Morphological and physiological differences in the upper trapezius muscle in patients with work-related trapezius myalgia compared to healthy controls: A systematic review.

Background: Trapezius myalgia is a common musculoskeletal complaint, characterized by pain, stiffness and tightness of the upper trapezius muscle. It is often work-related and caused by prolonged static and repetitive work tasks. It is hypothesized that this leads to various morphological and physiological alterations in muscle tissue but the pathophysiology is poorly understood.