Shoulder external rotation range of motion and pectoralis minor length in individuals with and without shoulder pain

Abstract

ABSTRACTBackground: There is evidence that pectoralis minor (PM) length influences scapula position and that scapula position relates to glenohumeral joint (GHJ) external rotation (ER) range of motion (ROM). Objectives: To explore the association between PM resting length and GHJ ER ROM in individuals with and without shoulder pain. The influence of GHJ ER ROM measurement position on this association was also evaluated. Design: Cross-Sectional. Methods: Fifty individuals (25 asymptomatic and 25 with shoulder pain) participated. PM resting length was measured using a tape measure with subjects standing, while GHJ ER ROM was quantified using a digital inclinometer with participants in both supine and seated positions. The same blinded investigator took all measurements. Results/Findings: A significant negative correlation between PM resting length and GHJ ER ROM in the seated position was noted in the asymptomatic group (r = −0.41; p = 0.04), but not in the symptomatic group (r = −0.33; p = 0.11). A nonsignificant negative correlation was also demonstrated in the supine position for both groups (r ranged from −0.35 to −0.17; p > 0.05). There was a significant group x position interaction (F = 4.06; p = 0.04) with more GHJ ER ROM (6.80°) for asymptomatic group in the seated position. Conclusions: PM length is not strongly correlated with GHJ ER ROM in individuals with or without shoulder pain. However, the position in which GHJ ER ROM is measured influenced the motion in asymptomatic individuals.