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Date Permissions Signed


Date of Award

Spring 2015

Document Type

Masters Thesis

Degree Name

Master of Science (MS)


Health and Human Development

First Advisor

San Juan, Jun G.

Second Advisor

Suprak, David N. (David Nathan)

Third Advisor

Cunningham, Wren L.


The purpose of this study was to investigate the effects of a five-week EMG biofeedback intervention on scapular stabilizer muscle activation, and scapular kinematics, in a healthy population. Twenty males and females participated in the study (n = 10 exercise with biofeedback, n = 10 exercise only). Both groups participated in exercises targeted at activating the serratus anterior and lower trapezius muscles three days a week for five weeks. The exercise with biofeedback group completed a biofeedback session once a week. All subjects were tested at baseline (week 1), week 6, and week 8 for muscle activation of the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA), as well as scapular kinematics. Statistical analysis was performed using a three-way mixed analysis of variance, and demonstrated that there was no significance A three-way ANOVA revealed no significance for scapular posterior tilt (p = 0.212), upward rotation (p = 0.668), or external rotation (p = 0.880) for neither group. A three-way ANOVA revealed no significance with mean EMG amplitude (p = 0.249). Therefore the hypothesis was rejected. There was a trend toward increased scapular upward rotation for both groups, as well as a decrease in mean UT EMG amplitude for the exercise only group, although not statistically significant. Lowered UT activation is indicative of better musculature control, and could potentially lead to positive alterations in scapular kinematics, observed as increased upward rotation, external rotation, and posterior tilt). This is thought to lead to an increase in subacromial space, and in turn, lessen the risk of onset SIS. The results from this study could assist in the development of a preventative type of program for a healthy population that is at a heightened risk for developing SIS. There is little research investigating the optimal duration and frequency for a preventative type of program, and this protocol used in this study could be a good foundation for future research investigating viable preventative tools for the onset of SIS.





Western Washington University

OCLC Number


Subject – LCSH

Shoulder girdle; Shoulder joint--Range of motion; Biofeedback training; Shoulder joint--Rotator cuff--Wounds and injuries--Prevention; Biomechanics




masters theses




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