NUTRITION AND NUTRITIONAL ERGOGENICS

1. CHAPTER 14 CHAPTER 14 NUTRITION AND NUTRITIONAL ERGOGENICS NUTRITION AND NUTRITIONAL ERGOGENICS

2. w Learn how dehydration affects performance, heart rate, and body temperature. (continued) Learning Objectives w Review the six categories of nutrients and learn what amount of intake is necessary for normally active men and women. w Discover the roles of carbohydrate, dietary fat, and protein supplements in athletic performance. w Find out which vitamins and minerals are most important in an athlete’s diet.

3. Learning Objectives w Examine how the body regulates electrolyte balance during exercise and maximizes muscle glycogen storage. w Find out what makes up a recommended precompetition meal and how to properly load the muscles with glycogen before an endurance event. w Learn the value in ingesting carbohydrates during and after endurance exercise and what constitutes the most effective sports drink.

4. Six Nutrient Classes w Carbohydrate w Fat w Protein w Vitamins w Minerals w Water

5. Recommended Balance of Nutrients w 55% to 60% carbohydrate w Less than 30% fat (less than 10% saturated) w 10% to 15% protein

6. Carbohydrate (CHO) w Provides energy, particularly during high-intensity exercise w Regulates fat and protein metabolism w Exclusive energy source for the nervous system w Synthesized into muscle and liver glycogen w Sources include grains, fruit, vegetables, milk, and sweets

7. DIETARY CARBOHYDRATES AND GLYCOGEN

8. MUSCLE GLYCOGEN AND EXHAUSTIVE EXERCISE

9. Simple sugars w Elevate blood glucose levels w Rely on insulin to move them to cells w When intake exceeds usage, stored within the cells as fat Complex CHOs w Require more time to breakdown w Produce smaller and slower rise in blood glucose w Has less impact on blood lipid levels CHO Types

10. Key Points Ergogenic Properties of CHO w Glycogen loading the muscles may delay onset of fatigue. w Maintaining normal blood glucose levels may allow the muscles to obtain more energy from blood glucose, sparing liver and muscle glycogen reserves. w Activities over 1 hour can be enhanced when carbohydrate is consumed within 5 minutes of, over 2 hours before, and at frequent intervals during the activity.

11. CHO INTAKE AND PERFORMANCE

12. PRE-EXERCISE CHO FEEDING

13. Did You Know…? Carbohydrate intake during exercise does not produce the same hypoglycemic effects as pre-exercise intake. This difference may be caused by increased muscle fiber permeability that decreases the need for insulin during exercise, or insulin-binding sites may be altered during muscular activity.

14. Fat w Makes up cell membranes and nerve fibers w Provides up to 70% energy at rest w Cushions vital organs w Produces all steroid hormones w Transports and stores fat-soluble vitamins w Preserves body heat

15. Key Points Ergogenic Properties of Fat w Use of FFAs for energy production can delay exhaustion. w Chronic endurance training results in more reliance on fat for energy. w For some individuals, caffeine promotes fat use and improves performance.

16. Protein w Makes up cell structure w Helps develop, repair, and maintain tissues w Produces hemoglobin, enzymes, and many hormones w Maintains normal blood osmotic pressure w Forms antibodies w Can be energy source w Breaks down into amino acids to be used by the body

17. Key Points Ergogenic Properties of Protein w Builds fat-free muscle mass. w Strength athletes need 1.4 to 1.8 g per kg body weight. w Endurance athletes need 1.2 to 1.4 g per kg body weight. w Diets exceeding 1.8 to 2.0 g per kg body weight per day have not been proven to provide additional benefits and may damage kidney function.

18. Fat soluble w A, D, E, and K w Absorbed from digestive tract and bound to lipids w Excessive intake can cause toxic accumulations Water soluble w B-complex and C w Absorbed from digestive tract with water w Excess is excreted Vitamins

19. B-Complex Vitamins w Include more than 1 dozen vitamins w Involved in energy production w If deficiency, supplementation may facility performance

20. Vitamin C w Formulates and maintains collagen in connective tissue w Helps metabolize amino acids w Helps synthesize epinephrine, norepinephrine, and corticoids w Promotes iron absorption w May help fight infection and function as antioxidant w Supplementation does not appear to improve performance if no deficiency exists

21. Vitamin E w Stored in muscle and fat w Prevents oxidation of vitamins A and C w Acts as antioxidant to disarm free radicals w May decrease risk of coronary artery disease w Supplementation has not been proven to improve performance

22. Minerals Electrolytes—mineral compounds that can dissociate into ions in the body Macrominerals—minerals that your body needs 100 g of per day Microminerals—minerals that your body needs less than 100 g of per day

