Figure 4.

Habitual patterns of trapezius muscle activity in the workplace. Representative activity of the dominant upper trapezius muscle is shown for 5-hour recordings obtained during a typical workday before (A) and immediately after (B) the 8-week multidisciplinary intervention. The root mean square (RMS) amplitude of the electromyographic signal was normalized to a submaximal reference voluntary contraction and plotted as a function of time. Habitual activity of the trapezius muscle during daily work activities was visibly reduced following the intervention.