EFFECT OF A CARBOHYDRATE-ELECTROLYTE DRINK ON ENDURANCE CAPACITY DURING PROLONGED INTERMITTENT HIGH-INTENSITY RUNNING

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 motoris ed treadmill on two occasions separated by at least 10 days. After an overnight fast, they performed repeated 15 second bouts of fast runnin g (at 80% VO(2)MAX for the first 60 minutes, at 85% VO(2)MAX from 60 t o 100 minutes of exercise, and finally at 90% VO(2)MAX from 100 minute s of exercise until exhaustion), separated by 10 seconds of slow runni ng (at 45% VO(2)MAX). On each occasion they drank either a water place bo (P) or a 6.9% carbohydrate-electrolyte (CHO) solution immediately b efore the run (3 ml/kg body mass) and every 20 minutes thereafter (2 m l/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 tr ials 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-e lectrolyte solution during repeated bouts of submaximal intermittent h igh intensity running does not delay the onset of fatigue.