Branched-chain Amino Acids and Alleviation of Muscle Damage and Fatigue in the Hyper-running Rat Model

Abstract

Oral administration of a mixture of amino acids during exercise reduced muscle damage and abolished post-exercise fatigue in the hyper-running rat model utilizing the stimulation of the ventromedial nucleus of the hypothalamus (VMH) (Okada et al., 2006 ACSM abstract). However, it has been suggested that branched-chain amino acids (BCAA) alone exert beneficial effects against exercise-induced muscle damage. PURPOSE: To determine effects and an optimum dose of BCAA alone on muscle damage and fatigue in hyper-running rat. METHODS: The BCAA mixture was given at doses of 0 (control), 0.5, 1.0,2.0, and 4.0 g/kg BW in a 0.5 % of carboxymethylcellulose solution. The BCAA mixture was composed of leucine, isoleucine, and valine at the ratio of 2: 1: 1 by weight. Hyper-running was induced by microinjection of bicuculine into the VMH via an implanted stainless steel guide cannula. Blood samples were collected at pre-running, immediately after the running, and up to 48 hours thereafter to determine creatine phosphokinase (CPK) activity and concentrations of lactic acid, ammonia, urea, and free amino acids. Food intake was measured before and after the running. RESULTS: The distance of running was not different among all groups. After the running, the CPK activity was elevated in all groups, having the highest CPK activity in the control and less than half as much in 0.5, 1.0, and 4.0 g/kg groups. In the control, the elevated CPK activity did not return to the basal level in 6 hours. At 2-hour post-running, CPK activities in 0.5, 1.0, and 4.0 g/kg groups were significantly lower than in the control. Blood lactic acid rose in all groups after the running, however, the rise was significantly less in 0.5, 1.0, and 4.0 g/kg groups than in the control. Plasma ammonia was increased in the control and the 4.0 g/kg groups 2 hours after the running. Plasma urea was elevated in 2.0 and 4.0 g/kg group than in other groups 6 hours after the running. Food intake was significantly reduced by 20 % in all but the 1.0 g/kg group after the running. CONCLUSIONS: Oral administration of the BCAA mixture alleviated muscle damage and blocked the onset of fatigue resulting from hyper-running at the optimum dose of 1.0 g/kg BW.