Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Recovery of Performance after Resistance Exercise: A Double‐blind Crossover Study

Abstract

Post‐exercise protein consumption enhances muscle and whole body anabolism for up to 24h by providing amino acids to support increased rates of protein synthesis. However, little research has addressed if high quality protein consumption may concomitantly facilitate the acute recovery of exercise performance. We aimed to determine if a whey protein supplement enhances whole body net protein balance during overnight and 24h recovery and whether supplementation supported greater recovery of exercise performance over this same period. In a double‐blind crossover design, 12 healthy resistance‐trained men (76 ± 8 kg, 24 ± 4 y, 14 ± 5% body fat; means ± SD) performed a strenuous bout of whole body resistance exercise in the evening prior to consuming either 25g of MuscleTech 100% Whey protein (REx+PRO) or an energy‐matched placebo (REx+CHO) immediately after exercise as well as the following morning (i.e., after 10h recovery). A third randomized trial involving no exercise or supplement served as a control trial (Rest). Participants ingested 2 mg [15N]glycine/kg to determine whole body nitrogen turnover, protein synthesis, breakdown, and net balance over 10 and 24h of recovery. Exercise performance was assessed before and immediately, 10h, and 24h after exercise using the following tests: i) knee extension repetitions‐to‐failure (REP) and maximal isometric strength (MVC); ii) peak (PP) and mean (MP) anaerobic power via Wingate, and; iii) countermovement jump as an indicator of neuromuscular fatigue. Data were analyzed using two‐way repeated measures ANOVA and, using Cohen's d effect size (ES), by calculating the Probability of REx+PRO Superiority (PS) versus REx+CHO (50% = no effect). There was a trend (P = 0.064; ES = 0.61; PS = 67%) toward an effect of condition on net protein balance during 10‐h overnight recovery. Over 24h, net protein balance was enhanced in REx+PRO (P = 0.036 vs. Rest; ES = 0.69; PS = 69%) but not in REx+CHO (P = 0.84 vs. Rest), which was mediated primarily through a reduction in protein breakdown (REx+PRO < REx+CHO; P < 0.01). Exercise decreased REP, MVC, PP, MP, and CMJ in post‐testing (all P < 0.05, Pre vs. Post). At 10h recovery, REx+PRO tended to enhance recovery of MVC (ES = 0.56; PS = 65%), MP (ES = 0.49; PS = 64%), and markers of neuromuscular function including jump height (ES = 0.49; PS = 64%), peak velocity (ES = 0.27; PS = 58%) and kinetic energy at take‐off (ES = 0.30; PS = 58%). At 24h, potential benefits to neuromuscular fatigue were negligible (ES for CMJ variables = −0.09 to −0.38; PS = 41–49%) whereas protein supplementation appeared to be beneficial for the recovery of MVC (ES = 1.15; PS = 79%), REP (ES = 0.44; PS = 62%), and PP (ES = 0.55; PS = 65%). There was no correlation between recovery in performance tests and whole body net balance at 10 or 24h (all P > 0.05, r < 0.3). In conclusion, whey protein supplementation enhances whole body net protein balance after an acute bout of whole body resistance exercise. The improvement in select exercise tasks suggests whey protein supplementation enhances the rate of performance recovery in trained young men.Support or Funding InformationSupported by Iovate Health Sciences Int. and Mitacs