肩胛動作異常的過肩運動員在水中太極運動的肩胛肌肉活化探究

Abstract

肩胛區域肌群，包含上斜方肌、下斜方肌和前鋸肌，對於肩胛的穩定和肩膀的運動至關重要。然而，過肩運動員常常存在肩胛骨穩定肌群肌力較弱的問題，在功能性的肩胛穩定訓練運動，可能導致上斜方肌過度活化。因此，本研究旨在調查過肩運動員肩胛動作異常者在水中和陸地上進行水中太極運動時，肩胛區域肌肉的活化情形。本實驗有二十一名肩胛動作異常的過肩運動員，在水中與陸地進行水中太極運動，同時使用表面肌電圖測量上斜方肌、下斜方肌、前鋸肌和闊背肌的肌肉活化，並計算肩胛區域的肌肉平衡比值:上斜方肌/下斜方肌、上斜方肌/前鋸肌和下斜方肌/前鋸肌，以評估肩胛穩定的控制能力。研究結果顯示，在水中進行水中太極運動時，上斜方肌的收縮力全面衰退，平均降至1.6-3.0%最大自主收縮（p < .001），而下斜方肌與前鋸肌略為減弱(下斜方肌:4.3-12.7%最大自主收縮，前鋸肌:6.3-11.7%最大自主收縮) 。這導致上斜方肌/下斜方肌比值降為0.4至0.7（p < .001），上斜方肌/前鋸肌比值降為0.3至1.0（p < .001）。當水中太極的進程達到更高穩定需求的動作時，便增進了肩胛穩定肌群的活化效果，與陸上環境的肌肉活化效果無顯著差異，這些動作包含:1)下斜方肌在水中太極的展翅運動（水中vs.陸地：5.9±0.7 vs. 9.4±1.5，p = .014），2)下斜方肌在水中太極的內折運動（水中vs.陸地：9.4±1.4 vs. 12.2±1.8，p = .033），3)前鋸肌在水中太極的內折運動（水中vs.陸地：6.9±1.9 vs. 5.8±2.1，p = .434）。慢速的水中運動，通常會導致水中測得的肌肉活化較陸地更低，但由於不成比例的肌力下降，水中環境使肩胛區域呈現較陸地上更理想的發力表現，平日過度活化的上斜方肌於此時被抑制，下斜方肌與前鋸肌皆因水中運動的促進而接近陸上表現。並且水中太極的水中肌肉顯示較高的下斜方肌/前鋸肌比值（水中vs.陸地的展翅運動：2.3 ± 0.6 vs. 0.6 ± 0.1，p < .001 和水中vs.陸地的匯集運動：2.2 ± 0.4 vs. 1.2 ± 0.2，p = .009），這代表下斜方肌與前鋸肌對肩胛作用的力偶旋轉軸往胸椎靠近，呈現肩胛內收的穩定姿勢，有助於肩胛胸椎關節的穩定性。在水中進行的水中太極運動，有效抑制過肩運動員的上斜方肌活化，改善肩胛肌肉平衡比值，提升肩胛穩定控制力。本研究結果指出，水中的水中太極運動在執行手臂運動時，能使肩胛肌群以適當的發力表現，控制肩胛處於較為內收的穩定位置，水中太極應為良好的肌肉再教育的運動形式，有助於提升肩胛動作異常的過肩運動員的肩胛區域健康。

The periscapular muscles, which include the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA), are crucial for scapular stabilization and shoulder movement. However, overhead athletes are known to have weak scapular stabilizers, and certain functional training exercises may primarily activate the UT muscles rather than the LT and SA. Therefore, this study aims to investigate the activation of periscapular muscles during Ai Chi exercises in water and on land for overhead athletes with scapular dyskinesis. Twenty-one overhead athletes with scapular dyskinesis performed Ai Chi exercises in water/on land while surface electromyography was used to measure muscle activation of the UT, LT, SA and latissimus dorsi (LD). The UT/LT, UT/SA, and LT/SA ratios were calculated to evaluate the scapular stability control. The findings revealed that during Ai Chi exercises in water, there was a significant decrease in UT activation (1.6-3.0% maximal voluntary isometric contraction, MVIC, p < .001). In contrast, the LT and SA showed a slight reduction in activation (LT: 4.3-12.7% of MVIC; SA:6.3-11.7% of MVIC), leading to a decreased UT/LT (0.4 to 0.7, p < .001) and UT/SA (0.3 to 1.0, p < .001). As the Ai Chi exercises progressed to movements with higher stability demands, the activation of the scapular stabilizing muscle group showed no significant difference between aquatic and land environments in the following: 1) LT during the Uplifting exercises (aquatic vs. land: 5.9 ± 0.7 vs 9.4 ± 1.5, p= .014), 2) LT during the Folding exercises (aquatic vs. land: 9.4 ± 1.4 vs 12.2 ± 1.8, p = .033), and 3) SA muscle during the Folding exercises (aquatic vs. land: 6.9 ± 1.9 vs 5.8 ± 2.1, p =.434). This can be attributed to the slow arm motions during Ai Chi exercises in water, leading to lower muscle activations compared to land-based exercises. However, as the exercises progressed and higher levels of stabilization were required, the activation of LT and SA increased, facilitating power transfer from the trunk to the arms in the water environment. The disproportionate decrease in periscapular muscle activations of UT, LT and SA in the aquatic environment led to better force performance compared to land exercises. Additionally, the aquatic Ai Chi exercises demonstrated higher LT/SA ratio (aquatic vs. land during the Uplifting exercises: 2.3 ± 0.6 vs. 0.6 ± 0.1, p < .001 and during the Gathering exercises: 2.2 ± 0.4 vs. 1.2 ± 0.2, p = .009), indicating improved thoracoscapular stabilization for the individuals with scapular dyskinesis. The aquatic Ai Chi exercises effectively inhibited the overactive UT and promoted appropriate muscle activation in the scapular region. These findings suggested that aquatic Ai Chi exercises may reeducate the periscapular muscles to stabilize the thoracoscapular joint and improve the scapular control in overhead athletes with scapular dyskinesis.