Differences in trapezius muscle activation patterns in office workers with and without chronic neck-shoulder pain,as quantified through exposure variation analysis

The purpose of this study was to quantify upper-trapezius muscle activation patterns using exposure variation analysis (EVA) in healthy computer workers and those with chronic neck-shoulder pain. Eight healthy and five chronic pain participants were asked to complete three computer-based tasks (TYPE, CLICK, and FORM) in two pacing conditions (self-paced and control-paced). EVA was used to quantify variation using five amplitude classes and five duration classes. Performance in each task was also quantified. Healthy workers and those with chronic pain did not differ in performance, and they both exhibited similarly low levels of muscle activation amplitude. Pain participants, however, were found to spend less time in lower duration classes across tasks and conditions. These results indicate that individuals with chronic neck-shoulder pain utilize movement strategies involving sustained durations of continuous muscle activation. This may be suggestive of decreased temporal variation in muscle activation patterns in those with chronic pain.