the air to your body and bike as you ride) and is not the GROUND speed off your computer. So if there is a head wind, add that speed to your ground speed to determine the velocity for this formula. And if it is a tail wind, subtract it from your ground speed. If you think about it, this makes sense - it is always easier to ride with a tail wind. This formula quantitates how much easier. **The constants K1 and K2 are for a road rider/bicycle/gear of 85 kg (187 lbs) or mountaion bike/rider/gear of 95 kg (210 pounds) . If you need to be more specific, the original derivation is referenced at the top of this page. But biking is NOT an exact science, and this formula will at least get you into the right ballpark. If you want the energy expended at the pedal in Calories/min: Cal/min (expended at the pedal) = [(K1)(Cv) + (K2)(Cv)(Cv)(Cv)]/69.78 As the body is only 25% efficient at best in converting Calories eaten into Calories delivered as power output, the number of Calories that would need to be eaten per minute to sustain a speed of Cv mph would be: Ingested Cal/min = {[(K1)(Cv x .497) + (K2)(Cv x .497)(Cv x .497)(Cv x .497)]/69.78}/.25 So if you know the average speed (velocity) of your ride, and the total time you were out, you can calculate the number of Calories "burned". Here are a few examples (average speed for the ride, on the flats): • 5 mph - 7 Cal/mile - 37 Cal/hr • 10 mph - 13 Cal/mile - 133 Cal/hr • 15 mph - 23 Cal/mile - 349 Cal/hr • 20 mph - 37 Cal/mile - 742 Cal/hr • 25 mph - 55 Cal/mile - 1374 Cal/hr • 30 mph - 77 Cal/mile - 2303 Cal/hr NUTRITION FOR TRAINING AND PERFORMANCE • Nutritional building blocks of all foods • What the muscle needs • Your total energy stores • Factors affecting digestion and absorption • Effects of exercise on the digestive tract • Additional considerations
  • o carbohydrate loading o potential hypoglycemia from pre race carbohydrates o post exercise glycogen loading window o vegetarian diet • Optimal cycling diet • Basic Nutrition Plan THE THREE BASIC BUILDING BLOCKS IN ALL FOOD (Carbohydrates, protein, and fats) Aside from being a pleasant reward after a hard ride, food is a necessity for the cyclist to provide the energy to move man and bicycle. All foods are made up of the nutritional building blocks of carbohydrates, fats, and protein plus a certain amount of water and fiber (undigestible and without any food value). Carbohydrates contain 4.1 Calories per gram and are the primary source of energy for most cyclists as well as athletes involved in short, maximum performance events. Fats are more important for slower endurance events. Protein, is used to maintain and repair cells, and is rarely a source of energy except in certain unique situations (such as malnutrition). HOW MUCH ENERGY DO YOU GET FROM WHAT YOU EAT (What is a Calorie?) Some foods provide more energy per ounce or gram than others. Not only does the fiber content (which is a filler and has little or no Caloric value) of foods vary, the energy contained in equal weights of the basic ingredients - carbohydrate, fat, and protein - is not equivalent. In the nutritional literature, the energy content of foods is, by convention, expressed in Calories (note the capital "C") as opposed to the use of calories or kilojoules (kj) in the scientific literature. The energy contained in one nutritional Calorie is the equivalent of a kilocalorie (1000 calories, lower case "c") or 4.18 kilojoules. Carbohydrates and protein each contain a little more than 4 Calories of energy per gram while a gram of fat has more than double the energy value at 9 Calories per gram. HOW DOES WHAT YOU EAT POWER THE MUSCLE CELLS? Although carbohydrates supply the majority of the energy for muscles during vigorous activity, fats can be a major contributor for less strenuous activities. Carbohydrate is stored as glycogen in muscle and liver cells. On a normal diet there is enough glycogen to support 2 hours of aerobic exercise before the bonk occurs. These internal stores can be extended by using oral carbohydrate supplements for events expected to last more than 2 hours. It is best to begin the carbohydrates at the start of the event as they are much less effective after the bonk has occurred. A well trained cyclist will need slightly more than 1 gram of carbohydrate per minute to sustain maximum performance, and oral supplementation (started at the beginning of the exercise, not after glycogen depletion has occurred) should replace carbohydrate at that rate. In addition to extending the time to fatigue in longer, moderate activity events, several studies have also suggested that maximal performance in a 1 hour, high intensity (time trial, ~80% VO2max) event can be improved with oral carbohydrate supplementation. Drinking a total of 1 liter of a 7% carbohydrate solution at the beginning and during the event improved times by 2%. Skeletal muscle oxidizes carbohydrate in the form of glucose, and other sugars must be converted to glucose by the liver before they can be used as fuel by the muscle. Studies have demonstrated no additional benefit for glucose polymers, fructose, or sucrose (common table sugar) which is a dimer of glucose and fructose, for carbohydrate replacement - aside from palatability. In large amounts, fructose can cause diarrhea. Although carbohydrates are superior to fats in supporting maximal performance, there is some controversy over the relative benefits of simple vs complex carbohydrates as the ideal
  • supplement to be used during prolonged exercise. Examples of complex carbohydrates are rice (200 Cal per cup), spaghetti (180 Cal per cup), and baked potatoes (140 Cal per large spud). Examples of other carbohydrates. A shift toward fat metabolism may be the physiologic explanation for the "second wind" that occurs during exercise (internal carbohydrate stores have been used, fatigue sets in, the body shifts to fat metabolism, and the "second wind" or feeling of a renewed source of energy returns). However, the trade off is the inability to maintain performance at the same %VO2 max. that is possible with carbohydrate supported metabolism. Muscle fatigue (the "bonk" in cycling, "hitting the wall" in running) generally occurs when the body's internal carbohydrate stores are depleted and there is a shift towards fat metabolism as the prime energy source for the exercising muscle (with maximum energy output limited to approximately 50% VO2 max.). It would be logical to assume that if adequate carbohydrates (to offset those expended) were replaced during a ride, the cyclist could maintain his or her pace indefinitely. Unfortunately this is not the case. Cyclists with low muscle glycogen stores but high blood glucose levels still experience fatigue at some point, even though the time to onset of fatigue was delayed by taking the carbohydrate supplements. Unknown factors, perhaps related to physical changes in the muscle cell itself, are thought to be responsible as this type of fatigue is more common in the untrained athlete.(see also Overtraining) Fats provide over 50% of the Calories expended during moderate exercise (less than 50% VO2 max.) even when adequate carbohydrates (glycogen) are available. As the level of exercise increases towards 100% VO2 max., the proportion of the total energy expenditures replaced by fats diminishes. And in maximum performance events, where metabolism becomes anaerobic (greater than 100% VO2 max.), fat metabolism ceases and only carbohydrates are available as an energy source. Although there has been speculation that using fats in a dietary program both during training and as supplements during competitive events might improve athletic performance, the only hard evidence to date suggests that it may help endurance (performing at <50%VO2 max) athletes involved in long events while there has been no evidence of a benefit at higher performance levels ie 90 to 100% VO2max. Protein is a maintenance material being used to repair muscle (and other) cell injuries - including the microtrauma that occurs with exercise. It is NOT used by the body as an energy source except in very malnourished states. Even in endurance activities such as the Tour De france, protein needs of 1.5 gms protein/kg body wt/day were easily met by a normal (unsupplemented) diet that replaced the total Calories expended. A review of the literature failed to demonstrate any advantasge to protein supplements (assuming an adequate daily protein intake) over pure carbohydrate supplements alone. And one study actually demonstrated a DECREASE in overall performance from the appetite suppressing effects of a high protein diet, decreased carbohydrate intake, and as a result diminished pre event muscle glycogen stores. HOW LONG CAN YOU EXERCISE WITHOUT EATING? (What are your total internal energy stores?) In the well fed and rested state, the human body contains approximately 1500 carbohydrate Calories (stored as glycogen) in the liver and muscle tissue, and over 100,000 Calories of energy stored as fat. This is adequate carbohydrate for several hours of brisk cycling, and enough fat to continue to support cycling at a reduced speed (50 - 60% VO2@max) for days. In order to avoid the "bonk" (the shift to fat metabolism with an accompanying deterioration in performance), supplemental carbohydrates need to be eaten during the early stages of rides that will be more than longer than 1 to 2 hours in length to supplement (and thus spare) the body's own glycogen stores. OVERVIEW OF FACTORS AFFECTING DIGESTION AND ABSORPTION (more detail)
  • Before we go any further, let's take a minute to discuss the role of the various parts of your digestive tract. • Mouth - important to begin the mechanical breakdown of food and add some digestive enzymes in saliva • Esophagus - transportation to the stomach • Stomach - further mechanical and enzyme breakdown; no absorption • Small intestine - completes enyzme breakdown and absorption of nutrients • Colon - storage and dehydration of residual from processed food; no absorption of nutrients When designing a nutritional program to supplement the body's energy stores for an athletic event, the rate of digestion and absorption of foods must be taken into account. The time needed for the stomach to start the digestive process, empty its contents into the small intestine, and have the food components absorbed into the bloodstream will directly affect how quickly any food will be available to the muscle to provide the supplemental Calories for exercise. You have some control over four major factors influencing the digestive process. • Solid versus liquid - liquids are emptied from the stomach more quickly than solids. • Fat content of the food - fat slows the digestive process and delays the availability of any Calories in the food to the muscles. • Sugar concentration - especially in liquids, a sugar content of more than 10% will slow stomach emptying. ( The use of complex carbohydrates, due to the decreased osmotic effect, will offset this to some degree and offers an alternative strategy to maximize Caloric intake to offset the metabolic needs of exercise.) • Physical activity level of the cyclist - the mechanical activity of digestion is slowed by any vigorous activity, usually starting at 70% VO2 max. Except in short, all out events, this is rarely an issue, and it is much less so for cycling than for running where the additional component of mechanical stimulation of abdominal contents from the sport itself slows digestive tract functioning. From the above four points, it is easy to see that the optimal food for a rapid, high energy boost during a ride would be a semi-liquid or liquid carbohydrate with minimal if any fat. On the other hand, an endurance athlete, competing at a lower VO2 max., might prefer a complex carbohydrate with some fat added to improve taste (and generally in a solid form), in order to slow emptying from the stomach and even out absorption over a longer period of time. Carbonation does not appear to affect the emptying rate of the stomach. Three independent studies found no difference in the gastric emptying rates of water, carbonated water, and carbonated carbohydrate drinks. Carbonated colas, which contain 160 Calories per 12 ounce can and the caffeine equivalent of half a cup of coffee, remain a favorite drink of many cyclists. EFFECTS OF EXERCISE ON THE DIGESTIVE TRACT Serious athletes often develop gastrointestinal (GI) disorders during training and competition - generally cramps, diarrhea, and nausea (although constipation has been reported). Cramps and diarrhea reflect an overactivity of the lower intestinal tract or colon, and are much more common in runners (and thus triathletes) than in cyclists. A recent survey of triathletes participating in a half iron man event revealed that 50 % complained of belching and flatuence (gas), and more symptoms occurred while running than at other times. Studies have demonstrated a reduced blood flow to the digestive system during vigorous exercise - an 80% reduction after 1 hour cycling at 70% VO2max. And there was a direct relationship in that individuals with the most severe symptoms had the greatest decrease in blood flows. The type of exercise also plays a role, and it is specualted that the mechanical trauma (a jostling effect) to the abdominal organs may explain why runners have more symptoms than
  • cyclists or swimmers. Changes in GI hormone levels have been noted with vigorous exercise, but a cause and effect relationship to symptoms has not been proven. Stress factors are probably more important as a cause of pre competition symptoms such as nausea, vomiting, and diarrhea (which in one study were present in 57% of the participants). Heartburn (or esophageal reflux)is more frequent when exercising within 2 hours of eating. The current feeling is that this increase in reflux is related to a combination of meal effects (especially fats) on the esophageal sphincter pressure (which prevents reflux of stomach contents into the esophagus), the increased volume of food and acid in the stomach available to reflux, and the mechanical jostling that occurs (especially with running). This is usually a minor problem for cyclists and is best handled by delaying exercise after eating or using an antacid of one of the over the counter acid reducing medications such as Tagamet or Zantac. Exercise delays stomach emptying, and the more vigorous the exercise, the greater the delay. Running once again appears to have a greater effect than cycling, presumeably because of the mechanical jostling of the stomach as well as other abdominal organs. In addition to the increase in esophageal reflux (noted above), the delay in stomach emptying can cause a sensation of fullness and nausea as well as limitign the immediate availability of Calories from the food eaten (as will be discussed shortly). In the survey referred to above, there appeared to be an additive effect from a high fat and protein pre event meal and the use of hypertonic drinks before and during the event. 40% of those drinking a hypertonic beverage had severe complaints compared with only 11% of those who had used isotonic drinks. An increase in small and large intestinal activity is the cause of abdominal cramps and is reflected in an increase in the frequency of defecation as well. It has been speculated that there might be changes in digestive hormones associated with exercise which then stimulate the colon. But it is more likely that once again the mechanical factor of jostling the bowel is a more important factor. A fiber rich, pre race meal can also play a role. In a recent post race survey, almost all the triathletes who had eaten a high fiber meal suffered from cramps. Minimizing cramps requires a focus on: • avoiding electrolyte imbalance (including dehydration) • avoiding riding too soon after eating • training at a level closer to your event (the more your event exceeds the maximum levels of your training, the more likely you will develop crampy abdominal pain). Most of these issues are more problematic for runners (and thus triathletes) than cyclists. Except for competitive cyclists, the effects of exercise on the GI tract are minimal. • If heartburn is a problem, timing of the ride to assure an empty stomach needs to considered (and for the competitive rider a 3 to 4 hour fasting period is already the recommendation to minimize a feeling of fullness and nausea). • Slow gastric emptying is generally not a problem for a recreational rider, but those with an especially sensitive stomach should plan to eat their last pre ride meal at least 3 to 4 hours before the ride. Small, frequent snacks while on the bike are recommended for rides of greater than 2 hours, and if it is going to be a vigorous workout, avoiding hypertonic sports drinks is recommended. • Stay hydrated. If you are dehydrated, the stomach will empty more slowly and there will be an accentuation of the decrease in blood flow to the small intestine. • Although some racers will eat a low residue diet for several days before an event to minimize cramps and the "call to stool", this greatly complicates diet planning, and for the rest of us, slowing the pace will usually decrease the urge until a bathroom is located. So let's review the tips to decrease GI problems: • pace yourself - the stomach empties better at <75%VO2max • hydrate - dehydration leads to decreased stomach emptying and nausea
  • • avoid concentrated (hypertonic) solutions • determine which foods work for you on your training rides • eat on your training rides - your digestive tract will adapt to eating while exercising • train - if you are in better shape, more blood will go to the digestive tract at any given level of exertion (additional information - Exercise and the Athlete - Presented at Sun Mountain Lodge 1/2004) ADDITIONAL CONSIDERATIONS IN PLANNING YOUR DIET PROGRAM • Carbohydrate loading • The insulin surge and potential hypoglycemia that is theorized to occur if sugary drinks are taken in the minutes before a competitive event is a potential in sedentary individuals eating sweets, but rebound hypoglycemia does not appear to be a practical problem for athletes. However, choosing to err on the side of caution, most authorities recommend avoiding all simple carbohydrates for the several hours before an event, starting carbohydrate supplementation in the few minutes immediately preceding the start of the activity. • Even though it appears that simple carbohydrates should be avoided in the hour or two immediately preceeding your ride, there is almost unanimous support for the benefits of a pre ride meal of complex carbohydrates 3 or 4 hours before the event. These carbohydrates not only "top off" your muscle and liver glycogen stores, the slow digestion and absorption of the complex carbohydrates may provide an ongoing glucose supplement from your intestinal tract even after the ride has started. And recent studies have demonstrated that using commercial energy bars or a high fat meal offer no performance advantages over a more traditional and less expensive complex carbohydrate such as oatmeal. • Maximizing liquid carbohydrate replacement while riding is a very important strategy for events lasting more than 2 hours. 1 to 2 grams of carbohydrate per minute can be absorbed and utilized to sustain prolonged exercise. In extreme events such as the Tour de France, as much as 50% of the daily energy expenditures can be replaced while on the bike. Although the sugar concentration has an effect on the rate of stomach emptying, the volume of fluid in the stomach plays a role as well. Keeping the stomach filled by frequent drinks will enhance the rate of gastric emptying. As sugar concentration increases, the risk of nausea and bloating rises as well. Almost everyone can tolerate a 7 to 10% concentration of glucose, but many cyclists will tolerate solutions of up to 15% to 20%. And the use of polymers will allow more carbohydrates to be ingested and absorbed while limiting to some degree the overall concentration of the solution. Fluid replacement rates of 500 ml per hour are appropriate for the majority of cyclists during prolonged exercise, but rates of up to 1 to 2 liters per hour have been reported in the Tour de France. The risk here is hyponatremia with the larger volumes. As an example, starting an event with 400 ml of an 18% glucose polymer solution in the stomach and drinking 100 ml every 10 minutes will deliver 108 grams of carbohydrate with 600 cc of fluid every hour. • Take advantage of the " glycogen window" that is open in the 4 hours immediately following vigorous exercise. During this interval, ingested carbohydrate will be converted into muscle glycogen at about 3 times the normal rate (and "the earlier the better" as some data suggests a 50% fall in the conversion rate by 2 hours and a complete return to normal repletion rate by 4 hours). Muscle glycogen repletion (after a 2 plus hour ride) usually proceeds at a rate of 5% per hour, and although it may require up to 48 hours for complete muscle glycogen replacement, most is accomplished during the first 24 hours
