Bitter Natalie L, Clisby Elizabeth F, Jones Mark A, Magarey Mary E, Jaberzadeh Shapour, Sandow Michael J
School of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.
J Shoulder Elbow Surg. 2007 Sep-Oct;16(5):563-8. doi: 10.1016/j.jse.2006.11.007. Epub 2007 Jun 8.
Balanced forces around the shoulder are important for normal function; however, rehabilitation guidelines are not well defined because the muscle contributions and optimal exercise technique to recruit them are poorly understood. This study aimed to determine (1) the conditions of resisted isometric external rotation that optimized the contribution of infraspinatus and (2) the load of external rotation at which the adduction strategy was most effective at reducing deltoid contributions. Eighteen subjects with healthy shoulders (n = 36) performed resisted isometric external rotation at 3 increasing loads--10%, 40%, and 70% of their maximal resisted external rotation voluntary isometric contraction--with and without adduction. Surface electromyographic activity of the infraspinatus, posterior and middle deltoid, and pectoralis major was recorded and normalized against the average activity of all 4 muscles, representing each muscle's relative contribution to the task. To optimize the relative contribution of the infraspinatus with the least deltoid involvement during isometric external rotation, a load between 10% and 40% maximal voluntary isometric contraction is appropriate. At low loads, use of the adduction strategy during external rotation reduces middle deltoid involvement. In contrast, the posterior deltoid is activated in parallel with the infraspinatus at low loads and may even act as an adductor with the arm by the side. This study provides a useful guide to optimize rehabilitative exercises for rotator cuff dysfunction; in particular, highlighting that activation of the deltoid could be counterproductive to infraspinatus retraining.
肩部周围的平衡力对正常功能很重要；然而，康复指南并未明确界定，因为对肌肉的作用以及募集这些肌肉的最佳运动技巧了解不足。本研究旨在确定：（1）优化冈下肌作用的抗阻等长外旋条件；（2）内收策略在减少三角肌作用方面最有效的外旋负荷。18名肩部健康的受试者（n = 36）在3种逐渐增加的负荷下进行抗阻等长外旋，负荷分别为其最大抗阻外旋自主等长收缩的10%、40%和70%，试验过程中分别有无内收动作。记录冈下肌、三角肌后束和中束以及胸大肌的表面肌电图活动，并以这4块肌肉的平均活动为参照进行标准化，以代表每块肌肉对该任务的相对作用。为了在等长外旋过程中以最少的三角肌参与来优化冈下肌的相对作用，10%至40%最大自主等长收缩之间的负荷是合适的。在低负荷下，外旋过程中使用内收策略可减少三角肌中束的参与。相比之下，在低负荷下，三角肌后束与冈下肌同时被激活，甚至可能在手臂位于身体一侧时作为内收肌起作用。本研究为优化肩袖功能障碍的康复锻炼提供了有用的指导；特别是强调激活三角肌可能会对冈下肌的再训练产生适得其反的效果。
