Millard-Stafford, M., Rosskopf, L. B., Patel, S. P., & Burrell, D. J. (1999). Fluid uptake during cycling and post-exercise rehydration: Carbohydrate-electrolyte drinks versus water. Medicine and Science in Sports and Exercise, 31(5), Supplement abstract 1612.

Relative fluid uptake during high-intensity cycling and post-exercise rehydration status were investigated using carbohydrate-electrolyte (CE) drinks and water. Trained cyclists (N = 15), completed three 50-minute rides at 5% above lactate threshold in a regulated environment (21 degrees Celsius). Three beverages were compared: water, CE with 6% concentration, and CE with 8% concentration. Before exercise, 250 ml of fluid was ingested. The volume of fluid ingested following exercise was equivalent to 150% of body mass (sweat) lost during the exercise.

It was found that there was no difference in the relative rate of fluid uptake between any of the contrasted conditions. Water caused greater urination than the CE beverages and could reduce the thirst drive more than the other two conditions.

Implication. For relatively short-duration (< 1 hour), continuous endurance training, water is as effective as carbohydrate-electrolyte drinks for fluid replacement.

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