ABSTRACT
Study Design Controlled laboratory study. Background The activity of the rotator cuff muscles has not previously been measured with indwelling electromyography (EMG) comparing ambulation and other movements. Knowledge of the relative contribution of these muscles during various tasks may help to guide rehabilitation progression. Objective To measure activity of the rotator cuff muscles and other shoulder muscles during normal ambulation, shirt and sling donning and doffing, and rehabilitation tasks commonly performed after rotator cuff surgery. Methods In 28 volunteers (15 men, 13 women; mean age, 32.2 years), indwelling EMG activity was measured in the supraspinatus, infraspinatus, teres minor, and subscapularis muscles during various tasks; and surface EMG activity was measured in the middle deltoid, biceps, and upper trapezius muscles. Results Using median EMG activity, in general, donning and doffing a shirt or sling recruited the rotator cuff muscles more than the other 7 tasks tested. Self-ranging motion using pulleys, especially in the scapular plane, was also consistently associated with greater recruitment of the shoulder muscles. Pendulum exercises, passive range of motion by a physical therapist, and self-ranging motion with a dowel recruited the shoulder muscles to a lesser extent. Conclusion Our results demonstrate that rehabilitation tasks such as pendulum exercises, passive range of motion by a physical therapist, and self-ranging motion with a dowel show low EMG activity, whereas pulleys in the sagittal plane and scapular plane show greater activity. Scapular plane activity was consistently higher than sagittal plane activity. Of all the tasks assessed, ambulation without a sling and donning and doffing a sling and a shirt consistently showed the highest activity. J Orthop Sports Phys Ther 2016;46(5):375-383. Epub 6 Apr 2016. doi:10.2519/jospt.2016.6090.