  • post event. The athlete who is training daily, or is in a multiday event, can use this glycogen window to their advantage to get a jump on the normal repletion process and minimize the chance of chronic glycogen depletion (and the fatigue that goes along with it). There is also suggestive evidence that the muscle stiffness that occurs after vigorous exercise is related to muscle glycogen depletion, so rapid repletion may have an added benefit of minimizing this day after effect. One caution though - many simple carbohydrate snacks such as chocolate chip cookies are more than 30% fat and if eaten in large quantities might exceed your planned daily fat intake of 20-30% of Calories. In contrast, complex carbohydrate foods such as pasta, bread, and rice offer significantly more carbohydrate per gram or ounce. And there are even special "recovery drinks" available. • Vegetarian diet. A growing number of cyclists are moving toward meatless meals or a completely meat free nutritional program. Not only are vegetarians healthier, with lower rates of chronic diseases such as heart disease, obesity, and colon cancer, but the fact that their diets are high in carbohydrates means they are constantly "carbo loaded". There are a few tips to remember if you are considering a life style change. o Vegans, who eat no animal products whatsoever including dairy, need to be certain they get enough vitamin B12 (from supplements and fortified foods such as cereal, bread, pasta, and brewer's yeast) iron (from beans, kale, dried fruit, and collard greens). Don't use supplements unless recommended by your physician because of the potential toxicity of too much iron. calcium (dark leafy vegetables, brocoli, citrus fruits) o Eat "balanced" protein (because of the mix of amino acids, non meat protein foods need to be eaten in combinations - same meal or in consecutive meals - to have the right balance of amino acid building blocks to allow the body to use them to build and repair tissue). pinto beans and rice grains (rice, bread, cereal) and legumes (peas or beans) o Eat a bit more than if you were eating meat as a protein source. For example a 3 ounce piece of meat contains about 21 grams of protein and is can be substituted with a cup of cooked grain and a cup of cooked beans. OPTIMAL CYCLING DIET Is there an optimum diet for the cyclist?? There is overwhelming evidence that adequate dietary carbohydrates are needed for maximum performance. At least 10 grams per kilogram of body weight per day. What is unclear is whether more carbohydrate (beyond 600 to 700 grams per day) will provide additional benefits.(Note that it is the absolute amount of carbohydrates that appear to be important, not the % of total daily Calories that are carbohydrates). And Fat?? If you are interested in multiday endurance events, there may be some advantage to several weeks of a moderate fat intake equivalent to 30% of total Calories. But there is no evidence this helps in single day, high performance (%VO2max greater than 60%) activities and there may be long term health consequences. As total Caloric needs increase, the only reason to consider a high fat (more than 15 to 20% of total Caloric needs) diet would be maintenance of a positive Caloric balance IF carbohydrates alone were not meeting the challenge. And finally, there is NO evidence tha more than 2 grams per kg per day of protein are beneficial in endurance, sprint, or power training/performance. There are three additional practical points for the cyclist (or other athlete) to remember. First, the body's normal liver and muscle glycogen will support the first 1 or 2 hours of exercise at 70% VO2 max. without any need for supplementation. And both a good training
  • program to improve the form and muscle efficiency of the individual as well as riding (or exercising) at a reasonable pace will postpone the onset of glycogen depletion and fatigue. Second is that taking in carbohydrates during the event provides an additional source of glucose "fuel" that will extend the length of time before the bonk occurs. This becomes important in rides of greater than 2 hours duration. As a general rule, the body can utilize 60 grams of ingested carbohydrate per hour to supplement muscle glycogen stores, and the stomach can handle between one and two quarts of fluid before nausea occurs. This does put an upper limit on carbohydrate supplementation during a ride but gives you some guidelines for developing your own program. And there is no problem in using solid food supplements as well, as long as enough fluids are taken along with them. Finally, eating a high carbohydrate diet for several days prior to the event will maximize your internal glucose (glycogen) stores, and will prolong the duration of activity until fatigue occurs. (But it will not increase the muscle's maximum energy output during that time.) Over the last 10 years there has been a notable interest in ultraendurance events. These include runs of more than 24 miles (ultramarathons), cycling events of 100 miles or more (double centuries), and combination events such as the Ironman triathlon. The principles of training nutrition are similar to those for any athletic event of 2 hours or more, with the exception that attempts to bend the "physiologic rules" outlined above have the potential for a much larger negative effect on preformance. Carbohydrates • dietary carbohydrates (simple/complex, liquid/solid, glycemic index) • fructose • carbohydrate loading (pre ride) • post ride carbohydrate replacement • protein as an aid to carbohydrate absorption • negative effects of carbohydrates Carbohydrates (CHO) provide most of the Calories for normal daily activities, becoming even more important as a fuel source during exercise. Carbohydrtes contain 4 Calories per gram, and provide between 40 and 60% of the Calories in a normal American diet. The basic building blocks of all carbohydrates are single sugar molecules (monosaccharides or simple sugars) made up of 6 carbon units. These can be linked together as complex carbohydrates (made up of multiples of the 6 carbon units). The linking of two monosaccharides results in a disaccharide, while long chains of sugar molecules are referred to as complex carbohydrates or polysaccharides. During digestion, these complex carbohydrates are cleaved into single 6 carbon molecular units, absorbed, and transported to the cells in the blood. These sugar molecules are either metabolized immediately to provide energy for the cell or stored in liver and muscle cells as glycogen to be used for future energy needs. Monosaccharides, the single sugar molecules, deliver energy to the body quickly as they do not need to be broken down (digested) into smaller pieces before absorption takes place. Glucose and fructose are the two most common monosaccharides in our diet. After absorption and transport to the cell, they can be stored as glycogen, a complex carbohydrate polymer of numerous glucose molecules. During training or competitive events, the body draws heavily from muscle glycogen for its energy supply. As glycogen reserves fall, there is an increasing dependence on absorbed glucose circulating in the blood stream. And for recovery, simple sugars (monosaccharides and disaccharides) replenish glycogen stores more quickly than complex carbohydrates. The Caloric value of carbohydrates is dependent on the level of exertion. Almost always exercise is aerobic and there is more than enough oxygen present at the cell level for efficient metabolism to occur. However, when the level of exercise outstrips the ability of the cardiovascular system to
  • provide adequate oxygen for efficient metabolism (one becomes anaerobic) only 1/19 as much ATP will be produced per gram of glycogen (or ingested carbohydrate) metabolized. Besides providing energy, sugars may affect our mood. There is some evidence that eating sugar may stimulate endorphins, and insulin released to help metabolize sugar may modify the amino acid levels in the blood stream resulting in an increase in serotonin in the brain - a chemical which can make you feel calm. DIETARY CARBOHYDRATES - simple vs complex, liquid vs solid Most dietary carbohydrates are in the form of the two monosaccharides sucrose (found in familiar table or cane sugar, apples, bananas, oranges) and lactose (milk sugar found in dairy products), or complex carbohydrates (starches) which are primarily supplied by grains. Before they can be absorbed from the intestinal tract, all disaccharides and complex carbohydrates must first be digested and converted back to a monosaccharide or single sugar form. For many years it was believed that a liquid carbohydrate concentration of 2.5% (glucose or glucose polymer molecules) was the maximum tolerated without slowing stomach emptying and causing nausea. However a recent study in cyclists demonstrated normal gastric emptying with a 6 - 8% solution, and nausea occuring only when concentrations were pushed above 11%. Interestingly, the old standbys, such as apple juice and cola drinks have a sugar concentration of 10% and, although the glucose polymer sports drinks can provide more Calories per quart at the same overall concentration, in controlled studies there has been no demonstrated performance advantage of these complex carbohydrates over simple sugars such as glucose alone. It appears that the major benefit of the polymers is the absence of the sweet taste and nauseating properties of high concentration isocaloric glucose drinks, minimizing this barrier to maintaining a high fluid intake. Along with liquid versus solid and simple versus complex, carbohydrates can also be rated by their glycemic index (GI). The GI refers to the rate at which the carbohydrate is absorbed into the blood stream and available as an energy source to the exercising muscle. Although simple (or one molecule sugars) are the most quickly absorbed, some complex carbohydrates can elevate the blood sugar almost as quickly. FRUCTOSE You will often hear about fructose as an alternative to glucose for the athlete. Fructose is a 6 carbon sugar (hexose) that does not need insulin for its transport into the cell and is preferentially extracted from the blood stream by the liver (versus the muscle cell). Does it have any benefit for the athlete as an energy source? Burelle Y et al (Int J Sport Nutr 1997 Jun;7(2):117-27) looked at the metabolism of glucose versus fructose eaten as a preexercise meal from 180 to 90 min before exercise in 6 subjects. They found that glucose provided more available energy than fructose, and concluded that for a PREEXERCISE meal, glucose should be favored over fructose. Although it does not appear to have any advantage as a preexercise carbohydrate, what about the role of fructose as a glycogen sparing drink during exercise? Massicotte D et al (J Appl Physiol 1989 Jan;66(1):179- 83) compared the oxidation of 13C-labeled glucose, fructose, and glucose polymer ingested (1.33 gm/kg) during cycle exercise (120 min, 50% max O2 uptake) in six healthy male subjects. Oxidation of the ingested glucose and glucose polymer (72% and 65 %, respectively, of the 100 gm ingested) were similar and both were SIGNIFICANTLY GREATER than oxidation of the exogenous fructose (54%). And, as expected, internal carbohydrate utilization was significantly lower with glucose (184g), glucose polymer (187g), and fructose (211g) than with the water (control, 230g) ingestion. Thus it appeared that fructose had no advantage (and perhaps even a disadvantage) to glucose as an immediate carbohydrate energy source and glycogen sparing drink when ingested DURING exercise. This was confirmed by Gautier JF et al. (J Appl Physiol 1993 May;74(5):2146-54). They measured the metabolic fate of fructose in a carbohydrate drink and concluded that when ingested repeatedly during moderate intensity prolonged exercise, fructose is metabolically less available than glucose, despite a high rate of conversion to circulating glucose. Although fructose ALONE has no advantages to glucose ALONE, there was a single study that suggested it was of some benefit when used in combination with fructose in a sports drink. Adopo E et al (Appl Physiol 1994 Mar;76(3):1014-9) studied the effects of a combination 50 gram fructose/50 gram glucose drink compared to a pure 100 gram glucose supplement. The
  • cumulative amount of exogenous carbohydrate metabolized in the combined carbohydrate drink was 21% greater than that observed when 100g of pure glucose alone was ingested. They speculated that this might be related to differing routes for absorption and metabolism of exogenous glucose and fructose, resulting in less competition for oxidation when a mixture of these two hexoses is ingested than when an isocaloric amount of glucose alone was ingested. They concluded that, from a practical point of view, these data may provide experimental support for using mixtures of carbohydrates in the energy supplements for endurance athletes. CARBOHYDRATE LOADING Carbohydrate loading, which traditionally involves avoiding all carbohydrates for several days, then forcing carbohydrates for the 2 or 3 days immediately prior to the event to maximize internal carbohydrate (glycogen) stores is not essential. A high carbohydrate diet alone (without the preceding carbohydrate depletion phase) will provide 90% of the benefits of the full program and avoid the digestive turmoil that the changes in diet that go with carbohydrate depletion and loading can produce. When should one consider using use carbohydrate loading? There are two relevant facts that to remember. First is that there are enough carbohydrates stored in the muscles to support 2 hours of vigorous cycling (which I'll define as cycling at greater than 70 to 80 % VO2max). The other is that as one increases exercise intensity above 50% VO2max, there is a shift from fat metabolism towards carbohydrate metabolism to provide the Calories being expended. Thus if you are planning to cycle for more than 2 hours, carbohydrate loading is a strategy to consider for increasing the time you can cycle at greater than 70% VO2max before "bonking". (Another strategy is to eat carbohydrates regularly from the time you start the ride to supply the Calories being expended and minimize the amount of stored carbohydrate being metabolized.) But the increase in glycogen stores from carbohydrate loading WILL only increase the duration of exercise to the bonk, NOT increase maximum performance (VO2max) during that time interval. I recently received this question; "Should I use the carbo loading technique if I'm overweight by let say 20 lbs.? What will help my body to burn it's own fat to use for energy?" As being overweight is mainly an issue of total body fat stores, and has very little to do with carbohydrate stores, the answer is that anyone, of any weight, who wishes to prolong exercise at 70 to 80% or more of VO2max beyond 2 hours can benefit from carbohydrate loading. On the other hand, if the intent is just to lose weight, not improve performance, one should actually be carbohydrate depleted, forcing the body to draw on fat reserves for the Calories burned rather than the usual combination of carbohydrate and fat stores. There has been some controversy as to what constitutes a high carbohydrate diet. It is not uncommon to see comments that as much as 60 to 70% of an athlete's total Calories need to be carbohydrate Calories to maximize performance. But as an Calories expended in training increase, it is more and more difficult to replace expended Calories with a diet of more than 50% carbohydrates. And fat, at 9 Cal/gram, is needed to avoid weight loss. So what is the answer?? Perhaps it is better to look at the total grams of carbohydrate eaten per day rather than the percentage of total diet as carbohydrates. We know that you will replace almost 100% of your muscle glycogen with 10 grams carb per kg body wt eaten over 24 hours. So as long as you get your 600 or 700 grams, the remainder of the 24 hour diet can be filled out with fat and protein. And as total Caloric needs increase, fat will help you maintain weight (stay in Caloric balance) while the 600 to 700 grams of carbohydrate per 24 hour base will prevent chronic muscle glycogen depletion. A recent Canadian study suggested that the carbohydrate loading effect might be sex specific as a group of men increased their time to exhaustion by 45% while the comparable women's group had no change. They speculated that women may rely more on fat than glycogen for their energy source. POST RIDE CARBOHYDRATE INTAKE In the 2 to 4 hours immediately post ride, orally ingested carbohydrates will be converted into muscle glycogen at 3 times the normal rate - and the earlier the better as some data suggests a 50% fall in the repeltion rate by 2 hours and a return to a normal repletion rate by 4 hours. Smart nutritional training will take advantage of this window of opportunity. PROTEIN AND CARBOHYDRATES
