J Korean Acad Rehabil Med Search


Journal of the Korean Academy of Rehabilitation Medicine 1998;22(1):126-132.
Quantitative Electromyographic Analysis of Deltoid and Supraspinatus Muscles during Shoulder Abduction.
Park, Jeong Mee , Oh, Han Seon , Lee, Jong Min
Department of Rehabilitation Medicine, Yonsei University Wonju College of Medicine.
견관절 외전시 삼각근과 극상근의 활동전위의 정량적 분석
박정미, 오한선, 이종민
연세대학교 원주의과대학 재활의학교실

Measurements of local shoulder muscle function during shoulder abduction are of a great interest in biomechanics research and in ergonomic applications. There have been so many opinions that the supraspinatus muscle acts in synergy with the deltoid muscle as a single unit throughout the shoulder abduction. However the specific actions of deltoid and supraspinatus muscles have been subjects of controversy. Electromyography is an established evaluation method of biomechanical study. It reflects the electrical activity at the muscle membrane level and indirectly the mechanical output of the muscle. The purpose of this study was to evaluate the role of deltoid and supraspinatus muscles during shoulder abduction by the comparison of motor unit action potentials using a quantitative electromyographic analysis method, to provide a good insight into the biomechanics of shoulder abduction.

Motor unit action potentials of deltoid muscle were seen earlier than those of supraspinatus muscle at the time of initiation of shoulder abduction. The Root Mean Square (RMS) voltage of deltoid muscle was increased gradually from 0o to 90o of shoulder abduction, and then decreased gradually above 90o to 180o of shoulder abduction. The RMS voltages of deltoid muscle were significantly higher than those of supraspinatus muscle at each degree of shoulder abduction wholly. There was no differences in the RMS voltages of deltoid muscle, during shoulder abduction between the loading of 1 kg and without loading. However, the RMS voltages of supraspinatus muscle were significantly higher in the loading state than without loading. The Mean Rectified Voltages (MRV) were similar to the RMS voltages of deltoid and supraspinatus muscles during shoulder abduction.

Based on these results, we concluded that the deltoid muscle was not only an initiator but also a major contributor in shoulder abduction, where as the supraspinatus muscle acts as a secondary muscle for the initiation of shoulder abduction and a supporting muscle when there is a resistance against shoulder abduction.

Key Words: Quantitative electromyography, Shoulder abduction, Deltoid, Supraspinatus


Browse all articles >

Terms of Use   |   Privacy Polity
Editorial Office
Department of Rehabilitation Medicine, Seoul National University Hospital
101 Daehak-ro, Jongno-gu, Seoul, Korea
Tel: +82-10-8678-2671    Fax: +82-2-6072-5244    E-mail: edit@e-arm.org; edit.karm@gmail.com
Business Registration: 110-82-07460                

Copyright © 2024 by Korean Academy of Rehabilitation Medicine.

Developed in M2PI

Close layer