Date of Award
Master of Physical Therapy (MPT)
Electromyography; Muscles -- physiology
Shoulder rehabilitation commonly overlooks the influence of scapular muscles in providing the stability necessary for the shoulder to function properly. When considering muscles acting on the scapulothoracic articulation, literature suggests that the lower trapezius is a key stabilizer of this articulation. Traditionally, the lower trapezius is exercised while the patient is in a prone position with the humerus abducted 1450 while performing forward elevation. Unfortunately, repeated overhead activity has been proven to increase the incidence of shoulder impingement. In an effort to avoid exercising the lower trapezius in a position that would compromise the shoulder complex, a modified position of 80° of abduction while performing prone external rotation was proposed.
Purpose: The purpose of this study was to determine whether the lower trapezius was more effectively recruited in the traditional or modified exercise position.
Methods: Ten subjects, both male and female, between the ages of21 and 24 years old, were tested. Electromyographical (EMG) data was collected from each subject's right lower trapezius muscle while he/she performed exercise in the traditional position without weight, the traditional position with weight, the modified position without weight, and the modified position with weight in random order.
Results: A significant difference was found in lower trapezius muscle activity when comparing exercise in the traditional position without the weight to exercise in the modified position without the weight. No significant difference was found in lower trapezius muscle activity when comparing exercise in the traditional position without weight to exercise in the modified position with weight and the traditional position with weight. There was also no significant difference in peak muscle activity across all four exercise conditions.
Conclusion: Exercise in the modified position with weight effectively recruits the lower trapezius and allows the patient to exercise in a position that does not compromise the shoulder complex.
Engelstad, Erika, "An electromyographic study of lower trapezius muscle activity during exercise in traditional and modified positions" (2000). Physical Therapy Scholarly Projects. 129.