  • There is some evidence that protein may help the absorption of carbohydrates in the immediate post ride window (several hours) that maximizes glycogen repletion in the muscles. But the most important part is not the protein, but maximizing carbohydrate intake during this time. A recent study (J Appl Physiol 2001 Aug;91(2):839-46) looked at glycogen resynthesis rates in eight male cyclists who performed two experimental trials separated by 1 wk. After glycogen- depleting exercise, subjects received either CHO (1.2 gram/kg/hour) or CHO+Pro (1.2 g CHO/kg/hr + 0.4 g Pro/kg/hr during a 3 hour recovery period. Muscle biopsies were obtained immediately, 1 h, and 3 h after exercise. Although there had been prior reports of increased glycogen synthesis with protein supplements when 0.8 gm CHO/kg/hr were studied, using this larger CHO intake did NOT result in increased muscle glycogen synthesis. Again, the amount of carbohydrate is the key to maximizing glycogen repletion. Can I substitute protein for carbohydrates in my training program? The simple answer is no. Although protein is necessary in a balanced training diet, inadequate carbohydrate and Caloric intake to meet the energy requirements of your regular daily training will lead to glycogen depletion and the risk of chronic fatigue.Go high protein/low carbohydrate and you'll be chronically bonked. NEGATIVE EFFECTS OF CARBOHYDRATES Tooth decay is a proven hazard. Eating simple sugars can cause wide swings in the blood sugar level as the body releases insulin to promote cell uptake and metabolism. These swings may: • promote the development of body fat stores • stimulate appetite and increase food cravings. • cause a dip in blood sugar and a psychological and physiological "crash" during your ride. THE BOTTOM LINE Pay attention to how sugar affects you and your riding. Do you physiologically "crash" a half hour after your sugar snack? If so, try these tips: • Don't eat pure sugar by itself. Eating a meal or snack that contains complex carbohydrates, proteins and fats may even out the swings. • Try fructose (honey, corn syrup) for energy. It does stimulate less insulin release than glucose. • If you miss the good feelings of something sweet in your mouth, try a sugar free candy. There is some evidence that even a sugar free sweet may, as a response to the taste alone, trigger endorphin release. • TRY COMPLEX CARBOHYDRATES (breads, rice, potatoes) which are digested more slowly. • Consider trying a complex carbohydrate drink on your ride, starting as you begin the ride and then drinking regularly every 15 to 20 minutes while on the bike. Either glucose alone or a combination of glucose and fructose. Bottom line: Go for that simple sugar snack if it's a quick burst of energy you need, but for sustained energy eat a bagel or other complex carbohydrate. Glycemic Index Carbohydrates as a food group are the backbone of the athlete's nutritional program. However, all carbohydrates are not equal (interchangeable) in their digestion, rate of absorbtion, and thus potential effect on the athlete's performance. Simple carbohydrates (single sugar molecules) are
  • rapidly emptied from the stomach, rapidly absorbed into the blood stream, and rapidly available to power the exercising muscle. But they also have the greatest potential to stimulate an insulin surge and reactive hypoglycemia. Although it has traditionally been taught that complex carbohydrates (single molecules of multiple simple sugar units chemically linked together) are digested and absored more slowly, producing a flatter and more sustained blood glucose level and a less intense insulin response (minimizing reactive hypoglycemia) this is not always the case. The glycemic index (G.I.) is a numerical system which measures how quickly an ingested carbohydrate triggers a rise in the circulating blood glucose level as compared to pure glucose -- the higher the number, the greater the blood sugar response. The GI ranks foods on a scale of 0 to 100 (with 100 being equal to pure glucose). All else being equal (liquid, non fat), the glycemic index will identify on the best, quick energy supplement for a competitive ride. The higher the GI, the quicker the energy boost. This discrepancy was first noted by diabetes specialists who were amazed to find that simple carbohydrate foods did not always produce the high and short-lived blood glucose responses traditionally attributed to them. For example, fruit and sweetened dairy products produced a relatively flattened blood glucose curve, sugar (sucrose) has a medium blood sugar profile, and some foods high in complex carbohydrates such as bread and potatoes actually produced a relatively rapid blood glucose response. Even dietary fiber does not necessarily delay absorption and flatten the blood glucose curve - blood glucose levels after eating whole-grain breads are similar to those after white bread. What is very clear is that there is no way to predict blood glucose responses (and the GI) from specific foods without actually measuring the response. Tables with specifics for different carbohydrates are available on the WWW. Understanding the variable effect of different carbohydrates on blood glucose levels gives us a tool to help advise those who need to closely control their blood glucose profiles with diabetics being a classic example of a population that benefits from tight control of blood glucose levels. Patients with high blood lipid levels also benefit from a more even blood glucose profile during the day. And the glycemic index has been proposed as a useful tool in weight control based on the observation that low GI foods seem to produce a longer lasting, satiated feeling after meals. Some athletes and coaches have speculated that altering the GI of the training diet or pre race meal might influence their performance with a low GI pre race meal conferring an advantage (less insulin surge and blood sugars remaining elevated over a longer period of time post meal). However, controlled studies have failed to demonstrate any advantages of a low compared to a high GI pre-race meal. A recent study attempted to blend sports nutrition guidelines with the real-life practices of competitive athletes. Six well-trained cyclists (average maximum oxygen uptake of 68 ml/kg/min) performed three trials in which they consumed a different pre-race meal two hours before undertaking an exercise test. The three test meals consisted of a high GI carbohydrate meal (mashed potatoes topped with pasta sauce), a low GI carbohydrate meal (pasta topped with the pasta sauce), and a placebo or control meal (subjects ate low-calorie jelly, believing it to be a new "sports jelly"). The cyclists rode for two hours at 70% of their maximum oxygen uptake, equivalent to marathon pace or about 80% of maximum heart rate. During the ride, blood and breath samples were collected to determine which food groups they were burning. And at the end of the two hours, the cyclists did a time trial lasting approximately 15 minutes. Fifteen minutes before starting their time trial, the cyclists consumed about 300 ml of a sports drink. Then, throughout the two hours of steady riding, they continued to take regular drinks of this carbohydrate mixture. In total, they drank about 700 ml per hour of the sports drink, taking in the recommended carbohydrate intake of about 60 g each hour. This study demonstrated that the intake of carbohydrate supplements during prolonged, moderate intensity exercise, met the energy needs of the athletes for the endurance test. Furthermore, use of supplements appeared to override any metabolic or performance effects due to the GI of the pre-event meal. These results suggest that in endurance events, athletes needn't worry about the glycemic index of the pre race diet, if they consume adequate amounts of carbohydrate drinks or foods during the endurance exercise events. Thus they can choose their pre-exercise menu based on personal preferences and previous experiences.
  • Lets summarize the current feeling about using the Glycemic Index to develop a training or exercise diet plan: 1. There is insufficient evidence to support the concept that athletes will benefit from eating low GI carbohydrate meals prior to prolonged exercise, if they use carbohydrate supplements during the ride. They should let practical issues and individual experience guide their choice of the pre-event meal. 2. A limited number of individuals may benefit from a low GI pre-event meal. Those athletes that show an exaggerated and negative response when they eat carbohydrate foods in the hour immediately before exercise (perhaps the 5% of the population that experience rebound hypoglycemia or blood sugar drop) may benefit from low GI foods. And during unusual endurance sessions, such as open water swimming, where practical difficulties prevent the athlete from consuming carbohydrate supplements during the session, the pre-event meal may have greater bearing suggesting that the slower absorption and release of glucose from a low GI carbohydrate meal might sustain blood glucose and enhance performance. 3. Athletes performing prolonged exercise should focus on maintaining adequate carbohydrate supplementation during the event. Which carbohydrate drink or food depends on their previous experiences, the logistics of the event, gastrointestinal tolerance, and the requirements for fluid replacement. A glucose-based sports drink with a moderate to high GI would seem to make the most sense to get the carbohydrate energy to the muscles quickly. 4. Assuming adequate carbohydrate intake, moderate and high GI carbohydrate foods would seem logical choices for glycogen repletion after exercise compared to low GI foods. 5. Other aspects (tasty, portable, cheap, easy to prepare and unlikely to cause stomach upsets) may outweigh the GI in making diet choices. These will be specific to the individual and the exercise situation. Fats Fats provide between 20 and 40% of our daily Calories in the average American diet. Approximately 95% of dietary fat is triglycerides, fats composed of a glycerol molecule and three fatty acid (FA) molecules. Cholesterol and phospholipids make up the other 5%. Cholesterol and phospholipids are essential building blocks for cell growth, while triglycerides are used primarily as a source of energy. Fats are an important energy source for the endurance cyclist, providing more than 50% of the Calories for activities performed at less than 50% VO2 max. As the level of exertion increases, the percentage of Calories provided by triglycerides decreases to the point that they play only a minor role as an energy source in short distance, maximum performance events (90 to 100% VO2 max). Almost all fat digestion occurs in the small intestine where these triglycerides are cleaved into their component molecules - glycerol and fatty acids. The fatty acid molecules are then transported through the blood, diffuse through cell membranes throughout the body where they are either directly metabolised as an energy source or reconstituted into triglycerides for storage, mainly in fat cells. (Excess carbohydrates in the diet are also converted into triglycerides for storage in the same cells). Barry Sears in The Zone has suggested that a diet composed of at least 30% fat Calories, 30% protein Calories, and only 40% carbohydrate Calories will improve competitive aerobic performance compared to the athlete's traditional high carbohydrate diet - which is relatively fat restricted with less than 20 to 25% total Calories as fat. Although various arguments have been put forward, such as: • no insulin release with fats and less insulin released with a low carbohydrate diet, so no worries about hypoglycemia,
  • • a "genetic" need to have a caveman (high meat and low carbohydrate) diet means a relative carbohydrate intolerance and inability to use a high carbohydrate diet effectively, • and a need to eat fat to keep the "fat burning" metabolic cell processes active, there is no scientific proof that eating a high fat diet improves high VO2 performance above that of an equal Caloric diet that is low in fat, and it has been suggested that any improvement is probably a placebo effect from that sense of well we all notice after eating foods containing a higher percentage of fat (assumed to be from their improved taste). There have been two well controlled studies demonstrating that high fat diets (70% fat in one, 38% in the other) increased the exercise to exhaustion time for activities performed at a moderate rate of 50% VO2 max (80 vs 42 minutes of cycling in one, 76 vs 70 minutes of running in the other). Glycogen sparing effects were studied to determine if there was a preferential shift to fat metabolism during exercise, but none were found. A third study tracked Calorie replacement after exercise in two groups (one on a low fat diet and the other eating normal and high fat foods) and found that those on the low fat diet did NOT replace the Calories they had expended during their training program while those on a more liberal fat diet did, suggesting that poorer performance on a multi day low fat diet might be the result of a cumulative Caloric deficit (during the training program) leading to limited muscle glycogen stores at the start of the event rather than to an intrinsic advantage of fat over carbohydrates as a primary energy source for the exercising muscle. The message to be carried away is, once again, one of moderation. Fats are OK, and indeed useful if they are eaten in a balanced diet that encourages adequate Caloric intake for the athlete in training. But there is no proof that, carbohydrate intakes being equal, pushing a high fat diet offers any additional performance advantages. A number of physiologic studies have proven that fat CANNOT sustain high level (80 - 100% VO2 max.) aerobic and anaerobic activity (remember that the cause of the "bonk" is a shift towards fat metabolism as glycogen stores are depleted), and that a high carbohydrate diet is best for replacing glycogen stores post exercise (a chronic deficit in replacing carbohydrates has been proven to lead to chronic fatigue). Recently a very nice study once again demonstrated that CHO, not fat, is necessary for maximum performance. Seven trained athletes (in a cross over study) rode for 2 hours at 65% VO2 max to deplete muscle glycogen stores (proven by biopsy before and after the 2 hour ride). They then ate an equal Caloric diet which was high CHO (83% CHO, 5% fat) or high fat (16% CHO, 68% fat) for the next 24 hours. Muscle biopsies were again done at 24 hours and demonstrated that the high carbohydrate diet had replenished 93% of the muscle glycogen vs only 13% for the high fat diet, and also that muscle triglycerides were 60% higher in those on the high fat diet. THEN they all cycled at their maximum self paced rate (time trial level of 75 - 80% VO2max) until they had completed a set amount of work (1600 kJoules). The high fat group could not maintain their VO2 and slowly dropped to 55% VO2max while the high carohydrate group maintained at 75 - 80% throughout the ride. And the high carbohydrate group finished at 117min vs 139min for the high fat group - almost 20% better in terms of time. This study clearly demonstrates that fats do NOT replete muscle glycogen, and it is muscle glycogen that limits maximum performance. Thus fats cannot replace CHO in rebuilding glycogen stores during a training program, and as fats are quite effective in quelling hunger and replacing carbohydrate Calories in the diet, athletes on a high fat training diet run the risk of chronic muscle glycogen depletion and poor performance. A final question has to do with the role of fats in the 4 hour period immediately preceeding the event. If the training diet has maximized muscle glycogen stores, it appears that a 4 hour pre race meal high in fat is equivalent to one that is high in carbohydrates for endurance activity at 50 to 60% VO2max. This has not been studied for high VO2max events, but at this time there is no evidence that fats offer any advantage to carbohydrates in the 4 hour prerace interval. What can one take away about fats for training and endurance? • muscle glycogen stores are a key to maximum performance at>80%VO2max o fats are not a substitute for carbohydrates in repleteing those muscle stores
  • o adequate Caloric intake during training is key to optimizing muscle glycogen stores • fats may extend performance at moderate levels of activity (50%VO2max) • IF there are optimum muscle glycogen stores, there is no advantage to a high fat content of the 4 hour pre event meal In terms of overall health, several decades of research and clinical studies have led the US Surgeon General and numerous other health authorities to recommend a diet that is higher in carbohydrate, lower in fats, and rich in fruits, vegetables, and whole grains. Such a diet is associated with a lowering of the risk of major chronic diseases including hypertension, atherosclerosis and heart disease, and certain cancers. As the negative effects of a high fat diet on health are well accepted, carbohydrates are clearly superior to fats for high intensity events (both for training and on event day), and fats may AT THEIR BEST be equal to carbohydrates for lower intensity, endurance events, there is no reason to emphasize fats in a training or day of event dietary program. And for those who still aren't convinced, it should be remembered that even the leanest athlete has plenty of stored fat available (approximately 100,000 Calories worth in a 70 kg male) without any need for diet supplements. A variation on this theme is reflected in fat containing energy bars which are alleged to improve performance by SELECTIVELY increasing fat metabolism. While there has been some evidence that an occasional long slow recovery ride in your training program MIGHT improve the ability to metabolize or use stored fat Calories for muscle energy, there is no scientific basis for the claims made by these products that eating any particular food or food type (i.e. fat) will enhance fat metabolism. An alternative to eating more fat would be to focus on a training program that stresses more miles at a relatively slow pace (60% VO2 max.) to improve the muscle cells ability to use internal fat stores. Another variation on this theme is to avoid carbohydrates in the pre ride meal, and minimize carbohydrate snacks while on that long slow ride to "force" the development of metabolic pathways that use fat energy (a planned "bonk' if you will). Then, or so goes the theory, when it comes time for that sprint at the end of a competitive event, now ridden with appropriate glucose supplementation during the ride and using more of you fat stores for muscle energy along the way, there will be more muscle glycogen remaining to give you the edge. TYPES OF FAT (vegetable vs animal - saturated vs non saturated) Protein Protein is used to repair cell injuries (muscles particularly) from the microscopic trauma that occurs with exercise. It is NOT a good energy source, and serves that purpose only in malnourished states. Even in endurance activities such as the Tour De france, protein needs of 1.5 gms protein/kg body wt/day were easily met by a normal (read unsupplemented) diet that replaced the total Calories used each day. All protein molecules are composed of building blocks called amino acids. Most protein digestion occurs in the small intestine where protein molecules are first split into their component amino acids which are then absorbed by the intestinal lining, transported via the circulatory system, and taken up by cells throughout the body. These amino acids are then used to rebuild cell proteins. Any excess protein in the diet is transformed (metabolised) into carbohydrates (gluconeogenesis) or fat. Protein itself is not stored in the body which means cell repair occurs from protein eaten that day or from amino acids released as protein is broken down elsewhere in the body. HOW MUCH PROTEIN DO YOU REALLY NEED?
