Change of pectoralis minor length, and acromial distance, during scapular retraction at 60° shoulder elevation

Abstract

As the pectoralis minor muscle is inserted into the coracoid process, an improper length of this muscle would affect scapular and shoulder motions. Therefore, this study is proposed to assess the effects on pectoralis minor's length and acromial distance after active scapular retraction in scaption at 60° elevation. Sixty right-hand-dominant participants (11 males, 49 females) were randomized into an intervention group and a control group. The intervention group performed pectoralis minor muscle stretching by active scapular retraction, while the control group were asked to sit in an upright position. The result shows that, the mean lengths of pectoralis minor in the intervention group were significantly increased when compared with those of the control group (p = 0.004 and p = 0.014 respectively). Simultaneously, the reduction in acromial distance of this intervention group was substantially greater than the control group's (p < 0.001 and p = 0.001 respectively). However, it should be noted that the results reported only relate to the period immediately following muscle stretching.

Keywords: Acromial distance; Active stretch; Pectoralis minor; Posture; Scapular plane.