Trapezius muscle activity, neck and shoulder pain, and subjective experiences during monotonous work in women.

The electromyographic (EMG) activity patterns of 18 female supermarket employees reporting neck and shoulder pain were compared with those of 6 of their female colleagues reporting no pain when doing cash-register work. It was found that the EMG activity of the trapezius muscle tended to show a lack of low and high levels among pain subjects, and that the time the trapezius muscle was at rest was longer in the group reporting no pain. In the non-dominant side, the muscle rest time was significantly longer (P < 0.05) in the group reporting no pain, and this group also showed a larger EMG activity difference between the dominant and non-dominant sides, indicating a less static bilateral muscle activation. Self-reports of negative experiences (stressed, exhausted and tense) were somewhat higher in the group reporting pain, while positive experiences during work (concentrated, stimulated and happy) appeared to be similar in the two groups of supermarket employees.