  • A team of researchers from Kent State University, Ohio, and McMaster University, Ontario, led by Dr. Peter Lemon studied a group of 12 male subjects during two months of resistance training. They found that a protein intake of 81 grams per day (0.99g per kg of bodyweight for a 180 lb male) resulted in a negative nitrogen balance. Nitrogen balance is a measure of protein metabolism. A negative nitrogen balance indicates that the protein needs of the body are not being met and protein is being scavanged from tissue elsewhere in the body to maintain essential body functions. This may lead to reduced gains in muscle mass and strength. Can you eat too much protein? This group also found that protein intakes above 2.62 grams per kg of bodyweight (214 grams for a 180lb male) provided no additional benefit in terms of nitrogen balance and increased the risk of renal overload and dehydration. Long term studies of large groups show that a high protein/low carbohydrate diet increases the risk of kidney stones and bone loss. These findings were substantiated by a University of Texas study of 10 volunteers on a high protein/low carbohydrte diet for two weeks. Blood uric acid levels (uric acid is a major cause of kidney stones) rose 90% and urinary levels of citrate (which inhibits kidney stone formation) dropped 25%. And finally, any extra protein Calories (beyond what you are expending per day) are stored as fat, not muscle. Protein is essential for endurance athletes as well as to aid muscle development. As far back as 1983, scientists demonstrated that two hours of exercise can drain the body of essential protein stores. Based on their findings, Dr. Lemon makes the following recommendations for protein intake for strength and endurance athletes: • Strength - 1.6-1.7 grams of dietary protein per kg of bodyweight • Endurance - 1.2-1.4 grams of dietary protein per kg of bodyweight The average 70 kg (154 pound) cyclist will need from 80 to 100 grams of protein per day. And for those at the elite level, the requirement may be as high as 1.7 grams of protein per kgm (120 grams for the ideal 70 kg rider). And as active athletes consume more daily Calories, a balanced diet without supplements will meet these increased needs. A literature review failed to find any support for protein supplements (assuming a balnaced daily diet with the normal distribution of protein intake) compared to a pure carbohydrates diet alone. In fact there is the potential for a DECREASE in overall performance from the appetite suppressing effects of a high protein diet which results in a decrease in carbohydrate intake and diminished pre event muscle glycogen stores. SOURCES OF PROTEIN Lean beef, skinless chicken, and fish will provide about 7 grams of protein per ounce. Beans will provide 6 grams per 1/2 cooked cup, and rice (and other cereal grains) about 3 grams per 1/2 cup serving. A cup of milk or yogurt supplies 8 grams of protein. So it's relatively easy to meet your basic protein requirements from 6-8 ounces of meat, 2-3 servings of dairy products, and 6-10 servings of cereal per day. A HIGH PROTEIN DIET (THE ZONE DIET) The ZONE is basically a Calorie restreicted, high protein diet used to facilitate weight loss. It has also been proposed as a nutrition strategy to improve athletic performance, reduce body fat and increase muscle mass. It recommends consuming 40% of your daily Caloric intake in the form of carbohydrate, 30% as protein, with fat making up the other 30%. An analysis should give us some insight into the effects of a high protein diet. If you are a 60 kg (132 pound) cyclist requiring 3000 Calories per day for your training program, a recommendation of 1.5 grams would translate into 90 grams of protein or 10-12% of your overall Calories (there are 4 Calories per gram of protein). However to reach 30% protein, you'd need to consume a massive 225 grams.
  • Here's what you'd need to eat each day: • 1 cup cottage cheese-----28 grams • 1 can (3oz) tuna fish----22 grams • 3 glasses milk-----------24 grams • 8 ounces lean beef-------66 grams • 1 cup kidney beans-------13 grams • 1/4 cup peanut butter----32 grams • 1 chicken breast---------27 grams • 3 egg whites-------------12 grams • TOTAL-------------------224 grams However, Dr. Sears doesn’t start with your Calorie needs (remember this is a Calorie restricted diet). He starts with your weight and then calculates you protein requirements. Dr. Sears recommends consuming between 0.8 and 1.0g of protein per pound of lean body mass. For an individual weighing 180lb, daily protein intake would work out between 127g and 158g per day. As he recommends that protein represent 30% of daily caloric intake, daily fat consumption (30% of Calories) works out to be 70g, and carbohydrate (40%) is 211g. The daily energy content of the Zone diet for this 180lb individual is approximately 2106 Calories. And that is how it helps you lose weight - the total Calories consumed using this approach is much less than an active athlete needs. What are the problems with the Zone diet diet for an athlete? As just pointed out, the recommended carbohydrate intake for our 180lb rider was 211g of carbohydrate per day. Such a recommendation is in sharp contrast to the majority of scientific research which proves the need for adequate carbohydrate to support maximal physical performance. For example, a recent study compared the effects of different levels of carbohydrate intake on the performance of two Swedish ice hockey team. Both teams took part in two games separated by three days. During this three-day gap, the players were assigned to one of two groups. The first group consumed a normal mixed diet that provided around 40% of energy from carbohydrate. Group two had their diet supplemented with extra carbohydrate. Energy from carbohydrate in the second group represented 60% of total energy intake. The study clearly showed an improvement in physical performance in the high carbohydrate group. Simply put, a diet containing only 40% of its calories from carbohydrate was insufficient to meet the energy needs of elite athletes. The Zone diet's recommendations for daily protein intake are a little closer to the mark. The amount of protein required by those participating in regular exercise sessions remains a topic of considerable debate. Nevertheless, there is research to show that both endurance and strength exercise increase protein requirements. But the Zone diet can accelerate fat loss. While it does not provide enough energy to meet the needs of a competitive athlete, it does restrict Calories and its emphasis on high levels of protein may also serve to enhance fat loss. A recent Danish study, published in the International Journal of Obesity, compared the effects of a high protein and a high carbohydrate diet on weight loss. A group of 60 subjects followed a restricted Calorie diet for six months. The participants were assigned to either a high carbohydrate or high protein diet. Those on the high protein diet consumed approximately 24% of their Calories from fat, 46% from carbohydrate, and 29% from protein. The diet for subjects on the high carbohydrate diet consisted of 28% from fat, 59% from carbohydrate, and 12% from protein. Scientists found that the high protein group lost almost twice as much fat as those on the high carbohydrate diet. Notice the similarity between the nutrient distribution in the high protein diet (46/29/24) and the recommendations in the Zone diet (40/30/30). The group following the high protein diet consumed 11.3 Calories for every pound of bodyweight each day - similar to the 11.7 Calories per pound of bodyweight suggested by the Zone diet. After analyzing the dietary intake of the groups, the research team realized those on the high protein diet had eaten less food. This accounted for the greater weight loss. There were several possible explanations for this reduction in food intake. Protein has a higher satiating (pronounced effect than carbohydrate. In other words, you feel less hungry when consuming a diet high in
  • protein. And a high protein intake seems able to suppress the following days energy intake to a greater extent than carbohydrate. The bottom line - The Zone diet is essentially a restricted calorie diet. For individuals wanting to lose body fat, there is no reason why the Zone diet would not prove effective. However it is unrealistic to expect that athletes will experience any significant improvements in performance as a result of the Zone diet. The recommendations for both carbohydrate and Caloric intakes are not sufficient to meet the energy requirements of regular daily training.Go high protein/low carbohydrate and you'll be chronically bonked. WHAT ABOUT PROTEIN SUPPLEMENTS TO A NORMAL DIET? In his review of the literature (original abstract) on dietary protein supplements, Dr. Richard B Kreider PhD (Department of Human Movement Sciences & Education, The University of Memphis, Memphis, Tennessee 38152. Email: kreider.richard@coe.memphis.edu) concluded that "dietary supplementation of protein beyond that necessary to maintain nitrogen balance does not provide additional benefits for athletes." Here is an excerpt of his review: BACKGROUND. Protein and amino acids are among the most common nutritional supplements taken by athletes. This review evaluates the rationale and potential effects on athletic performance of protein, purported anabolic amino acids, branched-chain amino acids, glutamine, creatine, and hydroxymethylbutyrate (HMB). LITERATURE. Two books, 61 research articles, 10 published abstracts, and 19 review articles or book chapters. FINDINGS. Dietary supplementation of protein beyond that necessary to maintain nitrogen balance does not provide additional benefits for athletes. Ingesting carbohydrate with protein prior to or following exercise may reduce catabolism, promote glycogen resynthesis, or promote a more anabolic hormonal environment. Whether employing these strategies during training enhances performance is not yet clear. There is some evidence from clinical studies that certain amino acids (e.g., arginine, histidine, lysine, methionine, ornithine, and phenylalanine) have anabolic effects by stimulating the release of growth hormone, insulin, and/or glucocorticoids, but there is little evidence that supplementation of these amino acids enhances athletic performance. Branched- chain amino acids (leucine, isoleucine, and valine) and glutamine may be involved in exercise- induced central fatigue and immune suppression, but their ergogenic value as supplements is equivocal at present. Most studies indicate that creatine supplementation may be an effective and safe way to enhance performance in intermittent high-intensity exercise and to enhance adaptations to training. Supplementation with hydroxymethylbutyrate appears to reduce catabolism and increase gains in strength and fat-free mass in untrained individuals initiating training; as yet, limited data are available to decide how it affects training adaptations in athletes. CONCLUSIONS. Of the nutrients reviewed, creatine appears to have the greatest ergogenic potential for athletes involved in intense training. FURTHER RESEARCH. All supplements reviewed here need more evaluation for safety and effects on athletic performance. Potential risks of excessive dietary protein or protein supplements include: • skimping on the carbohydrates needed for muscle glycogen repletion (risking the development of chronic fatigue) • dehydration • potential kidney damage over time • and excessive bone loss (as protein increases urinary calcium loss). THE BOTTOM LINE Protein is necessary for the active athlete, but more is not necessarily better. And this is especially so if you replace total Caloric needs with protein at the expense of carbvohydarates.
