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Fats in Sports

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Fats in Sports

  2. 2. Fats Lecture 5
  3. 3. Oils contain heart healthy fatty acids
  4. 4. 1. Explain ketosis and the effect it may have on training 2. Describe how the body uses fat to fuel exercise 3. State fat recommendations for athletes and calculate the amount of fat needed daily 4. Identify sources of dietary fat and assess an athlete’s dietary fat intake 5. Evaluate dietary supplements related to fat metabolism Learning Objectives
  5. 5. Introduction to Fats  The word “fat” has many different meanings  Primary source of energy at rest and during low- intensity exercise  Fat required in diet to provide essential fatty acids that body cannot manufacture and for absorption of fat-soluble vitamins  Most concentrated source of energy – 9 kcals/g  Fats are distinguished by their chemistry  Certain fats in food and in the blood are associated with cardiovascular disease
  6. 6. Fatty Acids (FAs)  FAs are chains of carbon and hydrogen ending with a carboxyl group (COOH) • Carboxyl group = a carbon with a double bond to oxygen and a single bond to oxygen/hydrogen
  8. 8. Fatty Acids (FAs)  Chain length varies from 4 to 24 carbons (even numbers only) • 2 carbons are added at a time  Double bonds are a distinguishing factor  Fatty acid series is a distinguishing factor  Most FAs used in human metabolism have 16-18 carbons
  9. 9. Oleic Acid – 18 carbons Cis double bond
  10. 10. Fatty Acids (FAs)  Saturated fatty acids have no double bonds between carbons • Saturated = no additional hydrogen atoms can be incorporated • Mostly found in animal products • Also plant oils – palm oil, coconut oil Used in cookies, cakes, donuts, pies • Ex/ palmitic acid, stearic acid, myristic acid
  11. 11. Fatty Acids (FAs)  Unsaturated fatty acids contain one or more double bonds between carbons  16-22 carbons and 1-6 double bonds • Monounsaturated fatty acid – only one double bond Ex/ oleic acid • Polyunsaturated fatty acid – 2 or more double bonds Ex/ linoleic acid, arachidonic acid
  12. 12. Saturated, Monounsaturated, and Polyunsaturated Fatty Acids
  13. 13. Vegetable oils are excellent sources of monounsaturated and polyunsaturated fatty acids.
  14. 14. It is important to know the amounts and types of dietary fats found in foods.
  15. 15. Cis and Trans Formations  Cis refers to groups on the same side of double bond between carbons • Most unsaturated fats are cis • Bend in the chain  Trans refers to groups on opposite sides of double bonds between carbons • Straight chain • Produced synthetically through addition of hydrogen atoms to unsaturated fatty acid Hydrogenation process – used in commercial food processing to make liquid oils more solid
  16. 16. Fatty Acid cis and trans Formations
  17. 17. Trans Fats  Hydrogenation of vegetable oils gives products desirable texture and longer shelf life  However, this produces trans fats – which are associated with increased risk for CVD • Increase LDL  American Heart Association (AHA) recommends no more than 1% of total kcals intake from trans fats – “intake should be as low as possible”  Read labels and check ingredient lists  Conjugated Linoleic Acid (CLA) – naturally occurring trans fat that may have some health benefits
  18. 18. Omega-3, -6, and -9 Fatty Acids  Polyunsaturated fats can be classified by placement of first double bond counted from last carbon on chain farthest from carboxyl group • Omega-3 Alpha-linoleic acid (ALA) Eicosapentanoic acid (EPA) Docosahexaenoic acid (DHA) • Omega-6 Linoleic acid Arachidonic acid • Omega-9 Oleic acid
  19. 19. Omega-3, -6, and -9 Fatty Acids
  20. 20. 3 Major Lipids  3 major types of lipids in human nutrition: 1. Triglycerides 3 FA’s attached to glycerol 95% of fat found in foods are triglycerides 2. Sterols Ex/ cholesterol 3. Phospholipids Phosphate-containing fats
