PURPOSE: Eccentric exercise results in prolonged muscle damage, fiber disruption and inflammation. Although inflammation is essential to recover from muscle damage, excessive inflammation may also induce secondary damage, and should thus be suppressed. The purpose of this study was to explore the effect of Branched-Chain Amino Acid (BCAA) on muscle inflammation and recovery after eccentric exercise.
METHODS: Ninety-six male SD rats (8 weeks old) were randomly divided into four weight-matched groups. These groups consisted of a non-exercise control placebo group (C-PLA; n = 8), a non-exercise control BCAA group (C-PCO; n = 8), with the other 80 rats exposed to either placebo (E-PLA; n = 40) or BCAA supplement (E-PCO; n = 40), as well as 120 min of eccentric exercise. Post-eccentric exercise, eight rats from each group were sacrificed per time point—0 h, 1d, 3d, 5d and 7d. Inflammatory cytokine and satellite cell responses were assessed for all time points. BCAA (Leucine: Isoleucine: Valine = 2:1:1) (1 g/kg body weight) or PLA (distilled water) were administered by oral gavage once a day, beginning at 3 days prior to eccentric contraction until killing.
RESULTS: HE staining of transverse sections of the muscle showed that muscle fiber necrosis and inflammatory cell invasion occurred to different degrees in PLA and BCAA group, the recovery of muscle fiber injury and decrease of inflammatory cell infiltration is faster in BCAA than PLA. On day7 post-exercise, CK was significantly lower in BCAA than PLA (15.73 ± 0.59 vs 19.09 ± 1.51 ng/ml, P < 0.05) and nonsignificant with C-PLA (15.73 ± 0.59 vs 14.47 ± 2.03 ng/ml, P > 0.05). BCAA administration resulted in a rapid inflammatory cytokine response with an earlier peak (IL-6 on Day1, max 99.92 ± 4.92 pg/ml and IL-10 on Day3, max 142.81 ± 23.06 ng/l) vs. PLA (IL-6 on Day3, max 99.06 ± 10.17 pg/ml and IL-10 on Day5, max 147.78 ± 11.18 ng/l). BCAA resulted in a rapid satellite cell response with an earlier peak in activation (MYOD max 1.10 ± 0.14, MYOG max 1.20 ± 0.13, at 1d post-exercise) vs. PLA (MYOD on Day3, max 1.07 ± 0.08 and MYOG on Day5, max 1.15 ± 0.06).
CONCLUSIONS: BCAA supplementation accelerate recovery from muscle damage by accelerating the process of inflammatory response during exercise-induced muscle damage.