  • BEVERAGES/FLUIDS Although water does not provide Calories, adequate fluid intake and hydration is at least as important as Calorie replacement in maximizing your athletic performance. The single biggest mistake of many athletes is their failure to replace their fluid losses during training and competitive events. And this is especially true in cycling where evaporative losses are significant and can go unnoticed even though sweat production and loss through the lungs can easily exceed 2 quarts per hour. To maximize your performance, it is essential that fluid replacement begin early and continue throughout a ride. A South African study comparing two groups of cyclists (one rehydrating, the other not) exercising at 90% of their maximum demonstrated a measureable difference in physical performance as early as 15 minutes into the ride. Fluid losses during exercise result in a decrease in the circulating blood volume as well as the water content of the muscle cells. And the impact on performance is directly related to the level of hydration (or dehydration). Unreplaced water losses equal to 2% of body weight impact heat regulation, at 3% there is a measurable decrease in muscle cell contaction times, and when fluid losses reach 4% of body weight there is a 5 to 10% drop in overall performance which can persist for up to 4 hours after rehydration takes place. Thus it is essential to anticipate and regularly replace fluid losses. Maintaining plasma volume is an important strategy to optimize your physical performance. For those who practice the philosophy "if a little is good, a lot is better", it should be mentioned that there are risks associated with overcorrecting the fluid losses of exercise. There have been reports of hyponatremia (low blood sodium concentration) leading to seizures in marathon runners who over replaced sweat losses (which contain both salt and water) with electrolyte free water alone. This is rarely a problem for cycling events of less than several hours duration (except under extreme environmental conditions of heat or humidity) and becomes an issue only for events lasting more than 5 hours. Under normal conditions, you should be drinking a minimum of 4 to 5 ounces of fluid every 15 minutes and should aim for 1 to 2 standard water bottles per hour. When extreme conditions of heat and humidity are anticipated, the following strategy may be of additional benefit: • drink 20 oz of cool water 2 hours before exercise • 8 to 16 oz 30 minutes before • and then 4 to 8 oz every 15 minutes on the bike If you want a simple measure of the effectiveness of your personal hydration program, weigh yourself before and after a long rides (without clothes to avoid inaccurate weights from sweat soaked clothing). A standard water bottle (20 ounces) weighs about 1 1/4 pounds or a pound of weight equals 16 ounces (1 pint) of fluid. This can help you to tailor YOUR OWN replacement program. Additional tips: • Hydrate before, during, and after the ride - force yourself to drink as thirst alone will not reflect complete rehydration, so learn to drink before you are thirsty. Using a CamelBak or similar device on long rides will eliminate worries about stopping and possibly losing your group. Watch the color of your urine, if you are doing a good job on replacement it should be colorless. • Don't skimp when using a sports drink - don't assume that because they contain electrolytes and carbohydrates you don't need to drink as much. And the sweet taste often keeps you from drinking, so take an extra bottle of plain water to alternate. • Keeping liquids cool has been shown to increase intake on a ride - either add ice the day of the ride or freeze half a water bottle of fluid the night before and top it off with water from the tap or extra sports drink just before the race. • Weigh yourself before and after the ride - most of your weight loss will be fluid (2 pounds equals 1 quart or "a pint's a pound"). A drop of a pound or two won't impair
  • performance, but any more and you need to reassess your personal hydration program. A gain of more than 1 or 2 pounds suggests you are compensating. • Wear the right clothing - light colored to reflect heat; a loose weave jersey; shorts made of one of the new "wicking" materials. • Wear your helmet - modern well vented helmets funnel the wind onto your head and are actually cooler than your bare head, and the helmet material can act to insulate your head from the heat of the sun's rays. Do electrolyte drinks (those containing minerals such as sodium and potassium) provide an advantage over pure water alone? Not for rides of 1 to 2 hours. When two groups exercised for 2 hours at 67% VO2 max (with average fluid losses of 2300 ml) there was no advantage to rehydrating with electrolyte drinks versus water alone. But as large volumes are needed for rehydration in long events, palatability and digestive tract tolerance are important in the selection of your replacement fluids. And for some riders electrolyte drinks are easier to consume. For longer rides, especially over 5 hours in durtion (100 miles) or in conditions of extreme heat and humidity, using electrolyte containing sports drinks for sodium replacement helps to prevent dilutional hyponatremia. How about carbohydrates? Two hours is the point at which carbohydrate supplements will consistently improve your performance by supplementing your internal glycogen stores. Cyclists can drink large volumes while competing and in extreme events, such as the Tour de France for example, competitors have been able to replace up to 50% of their energy expenditures drinking 20% carbohydrate solutions at a rate of 2 to 4 quarts an hour. If you'd like, you can calculate your exact Caloric replacement needs based on the duration and average speed of you ride. For a rough estimate, you need approximately 1/3 gram of carbohydrate per pound of body weight per hour to replace Calories expended. Certain carbohydrate containing liquids are more quickly emptied from the stomach and thus the sugar they contain more quickly absorbed into the bloodstream to be delivered to the muscles as an energy alternative to muscle glycogen. Drinks using glucose polymers can deliver additional Calories per ounce of fluid while remaining iso-osmotic) . The temperature of replacement fluids MAY impact the rate of stomach emptying - colder liquids empty more slowly and increase the potential for nausea and delay in getting the electrolytes, water, and glucose into your system. On the other hand, in ceratin situations, cooler fluids may be more palatable and help to keep you cool (a positive for a ride in extreme conditions). The balance point for drink temperature depends on your personal physiology and the ride conditions, so no absolute recommendations as to the "best" temperature can be made.The same considerations apply to post ride drinks. If you are under time constraints to get back to work, a cool fluid can help you cool down more quickly and cut down your "sweat time". NO studies have confirmed a benefit of fruit drinks (which contain fructose) over glucose drinks. Although fructose requires less insulin to enter muscle cells, it does not appear to provide a performance advantage for cycling. Taste alone is the only advantage. For many years it was believed that a 2.5% concentration of glucose or glucose polymer molecules was the maximum tolerated without delaying gastric emptying and causing nausea. However a recent study, in cyclists, demonstrated normal gastric emptying with 6 to 8% solutions, and nausea occurred only when concentrations were pushed above 11%. The old standbys - apple juice and cola drinks - have a sugar concentration of around 10%. Although glucose polymer sports drinks can provide more Calories per quart (concentration being equal) studies have failed to demonstrate a performance advantage of complex carbohydrate drinks over the simple sugar drinks alone (assuming the same total Calories were ingested. The advantage of the polymers is the absence of a sweet taste and nauseating properties of high concentration glucose drinks, which can be a barrier to maintaining an adequate fluid intake. The stomach does have volume limits which for most riders is around 800 ml (approximately 1 quart). this is particularly the case when pushing aerobic limits (gastric emptying diminishes as exercise approaches 100% VO2 max). If larger volumes are forced, nausea and abdominal distention can result. For reference, a regular water bottle is 1/2 quart, 16 ounces, or 480 ml.and the large ones are 3/4 quart. You should be able to drink at least 2 bottles per hour.
  • In summary, drinking 1 to 2 quarts per hour of plain water is adequate for rides of 1 1/2 to 2 hours. For longer rides, where the body's glycogen stores will be depleted, carbohydrate containing fluids take on increased importance (glucose containing liquids can deliver Calories from the mouth to the muscles in as little as 10 minutes as compared to solid foods and energy bars which empty more slowly from the stomach). In most individuals, an 8 to 10 % concentration is the optimal. Glucose polymers provide the ability to increase total Calories per quart without risking the side effect of an unpalatable, sweet taste. Aside from palatability, there is no proven advantage over simple sugar (glucose) drinks. Although there are many commercial drinks available, the old standbys such as apple juice and cola drinks are probably the least expensive per Calorie provided. In the pre and post ride period, the high Calorie, easily absorbed, glucose polymer sports drinks do offer an advantage for rapidly building (or restocking) glycogen stores.For those of you interested in saving a few $$, take a look at this site for some ideas on homemade energy drinks. For longer rides, don't forget the risks of overdoing rehydration with pure carbohydrate (electrolyte free) drinks alone. If you plan to ride more than two or three hours, it's worth considering a commercial electrolyte containing drink, and if you are going to be riding 5 hours or more, it is essential to pace your fluid replacement rate (and keep an eye on your weight during training rides to be certain you are not overcompensating). SPORTS DRINKS Commercial sports drinks are the easiest, but are pricey. Often times complex carbohydrates can be purchased in a health food store and mixed at home with a flavor of your choice or used to supplement a current favorite drink. Maltodextrin is a corn starch molecule which has been broken down into glucose polymers (chains of glucose molecules). When added to water or other drinks, it increases the energy content without the disadvantage of an overly sweet taste and a highly concentrated solution which will delay gastric emptying. It is useful during exercise or as a post ride supplement, but does not make provide any advantages to breads, cereals, grains, etc. as a regular daily energy source.Directions are usually available from the container, but can vary from 1/2 cup in 8 pounces to 3/4 cup in 32 ounces. You may need to experiment to find the best concentration for your personal physiology. A 16 ounce water bottle (480 cc) of a 7% sugar solution at 4 Cal per gram of carbohydrate will contain about 136 Calories. If you add 1/2 cup of Carboplex (a commercial maltodextrin) you will add another 220 Calories almost tripling the energy density (concentration) of your drink with minimal chances of nausea or other side effects. Here are some HOMEMADE SPORTS DRINKS. OF ADDITIONAL INTEREST There have been some encouraging studies on the use of glycerol to minimize the negative impact of dehydration on performance. For those interested in a commercial product, try the internutria website. Except under extreme conditions, electrolytes (particularly sodium chloride or salt) do not need to be replaced along with fluids. Basic Nutrition Plan The following basic nutrition plan for the competitive athlete is based on the nutritonal concepts discussed elsewhere. To review, these physiologic principles include: • a high carbohydrate training diet is a must to maximize muscle glycogen stores • there may be a slight increase in daily protein requirements, but replacement needs can be met with 1 gram protein/kg body wt/day • Caloric expenditures need to be consciously replaced to counteract the appetite suppression that follows from long hours of training • a 3 day carbohydrate loading program gives an edge to muscle glycogen storage
  • • a 4 hour pre event meal should be utilized to top off glycogen stores • some riders experience intestinal distress or symptoms of hypoglycemia if they eat in the 2 to 4 hours immediately before an event • Calories must be taken during an event of greater than 2 hours duration - solid foods may offer some advantages in longer events which are done at slower paces minimizing the issue of delayed gastric emptying • be particularly sensitive to fluid balance (loss vs replacement) as the risks of OVERHYDRATION increase with longer events. Don't forget to weigh yourself regularly during training as well as the event • salt replacement beyond a normal diet (ie commercially available sports drinks) is important only under extreme conditions or in events lasting 8 to 10 hours or more RECOMMENDED NUTRITION PLAN The following comments are intended for maximizing glycogen stores for competitive events and long distance recreational rides. They are NOT meant as a general prescription for 1 to 2 hour weekend outings. Specific recommendations based on type of ride can be found elsewhere. First, let's review a few basic tips that can be of benefit for your nutritional training program. • Practice eating while cycling - your stomach needs to get used to handling food while exercising. You cannot "train" your digestive tract to get bigger or stronger, but you can define your own limitations and personal quirks before the day of the big ride. • Don't switch fuels - stay with the on the bike foods you are used to eating. • Make it simple for your digestive system - use processed breads rather than whole grains, liquids rather than solids, cooked vegetables instead of raw ones, and minimze fat. • Don't fill up before the finish - anything you eat in the last 30 minutes will probably still be in your stomach, and if you sprint at the end might just end up coming back up. • Train more - the best way to train your digestive system is to get in better shape. The closer you come to your VO2max, the more inefficient your GI tract becomes. So by raising your peak level of performance, you widen the range in which your stomach functions strongly. BASELINE TRAINING DIET (the weeks and days before the event) • determine your daily Caloric needs as outlined in the section on energy requirements of cycling. • calculate your body weight (BW) in kg (Wt in lbs x .455 = BW in kg) • eat a baseline daily diet of: o protein - 1.5 gm x BW in kg (multiply x 4 to get daily protein Calories) o fat - 70 gm fat (the avg. American diet); at 9 Cal/gm = 630 Calories o carbohydrates - the balance of your total daily Calories (total requirements as calculated above minus protein Calories minus fat Calories)as starches, etc. • modify that diet for the specific periods noted below o Pre-event interval (4 days to the event) o During the event o Post event PRE-EVENT INTERVAL (4 days to the event)
  • 4 days prior to the event • 9 gm carbohydrate/kg BW/day (approx. 600 grams/day) • limit exercise to minimum needed to maintain flexibility 4 hours prior to the event • eat a 300 gm complex carbohydrate meal (rice, starch, pancakes, etc.) • a high Caloric density glucose polymer sports drink may be ideal here • define your own physiologic limits if you are accustomed to eating in the 4 hours interval before a ride - many riders get a psychological boost from eating a low fat meal or a liquid carbohydrate drink/gel during this interval (and as a bonus can supplement their internal glycogen stores for a ride of more than 1 to 2 hours) 4 minutes prior to the event • 45 gm carbohydrate (candy bar for example) DURING THE EVENT • calories o regular carbohydrate replacement - start immediately o 60 gram of carbohydrate as a minimum per hour o liquid preferred (i.e. sports drink) o 10% concentration optimal (equivalent to a cola drink) o start with half a water bottle (300 ml) in your stomach o complex carbohydrate drinks permit additional Calories • liquids o 800 ml/hour (std waterbottle = 590 ml) o drink at 10 - 15 min. intervals POST EVENT • 3 to 6 gm carbohydrate/ kg BW over the immediate 4 hours post event (100 grams per hour) - start immediately • a high Caloric density glucose polymer sports drink may be ideal here • protein appears to expedite glycogen replacement • 600 gm carb/day for 2 days to optimize repletion of muscle/liver glycogen. NUTRITION PLANS FOR 6 COMMON TYPES OF RIDES CONTENTS • Commute or Social Ride - mild to moderate effort, 15 to 20 miles • Basic Training Ride - moderate intensity, 15 to 50 miles • Intervals - intermittently high intensity, 10 to 30 miles • Long Distance Ride - moderate intensity, 50 to 100 + miles • Competitive Event - high intensity, 20 - 30 miles • Multiday Ride - moderate intensity, 50 to 100 miles per day
