Protein is always a hot topic in any gym locker room. For decades, athletes have believed that the more protein they eat the stronger and more muscle mass they will have. Many have succumbed to boring diets of amino acid supplements, egg whites, skinless chicken breast, dry tuna, and steak in an attempt to gain an edge over a competitor. Others spend countless dollars on cardboard tasting protein powders or bars that may or may not be beneficial and in most cases a turkey sandwich with a glass of milk would work just as well.
By the end of this learning unit, you will be able to make recommendations for the amount and type of protein athletes need depending on their training needs and sport of choice.
Protein is broken down, transformed, rebuilt and must be replaced everyday. Most athletes are aware of the importance of protein from a muscle mass perspective but may not be aware of proteins other critical roles including tissue repair, enzymes, antibodies, fluid balance, and lactic acid buffering.
Instructing athletes on how to mix and match sources of protein foods can help them improve protein intake especially athletes that do not eat much meat.
Protein is constantly being synthesized and broken down using amino acids from the blood stream. These amino acids may come from dietary source or from body protein sources such as muscle.
There is very little change in the rate of breakdown or synthesis of protein with endurance exercise. However resistance exercise stimulates the breakdown and synthesis of protein. If the athlete is fed and has lots of free amino acids available in the blood stream, this will boost the rate of synthesis. This promotes muscle growth and repair. If the athlete is not fed and the pool of amino acids are low, less synthesis can occur and therefore less muscle growth and repair. Only a small amount of protein is needed to stimulate muscle protein synthesis after a workout. Just 6-10g of essential amino acids, the amount found in about a 12 oz. glass of milk.
It is possible to get too much protein. Research does not show any additional benefit in physical performance with consuming more than 2 g of Pro/kg. Protein that is not used for body functions and muscle building can be stored as fat. Excess amounts of protein can also increase risk of dehydration.
There may be a time and place where a protein supplement may be beneficial. Athletes with high energy and training demands may find it difficulty to eat enough food or may have a hard time with access to food while traveling. However, those who restrict calories to maintain weight, women, and vegetarians may come up short on protein. Athletes unable to meet their calorie and protein needs through food due to high activity levels may benefit from a protein supplement. A protein supplement beverage is likely to be sufficient.
Protein supplements do come with some risks. They may contain ingredients that cause allergic reactions and banned substances that cause athletes to test positive on drugs screens. Wasting money on ineffective products is also a major risk.
The goal is to provide adequate protein to maximize muscle synthesis and repair. If protein is inadequate it can lead to poor performance and increased risk for illness, such as infection from cold and flu viruses.Low protein intake is also associated with sports anemia. Protein foods are typically some of your best sources of iron as well.
There is quite a bit of research into whether or not the timing of protein intake makes a difference on performance and recovery. It does appear that some protein prior to exercise can help prevent catabolism and increase anabolism.It’s ability to delay gastric emptying may improved satiety and delay hunger. However delayed emptying can also work against an athlete. Given that is takes much more effort to breakdown protein for energy, the athlete may perceive a need for greater exertion which causes fatigue.
Research definitely supports the benefit of protein consumption after training. When protein is available after training, it helps boost muscle protein synthesis rates. This results in faster and better recovery.
Athletes should aim for complete proteins post training. Whole foods are recommend however supplements may be more convenient and can be considered. Food safety should always be considered for post training meals. Many whole food protein sources require refigerationwhereas supplement bars or shakes do not. It would not be wise to eat a turkey sandwich that has been sitting in your car for 4 hours while you were running a marathon.
Pairing protein with carbohydrate with help with absorption due to the release of insulin. Insulin is an anabolic hormone, it help stimulate protein synthesis. There does appear to be a 60 minute to 3 hour window of time in which the body is better able to absorb and utilize protein following exercise. The closer to 60 minutes seems to be better.
The amount of protein needed is not that great. Just six g of essential amino acids or 6- 20 g of total protein. You can individual protein needs post exercise by calculating 0.1 g/kg body weight. For me that would be about 5 g of protein. I could easily get that and more from a tuna sandwich.