  21. 21. Triglycerides (TG, Trig)  Composed of 3 fatty acids and one glycerol  TGs are the predominant fat in food and in body  Usually contains a combination of different FAs
  22. 22. Triglycerides (TG, Trig)  “Triacylglycerol” is correct technical term  Triglycerides found in food contain a combination of saturated, monounsaturated, and polyunsaturated fatty acids • Foods are grouped according to predominant FA  Ex/ coconut oil classified as saturated fat since it is 92% saturated fat, 6% MUFA and 2% PUFA
  23. 23. Structure of Triglycerides
  24. 24. Fatty Acid Distribution in Selected Foods
  25. 25. Essential Fatty Acids  Two 18-carbon fatty acids are essential FA’s  The body cannot manufacture these, so they must be consumed in the diet  Widely found in foods • Alpha-linolenic acid (omega-3) – soy, canola, and flaxseed oils, green leafy vegetables, fatty fish and fish oils • Linoleic acid (omega-6) – soy, safflower, and sunflower oils
  26. 26. Omega-3, -6, and -9 Fatty Acids  Omega-3 fatty acids • i.e alpha-linolenic acid (ALA), EPA, DHA • Body can convert ALA to EPA and DHA, but amount is limited • Deep water, oily fish • Fish oil supplements • Flaxseed, green leafy vegetables, nuts • Soybean and canola oil
  27. 27. Omega-3, -6, and -9 Fatty Acids  Omega-6 fatty acids • i.e linoleic acid (vegetable oils), arachidonic acid (animal fats) • Eicosanoids = fatty acids w/ 20 carbons • Eicosanoids made from arachidonic acid are associated w/ CVD, diabetes, HTN, obesity • Omega-3 and omega-6 in competition for same enzymes • Optimal ratio 4:1 or less of omega 6:omega 3 • Typical Western diet = 15:1 or more
  28. 28. Omega-3, -6, and -9 Fatty Acids  Omega-9 fatty acid • i.e oleic acid • Olive oil • Decreased CVD risk if it replaces saturated and trans fatty acids in the diet
  29. 29. Sterols  4 ring structure known as “steroid”  One or more hydroxyl (OH) groups attached and no carbonyl (=C=O) or carboxyl (COOH) groups  i.e cholesterol, vitamin D, sex hormones, cortisol  Cholesterol • Only found in animal foods in which fat has not been removed • Important part of cell membranes • Also manufactured in the body by liver
  30. 30. Structure of Sterols
  31. 31. Phospholipids  Similar in structure to triglycerides  Contain phosphate  Structural component of cell membranes  i.e Lecithin • Found in soybeans, eggs, milk • Often used as an emulsifier such as in nonstick cooking spray
  32. 32. Type of fat consumed can influence CVD  Beneficial for prevention of heart disease (CVD): 1. Monounsaturated fatty acids 2. Polyunsaturated fatty acids 3. Omega-3 fatty acids
  33. 33. Type of fat consumed can influence CVD  Recommended that trans fat consumption be as low as possible due to increased risk of CVD • <1% of total kcals (AHA)  Excessive saturated fats and cholesterol can increase risk of CVD • <7% saturated fat/day (AHA) • <300 mg cholesterol/day; <200 mg if CVD (AHA)
  35. 35. Fats and Performance and Health  From a performance perspective… • Fat should provide 25-35% of total kcals/day (AHA) – lower than 20% can be detrimental • Fat provides energy at rest and during low- intensity exercise • Amount of fat intake for athlete will depend on: 1. Overall energy need (total kcals) 2. Macronutrient balance (pro, CHO, fat)
  36. 36. Digestion of Fats  Fats are large, insoluble molecules that must be bound to protein for transport in blood  Fat is primarily digested in the small intestine  Bile salts help to start breaking down fats  Pancreatic lipase is important digestive enzyme • Secreted by pancreas into the small intestine and helps to break down large fat molecules into smaller components Diglycerides, monoglycerides, free fatty acids
  37. 37. Digestion of Fats Fats are digested in two stages: Firstly, bile (released by the gall bladder) allows the fat to “mix” with water by breaking the fat into smaller droplets. This is called emulsification. bile Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol fatty acid molecules .
