When a client's arms fall forward during the Overhead Squat Assessment, NASM identifies this as an indication of overactive/shortened muscles (e.g., latissimus dorsi, pectoralis major/minor, teres major) and underactive/lengthened muscles such as the lower trapezius, middle trapezius, rhomboids, and rotator cuff.
The lower trapezius plays a critical role in scapular depression and upward rotation, helping keep the arms aligned overhead. Weakness in this muscle allows the scapulae to tip forward, contributing to the observed compensation. Strengthening the lower trapezius improves shoulder stability and posture during overhead movements. This is supported in NASM's corrective exercise strategies for the shoulder complex in the movement assessments section.