Effects of mobilization with movement on muscle strength and EMG activity of shoulder external rotator in individual with rotator cuff repair: A randomized controlled trial

Background Exercises that improve infraspinatus (ISP) muscle activation and limit excessive anterior translation of the humeral head are important for shoulder strength training in patients who have undergone rotator cuff (RC) repair. Posterior glenohumeral (GH) glide mobilization during external rotation (ER) strengthening exercise can limit the anterior translation of the humeral head. Objective To compare the ER strength and muscle activity of shoulder external rotator between ER strengthening performed at 0° and 90° shoulder abduction with and without posterior GH mobilization, at a single time point. Methods The study included patients who had undergone RC repair. Forty patients who underwent rotator cuff repair were randomized into two groups: with mobilization group (n = 20) and without mobilization group (n = 20). The with mobilization group applied posterior GH mobilization during ER strengthening at 0° and 90° shoulder abduction, whereas the without mobilization group performed ER strengthening at the same angles without posterior GH mobilization. Surface electromyography was used to record muscle activity in the infraspinatus, middle deltoid, and posterior deltoid. Fixed-base isometric dynamometry was used for shoulder ER strength. Group and shoulder abduction angle differences were analyzed using 2-way repeated-measures analysis of variance. Results Significant group-by-angle were observed for ER muscle strength and ISP/PD ratio. Post hoc testing revealed that ER muscle strength and ISP muscle activity were significantly higher in the group with mobilization than the group without mobilization at both 0° (p < .001) and 90° (p < .001) shoulder abduction angle. The ISP/PD ratio was significantly greater in the group with mobilization than in the group without mobilization group at 90 ° shoulder abduction angle (p < .001). Conclusion Our results suggest that posterior GH mobilization could be a useful strategy for immediate strength of shoulder ER rotation in patients who underwent an arthroscopic repair.