Post-exercise protein ingestion increases whole-body and muscle protein anabolism in adults. No study has specifically investigated the combined effects of exercise and protein ingestion on protein metabolism in healthy, physically active children. Under 24h dietary control, thirteen (7 males, 6 females) active children (~11y age; 39.3±5.9 kg) consumed an oral dose of [15N]glycine prior to performing a bout of exercise. Immediately after exercise, isoenergetic mixed macronutrient beverages containing a variable amount of protein (0, 0.75, and 1.5g/100ml for CON, LP, and HP, respectively) according to fluid losses. Whole-body nitrogen turnover (Q), protein synthesis (S), protein breakdown (B), and protein balance (WBPB) were measured throughout exercise and the early acute recovery period (9h combined) as well as over 24h. Post-exercise protein intake from the beverage was ~0.18 and ~0.32g/kg body mass for LP and HP, respectively. Q, S, and B were significantly greater (main effect time, all P<0.001) over 9h as compared to 24h with no differences between conditions. WBPB was also greater over 9h as compared to 24h in all conditions (main effect time, P<0.001). Over 9h, WBPB was greater in HP (P<0.05) than LP and CON with a trend (P=0.075) towards LP being greater than CON. WBPB was positive over 9h for all conditions but only over 24h for HP. Post-exercise protein ingestion acutely increases net protein balance in healthy children early in recovery in a dose-dependent manner with larger protein intakes (~0.32g/kg) required to sustain a net anabolic environment over an entire 24h period.
- protein synthesis
- lean body mass
- protein requirements
- physical activity
- Copyright © 2014, Journal of Applied Physiology