EMG examination of shoulder muscle activities in elevation focusing on the rotator cuff muscles in CKC exercise

Abstract

[Purpose] To clarify rotator cuff muscular activity in the raised position in closed kinetic chain (CKC) exercise. [Subjects] Twenty-nine cases were studied, 19 men and 10 women (average age 21.5 ± 4.7 years old, average body weight 60.1 ± 11.4 kg, average grip strength 34.35 ± 6.9 kg). [Methods] To determine the effects of CKC exercise on the upper limb, we measured the surface EMG of the infraspinatus, trapezius (upper fiber) and deltoid (middle fiber) muscles with the arm elevated. [Results] Our measurements revealed that at 150° elevation in the scapular plane of the upper limb, with 5% body weight load, the EMG activity of the infraspinatus muscle is approximately 30% maximum voluntary contraction (MVC). [Conclusion] The raised position in CKC exercise is effective in physical therapy for functional recovery of the infraspinatus muscle.