Rotator cuff muscles perform different functional roles during shoulder external rotation exercises
Article first published online: 26 JUL 2012
Copyright © 2012 Wiley Periodicals, Inc.
Volume 26, Issue 2, pages 236–243, March 2013
How to Cite
Tardo, D. T., Halaki, M., Cathers, I. and Ginn, K. A. (2013), Rotator cuff muscles perform different functional roles during shoulder external rotation exercises. Clin. Anat., 26: 236–243. doi: 10.1002/ca.22128
- Issue published online: 8 FEB 2013
- Article first published online: 26 JUL 2012
- Manuscript Accepted: 18 JUN 2012
- Manuscript Revised: 13 JUN 2012
- Manuscript Received: 20 FEB 2012
- exercise rehabilitation;
- axioscapular muscles;
The aim of this study was to compare activity in shoulder muscles during an external rotation task under conditions of increasing arm support to investigate whether changing support requirements would influence muscle recruitment levels, particularly in the rotator cuff (RC) muscles. Electromyographic recordings were collected from seven shoulder muscles using surface and indwelling electrodes. The dominant shoulder of 14 healthy participants were examined during dynamic shoulder external rotation performed at 90° abduction with the arm fully supported, partially supported, and unsupported. Linear regressions between arm support load and the averaged muscle activity across participants for each muscle showed infraspinatus predominantly contributing to rotating the shoulder whilst supraspinatus, deltoid, upper trapezius, and serratus anterior were predominantly functioning in support/stabilization roles. During dynamic shoulder external rotation in mid-range abduction, the RC muscles perform different functional roles. Infraspinatus is responsible for producing external rotation torque, supraspinatus is playing a larger joint stabilizer role, and subscapularis is contributing minimally to joint stability. The results also indicate that increasing support load requirements during an external rotation task may be a functionally specific way to retrain the stabilization function of axioscapular muscles. Manipulating joint stabilization requirements while maintaining constant rotational load is a novel method of investigating the differential contribution of muscles to joint movement and stabilization during a given task. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.