  • Different rides will require different nutritional support plans. In addition to differing Caloric requirements and recommendations, there are some specific do's and don'ts. This section will look at the 6 common types of rides and make recommendations on the 4 diet periods (as discussed in the section Nutrition for training and performance) for each ride. THE COMMUTE or SOCIAL RIDE This ride is done at a comfortable pace of 50-60% VO2 max. for 1 to 2 hours daily. The goal is to have a comfortable ride with energy left for the remainder of the day. • 4 days prior - balanced diet with 60-70% Calories from carbohydrates • 4 hours prior - eat a high carbohydrate breakfast 30 to 45 minutes before the ride • 4 minutes before - nothing special • during the ride - eating is optional for a ride of 2 hours or less • post ride - a mid morning snack might be a good idea but is not essential; a good balanced diet will replace the glycogen used during the ride • fluids - one water bottle per hour, perhaps a bit more in hot weather BASIC TRAINING RIDE This ride is just a bit longer than the 2 hour limit that can lead to the bonk, so snacking on the bike is important. As intensity increases above 60%, it is more important to avoid eating in the 4 hour pre-ride interval to avoid GI distress. • 4 days prior - balanced diet with 60-70% Calories from carbohydrates; at least 600 grams of carbohydrate the day prior to the ride • 4 hours prior - if the intensity is moderate, eating during this interval is OK; avoid excessively fatty foods and try to eat 2 hours before the ride • 4 minutes prior - nothing special • during the ride - start eating regular snacks, energy gels, or sports drinks at the beginning of the ride to replace the estimated Calories burned per hour • post ride - a post ride carbohydrate snack, particularly in the 10 to 15 minutes immediately afterwards, will take advantage of the window of maximum glycogen resynthesis and may cut down on muscle soreness • fluids - one water bottle per hour, perhaps a bit more in hot weather INTERVALS For intervals, it is key to have your stomach empty or you risk the GI distress that goes with exercising close to or above 100% VO2 max. You will also sweat more so that fluid replacement needs to be watched. If this is a ride of less than 1 1/2 to 2 hours, there is probably not a need to carbo supplement during the ride. • 4 days prior - balanced diet with 60-70% Calories from carbohydrates • 4 hours prior - don't eat in the 4 hours before this training ride • 4 minutes prior - nothing special, a candy bar or energy bar is OK if you're feeling hungry • during the ride - depends on the total time/distance to be covered. If it's truly focused on intervals, no carbos are needed
  • • post ride - a post ride carbohydrate snack, particularly in the 10 to 15 minutes immediately afterwards, will take advantage of the window for maximum glycogen resynthesis and may cut down on muscle soreness • fluids - one water bottle per hour as an absolute minimum LONG DISTANCE This ride will definitely cause you to bonk if you don't replace carbohydrates, so snacking on the bike is essential. As intensity increases above 60% VO2 max., it becomes more important to avoid eating in the 4 hour pre-ride interval to avoid GI distress. If this is really planned as a slow, long training ride, that is not as important. A 300 gram carbohydrate meal 3 to 4 hours before this ride helps "top off the tank" so to speak in terms of muscle glycogen stores. • 4 days prior - balanced diet with 70-80 % Calories from carbohydrates; at least 600 grams per day of carbohydrates in the 2 to 3 days prior to the ride • 4 hours prior - if the intensity is moderate, eating during this interval is OK, but avoid fatty foods and eat at least 2 hours before the ride. A 300 gram carbohydrate meal 3 to 4 hour pre-ride is recommended if possible • 4 minutes prior - nothing special • during the ride - regular snacks, energy gels, or sports drinks to replace the estimated Calories burned per hour • post ride - a post ride carbohydrate snack, particularly in the 10 to 15 minutes immediately afterwards, will take advantage of the window for maximum glycogen resynthesis and may cut down on muscle soreness. Eat a high carbohydrate meal that night after the ride. fluids - one water bottle per hour, perhaps a bit more in hot weather COMPETITIVE EVENT This is what it's all about, and good nutrition and planning your eating strategy can make a difference. You will need a good carbohydrate base to maximize your muscle glycogen reserves. And you need to avoid eating in the 4 hour pre-event interval to keep your stomach empty or you risk the GI distress that goes with exercising close to or above 100% VO2 max. You will also sweat more so fluid replacement needs to be watched. If this is a ride of less than 1 1/2 to 2 hours, there is no need to carbo supplement during the ride. • 4 days prior - balanced diet with 60-70% Calories from carbohydrates; 600 grams of carbohydrate per day in the three days prior to the event • 4 hours prior - don't eat in the 4 hours before this ride • 4 minutes prior - a candy bar, energy bar, or other carbohydrate snack is a good idea • during the ride - even for an event of 1 1/2 hours or less, a liquid carbohydrate supplement should be used. And if it's going to be longer, you will definitely need carbohydrate supplements (beginning regular snacks, energy gels, or sports drinks as soon as the event starts to replace the estimated Calories burned per hour • post ride - a post ride carbohydrate snack, particularly in the 10 to 15 minutes immediately afterwards, will take advantage of the window for maximum glycogen resynthesis and may cut down on muscle soreness. Eat a high carbohydrate meal that night to replace the muscle glycogen that was probably completely depleted during the event. • fluids - one water bottle per hour as an absolute minimum MULTI-DAY RIDE or BIKE TOUR
  • This ride is basically the same as the long training ride, but you need to be very careful to eat a high carbohydrate meal each evening or you will slowly become glycogen depleted and chronic fatigue will develop. If this is going to be a high intensity event on certain days, (intensity above 60% VO2 max.), it is important to avoid eating in the 4 hour pre-ride interval to avoid GI distress. But on those long slow days, that's not an issue. A 300 gram carbohydrate meal each day 3 to 4 hours before the ride will maximize glycogen reserves. This is the dietary program most appropriate for a multi-day bike tour. • 4 days prior - balanced diet with 60-70% Calories from carbohydrates; at least 600 grams per day of carbohydrates in the 2 to 3 days prior to the ride • 4 hours prior - if the intensity is moderate, eating during this interval is OK, but avoid fatty foods and eat 2 hours before the ride. A 300 gram carbohydrate meal 3 to 4 hour pre ride is recommended. • 4 minutes prior - nothing special • during the ride - regular snacks, energy gels, or sports drinks to replace the estimated Calories burned per hour • post ride - a post ride carbohydrate snack, particularly in the 10 to 15 minutes immediately afterwards, will take advantage of the window for maximum glycogen resynthesis and may cut down on muscle soreness. Eat a high carbohydrate meal that night after the ride, and try to eat at least 600 grams of carbohydrate per day above and beyond that needed to replace the Calories burned on that day's ride. • fluids - one water bottle per hour, perhaps a bit more in hot weather Nutrtition for Triathletes Developing a rational dietary program for the triathlete requires an understanding of the physiology of nutrition and how those principles are used in developing a practical nutrition plan. During the training phase, maintaining Caloric balance (eating enough Calories to replace those used during the day's exercise) is the biggest challenge faced by endurance athletes. Not only will daily Caloric requirements be significantly beyond normal dietary intake, the time available to eat (including snacks) is reduced by the time requirements of the training itself. This is particularly true with swimming and running as snacking while exercising is almost impossible. To avoid slowly losing ground nutritionally, you will need to closely monitor your daily Caloric expenditures, make a conscious attempt to snack throughout the day to replace thoise Calories, take advantage of the post exercise glycogen replacement window to restock muscle glycogen stores for the next day's training, and weight yourself daily to be sure you are staying in "Caloric balance". How about the triathlon itself? Nutrition during the pre-event interval (4 days, 4 hours, 4 minutes) is essentially the same as for all other competitive events. The body can store only so much glycogen in the muscles and liver during the 4 days before the competition, and the digestive tract can handle only so much volume in the 4 hour pre event meal. But the triathlete can take advantage of the 30 to 60 minutes before the event to take a final carbohydrate "boost". As eating while swimming is impossible and inadvertently swallowing water the rule, it makes sense to eat enough complex carbohydrate gel or drink (which will then be slowly emptied into the small intestine over the duration of the swim - with fluids being provided from swallowed water) to replace the Calories that will be expended during the swim (8 to 10 Calories/minute). To minimze GI upset, these carbohydrate Calories should be taken at least 30 to 60 minutes before the swim. The energy requirements of cycling have been covered elsewhere. As with all cycling events, the key to success is snacking - starting early (during the transition) and continuing to snack regularly during the ride. In the triathlon, where you will be finishing the event with a run, snacking is even more important as any extra Calories taken on board will not only make up for any Caloric deficit from the swim, but will also be available to help you during the run when snacking is much more difficult. When the run begins, the athlete should be Calorie neutral ie the Calories eaten in the minutes before the swim and during the cycling should equal or slightly exceed the Calories expended
  • during the swim and the ride. Now begins the real challenge - to replace as many of the Calories that will be expended with the run as possible. Running will slow gastric emptying and as a result, snacking may cause nausea. But the new gels and liquid supplements, if taken in small amounts, regularly, can help minimize the phenomena of "hitting the wall" late in the run. And of course adequate fluid replacement during competition (with particular attention to electrolytes) is essential for these long events. Remember, along with staying hydrated, Calories are the key, carbohydrates are preferred, and anticipting and replacing your energy needs with regular snacking before you notice hunger will be the most successful strategy. SNACKS/FLUIDS CONTENTS • Eating on the bike • Snack survey o Home made snacks o Energy gels • Beverages/fluids • Electrolytes • Common snacks list (cal/serving) o snacks on the run EATING ON THE BIKE The secret for maximum performance in events lasting more than 2 hours (the time at which muscle glycogen depletion generally occurs with cycling) is to snack frequently every 20 to 30 minutes. A successful program requires striking a balance between eating enough to prevent hunger and avoiding the pitfall of "if a little is good, a lot is better" philosophy with the risk of stomach distention, bloating, nausea, and a subsequent deterioration in performance if one errs on the side of eating too much. Recreational riders with the luxury of time will probably elect to stop to enjoy their snacks. Those in the competitive mode will more likely choose to eat on the bike to supplement their internal glycogen stores, beginning at the start of the event in anticipation of the delay in stomach emptying that will occur with strenuous exercise. Any Calories absorbed will delay glycogen depletion and prolong the exercise interval before the onset of fatigue or the Bonk. One note - many simple carbohydrate snacks such as chocolate chip cookies are more than 30% fat, and if eaten in large quantities might put you over the ideal daily intake of 20-30% fat. In contrast, complex carbohydrate snacks such as pasta bread and rice have a bit less taste appeal, but offer significantly more carbohydrate (and less fat) per gram or ounce. As a rule of thumb, the higher the level of intensity of the ride (closer to your VO2max), the simpler the carbohydrates (energy drinks, gels, and fruits). On longer rides and at lower heart rates, more complex snacks with complex carbohydrates and a higher fat content offer other alternatives. A reasonable goal during high intensity rides is 200 to 300 Calories (60 grams of carbohydrate) per hour. To plan for your ride, first estimate the number of calories you will expend (both total and per hour). Next decide on a "refueling" schedule - every 15 to 20 minutes is a practical compromise. Then, using the suggestions below, plan your snacks and the packaging strategy to carry them. And finally, do a road test to be sure this program fits your specific digestive tract physiology - the day of the ride or race is not the time to find out what doesn't work. The most common place to eat while cycling is, you guessed it, on the bike. This goes for the recreational cyclist as well as the competitive rider. A major considerations is safety. Eating while
  • on the bike takes some practice and concentration A mouthful of food can affect the rhythm of your breathing and can easily be aspirated into the windpipe. Keep the following tips in mind to avoid unnecessary risks: • Slow down. • Increase your concentration on the road, anticipating upcoming obstacles or hazards. • In a pace line, eat at the end, not in the middle or while pulling. • On hilly terrain, eat after you crest the hill, not while climbing. • Keep your food in your outside back pocket of your jersey. • Drink from your down tube bottle until it’s empty and then switch with your full seat tube bottle. SNACK SURVEY A survey of several cycling magazines for preferred on-the- bike snacks demonstrated a wide variety of approaches. Dried fruits were most common - presumably because of their high Caloric content, the ease of preparing bite sized portions, andthe fact they are relatively indestructible when carried on a long ride (an attribute that shouldn't be ignored!!). Two "prepared" delicacies were noted (but the exact Caloric could not be easily derived because of personal modifications of portion size). The first was a sandwich of jelly and cream cheese. The second, a mixture of peaches, honey, and water in a plastic bag pointed out that there is plenty of room for experimentation in the snack area. See the section on home made snacks for additional ideas. Commercial powerbars and sports drinks were a third option. Although they are often advertised as providing a particularly potent combination of ingredients and secret "supplements", they are no more effective on a gram for gram basis as an energy booster than other carbohydrate snacks. One advantage is that they are prepackaged, are readily available commercially, and do offer another taste and texture option for a snack. And now the newest kid on the block are the energy gels which come in a squeeze tube in syrup or paste form and offer an alternative to the hard to unwrap, difficult to chew, and relatively tasteless commercial energy bars. These products contain a combination of simple and complex carbohydrates in a palm sized packet of plastic or foil with a tear off end to allow the contents to be "sucked" out rather than chewed. They contain between 70 and 100 Calories per packet (17 - 25 grams of carbohydrate) and have the advantage of being completely fat free. Being a semi-liquid, they also empty more quickly from the stomach and give amore rapid energy boost than the solid energy bars. Being relatively new there is a lot of hype and little proof of their benefit over more traditional forms of carbohydrate (fig newtons for example) and they are relatively pricey at a $1 per packet.(See also the authors editorial comments on gel/energy bar additives). There are also some foods to avoid which may contribute to the stimulating effect of exercise on the digestive tract. These include dairy products as well as spicy, greasy, and oily foods. If you'd like to give them a try for taste variety, the best approach is to experiment with your own unique digestive tract function, starting off with small amounts of those foods and working up to larger portions. BEVERAGES/FLUIDS COMMON SNACKS LIST
  • See the section on snacks on the run for additional ideas when caught out on the road empty handed. SNACK (QUANTITY PER SERVING) - CALORIES - GMS OF CARB PER SERVING • small generic cookie (2) - 105 - 15 • large generic cookie (1) - 105 -15 • fig newton (1) - 50 - 20 • Chips Ahoy(1) - 50 - 20 • Oreo (1) - 65 - 9 • avg. banana (4 ounce) - 100 - 26 • avg. orange (4 ounce) - 65 - 16 • grapes (1 cup) - 57 - 16 • avg. apple (4 ounce) - 80 - 21 • raisins (1/3 cup) - 150 - 40 • apricots (10 halves) - 83 -22 • prunes (5 whole) - 100 - 53 • candy bar (1 oz) - 130 - 16 • Baked potato (1 avg.) - 220 - 51 • donut (1 avg.) - 125 - 14 • eclair (1 avg.) - 239 - 23 • toast (1 slice) - 64 - 11 • bagel (1) - 163 - 31 • cooked rice (1 cup) - 223 - 50 (See the section on rice for additional comments on this multipurpose carbohydrate cycling fuel). • yogurt (1 cup) - 140 - 15 HOMEMADE SNACK RECIPES AND IDEAS The following are several interesting ideas for homemade snacks to take on that next ride. They not only can provide some taste variety, but they are definitely easier on the wallet than the commercial energy bars. The following recipes are generally low or non fat (except those containing peanut butter). However, palatability - improved with a little fat - is often important to keep one eating during a ride, so try to find the balance for your tastes. • Puddings (fat free) o Make with skim milk for a fat free, high carbo treat on the bike. o 4 ounces = approx. 100 Cal and 22 grams of carbo • Brownies (fat free) o Follow the directions on the premixed package, but substitute 1 banana and 1/2 cup nonfat yogurt for the oil and eggs. Be careful with nuts and toppings which will add loads of fat. o 1 average serving = 100 Calories and 18 grams of carbo • Dry cereal in a sandwich bag - Capt. Crunch, Cinnamon Apple Cheerios
