Body Composition and Nutrition for Health

1. Body Composition and Nutrition for Health Powers Chapter 18

2. Nutritional Goals • Increase intake of fruits, vegetables (rich in fiber and potassium), and whole grains (complex CHO 55-60% total calories) • Increase consumption of poultry and fish, decrease red meat intake • Limit foods high in fat (particularly saturated and trans fat) to less than 30% total calories • Drink skim instead of whole milk • Limit high cholesterol food sources (butter, fat, eggs,…) to less than 300mg / day • Decrease sugar intake (no more than 15% of total calories) • Decrease salt intake (limit to 3g / day) US Dietary Goals (1977) Dietary Guidelines for Americans (2005)

3. Nutrient Classes • Water • Vitamins • Minerals • CHO • Fats • Proteins • RDA • quantity of nutrient needed to meet needs of a healthy person • % Daily Value • Standard used in nutritional labeling Powers CH 18, Figure 18.1, p 363

4. Water • 50 – 75% of body composition • 3 - 4% loss adversely affects aerobic performance • Binds with CHO (CHO restriction = increased water loss / depletion)

5. Vitamins • Organic catalysts involved in metabolic reactions • Fat-Soluble Vitamins • A, D, E, K • Can be stored in large quantities • Toxicity may develop • Water-Soluble Vitamins • Vitamin C • Maintenance of bone, cartilage and connective tissue • B Vitamins • Thiamin (B1) – CO2 removal as pyruvate enter KC • Riboflavin (B2) – (FAD) – transfer of energy in KC, ETC • Niacin – (NAD) – transfer of energy in KC, ETC • Folic acid, Pantothenic acid, Biotin, B6, B12 – coenzymes in MR

6. Minerals • Chemical elements (other than carbon, hydrogen, oxygen, nitrogen) associated with structure and function of the body • Major minerals • Calcium • stored in bone • Released when dietary intake inadequate (to increase plasma Ca++) • Iron • Important part of hemoglobin, myoglobin • Deficiency = anemia • Sodium • Directly involved in maintenance of resting cell membrane potential and AP generation in nerves / muscles • Primary electrolyte determining extracellular fluid volume

7. Carbohydrates Composed of carbon, hydrogen, oxygen • 4 kcal of energy per gram • Major source of energy for all tissues (particularly RBCs and NV System functions) 3 forms: • Monosaccharides (glucose, fructose) • Disaccharides (sucrose - gl + fr) • Polysaccharides (3 or more monos) • Complex Carbs: • Cellulose (fiber) – undigestible • Starch (corn, grains, beans) potatoes)

8. Fats • 9 kcal of energy per gram • Metabolized oxidatively – principal energy source only in longer duration / moderate intensity exercise • Absorption of fat-soluble vitamins • Cell membrane structure • 4 general groups: • Fatty acids • Triglycerides • Phospholipids (cell membrane, schwann cells,…) • Steroids • Cholesterol - sex hormone synthesis • LDL / VLDL • HDL • Phospholipids, steroids not energy sources

9. Proteins • 4 kcal of energy per gram • RDA = .8g protein/kg BW/day (1.0 – 1.2 for highly active) • 12-15% of caloric intake • Amino Acids • Building blocks (subunits) of proteins • AAs linked together by peptide bonds to form proteins • 20 needed by body to form enzymes, blood proteins,… • 9 “essential” AAs cannot be synthesized by the body (must be consumed)

10. Protein • Protein “quality” based on how well essential AAs are represented: • High “best” quality (high biologic value) = eggs, milk, fish • Moderate “good” quality = meat, poultry, cheese, soybeans • “Fair” quality (low biologic value) = grains, vegetables, seeds, nuts, legumes • Mutual Supplementation • Combining 2 incomplete proteins that, when eaten together, provide “complete” protein • Dietary variety increases chances of ingesting high quality AA combos • Complementary proteins: • Soybeans and rice • Peas and wheat • Beans and corn • Lentils and wheat or rice • Cereals and legumes • Whole grains and sunflower seeds Complete proteins: Contain all AAs needed (essential and non-essential) for synthesis of human tissue protein

11. Food Guide Pyramid Powers CH 18, Table 18.3, p375

12. Nutrition, Body Composition and Performance Powers Chapter 23

13. Carbohydrate Diets and Performance • CHO most important in prolonged moderate/heavy exercise • Supercompensation (original “CHO loading”) • 1 – prolonged strenuous exercise (goal - deplete ms glycogen) • 2 – fat / protein diet, very low CHO for 3 days w/ training • 3 – high CHO diet for 3 days w/ inactivity • Modified Plan (new strategy “CHO loading”) • 1 – tapering w/o (90 min – 40 min) + CHO 50% of diet (350g/d) • 2 – 20 min w/o + CHO 70% of diet (500-600g/d) for 2 days • 3 – rest + CHO 70% of diet • -or- 10g/kgBW for 1 day using foods high on glycemic index

14. Glycemic Index • Effect of ingestion of CHO-rich foods on blood glucose levels compared to a standard (usu. white bread) • High GI sources = high digestive enzyme activity / rapid bl glucose level alteration

15. CHO Intake prior to / during Exercise • 1-5g CHO per kg BW taken 1 – 4 hours before exercise or competition • CHO in liquid or gel form closer to competition • Easily digestible sources • Experiment with feeding methods during training (nothing new on race day) • Caution with high glycemic foods (fatigue, insulin over-response) Glucose supplementation during exercise most beneficial in event where Glycogen stores are likely to be depleted (60+ minutes in duration)

