阻力運動結合血流限制對股四頭肌關節性肌肉自主抑制族群之肌肉功能的急性影響

Abstract

關節性肌肉自主抑制 (arthrogenic muscle inhibition, AMI) 會影響運動單位的徵招， 是膝關節受傷後造成股四頭肌功能受限的原因之一，通常反應為導致中樞活化比 (central activation ratio, CAR) 不足，也可能影響最大自主等長肌力(maximum voluntary usometric contraction, MVIC)及發力率 (rate of torque development, RTD) 之表現。血流 限制運動 (blood flow restriction, BFR) 為近年新興之運動訓練輔助方法，透過製造局部 缺氧環境，有助於改善運動單位的徵招模式並提升肌肉活化。然而，目前缺乏探討 BFR 改善 AMI 與相關肌肉功能急性效應的研究。因此，本研究目的為探討:(一) 慢性膝關 節傷害族群的 CAR 與 MVIC 及 RTD 之相關性;(二) BFR 運動介入對此族群肌肉功能 之影響;(三) CAR 的變化是否可預測 MVIC 與 RTD 的改變。研究採隨機對照設計，共 招募 28 名 (11 男 17 女) 曾有單側膝關節傷病史之參與者，匹配後隨機分配至控制 (n=9)、 運動 (n=9) 與 BFR 組 (n=10)。運動組與 BFR 組在傷側腳進行三組股四頭肌等速向心 運動，BFR 組同時以 Delfi 血液限制系統進行 50%動脈阻塞壓力的加壓，而控制組為完 全靜止 6 分鐘。在介入前後收集股四頭肌 MVIC、RTD 與 CAR，並以斯皮爾曼等級相 關、2×3 混合設計變異數分析 (時間×組別)，以及逐步線性迴歸分別回應三個研究問題。結果顯示，CAR 與 MVIC、絕對 RTD 0-50 ms 和 0-100 ms，以及標準化 RTD 0-50 ms 皆具低強度正相關 (r = 0.410–0.493，p<.05);然而，三組在介入前後的肌肉功能變 化未有顯著效果 (p≥.05)。逐步迴歸分析顯示CAR的變化量可預測14.1%的絕對 RTD 0-100 ms 之變化量 (R2 = 0.14, p =.05;Δ 絕對 RTD (0-100 ms) = -0.291+ 0.104 [ΔCAR × Group])，尤其 BFR 組可使絕對 RTD 有更大幅度的提升。綜合上述，改善慢性膝傷害 族群的股四頭肌 AMI，其 MVIC 和 RTD 可能也會恢復。然而，造成 AMI 的原因可能 會隨著傷後時間不同而產生不同神經適應 (例如脊髓反射性抑制、皮質脊髓興奮性改變 或中樞神經系統抑制)，以及單次 BFR 運動可能因為疲勞而無法有效且一致的立即提升 肌肉功能，但其引起的中樞活化增加仍有助於促進 0–100 ms 絕對 RTD 提升，因此 BFR 運動可應用於傷後復健訓練或運動前熱身，可能利於發力率表現而使長期的神經適應改 變，建議未來研究可探討 BFR 對於股四頭肌 AMI 族群的長期神經適應的效果。

Arthrogenic muscle inhibition (AMI), characterized by altered motor unit recruitment, is a neural factor limiting muscle function after knee injury. AMI is typically show as reduced central activation ratio (CAR), subsequently reducing maximum voluntary isometric contraction (MVIC) and rate of torque development (RTD). Blood flow restriction (BFR) exercise is a novel technique that alters motor unit recruitment patterns during exercise by creating a hypoxic environment, thereby enhancing muscle activation. However, few studies investigate the acute effect of BFR exercise on AMI and associated neuromuscular function. Therefore, this study aims to investigate: (1) the relationship between CAR and MVIC or RTD in individuals with quadriceps AMI; (2) whether BFR exercise improves quadriceps muscular function; and (3) if improvement in CAR predict MVIC and RTD enhancements. 28 participants (11 males, 17 females) with a history of unilateral knee injury were included. They were matched and randomly assigned into control (n=9), exercise (n=9), and BFR groups (n=10). The exercise and BFR groups performed three sets of quadriceps isokinetic concentric exercise on the injured limb. The BFR group applied 50% arterial occlusion pressure, while the control rested six minutes. MVIC, RTD, and CAR were measured pre- and post-intervention. Spearman correlation analysis, 2×3 mixed-design ANOVA (time × group), and stepwise linear regression were used to answer each research question respectively. Results indicated weak and positive correlations between CAR and MVIC, absolute RTD at 0–50 ms and 0–100 ms, and normalized RTD at 0–50 ms (r = 0.410 – 0.493, p< .05). However, no significant effect in muscular function changes among three groups. Change in CAR predicted 14.1% of the variance in absolute RTD at 0–100 ms (R2 = 0.14, p = .05; Δabsolute 0-100 RTD ms = -0.291 + 0.104 [ΔCAR × Group]). In conclusion, reducing AMI appears beneficial for improving MVIC and RTD after chronic knee injuries. However, neural adaptations underlying AMI can vary depending on post-injury timeframe, resulting in different neural inhibition mechanisms, such as decreased spinal reflex inhibition, altered corticospinal excitability, or central inhibition.Although a single BFR training session may not consistently enhance muscular function due to fatigue, it may still promote central, thereby improving absolute RTD (0–100 ms). Hence, BFR may be incorporated into clinical rehabilitation or warm-up routines to facilitate long-term neural adaptations. Future studies should explore the chronic effects of repeated BFR training on neural adaptations in individuals with quadriceps AMI.