Fluid availability of sports drinks differing in carbohydrate type and concentration

Plasma D2O-accumulation profiles (qualitative indices of fluid-absorption rates) were determined in eight subjects after ingestion of 275 mL of five D2O-labeled beverages: a water placebo (W), 6% maltodextrin (6% M), and three solutions containing a 6%, 8%, and 10% glucose-fructose mix (6% GF, 8% GF, and 10% GF). Except for W all beverages contained 20 mmol sodium/L and 3 mmol potassium/L. No differences in plasma D2O accumulation were found. Plasma glucose increased at 20 and 30 min after ingestion of the carbohydrate drinks and returned to baseline (6% GF and 6% M) or below (8% GF and 10% GF) by 60 min. Insulin responded similarly and, except for a slightly lower value at 30 min for 6% GF, no differences were detected. It appears that fluids in drinks containing less than or equal to 8-10% carbohydrate (simple sugars or maltodextrins) are made available for dilution in body fluids at similar rates and should be similar in replenishing body fluids lost in sweat during exercise.