Department of Rehabilitation Center, Dang Dang Korean Medicine Hospital, Changwon, Republic of Korea.
Department of Physical Therapy, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
J Shoulder Elbow Surg. 2021 Jun;30(6):1230-1237. doi: 10.1016/j.jse.2020.08.031. Epub 2020 Sep 10.
The infraspinatus muscle has a crucial role in shoulder stability. Although axial shoulder rotation is useful for selective activation of the infraspinatus, no study has examined the influence of exercise position on axial shoulder rotation during shoulder external rotation (ER) exercises. Thus, this study investigated the muscle activity in the infraspinatus, posterior deltoid, and middle trapezius during shoulder ER exercises performed with and without controlled axial shoulder rotation in 2 different positions.
Twenty healthy subjects performed prone external rotation (PER) exercises with and without pressure biofeedback and seated external rotation (SITER) exercises with and without posterior humeral head gliding. Muscle activity during each ER exercise was measured using surface electromyography.
Exercise strategy (P < .001) and position (P < .001) had a significant main effect on muscle activity in the infraspinatus and posterior deltoid. However, no significant interaction between strategy and position was observed. For muscle activity in the middle trapezius, strategy and position had a significant interaction effect (P = .014). Muscle activity in the infraspinatus increased significantly with the use of strategies to control axial shoulder rotation, whereas muscle activity in the posterior deltoid and middle trapezius decreased significantly. For all 3 muscles, greater activity was observed in the prone position than the seated position.
We suggest that PER with pressure biofeedback can be useful to improve selective activation of the infraspinatus muscle while further eliciting infraspinatus muscle activity.
冈下肌在肩关节稳定性中起着至关重要的作用。虽然轴向肩关节旋转有助于选择性地激活冈下肌，但尚无研究探讨在进行肩关节外旋（ER）运动时，运动姿势对轴向肩关节旋转的影响。因此，本研究调查了在 2 种不同姿势下进行肩 ER 运动时，有无控制轴向肩旋转对冈下肌、三角肌后束和中斜方肌的肌肉活性的影响。
20 名健康受试者分别进行了有和无压力生物反馈的俯卧外旋（PER）运动，以及有和无肱骨后头部滑动的坐姿外旋（SITER）运动。使用表面肌电图测量了每次 ER 运动中的肌肉活动。
运动策略（P<.001）和姿势（P<.001）对冈下肌和三角肌后束的肌肉活性有显著的主效应。然而，策略和姿势之间没有显著的交互作用。对于中斜方肌的肌肉活性，策略和姿势有显著的交互作用（P=.014）。当使用控制轴向肩旋转的策略时，冈下肌的肌肉活性显著增加，而三角肌后束和中斜方肌的肌肉活性显著降低。对于所有 3 块肌肉，俯卧位的肌肉活性均大于坐姿位。
我们建议，使用压力生物反馈的 PER 可以有助于改善冈下肌的选择性激活，同时进一步引发冈下肌的肌肉活动。
