EFFECT OF CARBOHYDRATE-COMPOSITION ON FLUID BALANCE, GASTRIC-EMPTYING, AND EXERCISE PERFORMANCE

This study examined the effects of serial feedings of different carboh ydrate (CHO) solutions on plasma volume, gastric emptying (GE), and pe rformance during prolonged cycling exercise. Solutions containing 6 g% glucose-sucrose (CHO-6GS), 8.3 g% high fructose com syrup (CHO-8HF), 6.3 g% high fructose corn syrup + 2 g% glucose polymer (CHO-8HP), and a water placebo (WP) were compared. Ten trained male cyclists performe d four cycling trials consisting of 105 min at 70% VO2max followed by a 15-min all-out, self-paced performance ride. Every 15 min the men co nsumed one of the four test solutions. Blood samples were taken before , during, and after exercise to determine blood glucose and plasma vol ume changes. There were no significant differences in performance, GE, or plasma volume changes between trials. Blood glucose was significan tly elevated at the 105-min timepoint in all CHO trials when compared to WP. The CHO-8HF and CHO-7HP drinks resulted in a significantly high er delivery of CHO to the intestine. Higher rates of CHO oxidation dur ing the steady-state ride were observed only with the CHO-6GS drink.