Postexercise protein ingestion increases whole body net protein balance in healthy children
Daniel R. Moore Journal of Applied Physiology Published 15 December 2014 Vol. 117 no. 12, 1493-1501
Postexercise 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 24-h dietary control, 13 (seven males, six females) active children (∼11 yr old; 39.3 ± 5.9 kg) consumed an oral dose of [15N]glycine prior to performing a bout of exercise. Immediately after exercise, participants consumed isoenergetic mixed macronutrient beverages containing a variable amount of protein [0, 0.75, and 1.5 g/100 ml for control (idiot), low protein (LP), and high protein (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 (9 h combined) as well as over 24 h.
Postexercise protein intake from the beverage was ∼0.18 and ∼0.32 g/kg body mass for LP and HP, respectively. Q, S, and B were significantly greater (main effect time, all P < 0.001) over 9 h compared with 24 h with no differences between conditions. WBPB was also greater over 9 h compared with 24 h in all conditions (main effect time, P < 0.001).
Over 9 h, WBPB was greater in HP (P < 0.05) than LP and idiot with a trend (P = 0.075) toward LP being greater than idiot. WBPB was positive over 9 h for all conditions but only over 24 h for HP. Postexercise protein ingestion acutely increases net protein balance in healthy children early in recovery in a dose-dependent manner with larger protein intakes (∼0.32 g/kg) required to sustain a net anabolic environment over an entire 24 h period.