Electromyographic analysis of select eccentric-focused rotator cuff exercises

ABSTRACT

Background

Eccentric-focused rotator cuff exercises are clinically useful in rehabilitation; however, to what extent these exercises activate shoulder musculature is unknown.

Purpose

Investigate peak electromyographic (EMG) activity of shoulder musculature during eccentric-focused rotator cuff exercises to inform clinical decision-making.

Methods

Surface EMG activity was measured in 15 healthy subjects from 5 muscles of the dominant shoulder: supraspinatus, infraspinatus, upper trapezius, lower trapezius, and middle deltoid. Subjects performed 5 exercises: short-to-long scaption, sit-to-stand scaption, standing external rotation (ER), sidelying ER, and sidelying horizontal adduction. The effects of exercise and muscle on peak EMG activity were analyzed using two-way repeated-measures ANOVA and followed with post-hoc pairwise comparisons.

Results

Significant exercise-by-muscle interaction effect was found (p < .001). Short-to-long and sit-to-stand scaption elicited higher activity in supraspinatus and middle deltoid compared to other exercises (p < .05); however, no effect of muscle was found for these exercises (p > .05). Infraspinatus and lower trapezius demonstrated higher activity compared to other muscles during standing ER, sidelying ER, and sidelying horizontal adduction (p < .05).

Conclusion

Eccentric-focused exercises sufficiently activate the rotator cuff and is effective for use in rehabilitation. Caution must be taken as some exercises do not target specific musculature.

KEYWORDS:

• Eccentric exercise
• rotator cuff
• electromyography

Acknowledgments

The authors would like to gratefully acknowledge all participants who volunteered their time for this research study and Stephen J. Nicholas, MD, director of Nicholas Institute of Sports Medicine and Athletic Trauma, for his support of all research activities at the institute.

Disclosure Statement

The authors declare that there is no conflict of interest.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.