A comparison of the gastric emptying characteristics of selected sports drinks

The purpose of this study was to determine the effects of repeated ingestio n of drinks containing varying concentrations of carbohydrate on gastric em ptying rate during steady-state exercise. On five separate occasions, 14 su bjects cycled for 90 min at an average power output of 151 +/- 2 W. At 15-m in intervals, subjects ingested 227 +/- 3 ml of either water, 4% carbohydra te (CHO), 6% CHO, or 8% CHO. Gastric volume was determined prior to each dr ink and at 90 min using the modified double-sampling technique. Gross gastr ic volumes were significantly greater and mean gastric emptying rates and t he percentage of ingested beverage emptied from the stomach were significan tly less for 8% CHO. These data indicate that repeated ingestion of an 8% C HO beverage during exercise significantly reduces gastric emptying rate, wh ereas lower concentrations of carbohydrate do not. In addition, beverage os molality is not as important as beverage energy content in influencing gast ric emptying rate at these carbohydrate concentrations.