Title | Shoulder musculature activation during upper extremity weight-bearing exercise. |
Publication Type | Journal Article |
Year of Publication | 2003 |
Authors | Uhl TL, Carver TJ, Mattacola CG, Mair SD, Nitz AJ |
Journal | J Orthop Sports Phys Ther |
Volume | 33 |
Issue | 3 |
Pagination | 109-17 |
Date Published | 2003 Mar |
ISSN | 0190-6011 |
Keywords | Adult, Analysis of Variance, Arm, Electromyography, Exercise, Humans, Isometric Contraction, Muscle, Skeletal, Posture, Rotator Cuff, Shoulder Joint, Weight-Bearing |
Abstract | STUDY DESIGN: Repeated-measures design comparing 7 static weight-bearing shoulder exercises. OBJECTIVE: The purpose of this study was to determine the demand on shoulder musculature during weight-bearing exercises and the relationship between increasing weight-bearing posture and shoulder muscle activation. BACKGROUND: Weight-bearing shoulder exercises are commonly prescribed in the rehabilitation of shoulder injuries. Limited information is available as to the demands placed on shoulder musculature while these exercises are performed. METHODS: Eighteen healthy college students volunteered for this study. Surface bipolar electrodes were applied over the infraspinatus, posterior deltoid, anterior deltoid, and pectoralis major muscles. Fine-wire bipolar intramuscular electrodes were inserted into the supraspinatus muscle. Electromyographic (EMG) root mean square signal intensity was normalized to 1 second of EMG obtained with a maximal voluntary isometric contraction (MVIC). Subjects were tested under 7 isometric exercise positions that progressively increased upper extremity weight-bearing posture. RESULTS: There was a high correlation between increasing weight-bearing posture and muscular activity (r = 0.97, P < 0.01). There was relatively little demand on the shoulder musculature for the prayer and quadruped positions (2%-10% MVIC). Muscular activation was greater for the infraspinatus than for other shoulder muscles throughout most of the exercise positions tested. CONCLUSION: These results indicate that alterations of weight-bearing exercises, by varying the amount of arm support and force, resulted in very different demands on the shoulder musculature. Specifically, the infraspinatus was particularly active during the weight-bearing exercises used in this study. |
DOI | 10.2519/jospt.2003.33.3.109 |
Alternate Journal | J Orthop Sports Phys Ther |
PubMed ID | 12683686 |