The Effect of Humeral Head Depressor Strengthening on Individuals with Subacromial Impingement Syndrome.

Background and

Objectives

Subacromial pain syndrome (SAPS) is one of the most common musculoskeletal problems affecting the shoulder joint. In this study, we aimed to investigate the effectiveness of a rehabilitation program targeting humeral head depressor muscles on symptoms in individuals with SAPS. Materials and

Methods

Participants were sequentially assigned to study and control groups in a quasi-randomized design. While the control group received standard physical therapy and rehabilitation, the study group underwent a combined progressive exercise program, including humeral head depressor strengthening, peri-articular muscle exercises, scapular stabilization, and proprioceptive training. Acromio-humeral distance (AHD) and tendon thickness measurements were evaluated via ultrasonography (USG), while pain intensity, upper-extremity disability, and kinesiophobia were measured using the VAS and McGill Pain Questionnaire, DASH-T, and the Fear Avoidance Beliefs Questionnaire, respectively.

Results

Both the study and control groups showed statistically significant increments in AHD compared to the baseline. The first and final measurements changed from 7.92 mm to 10.54 mm and from 7.72 mm to 8.41 mm, respectively. However, the increase in AHD was greater in the study group relative to the control group, and the value was statistically significant. The study group showed significant improvements in pain and disability. Kinesiophobia levels, on the other hand, decreased in both groups, but a greater decrease was observed in the study group.

Conclusions

In this study, both the study and control groups showed an increase in AHD, but the combined exercise program targeting humeral head depressor muscles resulted in a greater improvement. Reduced tendon thickness indicated the eased motion of the rotator cuff, supporting the improvements in pain and disability. The program had a positive impact on psychosocial parameters, including pain-related kinesiophobia. Given the limited literature on the effects of such exercises on AHD and tendon thickness, this study provides an original contribution. Clinical Trial Registration: ClinicalTrials.gov identifier: NCT07228455.