Objective: The purpose of this study was to compare the behavior of the trapezius muscle in patients with chronic mechanical neck pain (MNP) and clinical signs of scapula dysfunction to healthy controls.
Methods: This is a cross-sectional, between-participant study of trapezius muscle behavior. Eighteen volunteers with chronic MNP and 20 healthy controls participated in the study. Participants performed isometric shoulder abduction, external rotation, and flexion at 3 intensities of effort (maximum voluntary contraction [MVC], 50% MVC, and 20% MVC). Electromyographic signals were recorded unilaterally from the upper, middle, and lower portions of the trapezius muscle during isometric shoulder contractions.
Results: Significantly greater levels of lower trapezius electromyographic signals were observed in patients with MNP compared with controls for the abduction (P < .027) and external rotation (P < .036) conditions but not for the flexion condition (P > .392). No differences in activity were observed in the upper (P > .248) or middle (P > .052) portions of trapezius between groups during any of the isometric shoulder girdle conditions.
Conclusions: These findings represent a change in the behavior of the lower trapezius muscle in individuals with MNP who exhibit clinical signs of scapular dysfunction. Clinicians should consider the potential involvement of the axioscapular muscles when assessing patients with chronic neck pain, as retraining scapular function may be required for the successful management of these patients.
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