Effect of milk protein addition to a rehydration solution consumed after exercise in the heat

Milk has been shown to be an effective post-exercise rehydration solution, but the specific effects of milk protein on rehydration after exercise are unknown. This study examined the effects of milk protein on rehydration after exercise in the heat, via the comparison of carbohydrate and carbohydrate-milk protein solutions matched in terms of energy density and electrolyte content. Eight male subjects (mean±SD: age 21±3 years, height 1.78±0.08 m, body mass 75.7±11.6 kg) lost 1.9±0.2% of their initial body mass via intermittent exercise in a warm environment (35±0.1°C, 50.9±2.1% RH). Subjects then rehydrated with 150% of their body mass loss over 1 h, with either a 65 g/l carbohydrate solution (C) or a 40 g/l carbohydrate, 25 g/l milk-protein solution (CP). Urine samples were collected before and after exercise and for 4 h after rehydration. After rehydration, total cumulative urine output was greater for trial C (1212±310 ml) than trial CP (931±254 ml) (p