  38. 38. Digestion of Fats • Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol fatty acid molecules . Lipase + fat molecule glycerol fatty acids
  39. 39. Digestion of Fats  Undigested fat in the stomach can: 1. Delay gastric emptying Athletes may limit fat intake when they do not want gastric emptying delayed, such as during endurance event when rapid movement of CHO-containing fluids into intestine is beneficial 2. Cause feeling of satiety Athletes may include fat-containing foods when they want to avoid feeling hungry for several hours
  40. 40. Absorption of Fats  Fat particles enter mucosal cells via passive diffusion (high to low concentration)  Majority are re-assembled into TGs • 12-18 carbon fatty acids • TG are incorporated into chylomicrons  Chylomicrons (lipoprotein) are large protein and fat molecules that help transport fat throughout body  Short (4 carbons) and medium chain fatty acids (6-10 carbons) pass through mucosal cells unchanged
  41. 41. Transportation of Fats  Blood • Water, RBCs, WBCs, oxygen, nutrients, electrolytes • Enters tissues via arteries and leaves via veins • Circulates within tissues via capillaries • Some components of blood are filtered out of capillaries as interstitial fluid  Lymph • Part of the blood that is not filtered out of capillaries for use by tissues • WBCs, proteins, fats • Moves through lymphatic system
  42. 42. Transportation of Fats  Chylomicrons are slowly released into lymph  Short and medium chain fatty acids are released into blood via the portal vein where they will be bound to a protein • Albumin is most common transport protein for fat
  43. 43. Transportation of Fats  Blood lipid levels are increased for several hours after fat consumption; highest ~3 hrs  TG portion of the chylomicron can be absorbed by adipocytes and muscle cells • Lipoprotein lipase (LPL) stimulates the release of FAs from TGs • FAs then rapidly absorbed by fat and muscle cells
  45. 45. Metabolism of Fats  Fat can be easily stored in the body • Esterification is the process of TG formation from glycerol molecule and 3 FAs • Insulin stimulates lipoprotein lipase activity • LPL breaks down circulating TGs from lipoprotein, feeing FFAs for uptake into fat cells • Once taken up into adipocytes, FAs are re-assembled into TGs for storage • Fats are stored in the body largely in form of TGs
  46. 46.  Main sites of fat storage: 1. Adipose tissue Subcutaneous fat – just beneath skin Visceral fat – surrounding internal organs 2. Liver 3. Muscle Intramuscular triglycerides • i,.e Heart muscle, slow twitch muscle fiber 4. Blood – small amount Visceral fat Metabolism of Fats
  47. 47. Metabolism of Fats  Advantages of fat storage • Contain twice the amount of kcals per unit than CHO and protein 9 kcal/g • Normal amount of energy stored as fat = 100,000 kcals (500 g of CHO (2000kcal) in the form of muscle glycogen, liver glycogen and blood glucose) • “Energy dense” nutrient • Anhydrous (no water associated with it) (when CHO is stored in the form of glycogen, ~ 2 g of water are stored along with every g of glycogen, increasing the weight without increasing the energy content)
  48. 48. Metabolism of Fats  Fat is an important source of energy for many athletes  However, process of metabolizing fat is complex and slow… 1. Fats must be mobilized from storage 2. Transported to appropriate tissues 3. Taken up into tissues 4. Translocated and taken up by mitochondria and oxidized via Krebs cycle 5. At steady state exercise, it takes ~10-20 minutes for fat oxidation to reach its maximal rate of activity
  49. 49. Metabolism of Fats  In order for fat to be used as energy, TGs stored as fat in adipocytes must be broken down via lipolysis → glycerol + 3 FAs  Lipolysis is catalyzed by HSL • Hormone Sensitive Lipase (HSL) = enzyme found in adipocytes that helps to mobilize fat • Stimulated by catecholamines, growth hormone, glucocorticoids, thyroid-stimulating hormone. • Inhibited by insulin – so, mobilization of stored fat is inhibited after meals
