Fennell Jeremy, Phadke Chetan P, Mochizuki George, Ismail Farooq, Boulias Chris
Spasticity Research Program, West Park Healthcare Centre; Faculty of Medicine, University of Toronto.
Spasticity Research Program, West Park Healthcare Centre; Faculty of Medicine, University of Toronto; Faculty of Health, York University.
Physiother Can. 2016;68(1):24-8. doi: 10.3138/ptc.2014-83.
We investigated the best position for shoulder retractor strengthening exercise to maximize middle trapezius activity and minimize rhomboid major activity. Although both trapezius and rhomboids are scapular retractors, rhomboids also act as downward rotators of the scapula, which can worsen subacromial impingement.
Twelve healthy participants (age 30 [SD 6] y) with no history of shoulder pain were recruited for this study, which used fine-wire electromyography to examine maximal muscle activation of the middle trapezius and rhomboid major muscle fibres in four different positions: with the shoulder in 90° abduction with elbow completely extended and (1) shoulder internal rotation, (2) shoulder neutral rotation, (3) shoulder external rotation, and (4) rowing (shoulder neutral rotation and elbow flexed 90°). The ratio of trapezius to rhomboid muscles was compared with Wilcoxon signed-rank tests.
Muscle activation ratio during shoulder retraction exercise was significantly lower by 22% (i.e., rhomboid was more active than middle trapezius) when performed with the shoulder in rowing position (elbow flexed) than with the shoulder in external rotation (elbow extended) position (p=0.031). All four positions produced coactivation of trapezius and rhomboids.
Rowing position may not be the best position for shoulder retractor strengthening in patients with impingement syndrome. The preferable position for maximizing middle trapezius activity and minimizing rhomboid activity may be shoulder external rotation with elbow extended.
我们研究了肩部牵开器强化锻炼的最佳姿势，以最大限度地提高斜方肌中部的活动并最小化菱形肌的活动。虽然斜方肌和菱形肌都是肩胛骨牵开器，但菱形肌还起到肩胛骨向下旋转的作用，这可能会加重肩峰下撞击。
招募了12名无肩部疼痛病史的健康参与者（年龄30[标准差6]岁）参与本研究，该研究使用细针肌电图检查在四个不同姿势下斜方肌中部和菱形肌主要肌纤维的最大肌肉激活情况：肩部外展90°且肘部完全伸展，以及（1）肩部内旋、（2）肩部中立旋转、（3）肩部外旋和（4）划船姿势（肩部中立旋转且肘部屈曲90°）。使用Wilcoxon符号秩检验比较斜方肌与菱形肌的比例。
与肩部处于外旋（肘部伸展）姿势相比，在划船姿势（肘部屈曲）下进行肩部后缩锻炼时，肌肉激活率显著降低22%（即菱形肌比斜方肌中部更活跃）（p=0.031）。所有四个姿势均导致斜方肌和菱形肌共同激活。
划船姿势可能不是撞击综合征患者肩部牵开器强化锻炼的最佳姿势。最大限度提高斜方肌中部活动并最小化菱形肌活动的优选姿势可能是肩部外旋且肘部伸展。