23. Calcium w Most abundant mineral in the body w Stored in the bones w Facilitates bone growth and maintenance w Essential in nerve impulse transmission w Activates enzymes and regulates cell membrane permeability w Essential for normal muscle function

24. Phosphorus w Commonly linked to calcium in form of calcium phosphate w Provides strength and rigidity to bones w Essential to metabolism and component of ATP w Part of cell membrane structure w Helps maintain constant blood pH

25. Iron w Helps form hemoglobin and myoglobin w Deficiency is relatively common, more so in women w If deficiency, supplementation can improve aerobic capacity

26. Sodium, Potassium, and Chloride w Separates electrical charge across neuron and muscle cell membranes w Maintain body's water balance and distribution w Maintain normal osmotic equilibrium and pH w Maintain normal cardiac rhythm

27. Did You Know…? Vitamins and minerals do not appear to have any ergogenic value in amounts beyond the RDA. Taking them in amounts greater than RDA will not improve performance and may be dangerous.

28. BODY WATER AT REST

29. Water w Makes up blood plasma, which transports and delivers nutrients to tissues w Makes up body fluids that regulate pH w Dissipates excess body heat during exercise w Maintains blood pressure

30. Key Points Water Balance During Exercise w Metabolic water production increases as body heat increases. w Water loss increases during exercise due to sweating. w Blood flow to the kidneys decreases to prevent dehydration. w If dehydration exceeds 2% body weight, physical performance is impaired.

31. DEHYDRATION AND PERFORMANCE

32. Key Points Electrolyte Balance During Exercise w Loss of water via sweating disrupts electrolyte balance. w Sodium and chloride are the most abundant electrolytes in sweat. w Excess electrolytes are excreted in the urine during rest, but less so during exercise. w Dehydration causes aldosterone to promote renal retention of sodium and chloride ions, raising their concentrations in the blood. This, in turn, triggers thirst.

33. DEHYDRATION AND HEAT PERFORMANCE

34. Key Points Replacing Fluid Losses w The need to replace body fluids is greater than the need to replace electrolytes. w Our thirst mechanism does not match our hydration state, so it is best to consume more fluid than thirst dictates. w Water intake during prolonged exercise reduces the risk of dehydration and optimizes performance. w Drinking too much fluid can result in hyponatremia (low levels of plasma sodium), which can cause confusion, disorientation, and seizures.

35. Key Points The Athlete’s Diet w There is no one typical diet of an athlete; yet, it is important that athletes and active people alike meet their RDA of nutrients. w Athletes can get the nutrition they need with a strictly vegetarian diet as long as the foods they select include a balance of essential nutrients and calories. w The precompetition meal can ensure a normal blood glucose level and prevent hunger; it should include 200 to 500 kcal of foods that are easily digestible and are eaten no less than 2 hours before competition.

36. ° Astrand’s Glycogen Loading 1. Complete an exhaustive training bout 7 days before event. 2. Eat fat and protein for next 3 days and reduce training load; this increases glycogen synthesis. 3. Eat a CHO-rich diet for remaining 3 days before event and reduce training load; because of increased glycogen synthesis, more glycogen is stored.

37. 7 days before competition w Reduce training intensity w Eat a normal, healthy mixed diet with 55% CHO 3 days before competition w Reduce training to daily warm-up of 10 to 15 minutes w Eat a CHO-rich diet Sherman’s Glycogen Loading

38. MUSCLE GLYCOGEN LOADING

39. MUSCLE GLYCOGEN RESYNTHESIS

40. Solution characteristic Rate of emptying Volume of the solution Increases with larger volumes Caloric content Decreases as the caloric density increases Osmolarity Decreases with hyperosmolar solutions Temperature Faster for cooler fluids than warm solutions pH Decreases with more acidic solutions Effects of Solution Characteristics on the Rate of Gastric Emptying

41. . w Slows at exercise intensities above 70% to 80% VO2max w Is same rate at rest as it is at exercise intensities below 70% VO2max . Gastric Emptying w Affected by an individual's fitness—the more fit, the less exercise affects it w Not affected by exercise duration w Affected differently by different types of activities

42. Key Points Designing Sports Drinks w Fructose, glucose, and maltodextrin may empty fastest from digestive tract. w Concentrations less than 11 g of CHO per 100 ml empty faster, but don't supply the full energy needed for prolonged exercise. w Athletes prefer a drink with a light flavor and no strong aftertaste. w During prolonged exercise, water intake is primary, but drinking 4 g to 8 g of CHO per 100 ml solution every 10 to 15 minutes reduces risk of dehydration and provides a partial energy supplement.