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Nutrition, Body Composition, and Performance

Nutrition, Body Composition, and Performance. Objectives. Describe the effect of various carbohydrate diets on muscle glycogen and on endurance performance during heavy exercise.

mechelle-cabrera
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Nutrition, Body Composition, and Performance

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  1. Nutrition, Body Composition, and Performance

  2. Objectives • Describe the effect of various carbohydrate diets on muscle glycogen and on endurance performance during heavy exercise. • Contrast the “classic” method of achieving a supercompensation of the muscle glycogen stores with the “modified” method. • Describe some potential problems when glucose is ingested immediately prior to exercise. • Describe the importance of blood glucose as a fuel in prolonged exercise, and the role of carbohydrate supplementation during the performance.

  3. Objectives • Contrast the evidence that protein is oxidized at a faster rate during exercise with the evidence that the use of labeled amino acids may be an inappropriate methodology to study this issue. • Describe the need for protein during the adaptation to a new, more strenuous exercise level with the protein need when the adaptation is complete. • Defend the recommendation that a protein intake that is 12 to 15% of energy intake is sufficient to meet an athlete’s need.

  4. Objectives • Describe the recommended fluid replacement strategies for athletic events of different intensities and durations, citing evidence to support your position. • Describe the salt requirement of the athlete compared to that of the sedentary individual, and the recommended means of maintaining sodium balance. • List the steps leading to iron deficiency anemia and the special problem that athletes have in maintaining iron balance. • Provide a brief summary of the effects of vitamin supplementation on performance.

  5. Objectives • Characterize the role of the pregame meal on performance and the rationale for limiting fats and proteins. • Describe the various components of the somatotype and what the following rating signify: 171, 711, and 117. • Describe what the endomorphic and mesomorphic components in the Heath-Carter method of somatotyping represent in conventional body composition analysis. • Explain why one must be careful in recommending specific body fatness values for individual athletes.

  6. Nutrition and Performance Carbohydrate Protein Water and Electrolytes Minerals Vitamins Precompetition Diet Outline • Somatotype Body Fatness and Performance • Body Composition and Performance

  7. Nutrition and Performance Recommended Range of Nutrient Intakes • 45–65% calories from carbohydrates • Meets needs of whole population • Addresses special needs • Type 2 diabetes • Athletes need more carbohydrates than the average person • Average intake only ~50% calories • 20–35% calories from fat • 10–35% calories from protein

  8. Nutrition and Performance Carbohydrate Diets and Performance • Muscle glycogen is depleted during heavy exercise • Time to exhaustion related to initial muscle glycogen store • Endurance performance is improved by a diet high in carbohydrates • Increases muscle glycogen and performance time • Muscle glycogen loading (“supercompensation”) • Goal is to maximize muscle glycogen in the days leading up to an event

  9. Nutrition and Performance Effect of Diet on Muscle Glycogen and Time to Exhaustion Figure 23.1

  10. Nutrition and Performance Muscle Glycogen Supercompensation • Classical method • Prolonged strenuous exercise to deplete glycogen stores • A high-fat/protein diet for three days while continuing to train • 90% CHO diet for three days with inactivity • Modified plan • Tapering workouts (90 to 40 minutes) over several days while eating 50% CHO diet • Two days of 20 minute workouts while eating 70% CHO diet • Day of rest eating 70% CHO diet before event • Both methods increase muscle glycogen to high levels • Only one day with carbohydrate intake of 10 g/kg body weight from high glycemic index foods required for very high muscle glycogen levels • Elevated muscle glycogen can last as long as five days

  11. Nutrition and Performance Modification of the Classic Glycogen Loading Technique Figure 23.2

  12. Nutrition and Performance Muscle Glycogen Replenishment • Takes about 24 hours to replenish muscle glycogen • Requires ingestion of 500–700 g carbohydrates • Limiting factor is glucose transport across cell membrane • Timing of glucose ingestion after exercise • Initiated immediately after exercise • Repeated each 2 hours for 6 hours • Type of carbohydrate • Glucose or glucose polymers better than fructose • Fructose may be better for replenishing liver glycogen • Including protein may increase glucose uptake

