Abstract

Objective: To examine the effect of a carbohydrate-electrolyte solution on endurance capacity during prolonged intermittent running. Methods: Nine subjects (eight men and one woman) ran to exhaustion on a motorised treadmill on two occasions separated by at least 10 days. After an overnight fast, they performed repeated 15 second bouts of fast running (at 80% VO2max for the first 60 minutes, at 85% VO2max from 60 to 100 minutes of exercise, and finally at 90% VO2max from 100 minutes of exercise until exhaustion), separated by 10 seconds of slow running (at 45% VO2max). On each occasion they drank either a water placebo (P) or a 6.9% carbohydrate-electrolyte (CHO) solution immediately before the run (3 ml/kg body mass) and every 20 minutes thereafter (2 ml/kg body mass). Results: Performance times were not different between the two trials (112.5(23.3) and 110.2(21.4) min for the P and CHO trials respectively; mean(SD)). Blood glucose concentration was higher in the CHO trial only at 40 minutes of exercise (4.5(0.6) v 3.9(0.3) mmol/l for the CHO and P trials respectively; p<0.05), but there was no difference in the total carbohydrate oxidation rates between trials. Conclusion: These results suggest that drinking a 6.9% carbohydrate-electrolyte solution during repeated bouts of submaximal intermittent high intensity running does not delay the onset of fatigue. Verf.-Referat