Time-dependent changes in the stiffness of the neck extensor muscles with prolonged sitting and the effect of exercise

Abstract

Background: Neck and shoulder exercises are recommended to improve Neck and Shoulder Pain (NSP). However, it is unclear why exercises for the neck and shoulder improve NSP, and methods for evaluating the effects of these exercises have not been clear. Objective: The purpose of this study was to investigate time-dependent changes in stiffness of the neck extensor muscles due to prolonged sitting and the effect of exercise. Methods: Twenty-five healthy adult women sat with their hands on a desk for 90 min looking at a computer screen and then performed neck and shoulder exercise. Shear wave velocities (SWV) of the neck extensor muscles (the upper trapezius, levator scapulae, rhomboid major, and splenius capitis muscles) were measured at 0, 30, 60, and 90 min after the start of sitting and after the exercise. At the same time, changes in NSP were recorded. Results: During prolonged sitting, SWV in the upper trapezius increased significantly with time (p < 0.001). Neck and shoulder exercise significantly decreased SWV and NSP (p < 0.001). Conclusions: The results of this study revealed objective changes in neck muscle stiffness by prolonged sitting. Neck and shoulder exercise may reduce muscle stiffness and contribute to relieve NSP.