  13. Nutrition and Performance The Winning Edge 23.1The Zone Diet • 40% carbohydrate, 30% protein, 30% fat • Protein intake: 1.8–2.2 g/kg FFM • Leads to eicosanoid production • Promotes vasodilation and lipolysis • Not recommended for endurance performance • Low-carbohydrate diet • Reduced time to exhaustion • Protein guideline results in calorie-deficient diet • Oversimplification of metabolic and physiological effects • Inconsistency in eicosanoid effects on muscle • Should be considered “ergolytic” rather than “ergogenic”

  14. Nutrition and Performance In Summary • Performance in endurance events is improved by a diet high in carbohydrates due primarily to the increase in muscle glycogen. • When workouts are tapered over several days while additional CHO (70% of dietary intake) is consumed, a “supercompensation” of the glycogen store can be achieved.

  15. Nutrition and Performance Carbohydrates Prior to or During a Performance • Improves performance by maintaining blood glucose • Rate of glucose use by muscle • 1–2 g/min • Rate of liver gluconeogenesis • 0.2–0.4 g/min • Does not spare muscle glycogen utilization • Allows maintenance of power output and lower RPE

  16. Nutrition and Performance Carbohydrates Prior to a Performance • Pre-exercise • 1–5 grams CHO•kg–1 body weight • 1–4 hours before exercise • Easily digestible solid or liquid food • Test for sensitivity to carbohydrate load in training • Carbohydrate intake immediately prior to exercise may impair performance • Hypoglycemia in sensitive individuals • Faster rate of muscle glycogen utilization

  17. Nutrition and Performance Carbohydrates During a Performance • Carbohydrate ingestion can maintain plasma glucose even as glycogen is depleted • Delays fatigue and improves performance • Can be ingested throughout exercise or 30 minutes prior to fatigue • 30–60 g CHO/hour is required • 375–750 ml/hr of 8% CHO solution • >8% CHO slows gastric emptying • CHO from glucose, sucrose, or glucose polymers • Addition of caffeine increases CHO oxidation • Adding protein may increase performance further • Conflicting evidence

  18. Nutrition and Performance Blood Glucose and Muscle Glycogen Use During Prolonged Exercise Figure 23.3

  19. Nutrition and Performance In Summary • Pre-exercise feedings should contain 1 to 5 g of carbohydrate per kilogram of body weight and should be taken one to four hours prior to exercise. • Muscle glycogen is depleted at the same rate, whether or not glucose is ingested during prolonged performance. • The ingestion of glucose solutions during exercise extends performance by providing carbohydrate to the muscle at a time when muscle glycogen is being depleted.

  20. Nutrition and Performance Protein Requirement During Exercise • Determined by: • Oxidation of individual amino acids (leucine) • Oxidation affected by carbohydrate intake • Provides no rationale for increasing protein intake • Whole-body nitrogen balance studies • N excretion in urine and sweat • Dependent upon: • Training state of the subject • Quality and quantity of protein consumed • Total calories consumed • The body’s carbohydrate stores • Intensity, duration, and type of exercise • Used to determine protein requirements for athletes

  21. Nutrition and Performance Effect of Exercise on Nitrogen Balance Figure 23.4

  22. Nutrition and Performance Effect of Initial Muscle Glycogen Levels on Sweat Urea Nitrogen Excretion Figure 23.5

  23. Nutrition and Performance Effect of Glucose Ingestion on the Rate of Leucine Metabolism Figure 23.6

  24. Nutrition and Performance Dietary Goals for Athletes • RDA 0.8 g•kg–1•day–1 • Met by diet having 12% calories from protein • Endurance training 0.8 g•kg–1•day–1 for light to moderate exercise 1.2–1.4 g•kg–1•day–1 for high-intensity exercise • Strength training 0.9 g•kg–1•day–1 for maintaining strength 1.6–1.7 g•kg–1•day–1 for adding muscle mass • Average athlete intake 16% calories from protein or 1.5 g•kg–1•day–1 10–18% calories from protein in vegetarians