  50. 50. Metabolism of Fats  Mobilizing fat from storage is best 3-4 hours after eating (post-absorptive), fasting, starvation, and when stressed (including exercise)  After lipolysis… • FFAs and glycerol circulate in the blood • Glycerol carried in blood to liver where it can be converted to glucose or re-assembled into triglycerides • FFAs attach to protein (albumin) and are distributed to other tissues in body for metabolism
  51. 51. Mobilization and Transportation of Stored Triglyceride
  52. 52. Metabolism of Fats  1 ATP used along with CoA to convert FA chain to fatty acyl-CoA in the outer mitochondrial membrane  Then fatty acyl-CoA must be transported into mitochondria where it undergoes beta- oxidation via carnitine transport mechanism • Carnitine – synthesized from AAs lysine and methionine and is required for transport of fatty acids
  53. 53. Metabolism of Fats  Beta oxidation involves 4 chemical steps during which 2 carbon segments are cleaved off the FA chain and converted to acetyl CoA, which can then enter Krebs cycle • Each acetyl CoA derived from a FA chain can be oxidized to eventually form 12 ATP
  54. 54. Ketosis  Acetyl CoA can be catabolised to produce ketone bodies: • Acetoacetate • Beta-hydroxybutyrate • Acetone  “Overflow” pathway  The liver can produce up to 185 g ketones/day • Ketones supply ~2-6% of body’s energy needs after overnight fast  Normal blood ketone concentration: < 0.05 mmol/L  Normal urine ketone concentration is zero
  55. 55. Ketosis  Ketosis is an abnormal increase in ketone bodies or a blood ketone concentration of >0.06 mmol/L  Occurs when fatty acid oxidation is accelerated due to: • Low CHO intake due to starvation state (self- restriction or involuntary) • Impaired CHO metabolism (diabetes) Dangerous, can result in ketoacidosis = pH of blood more acidic than tissue and can result in coma, death
  56. 56. Ketosis – How are ketones formed?  Normally w/ an adequate CHO intake… • Glycolysis converts glucose to pyruvate • Pyruvate transported to mitochondria where it is metabolized to acetyl CoA • Acetyl CoA joins with oxaloacetate in the 1st step of the Krebs cycle
  57. 57. Ketosis – How are ketones formed?  But, with a low CHO diet… • Body must find other sources of acetyl CoA – fatty acids and some amino acids • As more FAs are broken down to provide acetyl CoA, supply of oxaloacetate decreases • Acetyl CoA accumulates and ketone bodies are produced
  58. 58. Ketosis  2-3 days of low CHO intake… • Body can produce glucose from other sources – lactate, amino acids • 2/3 fuel used by brain is glucose; 1/3 ketones
  59. 59. Ketosis  After a few days of low CHO intake… starvation • Muscle glycogen depleted with no resynthesis • Loss of some skeletal muscle • Glucose will be primarily made from glycerol (obtained via lipolysis) • Ketones will be primary fuel source for brain • Weight (fat) loss
  60. 60. Ketosis  Low CHO, calorie-restricted diet is popular method for weight loss  Not likely to be beneficial for athletic performance – likely will have a negative effect on training and performance • Muscle loss • Depletion of glycogen  Clinical uses of ketosis include: • Supervised weight loss for overweight/obese • Supervised ketogenic diet for seizure control
  61. 61. Ketosis
  62. 62. KEY POINTS 1. Fats are stored as TG formed from a glycerol and 3 FAs 2. Fat is energy dense, containing 9kcal/g 3. In order to be used, fats must be translocated, or broken down from their storage and transported to the site of usage 4. In order to metabolised aerobically, FAs must be converted to fatty acyl-CoA, transported into the mitochondria, and converted to acetyl CoA via -oxidation
  63. 63. KEY POINTS 5. Fats are more readily metabolised by tissue with a higher aerobic capacity 6. Ketone bodies can be produced as a result of fat metabolism and overreliance on fat metabolism can result in ketosis
  65. 65. Fats as an Energy Source During Exercise  Primary source of energy at rest and during low-intensity exercise  Advantages • Fat is abundant in food supply • Energy dense • Stored in substantial amounts in adipose tissue • Produces large amount of ATP
