The aim of this study was to investigate the effect of β-Hydroxy-β-methylbutyrate (HMB) supplementation on anti-inflammatory cytokines including IL-4, IL-10 and TGF-β during an acute bout of resistance exercise (RE) in young resistance trained men. Ten resistance-trained men in a randomized, double-blind, placebocontrolled and crossover study, were administered a 7-day HMB supplementation (3×1 g.d-1 of HMB) and placebo (3×1 g.d-1 of Maltodextrin) with a 7 days washout period. After supplementation periods, subjects performed three sets of bench press, lat pull down, leg extension, leg curl, biceps curl, triceps curl and shoulder press to failure with 85% of one repetition to maximum (1RM). Blood samples were obtained before- (Pre), immediately post- (IP) and 1 hour-post RE (1h P) to assess serum concentrations of IL-4, IL-10 and TGF-β1. The data were analyzed using 2 (treatment: HMB and Placebo (PL)) × 3 (time points: Pre, IP and 1hP) repeated measures analysis of variance (ANOVA) followed by the Bonferroni post hoc test with a significant level of p<0.05. Serum IL-4 was significantly higher at IP resistance exercise in HMB compared to placebo. Circulating IL-4 and TGF-β1 were significantly raised at IP compared to Pre in both HMB and placebo treatments. No significant differences between treatments were observed for IL-10 and TGF-β1at any time points. In conclusion, HMB supplementation increased the circulating level of IL-4 during RE in resistancetrained men, which may attenuate inflammatory markers and facilitate adaptation to RE.