  25. Nutrition and Performance In Summary • The protein requirement for those engaged in light-to-moderate endurance exercise is equal to the RDA of 0.8 g•kg–1•d–1; however, it is 1.2–1.4 g•kg–1•d–1 for athletes who participate in high-intensity endurance exercise. • For resistance training, there is more dispute about the requirement. It may be only 0.9 g•kg–1•d–1 for those maintaining strength or as high as 1.6–1.7 g•kg–1•d–1 for those adding lean mass and strength. • Bottom line: The average protein intake of an athlete exceeds 1.5 g•kg–1•d–1, more than enough to cover the higher protein requirement.

  26. Nutrition and Performance Fluid Replacement—Before Exercise • Goal is to be euhydrated before exercise • Foods and beverages consumed before meals should be sufficient • If additional fluids are needed: • Slowly drink beverages at least four hours prior (~5–7 ml•kg–1) • Drink more fluid if urine is dark or none is produced two hours prior (~3–5 ml•kg–1) • Sodium in beverages of food helps retain fluid • No evidence that glycerol hyperhydration improves performance • Increasing plasma volume with high sodium beverages improves performance in the heat

  27. Nutrition and Performance Water Replacement—During Exercise • Goal is to reduce risk of excessive dehydration • Greater than 2% body weight loss • Fluid replacement during exercise associated with: • Lower HR • Lower body temperature • Lower RPE • Important for both prolonged and intermittent exercise

  28. Nutrition and Performance Responses to Exercise With Different Volumes of Fluid Replacement Figure 23.7

  29. Nutrition and Performance Water Replacement—During Exercise • Athletes should estimate sweat rates • Measure pre- and post-exercise body weight • Beverage characteristics • Temperature between 15–21°C • Contain ~20–30 mEq•L–1 sodium and 2–5 mEq•L–1 potassium • Contain 5–10% carbohydrate • Mixture of glucose, sucrose, fructose, and maltodextrin results in greatest carbohydrate delivery • Caffeine does not • Create water-electrolyte balance • Cause hyperthermia or reduce exercise-heat intolerance

  30. Nutrition and Performance Water Replacement—During Exercise • Factors affecting fluid absorption • Glucose concentration • Gastric emptying slower above 139 mM • Fluid volume • Optimal volume is 600 ml • Temperature • Cold drinks absorbed faster than warm drinks • Exercise intensity • Gastric emptying slower above 65–70% VO2 max

  31. Nutrition and Performance Factors Affecting Fluid Absorption From the Gastrointestinal Tract Figure 23.8

  32. Nutrition and Performance Water Replacement—During Exercise • Recommendations: • Events <1 hour (80–130% VO2 max) • 500–1,000 ml water only • Events of 1–3 hours (60–90% VO2 max) • Contain 10–20 mEq•L–1 NaCland 6–8% carbohydrate • 500–1,000 ml to meet carbohydrate need • 800–1,600 ml water to meet fluid need • Events >3 hours • Contain 10–20 mEq•L–1 NaCland 6–8% carbohydrate • 500–1000 ml to meet carbohydrate and fluid need • For rapid rehydration • ~1.5 L fluid for every kg of weight loss

  33. Nutrition and Performance Salt • Athletes require more salt than sedentary individuals • Must replace salt lost in sweat • Most people consume more salt than is required • Salt needs should be met at meals • Not by consuming salt tablets • Body weight is the best test of salt/water replacement • Constant body weight indicates adequate salt and water intake

  34. Nutrition and Performance The Winning Edge 23.2Hyponatremia • Dangerously low Na+ concentration • Plasma sodium ≤135 mM • Caused by rehydration with water or hyponatremic drinks during long (4+ hours) events • May lead to weight gain during event • Recommendations: • Work to minimize risk of both hyponatremia and dehydration • Drink to match fluid loss on a schedule • Match fluid intake to sweat loss and thirst • Consume salty foods and beverages