  66. 66. Fats as an Energy Source During Exercise  Disadvantages • Takes time to transport and metabolize (many steps) • Requires oxygen so it can only be used in aerobic metabolism Limited to activities that use oxidative phosphorylation
  67. 67. Energy expenditure and fuel utilization during running can be measured through indirect calorimetry and RER. It is important to know the relative (percentage) and absolute amount of fat utilised as a fuel
  68. 68. Relative and Absolute Fat Oxidation  Respiratory Exchange Ratio (RER) is the ratio of CO2 produced to the amount of O2 consumed  RER is 1.0 during CHO metabolism  RER is 0.70 during fat metabolism • “Relative” Percentage of energy derived from CHO or fat • “Absolute” Total amount of energy expended (kcal/min) • If we know relative and absolute energy expenditure, we can determine caloric expenditure (kcal/min) from fat and CHO
  69. 69. Energy Expenditure and Fuel Utilization  Case Study – • 49 yr old male training for first marathon • Some previous recreational running experience • 168cm and 82.5 kg
  70. 70. Energy Expenditure and Fuel Utilization  The RER increases with each successive increase in exercise intensity  As RER increases, the % of energy supplied by fat metabolism declines  “Crossover concept” – the point in exercise intensity when CHO increases and becomes predominant source of energy and the utilization of fat declines to a lesser percentage
  71. 71. Figure 6-15 p214
  72. 72. Energy Expenditure and Fuel Utilization  Case Study – • 49 yr old male training for first marathon • Some previous recreational running experience • 168cm and 82.5 kg
  73. 73. Figure 6-16 p215
  74. 74.  If fat is such a good energy source, why does fat metabolism decline as exercise intensity increases? • Lower intensity exercise, increase in fat oxidation • As exercise intensity continues to increase, there is increase reliance on fast-twitch muscle fibers • rely on more on anaerobic energy systems • poor ability to oxidise fat • Use anaerobic glycolysis, they produce lactate • Lactate inhibit plasma protein albumin to bind and carry FFAs in the blood Energy Expenditure and Fuel Utilization
  75. 75. Energy Expenditure and Fuel Utilization  Fat oxidation during prolonged steady state exercise • Prolonged period of time lead to muscle glycogen depleted • Rely more on fat oxidation • Gradual decline in RER
  76. 76. Figure 6-17 p216
  77. 77.  Do You Have to Burn Fat to Lose Fat? • Low-intensity aerobic exercise (“fat-burning zone”) • RER is lower during lower intensity exercise • % of energy derived from fat is high • Total amount of energy expended is lower Energy Expenditure and Fuel Utilization
  78. 78. Energy Expenditure and Fuel Utilization  Case Study – • 49 yr old male training for first marathon • Some previous recreational running experience • 168cm and 82.5 kg
  79. 79. Energy Expenditure and Fuel Utilization  Most important factor in weight and fat loss is total caloric expenditure, not exercise intensity or the source of fuel used during exercise 918 kcal 804 kcal 300 kcal 250 kcal
  80. 80.  Do You Have to Burn Fat to Lose Fat? • Not necessary to burn fat during exercise to lose body fat • Total energy expended is more important than % expended from fat Energy Expenditure and Fuel Utilization
  81. 81. Effects of Training on Fat Usage  General adaptations • Endurance training results in an enhanced ability to oxidize fat • FAs are more easily mobilized from adipocytes • Advantageous for endurance athletes – can rely more on fat metabolism and spare glycogen for later in the race
  82. 82. KEY POINTS 1. Fat utilisation can be determined by the respiratory exchange ratio (RER), which is the ratio of CO2 produced to oxygen consumed. 2. The % of energy derived from fat metabolism decreases as activity and exercise intensity increases. 3. As exercise intensity increases, the total amount of energy derived from fat metabolism increases, reaches a peak, and then begins to decrease.