  • o 1 ounce = 110 Cal and 25 grams of carbo • Pancake Sandwich o Toast or microwave 2 frozen pancakes (waffles) o Spread with jam and wrap in a baggie o 2 - 4 inch pancakes + jam = 195 Cal and 35 gram of carbo • Energy "gel" o Mix an energy drink at 5 times the recommended concentration (cytomax tropical fruit was the brand mentioned) and then carry a second water bottle to wash it down. • Not quite cheesecake o Sandwich shortbread cookies with non fat cream cheese and raspberry jam. The three components can be carried separately and mixed during stops as well. • Commercial squeeze tubes (refillable) o fruit prepared as baby food o bananas and peanut butter mashed together o peanut butter and banana flavored energy gel • Trail putty o 1/2 cup of peanut butter o 2 tablespoons honey o 2 1/2 tablespoons dried non fat powdered milk o 1/2 cup raisins o Roll into a log, then roll in coconut or chocolate. o Chill and then wrap in plastic wrap. • Four blender ideas - for before or after the ride o 1) 1/2 cup orange juice 1/2 cup pineapple juice 2 bananas touch of honey o 2) plain non fat yogurt skim milk banana pineapple chunks ice cubes o 3) milk orange juice bananas o 4) cranberry juice orange juice strawberries pineapple chunks bananas frozen fruit bars ice cubes • Muffins These may be the ideal cycling snack. It's just a handful in size, and can be tailored to your needs. The only drawback is that they tend to crumble the longer they are in your jersey. Here's one recipe for an example: Oatmeal raisin muffins o 1 1/2 cups whole wheat (or white) flour o 1 cup uncooked oatmeal o 1 tablespoon baking powder
  • o 3 tablespoons sugar (try honey if you'd like) o 1/2 cup raisins (other fruits are optional) o 1/4 - 1/2 cup nuts if desired (they are high in fat) o 2 egg whites o 1 cup non fat milk o 1/4 cup vegetable oil o Preheat oven to 400 F. Mix flour, oatmeal, baking powder, sugar, and raisins in a large bowl. In a second bowl beat egg whites, then stir in milk and oil. Add liquid to flour mixture and stir till blended - do not overmix. Bake 15 to 20 min. until muffins spring back when touched. HOMEMADE SPORTS DRINKS For many years it was believed that a 2.5% concentration (glucose or glucose polymer molecules) was the maximum that could be tolerated without delaying gastric emptying and producing nausea. However a recent study of cyclists demonstrated normal gastric emptying with 6 to 8% solutions, and nausea occurred only when concentrations were pushed above 11%. The old standbys - fruit juices and cola drinks - have a sugar concentration of around 10% (a typical carbonated drink will contain 38 grams of sugar per 12 ounces with 140 Calories). Although sports drinks supplemented with glucose polymers can provide more Calories per quart at the target 10 - 11% concentration, studies have failed to demonstrate a performance advantage of complex carbohydrate drinks over those compoced of simple sugars if the same total Calories were ingested. The advantage of the polymers is the absence of a sweet taste and nauseating properties of high concentration glucose drinks, which can be a barrier to maintaining an adequate fluid intake. Many people enjoy their own homemade versions of commercial sports drinks. The basic recipe is not complicated and homemade sports drinks can provide all of the same benefits when mixed properly. Gatorade (tm) is formulated to give the following per 8oz serving: • 14grams Carbohydrate (5.9%) • 110 mg Sodium • 30mg Potassium • 52 Calories Alternatives to this commercial product can be made using one of the following recipes: Recipe #1 • 10 tbs. sugar (5/8 cups or 120 grams) • .75 tsp Morton Lite salt (4.2 grams) • 1 package of unsweetened Coolade mix for flavor • Water to make 2 liters Nutrition Information (per 8 ounces). The recipe will give a total of 124 grams of solute which in 2 liters water gives a total of 6.2% concentration. • 14.2 grams carbohydrate (6%) • 53 calories • 103 mg Sodium • 121 mg Potassium
  • You'll notice that the amount of potassium is quite a bit higher than Gatorade, but the rest is pretty close. As excess potassium is eliminated from the body by the kidneys, and some experts feel a high potassium helps to minimize muscle cramps - and hypertension if taken long term - this is not necessarily bad. However, if you wanted to reduce the potassium to the level of a Gatorade product, another option would be to use 1/2 tsp. each of regular salt and the Morton Lite Salt. This would change the composition to: • 104mg sodium • 40mg potassium Recipe #2 (if you wanted to reduce the amount of potassium, or simply didn't want to buy some Morton Lite Salt • 1/2 cup orange juice • 9 tbs. Sugar • 3/8 tsp Salt • Water to 2 liters Nutrition Information (per 8 ounces): • 14.4 grams carb (6.1%) • 104 mg sodium • 28.4 mg Potassium (you could substitute 2 tbs. of lemon juice for the orange juice and it would come out the same - or at least close). Recipe #3 (using cups and quarts) • 4 tablespoons sugar • 1/4 teaspoon salt • 1/4 cup boiling water • 1/4 cup orange juice (not concentrate) or 2 tablespoons lemon juice • 3-3/4 cups cold water o 1. In the bottom of a pitcher, dissolve the sugar and salt in the hot water. o 2. Add the juice and the remaining water; chill. • Yield: 1 quart Nutrition Information (per 8 ounces): • Calories - 50 • carbohydrate 12 grams • sodium 110 milligrams • potassium 30 milligrams
  • Recipe #4 (if you prefer an all fructose drink) • 125 mL (1/2 c) orange juice (or other sugar-containing beverage) • 125 mL (1/2 c) water • 0.25 mL (pinch) salt Nutrition Information (per 8 ounces): • Calories - 59 • carbohydrates 14 grams • sodium - 118 mg Recipe #5 Lemon-orange sports drink • 1 caffeine-free lemon tea bag • Water • 2 tablespoons sugar • 1/8 teaspoon salt • 4 tablespoons orange juice o Bring 16 ounces of water to a boil. o Steep lemon tea bag. o Dissolve sugar and salt in the tea and let cool. o Combine the tea and orange juice and chill. Nutrition Information (per 8 ounces): • Calories - 60 • carbohydrates - 15g • sodium -130mg Energy Gels/Sports Drinks Energy gels, energy bars, and sports drinks all provide carbohydrate supplements for the cyclist but with differing water contents. Solid energy bars are easy to carry, but require conscious attention to maintaining hydration (drinking). Sports drinks help to maintain hydration as they resupply your energy needs, and gels split the difference. Which one you choose to use depends more on personal preferences than performance advantages. Energy gels (also called carbo gels) are a thick carbohydrate syrup or paste designed as an alternative snack supplement to extend your muscle glycogen stores and provide additional Calories and energy for rides of more than 2 hours. They contain a combination of simple and complex carbohydrates (usually maltodextrin, rice syrup, or polysaccharides) packaged in a palm sized packet of plastic or foil with a tear off end to allow the contents to be "sucked" out rather than chewed, and provide between 70 and 100 Calories (17 - 25 grams of carbohydrate) per packet. An additional advantage is that they are completely fat free minimizing any delay in gastric emptying. To provide the 60 grams of carbohydrate per hour usually suggested to supplement exercising muscle glycogen supplies, you would need a gel packet every 30 to 45 minutes.
  • Being semi-liquid, they should empty more quickly from the stomach providing a more rapid energy boost than solid sports bars, but at this time studies comparing solid and gel carbohydrate supplements haven't been published. And in a previous study of solid vs liquid carbohydrate supplements, cycling performance was similar in the two groups of cyclists using equivalent amounts of water and carbohydrate consumed either as a sport drink or as a solid sport bar with a water chaser. This suggests that aside from taste and ease of use, energy gels are a relatively pricey snack with little to recommend them over bagels or fig newtons as an on the bike carbohydrate supplement. Yet I will regularly receive annecdotes such as this: "I have to disagree with your point about no proven help from gels. I am an ultramarathon cyclist- having completed numerous double centuries. I train long, hard miles and have had to be extremely targeted in my Calorie intake for training. After trying a variety of products, I found my solution. *** and Sustained Energy drink from ***. I agree- gels don't make you fast. However, Calories must be replaced when cycling, and replacing calories with pure sugar has been a disaster for me (and many people I know). ** and ** provide the proper Calories without the sugar. All the endurance riders I know here in Northern California use the products. We swear by them. They do work. The only time we drink Coke is near the end of a ride when we need a spike of energy (and caffeine) and aren't worried about the side effects of sugar." Is there any scientific data to back up this observation? I was able to find two articles that might provide some factual evidence. The first looked specifically at absorption rates of sugars in the small intestine. It failed to substantiate any difference in absorption rates of simple glucose versus a complex carbohydrate - assuming a normal intestinal tract. The second looked one step further along the absorption process by studying blood sugar levels (all complex carbs are broken down in the small intestine BEFORE being absorbed) to see if perhaps a difference could be demonstrated. Again, blood glucose levels were the same (both in terms of blood sugar levels and timing) with simple glucose and complex carbohysrates. So what is the answer?? Perception of improvement, whether placebo or unproven fact, should not be ignored. However, the scientific literature offers no credible rationale to differntiate the benefits of the glucose from Coke versus a complex carbohydrate in the commercial product sold by ***. I wonder (unproven speculation) if the riders are really taking in equal amounts of carbohydrates per 15 minute interval when they use cola drinks with simple glucose versus complex carbs? Gels are easier to use, and less sweet per Calorie consumed. These two facts alone may be a subtle bias towards a more proactive and complete replacement of Calories used with a commercial product. For now the use of gels remains a personal choice, but without any hard facts to back up the marketing hype often encountered. Most gels will also list additional ingredients. Some of the more common additives are: • medium chain triglycerides • caffeine • ginseng • amino acids • chromium Do they add anything?? For comments see the author's editorial comments on gel/energy bar additives and the section on nutritional supplements. There is a nice comparison of commercial energy supplements at the University of Arizona website. Or you can make your own energy gels. Are energy gels worth it?? It is really a matter of personal preference. Some riders cannot chew and swallow a sports bar while pedaling. Others develop taste fatigue to sports drinks on long rides. For these individuals, gels provide another alternative. But aside from taste and texture, there are no PROVEN performance advantages no matter what the claims you've seen in their ads, and they are expensive if used on a regular basis on those long rides.
  • Optimizing Personal Athletic Performance ENERGY BARS, ENERGY GELS - ARE ADDITIVES HELPFUL?? Every week, it seems, there is a new high energy snack available to improve your personal performance. Just buy this one, the ads tout, and you’ll increase your performance overnight. And of course this enhanced product comes with a price tag that increases with each new variation. To sort things out, let’s look at the available facts on these products and the additives they contain - and then you can make up your own mind. First, let’s review the basic physiology of energy the energy transfer from food to your muscles. Food energy is released through a chemical reaction with oxygen in a process called oxidation. When this occurs outside the body - for example the burning of oil (a fat) in a lamp or the use of a flaming sugar cube (a carbohydrate) as a decoration in a dessert - this energy is released as heat and light. In the body however, food energy needs to be released more slowly and in a form that can be harnessed for basic cell functions and transformed into mechanical movement by the muscle cells. All foods are composed of carbohydrates, fats, and protein. Carbohydrates are the primary energy source for the average cyclist and for all athletes involved in short, maximum performance events. Fats, which can also serve as an energy source for cell functions assume more importance in endurance events done at less than 50% VO2 max. Proteins are used to maintain and repair body tissues. The energy contained in equal weights of carbohydrate, fat, and protein varies. It is measured in Calories ( note the capital C). Carbohydrates and protein both contain 4.1 Calories per gram (120 Calories per ounce) while fat contains almost twice as many per ounce at 9 Calories per gram. The disadvantage of the high energy density of fat as a fuel to support exercise is that it is metabolized through pathways that differ from carbohydrates and will support exertion at 50% VO2 max. at most. This makes it ideal for endurance events, but unacceptable for high level aerobic activities which are fueled by carbohydrates in the form of muscle glycogen or blood sugar (glucose). Over the last few years it has been suggested that a diet composed of at least 30% fat Calories improves competitive aerobic performance over a high carbohydrate diet - relatively restricted in fat Calories (20-25%). Although various arguments have been put forward: • no insulin release with fats and less insulin released with a low carbohydrate diet, so no worries about hypoglycemia • a "genetic" need to have a caveman (high meat and low carbohydrate) diet means a relative carbohydrate intolerance and inability to use a high carbohydrate diet effectively • a need to eat fat to keep the "fat burning" metabolic cell processes active there is no proof that eating a high fat diet improves high VO2 max performance above that of a balanced diet minimizing fat, and it has been suggested that any improvement is probably a placebo effect from the sense of well being associated with eating foods containing a higher percentage of fat (assumed to be from their improved taste). There have been two well controlled studies of high fat diets (70% fat in one, 38% in the other) showning an increase in the exercise to exhaustion time for activities at 50% VO2 max (80 vs 42 minutes of cycling in one, 76 vs 70 minutes of running in the other). Glycogen sparing effects were studied to determine if there was a preferential shift to fat metabolism during exercise, but none were found. A third study tracked Calorie replacement after exercise in two groups (a low fat diet vs normal/high fat foods) and found that those on a low fat diet did NOT replace the Calories expended during their training program while those on a more liberal fat diet did, suggesting
  • another reason for poor performance on a low fat diet - long term Caloric deficit during the training program with limited muscle glycogen stores going into the event. On the other hand, there are a number of physiologic studies that demonstrate fat CANNOT sustain high level (high VO2 max.) aerobic and anaerobic activity (the cause of the "bonk" as glycogen stores are depleted), and that a high carbohydrate diet is best for replacing glycogen stores post exercise (a chronic deficit in replacing carbohydrates has been proven to lead to chronic fatigue). The cycling study mentioned above demonstrated no difference in the cycling time to exhaustion at 90% VO2 max on a high fat (70%) vs a low fat (12%) diet eaten for 2 weeks before the event. In addition to the questionable exercise performance benefits, it has been proven beyond any doubt that a long term high fat diet leads to heart disease. And for those who still aren't convinced, it should be remembered that even the leanest athlete has plenty of stored fat available (approximately 100,000 Calories worth in a 70 kg male) without any need for diet supplements. FACT NUMBER ONE - BASED ON NUMEROUS PHYSIOLOGIC STUDIES, GLUCOSE OR CARBOHYDRATES ARE THE PREFERRED ENERGY SOURCE FOR MAXIMUM PERFORMANCE AEROBIC EVENTS (GREATER THAN 50% VO2 MAX). Let’s look at the basic energy bar and energy gel. Commercial powerbars are mainly carbohydrates (of varying types) and also contain those special supplements that I’ll mention below. Their main advantage is that they are prepackaged, are readily available commercially, and do offer another taste and texture option for a snack. But as a carbohydrate snack, they are no more effective on a gram for gram basis as an energy booster than other carbohydrate snacks. In fact a recent study from Ball State University demonstrated that a pre event meal of old fashioned oatmeal gave the same boost to endurance performance as a commercial energy bars. Energy gels offer an alternative to the hard to unwrap, difficult to chew, and relatively tasteless commercial energy bars. These products contain a combination of simple and complex carbohydrates in a palm sized packet of plastic or foil with a tear off end to allow the contents to be "sucked" out rather than chewed. They contain between 70 and 100 Calories per packet (17 - 25 grams of carbohydrate) and have the advantage of being completely fat free. Being a semi- liquid, they also empty more quickly from the stomach and their only advantage may be in the fact that this may provide a more rapid absorption and thus a more rapid energy boost than the solid energy bars. There is no proof of their benefit over more traditional forms of carbohydrate (fig newtons for example). FACT TWO - THERE IS NO EVIDENCE THAT THE CARBOHYDRATE IN ENERGY BARS OR ENERGY GELS IS MORE EFFECTIVE TO SUPPLY MUSCLE ENERGY THAT, FOR EXAMPLE, THE CARBOHYDRATE IN TRADITIONAL ENERGY SNACKS SUCH AS FIG NEWTONS. Now let’s look at the additives. Basically they fall into the categories of: • caffeine • electrolytes • minerals • fats CAFFEINE Some of these products will contain small amounts of caffeine or guarana (a Brazilian seed high in caffeine), about 25 mg per serving. As noted below, most studies demonstrating performance enhancing effects have used much larger doses and it is doubtful that there is any benefit from the caffeine in these supplements. Caffeine is a member of a group of compounds called methylxanthines found naturally in coffee beans, tea leaves, chocolate, cocoa beans, and cola nuts. During prolonged exercise, the onset of fatigue correlates closely with the depletion of muscle glycogen stores (and is delayed if