  35. Nutrition and Performance In Summary • Fluid replacement during exercise reduces the heart rate, body temperature, and perceived exertion responses to exercise, and the greater rate of fluid intake, the lower the responses. • Cold drinks are absorbed faster than warm drinks, and when exercise exceeds 65% to 70% VO2 max, gastric emptying decreases. • For exercise lasting less than one hour, the focus is on water replacement only. When exercise duration exceeds one hour, drinks should contain Na+, Cl–, and carbohydrate.

  36. Nutrition and Performance In Summary • Salt needs are easily met at mealtime, and salt tablets are not needed. In fact, most Americans take in more salt than is required.

  37. Nutrition and Performance Iron • Deficiency affects VO2 max and endurance • Component of hemoglobin and cytochromes • Iron deficiency in athletes • Due to decreased intake and decreased absorption • Due to increased loss • Through sweat, feces, and urine • Iron supplementation • Rapidly restores hematocrit and VO2 max • Slower increase in mitochondrial activity and endurance • Increase iron intake through foods • Supplements may be indicated

  38. Nutrition and Performance Stages of Iron Deficiency

  39. Nutrition and Performance Recovery of Various Physiological Capacities with Iron Repletion Figure 23.9

  40. Nutrition and Performance Vitamins • Important for energy production • Coenzymes associated with aerobic metabolism • Supplementation: • Not necessary on well-balanced diet unless clear deficiency is known • Some small athletes who consume low-energy diets may have deficiencies • Toxicity with large doses of fat-soluble vitamins and vitamin C

  41. Nutrition and Performance In Summary • Iron deficiency in American athletes may be related to an inadequate intake of dietary iron as well as a potentially greater loss in sweat and feces. In spite of this deficiency, athletes may absorb less than half of what a sedentary group of anemic individuals absorbs. Iron supplementation may be recommended for female athletes as a result of an annual clinical assessment of iron status. • Vitamin supplementation is unnecessary for an athlete on a well-balanced diet. However, for those with a clear deficiency, supplementation is warranted.

  42. Nutrition and Performance Precompetition Diet • Purposes • Provide adequate hydration • Provide carbohydrates to “top off” liver stores • Avoid the sensation of hunger • Minimize GI tract problems • Allow the stomach to be relatively empty at start of competition

  43. Nutrition and Performance Precompetition Diet • Content • 500–1,000 kcals • 3 hours prior to event • Mostly complex carbohydrates • Limit simple sugars, especially fructose • Low in fat • Slowly digested • Low in protein • Contributes to acids in blood

  44. Nutrition and Performance Example of Pregame Meals

  45. Nutrition and Performance In Summary • The pregame meal should provide for hydration and adequate carbohydrate to “top off” stores while minimizing hunger symptoms, gas, and diarrhea. Varieties of commercially available liquid meals are consistent with these goals.

  46. Body Composition and Performance Body Composition and Performance • Body composition differs among athletes • Success in different events associated with certain characteristics • Quantifying body composition • Somatotype • Percent fat

  47. Somatotypes Somatotypes • Endomorphy • Relative predominance of soft roundness and large digestive viscera • Mesomorphy • Relative predominance of muscle, bone, and connective tissue • Ectomorphy • Relative predominance of linearity and fragility • Determining somatotype • 1 to 7 scale • Three-number sequence of three components

  48. Somatotypes Extremes of Somatotypes Figure 23.10

  49. Somatotypes Contrast of Somatotypes Between College Students and Athletes Figure 23.11

  50. Somatotypes Body Fatness and Performance • Optimal body fatness for health • Males: 10–25% • Females: 15–25% • Optimal body fatness for performance • Differs between men and women • Varies within gender and sport • It is natural for some athletes to have higher body fatness than others in order to perform optimally • Should be based on individual health status, not on team average • Be aware of error in measurement of percent fat

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