16. CHO in Sports Drinks • Valuable in endurance events • CHO content promotes water absorption • Most sports drinks contain electrolytes (NA+, K+, CL-,…) useful in cases of excessive sweat loss CHO content greater than 8% in solution = decreased gastric emptying

17. CHO Uptake Post-Exercise • Increased muscle cell permeability to glucose • Increased glycogen synthase activity following heavy exercise • Increased muscle sensitivity to insulin • Glucose polymers best for synthesizing muscle glycogen • Fructose best for replenishing liver glycogen • CHO paired with protein (4 CHO : 1 protein) assists in rapid glucose uptake

18. Protein Requirements During Exercise • RDA = .8g protein / kg BW / day (1.0 – 1.4 for highly active – as high as 1.6 to adding lean mass / strength??) • 12-15% of caloric intake • Greater energy requirement from protein if CHO is stores are low • BOTTOM LINE • Athlete’s avg protein intake > 1.5 (more than enough to cover high protein requirement)

19. Protein Absorption • AAs absorbed mostly in SI • Excessive amounts of 1 AA can impair absorption of others in SI • Predigested proteins (containing free AAs) can overwhelm available transport mechanisms, reducing total AA absorption • Mutual supplementation less effective if all essential AAs are not ingested w/in 2 hr period • Dietary variety increases chances of ingesting high quality AA combinations

20. Water and Electrolytes • Pre-event hydration • Exercise < 1 hr - high intensity (> 80% VO2 Max) = 300 – 500ml w/ 30-50g CHO • Exercise > 1 hr – moderate intensity (30 – 80% VO2 Max) = 300 – 500ml H2O • Hydration during exercise • High intensity EX < 1 hr = 500 - 1,000ml H2O • EX 1-3 hrs = 800 – 1,600ml / hr H2O + CHO, electrolytes

21. Hydration Strategies • Fluid replacement during exercise reduces HR, body core temp • Cold drinks are absorbed faster than warm • Gastric emptying decreases at intensity > 65-70% VO2 Max • CHO and electrolyte replacement (w/ H2O) is less critical in exercise < 1 hr duration

22. Hyponatremia

23. Water-Logged… Hyponatremia - clinically defined as a blood electrolyte (mainly sodium) concentration <135 mmol/L (normal values are about 136-142). This usually happens when an athlete exercises for an extremely long period of time in the heat while drinking mainly water or relatively dilute electrolyte drinks. The combination of high salt loss in the sweat, combined with lots and lots of water with inadequate salt intake, results in the blood becoming dilute. Why is hyponatremia a bad thing? Your body is always going to try to equalize the concentration of the fluid in your blood with the fluid in your body tissues. So having all that dilute fluid in your bloodstream means that your blood plasma (the liquid portion of your blood) is going to get filtered into your tissues. Remember in high school biology class sticking a live sponge or starfish into a bucket of fresh water when the teacher’s back was turned? The poor creature didn’t like it very much and swelled like a blimp. The sponge didn't like it much either! Now imagine the same thing happening to your brain when you’re hyponatremic. Now don’t you feel guilty?

24. Pre-Competition Diet • Provide adequate hydration • Provide CHO to “top off” already high CHO stores in liver • Avoid sensation of hunger on a relatively empty stomach • Minimize GI distress • Timing??

25. Somatotype and Body Composition Assessment

26. Somatotype

27. Body Mass Index BMI describes relative weight for height Determined by dividing weight (kg) by square of the height (meters) Interpretation limited to body comp

28. > 30 BMI = Obese Gross obesity related more to increases in fat cell # (hyperplasia), than fat cell size (hypertrophy) Diseases linked to obesity: Hypertension Type II diabetes Coronary heart disease Stroke Gall bladder disease Sleep apnea Respiratory problems Cancer (colon, breast, prostate) Obesity

29. Body Composition • % BF – Norms: • M = 10-20%, F = 15-25% • % BF – Athletes? • Lower limit • Males? Females?

30. Hydrostatic Weighing • Measures amount of water displaced by body while submerged • Determines lean v. fat mass based on Archimedes Principle: • A body is pushed up (out of water) with a force equal to the weight of the water displaced by the body (based on volume) • FB = vol. of body x wt of water per unit vol. • SG = wt / FB Water density = 1g/ml Body fat density = .9g/ml (SG<1 – floats) Lean tissue density = 1.1 (SG>1 – sinks)

31. Air Displacement Plethysmography (Bod Pod) • Uses body mass and volume to analyze air displacement and, from that, calculate your whole-body density

32. Dual Energy X-ray Absorptiometry (DEXA) • Single x-ray source used to determine whole body and regional estimates of lean tissue, bone, mineral, and fat • Highly accurate- Valuable for bone mineral density analysis

33. Bioelectrical Impedence • Stick-on electrodes placed onto hand and foot. Outer electrodes supply electric current, inner pair measure resistance to electrical conduction Lean tissue and water conduct electricity better than fat Resistance to current = higher fat content somewhat practical in field testing

34. Skinfold Thickness • Estimate total body fat based on a series of skinfold thickness measurements

35. Weight Gain / Weight Loss • Energy Balance: • Positive = energy intake > energy expenditure • Negative = energy expenditure > energy intake • kcals burned = BMR + Thermogenesis + Exercise • 3,500 kcal reduction = 1lb loss Reasonable weight reduction rate?? Influence of weight training?? Influence of “cycling” on BMR??