The effects of a humeral head posterior gliding strategy on changes in muscle activities of the infraspinatus during external rotation of the shoulder

Abstract

Background/aims It is important that shoulder rehabilitation programmes incorporate exercises that selectively activate the infraspinatus. In this study, changes in infraspinatus and posterior deltoid electromyography activity during a sitting external rotation exercise with and without the use of a humeral head posterior gliding strategy were investigated. Methods A total of 12 healthy men participated in this study. The activity of the infraspinatus and posterior deltoid was measured during the sitting external rotation exercise, performed with and without humeral head posterior gliding. Differences in the electromyography activity of the infraspinatus and posterior deltoid, with and without humeral head posterior gliding, were analysed using paired t-tests. Results Infraspinatus activity was significantly higher with humeral head posterior gliding than without it (P<0.001). Conversely, posterior deltoid activity was significantly lower with humeral head posterior gliding compared to without it (P<0.001). Conclusions Based on these results, humeral head posterior gliding is recommended for the selective activation of the infraspinatus when performing shoulder external rotation exercises, with the shoulder abducted at 90°.