支鏈胺基酸增補對下坡跑後肌肉生長抑制激素-myostatin及肌肉損傷與發炎指標之影響

Abstract

研究背景：肌肉生長抑制激素 (myostatin, MSTN) 是肌肉生長的負調控因子，而運動誘發肌肉損傷 (exercise-induced muscle damage, EIMD)，會引起 MSTN 濃度的改變。過去研究指出增補支鏈胺基酸 (branched-chain amino acids, BCAA) 似乎能夠減緩EIMD，但對於 MSTN 的影響仍不清楚。本研究目的為探討增補 BCAA 在單次激烈運動過後對 MSTN 及肌肉損傷及發炎指標之影響。方法：13位健康男性 (23.6 ± 4.8歲) 依照平衡次序法接受 BCAA + 下坡跑 (BCAA) 或安慰劑 + 下坡跑 (PLA) 處理。增補時間點共三次，分別為運動前15分鐘、運動後立即與運動後3小時，受試者每次增補劑量為100 mg/kg。於增補前 (pre)、運動後立即 (0 h)、運動後3小時 (3 h)、運動後24小時 (24 h)、運動後48小時 (48 h) 五個時間點，測量血漿 MSTN、血清介白素6 (interleukin 6, IL-6)、血清肌酸激酶 (creatine kinase, CK)、延遲性肌肉痠痛 (delayed-onset muscle soreness, DOMS) ，及最大等長肌力 (maximum voluntary isometric contraction, MVIC) 五個指標。所得數據以重複量數二因子變異數分析進行統計處理以及皮爾森積差相關進行分析。結果：MSTN變化率有交互作用 (p=.046)，BCAA以及PLA處理在0 h與3 h顯著高於pre，BCAA 處理 48 h 顯著高於 24 h；PLA 處理 48 h 顯著低於 0 h、3 h。IL-6無交互作用，0 h 顯著高於 pre，3 h 顯著高於其餘四時間點。DOMS 有交互作用 (p=.012)，在 3 h 及 24h，BCAA 顯著低於 PLA 處理。CK 以及 MVIC 無交互作用，後測四個時間點與 pre 達顯著。MSTN 與 CK、IL-6 在 0 h 與 3 h 分別呈現中度正相關。結論：本研究發現 MSTN 會在單次激烈運動後立即上升，並且與 IL-6、CK 等指標呈現正相關，推測 EIMD 會短暫造成 MSTN 上升，且增補 BCAA 並不會抑制此現象，但會暫時減緩 DOMS 的發生。

Background: Myostatin (MSTN) is the negative signalling factor for muscle growth. Exercise-induced muscle damage (EIMD) would alter MSTN levels. Previous studies had indicated branched-chain amino acids (BCAA) supplementation might alleviate EIMD, but the effect on MSTN remains unclear. This study aims to investigate the effects of BCAA supplementation on MSTN and muscle damage indicators following a single bout of intense exercise. Methods: Thirteen healthy males (aged 23.6 ± 4.8 years) receiving either BCAA with downhill running (BCAA) or placebo with downhill running (PLA) with a randomized, counterbalanced design. Participants were all supplemented with 100 mg/kg of BCAA/PLA at 15 min before exercise, immediately after exercise and 3 h after exercise. Plasma MSTN, serum interleukin 6 (IL-6), serum creatine kinase (CK), delayed-onset muscle soreness (DOMS), and maximum voluntary isometric contraction (MVIC) were measured at five time points: pre-supplementation (pre), immediately after exercise (0 h), 3 hours post-exercise (3 h), 24 hours post-exercise (24 h), and 48 hours post-exercise (48 h). Data were analysed using two-way ANOVA repeated measure and Pearson correlation of statistical analysis. Results: There was a significant interaction effect on MSTN levels (p=.046). In the BCAA treatment, MSTN levels were significantly higher at 0 h and 3 h compared to pre-exercise, and at 48 h compared to 24 h. In the PLA treatment, MSTN levels were significantly higher at 0 h and 3 h compared to pre-exercise, and significantly lower at 48 h compared to 0 h and 3 h. IL-6 showed no interaction effect but was significantly higher at 0 h compared to pre-exercise, and at 3 h compared to the other time points. CK showed no interaction effect but was significantly higher at 0 h, 3 h, 24 h, and 48 h compared to pre-exercise, with 3 h and 24 h significantly higher than 0 h, and 24 h significantly higher than 3 h and 48 h. DOMS showed a significant interaction effect (p=.012), with BCAA significantly lower than PLA at 3 h and 24 h. MSTN was positively correlated with CK and IL-6 at 0 h and 3 h. Conclusion: This study found MSTN levels increased after a single bout of intense exercise and positively correlated with IL-6 and CK. It is suggested that EIMD temporarily increased MSTN levels, and BCAA supplementation did not inhibit this increase but temporarily alleviated DOMS.