Effects of beta-hydroxy-beta-methylbutyrate on muscle damage after a prolonged run

This study examined the effects of supplemental beta-hydroxy-beta-methylbut yrate (HMB) on muscle damage as a result of intense endurance exercise. Sub jects (n = 13) were paired according to their 2-mile run times and past run ning experience. Each pair was randomly assigned a treatment of either HMB (3 g/day) or a placebo. After 6 wk of daily training and supplementation, a ll subjects participated in a prolonged run (20-km course). Creatine phosph okinase and lactate dehydrogenase (LDH) activities were measured before and after a prolonged run to assess muscle damage. The placebo-supplemented gr oup exhibited a significantly greater (treatment main effect, P = 0.05) inc rease in creatine phosphokinase activity after a prolonged run than did the HMB-supplemented group. In addition, LDH activity was significantly lower (treatment main effect, P = 0.003) with HMB supplementation compared with t he placebo-supplemented group. In conclusion, supplementation with 3.0 g of HMB results in a decreased creatine phosphokinase and LDH response after a prolonged run. These findings support the hypothesis that HMB supplementat ion helps prevent exercise-induced muscle damage.