A comparison of the effects of milk and a carbohydrate-electrolyte drink on the restoration of fluid balance and exercise capacity in a hot, humid environment

To determine the effect of skimmed milk (MILK) and a sports drink (CHO-E) in restoring fluid balance following exercise-induced dehydration and on subsequent exercise performance. Seven physically active males cycled intermittently in the heat until 2% body mass was lost. During a 1h rehydration period a CHO-E (23mmol Na+/L) or MILK (32mmol Na+/L) was consumed in a volume equivalent to 150% of body mass loss. Following a 3h recovery period, subjects cycled to exhaustion at 61% VO2peak in hot-humid conditions (35°C, 63%). Participants were in positive fluid balance at the end of the 3h recovery period when MILK (191 ± 162 mL) was consumed and euhydrated on CHO-E (-135 ± 392 mL). This difference in fluid balance (326 ± 354 mL), equivalent to 0.4% BM, approached significance (P=0.051). No differences were observed in plasma volume between trials but serum osmolality and stomach fullness were higher on MILK than CHO-E (P