Shoulder Muscle Recruitment Patterns During Commonly Used Rotator Cuff Exercises: An Electromyographic Study

Abstract

Background and Purpose Graduated rotation exercises performed with the arm by the side are commonly used to improve rotator cuff (RC) muscle function. The aim of this study was to compare the pattern of recruitment of the RC muscles with that of other shoulder muscles that rotate the shoulder joint during these exercises. Subjects The nondominant shoulders of 15 subjects who were healthy were tested. Methods Activity in the infraspinatus, supraspinatus, subscapularis, latissimus dorsi, pectoralis major, and posterior deltoid muscles was recorded. Low-, medium-, and high-intensity rotation exercises were performed with a pulley system. Results As the intensity of both internal and external rotation exercises increased, activity increased in a systematic manner in all muscles capable of producing rotation torque during concentric and eccentric contractions. Discussion and Conclusion The results indicate that, in people who are healthy, the motor strategy used to deal with increasing rotation resistance with the arm in a pendant position is to gradually increase activity in all shoulder rotation torque-generating muscles.