Purpose: The purpose of this study was to examine the effect of branched-chain amino acid (BCAA) supplementation on indices of muscle damage. Methods: Eight healthy active college students participated in a double-blinded crossover study. The subjects ingested either 92 mg/kg BW of BCAA (BCAA) or placebo (PLA) capsules 60 min before exercise respectively. They exercised at 60% VO(subscript 2max) on cycle ergometer for 30 minutes. Blood samples were collected prior to supplementation, immediately prior to exercise, and 0, 15, 60 min after cycling (P0, P15, P60) for analysis of creatine kinase (CK) and lactate dehydrogenase (LDH). The data were analyzed by two-way repeated measures ANOVA and significance was accepted at α=.05. Results: No interactions between treatment and timing were found. Significant main effect was found for treatment and timing on CK and for the main effect of treatment, BCAA's response of CK were significantly lower than PLA (BCAA: 167.30±90.55 U/L; PLA: 200.17±117.46 U/L, p＜.05). Significant main effect was found for timing on LDH. Conclusions: These results indicate that supplementary BCAA 60 min before cycling decreased serum concentrations of the intramuscular enzymes CK after moderate cycling exercise. The effects of BCAA supplementation are suggested to reduce the risk of muscle damage.
