We found that the upper trapezius was activated more during the wall slide and scapular plane shoulder elevation exercises than during the push-up plus against the wall.
This could be because the wall slide and scapular plane shoulder elevation exercises require scapular elevation for proper performance, with the upper trapezius being a primary agonist for this motion.
Others have hypothesized that excess upper trapezius activity is unfavorable because it has been linked to abnormal scapular kinematics in patients with shoulder impingement syndromes, and it has been viewed as a compensatory strategy for moving the scapula in the presence of weak serratus anterior activation.
We find it important to note that some amount of upper trapezius activity is expected and is desirable because the upper trapezius works synergistically with the serratus anterior to provide the necessary upward rotation and elevation of the scapula during humeral elevation.
During rehabilitation of patients with shoulder impingement syndromes, the challenge may therefore be to discourage compensatory or exaggerated shoulder shrugging types of movements while still encouraging adequate scapular elevation and upward rotation during the performance of overhead activities.