I have mentioned chocolate milk before and some of you may have seen it mentioned in the media. It covers several bases for exercise recovery including protein, carbohydrate, and fluid needs. It also supplies a key amino acid, leucine, from the whey protein component. Leucine is essential for muscle protein synthesis.
R IH2N – C – C =O I I H OH PROTEIN: PUNY TO POWERFUL Lona Sandon, M.Ed., R.D., L.D. Assistant Professor
OBJECTIVES Discuss the importance of proteins in the diet Discuss the main functions of proteins in the body Discuss how much protein should be consumed and the various factors that can affect the protein needs of athletes Discuss protein supplementation and its place in sport nutrition Explain the importance of protein intake for the athlete involved in daily training Discuss the type, quantity, and timing of protein consumption before, during, & after exercise.
IMPORTANCE OF PROTEIN 2nd only to water as an ingredient for tissues & structures Needed for muscle maintenance Constant turnover – breakdown & rebuild Can be metabolized for energy Must be replaced daily Critical for enzymes & body functions Inadequate protein can hinder sports performance
COMPOSITION QUALITY Complete High contain all essential AA Typically animal proteins Animal products & soy Contain all essential AA Enough AA for synthesis of Incomplete non-essential AA May contain all essential AA Good digestibility (95%) but in inadequate amounts Mainly plant sources Low Plant sources Complementary PRO Limiting amino acids 2 or more incomplete PROs to Ex. Grains & low lysine make a complete PRO Limited digestibility (85%) TYPES OF PROTEIN FOR ATHLETES
HIGH-QUALITY PROTEIN A complete protein Contains extra amino acids for protein synthesis Good digestibility Usually from animal- derived foods & soy
LOW-QUALITY PROTEIN An incomplete protein One or more limiting amino acids Usually from plant- derived foods
NITROGEN BALANCE Used as indicator of adequacy of total calorie & protein intake When calorie intake is low, protein is broken down resulting in negative N2 balance Negative N2 balance can result in poor athletic performance, muscle loss N2 balance = (Nitrogen in) – (Nitrogen out)
NORMAL PROTEIN TURNOVER Muscle Protein Synthesis Breakdown Muscle free amino acid pool De novo formation Oxidation Dietary Body Blood amino acids protein protein Adapted from: Gibala & Hawarth, 2006
PROTEIN TURNOVER Endurance/aerobic exercise seems to have little impact on PRO synthesis or breakdown Resistance exercise stimulates PRO synthesis (muscle anabolism) while also increasing breakdown (muscle catabolism) Being in a fed state increases synthesis during exercise recovery, promoting muscle growth 6-10 g essential AA acids stimulate anabolism post training
HOW MUCH PROTEIN IS NEEDED? AMDR = 10-35% of daily calories Adapted from: Fink, Burgoon, Mikesky, 2006
FACTORS INFLUENCING PROTEINNEEDS Total energy intake If adequate kcal, calculate PRO needs in middle of range Adequate calories allow for maximum use of PRO Desire to lose or gain weight Calculate PRO needs at high end of range for both weight loss or gain Higher level needed for muscle recovery & maintain positive N2 balance Carbohydrate availability If CHO intake low, calculate PRO at higher end of range
FACTORS INFLUENCING PROTEINNEEDS Exercise intensity and duration High levels require higher PRO needs 2-6% energy may come from PRO breakdown during endurance training Training status/fitness level Higher levels for less fit athletes Training adaption occurs after ~2 weeks, then become more efficient using PRO, requiring less
FACTORS INFLUENCING PROTEINNEEDS Dietary protein quality Vegetarians have higher PRO needs, calculate at higher end of range Age Youthathletes need higher end of range Masters athletes may need higher levels
PROBLEMS OF TOO MUCH PROTEIN Used for energy or converted to fat Increases fluid needs & risk of dehydration High PRO sometimes means high fat & cholesterol intake Displaces other healthful foods; missing essential vitamins/minerals Fat weight gain not muscle
PROTEIN SUPPLEMENTS? Ask the following questions: What is the quantity of protein or amino acids in the product? Is the supplement necessary? Evaluate usual intake first. What is the cost? Will it enhance performance? Does the supplement have any harmful effects?
