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

Knitter, A. E., L. Panton, J. A. Rathmacher, A. Petersen, and R. Sharp. Effects of b-hydroxy-b-methylbutyrate on muscle damage after a prolonged run. J Appl Physiol 89: 1340–1344, 2000.—This study examined the effects of supplemental b-hydroxy-b-methylbutyrate (HMB) on muscle damage as a result of intense endurance exercise. Subjects (n 5 13) were paired according to their 2-mile run times and past running 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, all subjects participated in a prolonged run (20-km course). Creatine phosphokinase and lactate dehydrogenase (LDH) activities were measured before and after a prolonged run to assess muscle damage. The placebo-supplemented group exhibited a significantly greater (treatment main effect, P 5 0.05) increase 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 5 0.003) with HMB supplementation compared with the 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 supplementation helps prevent exercise-induced muscle damage.