ROLE OF DIETARY CARBOHYDRATE INTAKE ON THE ERGOGENIC EFFECTS OF CARBOHYDRATE SUPPLEMENTATION 719:

Most of the related literature examining carbohydrate supplements have shown an increase in time to exhaustion during endurance exercise of relatively moderate intensity levels (50-80%). However, two major factors that have been overlooked in most of the studies were 1) the amount of daily dietary carbohydrate intake of the subjects, and 2) high intensity intermittent exercise (which mimic most team sports). The carbohydrate drinks may have increased the amount of carbohydrates consumed by the subject to a level which they would have received following a high carbohydrate and balanced diet. This may be one explanation as to why the drinks are so effective. Therefore, the purpose of this study was to examine the effects of low (40%) and high (70%) dietary carbohydrate intake on the ergogenic effects of a glucose polymer consumed immediately prior to the start of intermittent low and high intensity exercise. Subjects (n=20) were assigned to either the low (≅45%, n=10) or high (≅65%, n=10) dietary carbohydrate group based on an assessed diet history using Auto-Nutritionist IV. The subjects completed two randomly assigned exhaustive cycle exercise conditions (carbohydrate and placebo), which consisted of 30 sec. at 90% VO2 max and 2:00 min. at 40% VO2 max repeated until exhaustion. The diets were determined for each subject individually based on BMR and activity levels, with the low dietary CHO groups kilocalorie consumption targeted at 40% CHO, 20% protein and 40% fat, whereas the high dietary CHO group consumed a targeted diet of 70% CHO, 18% protein and 15% fat. Two way ANOVA revealed no significant interaction between CHO and placebo for the two groups (p=0.961) nor was the main effect significant between CHO and placebo (p=0.296). Regression analysis revealed a non significant correlation (r=0.008, p=0.97) between percent dietary CHO and percent change in time to exhaustion. Although some studies indicate that CHO supplementation increased time to exhaustion during endurance exercise, this examination concluded CHO supplementation immediately prior to intermittent high and low intensity exercise does not increase time to exhaustion.