  83. 83. KEY POINTS 4. If exercise continues at the same intensity for long periods of time, the relative amount of energy derived from fat metabolism increases slightly (if the athlete does not consume any CHO during exercise) 5. Regular aerobic exercise training increases the body’s ability to metabolise fat, particularly during exercise at the same absolute exercise intensity. 6. Increasing the amount of fat in the diet increases reliance on fat as an energy source at rest and during lower intensities of exercise, but does not result in improved performance at higher exercise intensities
  85. 85. Fat Recommendations for Athletes  Total daily fat intake depends on total energy, CHO and protein intake. 1. Total energy (kcals) needed 2. Macronutrient balance Higher CHO/protein intake typically means lower fat intake Severe restriction of fat intake not recommended
  86. 86. Fat Recommendations for Athletes  Often expressed as a % of total energy intake • 20 to 35% total caloric intake  May be expressed on g/kg body weight basis • ~1.0 g/kg daily is general guideline • May need to be as high as 2.0 g/kg for endurance athletes or 3.0 g/kg for ultraendurance athletes
  87. 87. Misconceptions of Fat  Fat is perceived negatively by society and fat intake is often restricted  People believe that a high fat intake results in increased body fat  However, increases in body fat are due to the excess consumption of total energy (kcals)  Overconsumption of any of the macronutrients (fat, CHO, protein, alcohol) can result in increased body fat  Some athletes have a “fat phobia” or believe fat to be forbidden
  88. 88. Fat Recommendations for Athletes  Reducing caloric intake by reducing dietary fat intake over several weeks or months may help athletes a loss of body fat. • Reducing body fat may result in improved performance i.e low % body weight for a runner is beneficial because it is less weight to be moved • Fat intake is typically reduced since reductions to CHO or protein intakes may be detrimental to performance • Athletes may consume a short-term, low fat diet to achieve body composition goals
  89. 89. Fat Recommendations for Athletes  Inadequate fat intake can negatively affect training, performance and health. 1. Inadequate replenishment of intramuscular fat stores (muscle triglycerides) 2. Inability to manufacture sex-related hormones Testosterone, estrogen 3. Alteration in the ratio of HDL:LDL Decline in HDL 4. Inadequate fat-soluble vitamin intakes When <0.75 g/kg fat intake 5. Essential fatty acid deficiencies Linoleic and alpha-linolenic
  90. 90. KEY POINTS 1. To determine the appropriate fat intake, the athlete must consider total caloric, CHO and protein intakes. 2. Some athlete consume too much fat relative to the amount of CHO and protein needed. They need to slightly increase CHO and protein intakes and reduce fat intake to a degree. 3. Some athletes chronically consume too little dietary fat as part of a semi starvation diet, and training, performance, and health may suffer. 4. If done appropriately, reducing fat intake can be an effective strategy for body fat loss.
