Nutritional Recommendations for the Physically Active Person

1. Nutritional Recommendations for the Physically Active Person Chapter 7 Part 3

2. Nutritional Status Inadequate nutrition Lethargy Early fatigue Irritability Poor training and competitive performance Increased incidence of injury Infection Excessive weight fluctuations

3. Carbohydrate Intake • A low-carbohydrate diet rapidly compromises energy reserves for vigorous physical activity or regular training.

4. Nutritional Status • Training diet for physically active • Adequate refueling day to day • Recover between daily sessions • Multiple workouts • Nutritional strategies • > 90 min – CHO becomes limiting factor

5. Position Stand • Optimum diet for most sports • CHO contributes 60-70% of total energy intake • After each bout of exercise • Sufficient CHO to replenish glycogen stores • Maximize subsequent performance

6. Position Stand (cont) • CHO – after exhaustive exercise • 50 g every 2 h • Moderate and high glycemic foods • Goal – 600 g in 24 h

7. CHO Intake • Recommendations • 6-10 g CHO/kg BM/day • Endurance training • 10 g CHO/kg BM/day • This is quite a bit of food • 70kg person = 2800 kcal of CHO

8. CHO Intake • Tour de France • 6 h per day • 12-13 g/kg body weight/day • Close to 4000 kcal of CHO/day

9. CHO Intake • More recently • 1.0-1.8 g/kg BM/hr • Feedings every 15-60 min • Still over 3000 kcal of CHO/d

10. Timing of CHO Intake • Highest rates of glycogen storage • First hour post exercise • Activation of glycogen synthase • Glycogen depletion • Exercise-induced insulin sensitivity • Permeability of muscle cell to glucose • Storage rates • 7.7 mmol/kg/wet weight/h (first 2 h) • 4.3 mmol/kg/ww/h

11. Exercise Effects on Vitamin Needs • Exercise enhances energy metabolism • Exercise increases total energy expenditure • Is there an increased need, deficiencies of vitamins? • Do athletes have normal vitamin status? • Do athletes require vitamin supplements?

12. Vitamins and Performance • B complex • Coenzymes in reactions during catabolism • Fat, CHO, protein • Vitamin B6 or Thiamin • Vitamin C • Negligible effects on endurance • Vitamin E • Deficiencies impair muscular function • No benefit with excess consumption

13. Vitamins and Performance • 50 years of research • Fail to support vitamin supplements to improve performance • aerobic and anaerobic exercise

14. Vitamins and Performance • Daily supplements of vitamin C • 500-1500 mg of per day • May reduce infections • Glutamine • Fuel for the immune system • Supplementation reduces the risk of infection

15. Vitamin-Mineral Deficiencies • Most often occur in: • Vegetarians • Groups with low energy intake • Elimination of one or more food groups • Individuals who consume • Processed foods • Simple sugars - low micronutrient density

16. Megavitamins • Contain doses at least 10 and up to 1000 times the RDA • Excess vitamin C = kidney stones • Excess vitamin B6 = liver disease and nerve damage • Excess riboflavin (B2) = impaired vision • Excess niacin = vasodilatation and inhibition of fatty acid mobilization during exercise

17. Megavitamins • Folate = trigger an allergic response • Excess vitamin E = headache, fatigue, blurred vision, gastrointestinal disturbances, muscular weakness, and low blood sugar • Excess vitamin A = toxic to the nervous system • Excess vitamin D = damages kidneys

18. Antioxidants • Aerobic exercise metabolism increases the production of free radicals. • Antioxidants: • ß-Carotene • Vitamin C • Vitamin E • Selenium, copper, manganese, and zinc • Coenzyme Q10

20. Vitamin E • Vitamin E deficient animals • Reached exhaustion earlier • Sufficient Vitamin E • Reduced oxidative damage to muscle fibers

21. Vitamin E

22. Immune System • Innate • Skin and mucous membranes • Body temperature • Specialized defenses • Natural killer cells, diverse phagocytes, and inflammatory barriers

23. Immune System

24. The Skin • Continuous barrier • Protection • Dead cells on outside

25. Exercise Immunology • Acquired immune system • Specialized B (bone)- and T (Thymus)-lymphocyte cells. • B cells • Produce antibodies • T cells • Cytokines and toxic granules

26. Theoretical Model

27. Exercise Intensity and the Immune System • Moderate exercise • A bout of moderate exercise boosts natural immune functions and host defenses for up to several hours.

28. Exercise Intensity and the Immune System • Exhaustive exercise • A prolonged period of exhaustive exercise (and other forms of extreme stress or increased training) severely impairs the body’s first line of defense against infection.

29. Exercise Intensity and Risk of Infection

30. Minerals • Excessive sweating • Loss of body water and related minerals. • Mineral loss • Replaced with well-balanced meals. • Single-mineral supplementation • Potential adverse consequences.

31. Trace Minerals and Exercise • Strenuous exercise may increase excretion of the following four trace elements: • Chromium • Copper • Manganese • Zinc

32. Exercise and Food Intake • Energy intake needs to be balanced with energy expenditure. • Regular moderate-to-intense physical activity • Increase daily energy intake to match their higher level of energy expenditure.

34. Exercise and Food Intake • Many athletes, particularly females, do not meet energy intake recommendations. • Active women (20-60 miles/wk) • 35 kcals/kg BM • Discrepancies in reported kcals and activity? • Active become more sedentary when not exercising • Increased metabolic efficiency • Expend less energy