Coyle et al., JAP , 1986

1. CHO metabolism during prolonged exercise (~72% VO2max) to exhaustion w/ and w/out CHO feedings (every 20 min) Coyle et al., JAP, 1986

2. Fat metabolism during prolonged exercise (~72% VO2max) to exhaustion w/ and w/out CHO feedings (every 20 min) RER data Coyle et al., JAP, 1986

3. Substrate use during exercise to exhaustion w/ and w/out CHO feeding Coyle et al., JAP, 1986

4. Fluid & CHO Intake during Exercise • water (placebo) • 5% glucose polymer • 6% glucose/sucrose solution • 7% glucose polymer/fructose Murray et al., MSSE, 1987

5. CHO and fluid feeding during intermittent exercise • no difference for plasma Na+ or K+ • no difference in RPE • no difference in RER • no difference in plasma La • no difference in Power 1 (240 revolutions) • time of Power 2 (480 revolutions) shorter for sucrose/glucose and glucose polymer/fructose trials • most complaints with glucose polymer trial Murray et al., MSSE, 1987

6. Hepatic glucose output (HGP) and glucose uptake (Rd) w/ and w/out CHO feedings during prolonged exercise (~70% of VO2max) McConell et al., JAP, 1994

7. CHO Feeding during Prolonged Exercise •  blood glucose • maintains CHO oxidation rate •  time to exhaustion/performance • conserves liver glycogen •  muscle glucose uptake •  plasma insulin •  plasma FFA • no effect on muscle glycogen utilization (in cycling studies)

8. CHO feeding during prolonged exercise • time of CHO feeding • few differences in CHO type • upper limit of exogenous CHO oxidation • difference in CHO oxidation between running and cycling protocols?

9. Early studies on diet and performance • high-fat diet  RER and  RPE (Krogh & Lindhard, 1920) • correlation between blood [glucose] and physical condition at end of Boston Marathon (Levine et al., 1924)

10. Bergström et al., Acta Physiol Scand, 1967

11. Bergström & Hultman, Scand J Clin Lab Invest, 1967

12. Benefits of CHO Loading •  muscle glycogen stores •  time to exhaustion • no benefit on performance of <90 min (Hawley et al., 1997; Madsen et al., 1990)

13. Effects of High-CHO Diet •  time to exhaustion •  muscle glycogen stores •  use of CHO for energy Effects of High-fat Diet •  plasma [FFA] and FFA uptake •  IMTG •  use of fat (70% from IMTG) for energy •  ß-oxidation enzymes

14. Hawley et al., J Sports Sci, 1995

15. Point 5: A high-CHO diet maximizes performances during training(TD Noakes, MSSE, 1997) • Athletes do not each high-CHO diets during training. • Literature doesn’t support that dietary-CHO during training diminishes training or performance (Lamb et al., 1990; Sherman & Wimer, 1991; Simonsen et al., 1991). • Studies have shown that a period of adaptation to low-CHO diet may improve subsequent performance (Lambert et al., 1994; Muoio et al., 1994)

16. Effect of High-Fat Diet

17. Early Studies of Diet Effects

18. Effect of Dietary CHO in Untrained Subjects

19. Effect of CHO intake on muscle glycogen and rowing power (3x2500 m) * * Week 4 was significantly greater than low-CHO diet group Simonsen et al., JAP, 1991

20. Effect of Dietary CHO on Muscle Glycogen Repletion Costill & Miller, Int J Sports Med, 1980

21. Sport Nutrition: Carbohydrate Before exercise • CHO intake helps “top off” glycogen stores During exercise • CHO intake not important until later in exercise (but before onset of fatigue) After exercise • high CHO intake increases rate of glycogen storage – CHO type doesn’t matter