Abstract

Context:  Performing shoulder-abduction exercises with scapular retraction has been theorized to reduce the potential for shoulder impingement. However, objective data to support this premise are lacking.
Objective:  To evaluate the influence of active scapular retraction on acromiohumeral distance (AHD) at 4 shoulder-abduction angles using real-time ultrasound.
Design:  Cross-sectional study.
Setting:  University laboratory.
Patients or Other Participants:  Twenty asymptomatic individuals (10 men, 10 women; age = 22.9 ± 2.8 years, height = 169.3 ± 9.5 cm, mass = 65.5 ± 12.9 kg) were recruited.
Main Outcome Measure(s):  Real-time ultrasound images of AHD were obtained during nonretracted and retracted scapular conditions at 0°, 45°, 60°, and 90° of shoulder abduction. A 2-factor analysis of variance with repeated measures was used to evaluate the influence of shoulder retraction on AHD across shoulder-abduction angles.
Results:  A scapular-retraction condition × shoulder-abduction–angle interaction for AHD was found (F3,57 = 4.56, P = .006). The AHD was smaller at 0° (10.5 versus 11.2 mm, respectively; t19 = 2.22, P = .04) but larger at 90° (9.4 versus 8.7 mm, respectively; t19 = −2.30, P = .04) of shoulder abduction during the retracted than the nonretracted condition. No differences in AHD were observed between conditions at 45° (t19 = 1.45, P = .16) and 60° (t19 = 1.17, P = .86) of abduction.
Conclusions:  The observed differences in AHD at 0° and 90° of shoulder abduction were small and did not exceed the established minimal detectable change for either angle. Our findings suggest that active scapular retraction during shoulder abduction has a minimal influence on AHD at 0° and 90° in healthy individuals. Further investigations are needed to determine whether scapular retraction influences AHD in individuals with subacromial impingement.