Nutrition and Exercise

1. Nutrition and Exercise • Carbohydrates. • Lipids. • Protein. • Vitamins, minerals and water. • Diet and exercise. • Drugs in sport.

2. You are what you eat

3. Food means health

4. Types of food • Carbohydrate, lipid, protein. • Biologic fuel. • macronutrients to maintain body structure and functional integrity.

5. Carbohydrates • Mono-, oligo- and polysaccharides. • Differ by number of simple sugars linked within the molecule. • Basic unit is monosaccharide, with > 200 forms in nature.

6. Monosaccharides • Glucose (dextrose or blood sugar), is produced through digestion of more complex carbohydrates. • Fructose (fruit sugar) is the sweetest simple sugar. • Galatose is not found in nature, it is combined in milk sugar.

7. Oligosaccharides • Sucrose (cane sugar) is the most common dietary disaccharide. • Lactose (milk sugar) is composed of glucose and galatose in milk. • Maltose (malt sugar) does not form significant component of a normal person’s diet.

8. Polysaccharides • Starch and fiber are common plant polysaccharides. • Starch - the storage form of carbohydrate in plants. • Fiber - nonstarch polysaccharide such as cellulose. • High water content in fiber - “bulk” to food residues in small intestine.

9. Polysaccharides • Glycogen - storage carbohydrate to mamalian muscle and liver. • Converted to glucose when needed. • If depleted, glucose synthesis from other nutrients, principally protein. • Upper limit of glycogen storage is 15 gm/kg.

10. Function of carbohydrates • Serve as fuel, particularly during exercise. • Spare protein break down. • “Primer” for lipid metabolism. • Essential for CNS functioning.

11. Carbohydrate (CHO) deficiency • Dietary restriction of CHO rapidly depletes liver and muscle glycogen. • Adversely affects intense short-term and prolonged submaximal exercises.

13. Lipids • Long hydrocarbon chains. • Simple, compound and derived lipids. • Triglycerides are the most plentiful lipids in the body. • A cluster of glycerol with 3 clusters of fatty acids.

14. Lipids • Saturated and unsaturated fatty acids (FA). • Saturated FA contains no double bonds between carbon atoms. • Unsaturated FA contains at least one double bond between carbon atoms.

15. Lipids • 62% of FA in butter are saturated. • Only 20% of FA in margarine are saturated. • Margarine also increases LDL cholesterol and decreases HDL cholesterol concentration.

16. Compound lipids • Triglyceride in combination with other chemicals. • Phospholipids, glycolipids, lipoproteins. • Lipoproteins constitute the main form for lipid transport in the blood. • HDL, LDL and VLDL.

17. Derived lipids • Derived from simple and compound lipids. • Cholesterol is a derived lipid. • Even on a cholesterol free diet, the body synthesizes 0.5 to 2 g of cholesterol per day. • Cholesterol is needed for plasma membranes, synthesis of vitamin D, some hormones and bile.

18. Lipids • For better health, lipid intake should be < 30% of the total energy content of the diet. • Among the lipid intake, at least 70% should be in the form of unsaturated FA.

19. Role of lipids • Largest energy pool of the body (75 times that of CHO). • Cushioning of organs. • Insulator for thermal fluctuation. • Carrier and transport medium for Vitamin A, D, E and K.

21. Proteins • Greek word meaning “of prime importance”. • The body requires 20 amino acids (AA) for protein synthesis. • 8 AAs cannot be synthesized by the body, which are the essential AAs.

22. Proteins • A daily intake of 0.83 g/kg body mass is recommended. • Infants should take 2 to 4 g/kg, and pregnant women should take 20 g/kg of body mass.

23. AA supplement • AA supplement above the recommended intake does not increase muscle mass or improve muscular strength, power or endurance. • Could adversely load the liver and kidney.

24. Nitrogen balance • If +ve N balance, N intake > excretion, protein will be retained and new tissues will be synthesized. • Exercise would lead to protein break down particularly when CHO is depleted.

26. Vitamins • Organic substances needed by body in small amount. • No energy value. • At least 13 vitamins, and only vitamin D can be manufactured by the body. • Vitamin C is a strong antioxidant.

27. Vitamins • “If little is good, more must be better”? • Vitamin supplement has not been shown to improve exercise performance for people with adequate nutritional intake. • Lipid-soluble vitamins (A,D,E,K) should not be consumed in excess.

28. Minerals • Approximately 4% of the body’s mass is composed of minerals. • Major vs. trace minerals. • Provide structure (bones). • Function (muscle and nerve). • Regulate cellular metabolism (enzyme).

31. Minerals • Ca and P constitute 2.5 % of body mass. • Fall in estrogen at menopause decreases calcitonin, which is needed for Ca absorption.

34. Minerals • Mg is present in about 300 enzymes. • Iron is present in 80 % as its active compound haemoglobin. • Na+, K+ and Cl- are termed electrolytes because they exist in charged forms. • Electrolytes maintain electrical gradient across cell membrane.

35. Water • Most remarkable nutrient. • Serves as the body’s transport and reactive medium. • Important for heat regulation. • Without water, death occurs within days.

36. Water • About 2.5 L of water is needed each day for a sedentary person. • 15 mL of water is needed to remove 1 g of solute. • Hyponatremia is associated with excessive fluid intake and insufficient Na+.

38. An optimal diet is a diet that contains all the nutrients needed for tissue maintenance, repair, and growth without excess energy intake.

40. Nutrient requirement • Young adult females: 2100 kcal. • Young adult males: 2700 kcal. • CHO is most rapidly depleted. • After exhaustive exercise, at least 1 or 2 days rest with high CHO intake is needed to replenish the glycogen level.

41. Exercise meal 1 • Fasting before exercise makes no physiological sense. • A meal containing 150-300 g CHO consumed 3-4 hours before exercise improves performance by maximising muscle and liver glycogen storage.

42. Exercise meal 2 • CHO consumption during exercise benefits both intense and endurance types of work. • Too much CHO immediately before exercise is detrimental to performance. • Ideal rehydration solution contains CHO concentration between 5-8 %.

43. Drugs in sport 1 • Belief of competitors are using drugs. • Overriding desire to win. • Pressure from authority or peers. • Deprived legitimate resources. • Ignorance.

44. Drugs in sport 2 • The Olympic Movement Anti-Doping Code. • Prohibited substances: • stimulants, nacrotics, anabolic agents, diuretics, peptide hormones. • Prohibited methods: • blood doping, artificial O2 carriers, pharmacological or chemical/physical manipulation.