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Surface Electromyographic Analysis of Suprascapular and Infrascapular Muscle Balance During Selected Exercises

1 May 1998


The purpose of this study was to determine the balance between the suprascapular and infrascapular muscles (SS :IS) to better direct clinicians in the development of shoulder rehabilitation programs. This was accomplished by using surface electromyography (SEMG) to identify common ratios during 3 exercises in seventy-three subjects without known shoulder pathology. Mean, standard deviation, standard error, and p-values were calculated for each of the three exercises. Subjeqts demonstrated suprascapular dominance with scaption (1.32:1) and infrascapular dominance with press-up (1 :5) and rowing (0.75:1). Standard error for scaption, press-up, and rowing were 0.1 , 0,.02, and 0.08 respectively. Rectified, smoothed and demeaned SEMG for each;: exercise revealed similar trace patterns among subjects suggesting common ratios within each exercise. Based on these results, success in shoulder rehabilitation programs may be enhanced when treatment is structured around restoring and maintaining the balance of scapular musculature, as opposed to blindly employing unfocused strengthening protocols.


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