Changes in stiffness of the dorsal scapular muscles before and after computer work: a comparison between individuals with and without neck and shoulder complaints

The aim of this study was to compare the stiffness of the dorsal scapular muscles before and after computer work between individuals with and without neck and shoulder complaints. Thirty subjects were divided into patient (n = 18) and control (n = 12) groups. The stiffness of the upper trapezius, levator scapulae, and rhomboid major was measured using ultrasound elastography before and after a 30-min typing task. The strain ratio of the muscle to an acoustic coupler was calculated (a lower strain ratio value indicates greater muscle stiffness). At baseline, the strain ratio of the upper trapezius in the patient group (3.762 +/- 1.679) (mean +/- SD) was significantly lower than that of the control group (7.763 +/- 5.921) (p = 0.041). No significant change in the strain ratio of the upper trapezius after the typing task was observed in the patient group (4.158 +/- 3.465) (p = 0.549). A significant decrease in the strain ratio of the levator scapulae after the typing task was observed in the patient group (before: 9.006 +/- 7.079, after: 5.718 +/- 2.847) (p = 0.022), whereas there was no significant change in the control group (p = 0.436). The increase in stiffness of the upper trapezius is an objective finding and may be a persistently altered condition in individuals with neck and shoulder complaints. The patterns of change in stiffness of the levator scapulae are different between individuals with and without neck and shoulder complaints.