  • glycogen is spared). The metabolism of free fatty acids as an alternative energy source can lead to decreased use of muscle glycogen. Caffeine can increase blood free fatty acids, and in one study produced a 50% increase at 3 to 4 hours. This effect was seen after 300 mg of caffeine (An average 6 ounce cup of brewed coffee contains 100 - 150 mg of caffeine). There is also speculation that some of its benefits may be secondary to a central nervous system effect as a stimulant, and some recent work has demonstrated a direct positive effect on the muscle fiber itself. In one controlled study, subjects were able to perform for 90 minutes to fatigue as compared to 75 minutes in controls (a 20% increase) after the drinking the equivalent of 3 cups of coffee or 6 caffeinated colas 1 hour before, even though values for heart rate and oxygen uptake were similar in both groups. But there are also potential side effects. Caffeine can cause headaches, insomnia, and nervous irritability. In addition it is a potent diuretic and can lead to dehydration. However its biggest negative is that in high concentrations it is considered a drug and is banned by the US Olympic Committee and US Cycling Federation (to exceed the US cycling Federation's legal limit for caffeine - urine concentration of 12 micrograms/ml - one would have to ingest 600 mg of caffeine and have a urine test within 2 to 3 hours). The bottom line is that most endurance athletes consider caffeine useful if used correctly. This includes a period of abstinence for several weeks before the event as habitual use induces tolerance. Guarana is a South American herb used as a natural source of caffeine and can be found as a supplement in energy gels or bars, and cola nut is another natural source of caffeine sometimes found in the ingredient list. ELECTROLYTES The minerals sodium, potassium, and chlorine are collectively referred to as electrolytes. They are dissolved in the intra (within) and extra (outside) cellular water in your body as charged particles (ions) and are responsible for maintaining a proper electrical gradient across the cellular membrane - required for the proper functioning of each cell. A normal diet contains these three minerals in excess, and the kidneys control the loss from the body. As a result there is no requirement for diet supplementation except in extreme conditions. MINERALS Minerals are chemical elements found in the body either in their elemental form or complexed with organic compounds. Like vitamins, they are essential for normal cell functioning. The two most prevalent minerals, calcium and phosphorus, are major components of bone while sodium and potassium are found in all tissue fluids, both within and around cells. Magnesium, chloride, sulfur, and zinc are other minerals that play a key role in cell function. The trace elements iron, manganese, copper, and iodine are found in much smaller quantities, but play essential roles as catalysts in basic cellular chemical processes. These minerals, found in all foods, are kept in balance through regulation of both absorption and excretion. As a result of this control, they are easily provided by a balanced diet. Only calcium and iron may be required by some athletes in increases amounts. Because of toxic side effects when taken in large amounts, minerals as a group are not recommended as routine dietary supplements. FACT THREE - ASIDE FROM CAFFEINE, WHICH MAY PROVIDE PERFORMANCE ENHANCEMENT IF USED CORRECTLY AND IN LIMITED AMOUNTS, THERE IS NO EVIDENCE THAT OTHER ELECTROLYTE OR MINERAL ELEMENTS PROVIDE A PERFORMANCE EDGE. FATS Then there is the issue of energy bars or gels which contain fat and are alleged to:
  • • improve performance • SELECTIVELY increase fat metabolism • and aid in weight loss. While there has been some evidence that an occasional long slow recovery ride in your training program MIGHT improve the ability to metabolize or use stored fat Calories for muscle energy, there is no scientific basis for the claims made by these products that eating any particular food or food type (i.e. fat) will enhance fat metabolism. Medium chain triglycerides are merely a form of fat which is more easily absorbed from the intestinal tract, but is metabolized by the muscle cells exactly like all other fats and is probably of no more benefit than the extra pat of butter on your pancakes before the ride. And there are at most a few grams per bar or package providing a minimal addition to the Carbohydrate Calories. An alternative to eating more fat would be to focus on a training program that stresses an increased number of miles at a relatively slow pace (60% VO2 max.) to improve the ability to use your own internal fat stores. Another variation on this theme is to avoid carbohydrates in the pre ride meal and minimize carbohydrate supplementation while on that long slow ride to force the development of metabolic pathways that use fat energy (a planned "bonk' if you will). Then, or so goes the theory, when it comes time for that sprint at the end of a competitive event, ridden with appropriate glucose supplementation, there will be more muscle glycogen remaining to give you the edge. FACT FOUR - THERE IS NO EVIDENCE OF PERFORMANCE ENHANCEMENT FROM DIETARY FAT SUPPLEMENTATION, EITHER BEFORE OR DURING A COMPETITIVE EVENT. PROTEIN Fianlly, there has been the suggestion that a combination of protein (amino acids) and carbohydrates in a ratio of 1:4 is more effective in sports drinks used while riding and as supplements for glycogen repletion immediately after a ride. The data for any benefit post ride recovery period is weak (and seems to be related to the amount of carbohydrate used - 1 gram/kg/hr x 3 hours appears to maximize repletion rates) at best, and at the moment there is no information in the literature to support a benefit to protein enhanced carbohyrate sports drinks while riding. So what is the message here? Basically that a good balanced diet is the best approach during the pre and post event training program, there are no nutritional shortcuts to improved athletic performance, and although they may do no harm, there is little evidence that expensive dietary snacks provide any advantage over cookies, coke, or other more traditional (and less expensive) snacks aside from providing a variation in taste, consistency, or packaging BICYCLING AND WEIGHT CONTROL There is an epidemic of obesity in countries such as the US and western Europe, with current statistics indicating that more than 50% of American adults are either overweight or obese. Although studies have supported a role for genetics, our genes have been the same for thousands of years but only recently has obesity increased so dramatically. In addition, the idea that there are some of us with a low "Resting Energy Expenditure" (REE) who are at increased risk of gaining weight on a normal diet (when compared to our peers) has been layed to rest as well. It appears that reduced physical activity, which is not compensated for with a decrease in food intake, is the major culprit. And the difference is about 300 Calories a day, which could be offset by an hour of easy cycling per day. The National Weight Control Registry is an 8 year old project that has studied weight loss in 3500 extremely obese patients who lost (and maintained the loss) of an average of 60+ pounds. The
  • common factor?? A high level of physical activity with an average weekly expenditure of 2545 exercise Calories in women and 3293 Calories in men (equal to an hour of moderate physical activity per day) coupled with an estimated intake of 1500 Calories per day. These Calories were eaten in 4 or 5 small meals throughout the day rather than skimping on breakfast and lunch and then eating a much larger meal at night. And it was a low fat diet with 23% of total Calories coming from fat. Most had failed to maintain their weight loss with other weight loss regimens, and almost universally attributed the success in this program to the sustained increase in their weekly level of physical activity. Physical activity has a positive effect on your weight and figure by: • increasing energy output and Caloric expenditure • supressing appetite • increasing Basal Metabolic Rate (BMR) or Resting Energy Expenditure (REE) • maintaining lean body mass at the expense of fat The basic premise of all weight control programs is that weight loss occurs when the number of Calories expended (or "burned") over a 24 hour period is greater than the number consumed. The net deficit (covered by Calories from the fat reserves) results in weight loss. (1 pound of body fat = 3500 Calories) WEIGHT LOSS(IN LBS) = (CALORIES BURNED - CALORIES CONSUMED)/3500 Cycling will increase your daily Caloric output in two ways. First, and most obvious, is the energy required to move you and your bicycle against the resistance of air and gravity. A second, more indirect effect is through subtle changes in your daily routine to include more physical activity (such as walking up a flight of stairs instead of taking the elevator) because of an increased sense of vigor and well-being. Many dieters worry that increased physical activity will increase their appetite. However a recent carefully controlled study of overweight individuals did not reveal a proportionate increase in appetite with exercise, lending support to the positive role of physical activity in reaching the goal of a negative Caloric balance and resulting weight loss. In fact, vigorous exercise actually suppressed appetite for several hours, suggesting that this short term effect can be used as an effective appetite control strategy by planning your exercise immediately prior to your major meal of the day. Regular exercise also increases your basal metabolism rate or BMR (the number of Calories utilized by the body at rest to maintain basic life processes). An increased BMR is associated with all aerobic conditioning activity and is maintained with as little as 30 to 40 minutes of exercise 3 to 4 times a week. One study indicated that the increase in BMR with regular exercise may be even more pronounced in the older athlete. Not only is there an increase in your overall BMR with regular exercise, there is an additional 12 hour post-exercise boost in the BMR. As a rule of thumb, this adds 15 bonus Calories for every 100 Calories burned during your aerobic activity. To capitalize on this post exercise bonus, consider two (or more) rides per day - perhaps in the morning and after work - rather than a single ride of equal duration. Finally, regular physical exercise will protect muscle mass (at the expense of fat) during periods of weight loss. In two groups (one active and one more sedentary) with an equally negative Caloric balance and an equal weight loss, the exercise group will lose less muscle mass than the diet only group. A common question is whether exercise can facilitate selective fat loss from the limb(s) exercised i.e. can fat be taken off the thighs by bicycling. Unfortunately this doesn't happen. Take the extreme example of a regular or professional tennis player who uses one arm almost exclusively. Comparison of fat fold thickness in both arms will NOT demonstrate a difference or assymmetry between them. Thus any exercise will promote fat loss from the body as a whole but cannot be targeted to any specific body area. However, there is still the benefit of improving the tone of the muscle or muscle groups exercised which has the same apparent affect to "slim" the area.
  • SHORT CUTS? Some authors have suggested that riding at slow speeds (<50% VO2 max) is preferred for a weight loss program as more of the Calories expended will be supplied from fat tissue storage at lower levels of exercise. Let's look at this argument in more detail. If you ride at 65% VO2max, your body's fat stores will provide about half of your Caloric needs and the other half will come from glycogen reserves. At 85% VO2max, the relative number of Calories supplied from fat fall to about one third of the total number expended with the balance again coming from glycogen reserves. However, if one looks at the absolute numbers, a fit cyclist riding 30 min at 65% VO2max will burn about 220 Calories (110 fat Calories, 110 Calories from carbohydrate or glycogen stores). The same cyclist, riding at 85% VO2max will burn an additional 100 Calories (total of 320 Calories over the 30 minutes), with 110 Calories still coming from fat and the balance of 220 coming from carbohydrates. So even though fat provides a smaller percentage of the total energy needs, the actual number of fat Calories burned during the 30 minutes of exercise remains unchanged. Even if the duration of the faster ride were shortened so that total Calories expended were equal (but proportionally more fat Calories with the slower pace) during both rides, a recent study at Georgia State University demonstrated an equivalent weight change i.e. there was no support for the idea that metabolizing fat for energy resulted in a greater weight loss. Another study at West Virginia U. study assigned 15 women to a low intensity (132 beats per minute) or high intensity (163 bpm) exercise group, both exercising for 45 minutes, 4 times a week. There was a decrease in overall body fat the high intensity group, but not the low intensity one, further evidence that it is total Calories expended, not the source of those Calories (CHO vs. fat) that makes the difference in an exercise supported weight loss program. It is the final balance between total Calories burned (from ANY source - carbohydrates, fats, or protein) and those eaten (i.e. the NET NEGATIVE CALORIC BALANCE) that determines whether weight is gained or lost. The advantage of riding more slowly is that it may make the ride a more enjoyable experience for the novice rider, and the pace can be maintained for hours. If you have only a limited amount of time to ride, the faster your average speed, the more Calories you will burn and the more weight you will shed. In fact there has been speculation that when you exercise at a slow pace, and preferentially burn fat Calories while maintaining muscle glycogen stores, any post ride carbohydrate loading may find the "tank full" (ie muscle glycogen stores) so to speak, and any additional carbohydrate Calories will be converted into fat instead. The bottom line is to ride at a pace that is comfortable for you, push yourself occasionally for the cardiovascular benefits, and avoid eating more Calories than you expend if your goal is to lose weight. Another suggestion has been that caffeine (3 to 4 cups of coffee) per day, because of it's enhancement of fatty acid metabolism, would facilitate weight loss. There is no evidence to support this approach, perhaps related to the fact that the regular use of caffeine eliminates this particular physiologic effect. THE ZONE The Zone by Barry Sears takes a unique approach to weight loss. He claims that his relatively high fat diet (40% carbohydrates, 30% protein, 30% fat vs the usual athlete's diet of 60/15/25) not only provides increased athletic performance but also promotes weight loss. However most performance experts are skeptical and years of nutritional research fail to support either point. According to his theory, too much carbohydrate intake causes obesity as well by stimulating the pancreas to release excessive amounts of insulin. He then speculates that over time the body becomes resistant to insulin causing the pancreas to secrete even larger quantities. And these high levels stimulate fat synthesis. Unfortunately, it's a case of putting the cart before the horse. Obesity, not high carbohydrate intake, lead to insulin resistance at the cell level with a secondary overproduction by the pancreas. And insulin senitivity can be restored by weight loss. In fact, a recent Cornell University study of volunteers on an ad lib (eat as much as you want) diet of either high (37%) fat or low (22%) fat content for 11 weeks demonstrated that those on a low fat diet ate fewer Calories and lost an average of 5.5 pounds - twice the loss of those subjects on the higher fat diet.
  • Another study in a British medical journal showed that obese subjects who lost weight maintained their weight loss better on a high carb diet. Again, it appeared that it was easier to eat excess Calories with a high fat than a high carbohydrate diet. And fewer Calories means less weight gain. The conclusion - BY LIMITING (NOT ELIMINATING) DIETARY FAT, YOU CAN CUT CALORIES AND LOSE WEIGHT WITHOUT SACRIFICING NUTRITION OR ATHLETIC PERFORMANCE. FOUR PRACTICAL TIPS • Dieting alone doesn't help You will lose weight, but it will be more than fat. Some is muscle (which actually burns Calories for you!!) and can leave you thinner, but also slower and weaker. And with less total muscle mass, a return to pre diet eating patterns can actually lead to more rapid weight gain and stabilization at a higher level than where you started. • Ride This will help to maintain your muscle mass while you are shedding fat. And even at a recreational pace of 15 MPH, 1 hour a day of riding will burn almost 4000 Calories per week (the equivalent of a pound of fat) in addition to your normal activities. • Eat a high carbohydrate diet The diet that is best for endurance performance (60 to 70% carbohydrate, low in fat) is also the best for weight loss. And small changes will add up - cut that portion of meat or chili in half, and add potatoes, rice, or pasta to make up the difference; eat bagels instead of muffins (which usually contain oil); substitute yogurt for sour cream or fruit for desert. • Do some weight training This will help to maintain muscle mass, and as riding uses mainly the lower body muscles, it will help to protect the upper body during this time of negative Caloric balance. A program of 20 to 30 minutes three times a week will maintain what you have already. And the increased muscle tone and positive feeling that go with it are a big plus to keep you on track.