  92. 92. Translating daily fats recommendations to food choices  Amount and types of fats in food • Predominately saturated: (<7% total kcals/day) • Hard (stick) margarine • Butter • Cream • Coconut oil
  93. 93. Translating daily fats recommendations to food choices  Predominantly monounsaturated: • Olive, canola, and peanut oils • Some safflower oils • Avocado • Olives • Nuts
  94. 94. Translating daily fats recommendations to food choices  Predominantly polyunsaturated: • Corn, soy, and flaxseed oils • Some safflower oils • Liquid and soft (tub) margarines • Mayonnaise and some salad dressings • Sunflower, pumpkin, and flax seeds
  95. 95. Fats and Oils
  96. 96. High Fat Foods
  97. 97. Meat, Fish, Poultry and Dairy
  98. 98. Snack Foods
  99. 99. Fat Substitutes  Some foods are made with fat substitutes • Often made from CHO sources • Many fat-free products do not have fewer kcals than original product • Olestra (Olean®) • Fat substitute composed of sucrose polyester • Cannot be absorbed due to its chemical structure • May inhibit absorption of fat soluble vitamins • Side effects – abdominal cramping, loose stools
  100. 100. KEY POINTS  The amount and types of fat in food varies  Athletes often choose lower fat versions of food  Many “fat-free” products are not low in calories
  102. 102. Caffeine  Caffeine is a central nervous stimulant that helps to delay fatigue  Dose: 2-3 mg/kg body weight for endurance  Consensus opinion: caffeine may enhance FFA mobilization during endurance exercise, but fat oxidation is not significantly increased and muscle glycogen is not spared
  103. 103. Caffeine  Evidence that caffeine can enhance endurance performance • Distance runners, cyclists, cross country skiers  Also evidence that caffeine can improve performance for those engaged in high intensity activities lasting 1-20 min • Runners, cyclists, swimmers, rowers  Evidence for improving performance in athletes in other sports has been inconclusive
  104. 104. Caffeine  Dose for endurance athlete: 2-3 mg/kg body weight  Caffeine takes 30-45 minutes to get into cells  Half life of caffeine is ~ 5 hours  Caffeine has side effects: • Increase in heart rate • GI distress • Interference with sleep  Caffeine is addictive and sudden withdrawal can result in severe headaches  Trial and error
  105. 105. Caffeine  Caffeine can be consumed via: • Pills – 1 tablet = 100 mg; 1 Excedrin = 65 mg • Energy bars – 1 bar = 50-100 mg • Energy shots – 2 oz = 200 mg • Gels – 1 oz = 50 mg • Energy drinks – 8 oz = 80 mg (Red Bull) • Coffee – 8 oz = 85-90 mg • Soda – 12 oz = 36 mg
  106. 106. Caffeine  Caffeine is a banned substance at certain concentrations by some sports-governing bodies • NCAA: post-competition >15 mcg/ml urine level would disqualify Equivalent to 6-8 cups of coffee 2-3 hours prior to competition • IOC: monitors caffeine levels, but does not disqualify  Caffeine intoxication is possible, but rare  Caffeine not recommended for children or adolescents (AAP, ACSM)
  107. 107. Carnitine Supplements  Carnitine is essential to transport FA into mitochondria where they are broken down for energy  Found in food and synthesized in the body from lysine  Deficiencies are rare  Supplement dose: 2 to 4 g/day  Supplements seem to be safe at such dosages
  108. 108. Carnitine Supplements  Studies show that carnitine supplements do not increase carnitine content of muscles  Carnitine may play role in increasing blood flow to muscles, reducing oxidative stress (Huang & Owen, 2013)  No evidence of altered fat metabolism or improved performance; however, no evidence of detrimental performance either
  109. 109. Medium-chain Triglyceride Supplements  MCTs contain 6-10 carbon atoms  Rapidly absorbed via portal vein and easily transported to mitochondria  Studies show MCT ingestion does not alter fat metabolism, spare muscle glycogen or improve performance (Hawley, 2002; Horowitz and Klein, 2000)
  110. 110. Medium-chain Triglyceride Supplements  May impair performance in some cases • Negative side effects include GI upset • (Goedecke et al., 2005) – found that ingestion of MCT by ultraendurance cyclists compromised sprint performance d/t GI upset
  111. 111. Omega-3 Fatty Acids  Marketed to athletes to reduce inflammation, reduce effects of oxidative stress and counteract immune dysfunction associated w/ strenuous exercise  Recommended dose 1-2 g/day • FDA recommends to not exceed 3 g/day  Studies show omega-3 FA’s do not appear to positively affect inflammation or immune response or to positively affect performance
  112. 112. 1. Fat is the most energy-dense nutrient found in food 2. Fat is the primary energy source at rest and during low-intensity activity 3. Caution should be used when restricting fat because athletes can reduce the fat in their diets too much SUMMARY