WHEN ARE PRO SUPP. NEEDED? Very high calorie & PRO needs due to training During traveling or when food availability it limited Vegan athletes Kcal restricting athletes Female athletes more likely to eat low PRO
RISKS OF PRO SUPPLEMENTS Allergic reactions to added ingredients Contaminated with banned substances Nutrient-nutrient interactions Lost money
PRO & DAILY TRAINING Aim to maximize muscle PRO synthesis Repair microtrauma of muscles caused by training If inadequate, rely on body sources leading to protein losses Decreased performance Increases risk of illness Sports anemia Low hemoglobin
PRE-TRAINING PROTEIN Recent research suggests PRO prior to exercise may: Provide energy for muscle cells Decrease catabolism of muscle tissue Increase muscle protein synthesis Decreases gastric emptying Leading to longer satiety Gradual release of nutrients into blood stream Prevent hunger during training/competition Consume 1-3 hours prior to training May increase perceived exertion
4-24 HOURS PRIOR TO TRAINING Consider time before training Choose lean proteins 3-6 ounces of meat or equivalent complementary non-meat PRO sources 8-12 fl oz of dairy 1 oz nuts, seeds CHOs, not proteins, should predominate Familiar foods
1 -4 HOURS BEFORE TRAINING Focus on CHO Small amounts of PRO may be tolerated 2–4 oz lean meat 8 fl oz milk, yogurt Lean protein sources preferable
PROTEIN DURINGTRAINING/COMPETITION? PRO can serve as an energy source Too slow for intense activity Must go through liver before getting to muscle except BCAAs Benefit of consumption questionable Hydration beverages (Accelerade) with PRO does not appear to improve performance/endurance AA taste bad in sports drinks
PROTEIN DURINGTRAINING/COMPETITION? Research supporting BCAAs Ingestion may prevent central nervous system fatigue due to low blood levels Research results inconsistent Limited effect on performance
PROTEIN AFTER TRAINING Critical for recovery Increased rate of PRO synthesis Availability of food effects synthesis rate Positive PRO balance dependent on: AA composition AA blood concentration Timing of feeding
PROTEIN AFTER TRAINING Type: Influences hyperaminoacidemia Complete PROs Casein Whey Soy Foods containing essential AAs Whole food sources recommended
PROTEIN AFTER TRAINING Better absorption when consumed with CHO Increased circulating insulin promotes protein synthesis Improved recovery & muscle repair Best if consumed within 60 min to 3 hours of exercise
HOW MUCH? EXAMPLES 6 grams essential AAs Chocolate milk PRO synthesis Yogurt & nuts General recommendations Meat sandwich on whole 6-20 g PRO post exercise wheat Consume within 3 hours or less of exercise for maximum effect of muscle building hormonesPROTEIN AFTER TRAINING
CHOCOLATE MILK FOR RECOVERY Provides PRO & CHO in amounts shown to promote muscle synthesis & glycogen repletion Provides essential AA & BCAA important for muscle anabolism Provides Na+ & K+ lost in sweat Promotes greater fluid replacement & retention compared to sports drinks Contains many other essential vitamins/minerals
SUMMARY PRO is a key nutrient for muscle mass Complete, high quality & complementary PRO can provide essential AAs for athletes Athletes should achieve a positive N2 balance for muscle building & repair Athletes have higher PRO needs than non-athletes 1.4-2 strength, 1.2-2 endurance, 1.2-1.6 team sports PRO needs depend on: weight, training status, calorie & CHO intake, weight gain/loss, quality & type PRO before & after exercise can benefit athletes
REFERENCESFink HH, Burgoon LA, Mikesky AE, eds. Practical Applications in Sports Nutrition. Sudbury, MA: Jones and Bartlett; 2012Gibala MJ. Howarth KR. Protein and exercise. In: Dunford M, ed. Sports Nutrition: A Practice Manual for Professionals, 4th ed. American Dietetic Association; 2006.Roy BD. Milk: the new sports drink? A review. J Int Soc Sports Nutr. 2008;5:15.