Electromyographic Activity of Selected Shoulder Muscles in Commonly Used Therapeutic Exercises

Bryon T Ballantyne, Sally J O'Hare, Jodie L Paschall, Mary M Pavia-Smith, Angela M Pitz, Jerry F Gillon, Gary L Soderberg
1993 Physical Therapy  
and Purpose, The purpose of this study was to evaluate and compare the muscle actiuity of the supraspinatus, infiaspinatus, feres minor, and lower trape~dus muscles during commonly prescribed therapeutic exercises in subjects with and without shoulder pathology. Subjects. Twenty healthy subjects (9 male, I1 female) and 20 subjects with recuwent unilateral shoulder pain and weakness (14 male, 6 female), aged 18 to 40 years @=28, SD=5.8), participated in this stud'. Metboris. Subjectsperformed
more » ... ubjectsperformed each of the following exercises using a hand-held weight: prone lateral (8ctemal) rotation, sidelying lateral rotation, and arm elevation in the scapular plane. Indwelling fine-wire electrodes recorded electromyographic (EMG) activity during each exercise. The EMG activity in five phases of ccmcentric contraction of each exercise was averaged and divided into three equal time intetvak;. Mean EMC values normalized to muximl activity for the entire phase of concentric contraction and for each of the three intervals were used in subsequent analyses. Results. Two-way repeated-measures analyses of variance (ANOVAs) revealed between-group d1ferences only in the prone lateral rotation exercise. Compared with subjects without shoulder pathology, subjects with shoulder pain showed signtjicantly greater EMC activity in the infiaspinatus muscle and less activity in the supraspinatus muscle during this exercke. Conclusion and .Discussion. These results suggest that the pattern of muscle activation during specijic shoulder movements in patients with shoulder pain m y be related to pathology. Future studies are needed to detennine whether an imbalance in neuromuscular control is a factor contributing directly to shoulder dys&nction or whether such an imbalance is seconda y to some pathology. [Ballantyne BT, O'Hare SJ, Paschal1 JL, et al. Electromyographic activity of selected shoulder muscles in commonly used therapeutic exercises. Pbys T h e 199.3; 73::668#2.]
doi:10.1093/ptj/73.10.668 pmid:8378423 fatcat:j6exj5oemjd2peutgvvcmy4m6i