1. Carbohydrates Chapter 5

2. What are Dietary Carbohydrates? Organic compounds containing –Carbon –Oxygen –Hydrogen Formed naturally in nature Synthesized ~4 kcal/gram

3. Types of Carbohydrates Simple CHO –Monosaccharides Glucose (dextrose, grape sugar) Fructose (levulose, fruit sugar) Galactose (milk sugar) –Disaccharide Maltose (malt sugar, glucose & glucose) Lactose (milk sugar, glucose & galactose) Sucrose (cane or table sugar, glucose & fructose)

4. CHO Types Complex CHO –3 or more glucose molecules –Polysaccharide (3-9 molecules) Plant starches Animal starch (glycogen) –or glucose polymer (10 or more molecules) Maltodextrin polycose –Fiber

7. Concentration Units Mole = gram molecular weight A mole is the weight in grams of a particular substance, like glucose Example –Glucose is C 6 H 12 O 6 –Atomic weight of C is 12, H is 1, O is 16 –Multiply the atomic weight X the number of that element in the molecule and sum it up. - 1 mole glucose is 180 grams

11. TABLE 4.7 Major hormones involved in regulation of blood glucose levels HormoneGlandStimulusAction InsulinPancreasIncrease in blood glucose Helps transport glucose into cells; decreases blood glucose levels. GlucagonPancreasDecrease in blood glucose; Exercise stress Promotes gluconeogenesis in liver; helps increase blood glucose levels. EpinephrineAdrenalExercise stress; decrease in blood glucose Promotes glycogen breakdown and glucose release from the liver: helps increase blood glucose levels CortisolAdrenalExercise stress; decrease in blood glucose Promotes breakdown of protein and resultant gluconeogenesis; helps increase blood glucose levels

12. Causes of Muscular Fatigue Related to CHO Use Muscle Glycogen Depletion –Fatigue begins to occur at approx 30-40 mmole/kg –Short duration high intensity (<60 sec) not affected until glycogen drops below 20 mmole/kg

13. Causes of Fatigue Continued Liver Glycogen Depletion –Normoglycemia: 60-100 mg/dl –Hyperglycemia: >140 mg/dl –Hypoglycemia: <45 mg/dl –Decreased levels of BCAA in blood Reactive Hypoglycemia

15. Glycemic Index (GI) The GI reflects the rate of digestion and absorption of CHO GI = Blood glucose area after test food Blood glucose area after reference food X 100

16. Glycemic Load Glycemic index relative to the serving size Some CHO have high GI but are consumed in small quantities per serving GL = (GI x CHO/serving)/100 Ratings of glycemic loads –High GL = >20 –Medium GL = 11-19 –Low GL = <11

18. Use Of GI In Sports Nutrition Before Exercise: A low-GL CHO should be eaten, particularly before prolonged exercise, to promote sustained CHO availability During Exercise: Moderate to High-GL CHO foods or drinks are most appropriate After Exercise: High-GL CHO for glycogen resynthesis

19. Major Factors Influencing Skeletal Muscle CHO Metabolism During Exercise Exercise Intensity Exercise Duration Training Diet

20. Effect of Intensity of Exercise on CHO Utilization

23. Effect of Exercise Duration on CHO Utilization

27. Effect of Training on CHO Utilization

30. Effect of Diet on CHO Utilization

31.  Mixed Diet ) Low CHO  High CHO

34. How Much and What Kind of CHO? Minimum of100 grams CHO/day necessary for nervous system For hard training lasting at least 90 minutes per day –8-10 g/kg of CHO –2 g/kg PRO –Remainder as fat Type of CHO varies with timing –High glycemic CHO get on board faster –Low glycemic CHO have sustained effect

35. Consumption 1-2 hours Before Exercise Up to 3 g/kg of CHO 5 mL/kg fluid (2 cups for 75 kg) Low to moderate glycemic index CHO Minimal fat and protein

36. Less Than 1 Hour Before Exercise Individuals prone to reactive hypoglycemia should avoid CHO, especially high glycemic CHO –May increase glycogen use 1-2 grams/kg low to moderate GI

37. 5-10 min Before Exercise Hypoglycemic response is attenuated –At >50% of VO 2 max the glycemic response is depressed –Epinephrine is increased which helps maintain blood glucose 50-60 grams of glucose polymer in 40- 50% solution (Gatorlode)

38. During Exercise Maximal use of exogenous CHO is ~ 70 grams per hour Feedings every 15-30 minutes 5-10% solution of 15-20 grams every 15- 20 min –8 oz of Gatorade contains approx. 15 grams of CHO –Fructose may cause stomach upset Always test feeding prior to competition

39. After Exercise Glycogen resynthesis rate is about 5-7% per hour 2 hour window following exercise for maximal resynthesis 1 gram CHO/kg immediately after exercise and every 2 hours for 4-6 hours High glycemic foods Combination of CHO and protein is best in a 3:1 ration of CHO to protein.

40. Table 4.8 CHO Loading Original Classic Method Day 1Depletion exercise Day 2High-protein/fat, 15-20% CHO Day 3High-protein/fat, 15-20% CHO Day 4High-protein/fat, 15-20% CHO Day 5High CHO (70-80%) Day 6High CHO Day 7High CHO Day 8Competition

41. Table 4.8 CHO Loading Contemporary Recommended Method Day 1Depletion exercise (optional) Day 2Mixed diet (50-55% CHO) Day 3Mixed diet Day 4Mixed diet Day 5High CHO (70-80%) Day 6High CHO Day 7High CHO Day 8Competition

44. Alcohol As An Energy Substrate 7 kcal/gram By-products of alcohol metabolism released in blood appear to be of little importance to exercising muscle Alcohol consumed prior to exercise may contribute 5% of energy over 90 min of exercise Alcohol requires more O 2 for metabolism than CHO or fat

45. Alcohol may interfere with glucose metabolism Reduced aerobic endurance at 80-85% of VO 2 max May reduce rate of gluconeogenesis Typically represents non-nutritive excess calories contributing to fat storage