Influence of shoulder anterior aspect musculature stretching on scapular kinematics

Abstract

The adequate scapular kinematics is very important for normal shoulder function. Healthy subjects show a pattern of progressive upward rotarion, posterior tilt during humeral elevation, and scapular external rotation that happens at the end of the arm range of elevation. Literature shows that subjects with shoulder impingement present decreased upward rotation, posterior tilt and increased scapular internal rotation. It is believed that these alterations contribute to the subacromial space narrowing and, consequently, to shoulder impingement. One of the various factors that may contribute to scapular movement alterations is the anterior shoulder muscles shortening. Because of greater passive tension, pectoralis minor muscle may limit normal scapular movements. Past study demonstrated that healthy individuals with short pectoralis minor muscle present scapular kinematics similar to that showed by patients with subacromial impingement. Besides, the muscles that insert on coracoids process may lead to an anterior-inferior scapular tilting, contributing to the narrowing of the subacromial space and to the emergence of symptons. Hence it is recommended that stretching of this musculature be included to the treatment of this dysfunction. However, there is no data in Literature that show the effect of this exercise on correction of scapular kinematics. Therefore, the goal of this study is to evaluate the influence of anterior shoulder muscles stretching on scapular kinematics. For that twenty five healthy subjects with anterior shoulder shortening will undergo a stretching program and scapular kinematics will be analysed before and after this intervention. Scapular kinematics will be evaluated with 3SPACE® Liberty® (Polhemus Inc.) electromagnetic evaluation system. The stretching program will last eight weeks and will be done three times a week in alternate days. The understanding of this intervention effect will bring great scientific base for its use during shoulder rehabilitation. (AU)