This study extends the concept of tension, in part by observing changes in tension during the workday, to identify episodes causing elevated tension and relate them to bodily responses. Methods Both questionnaires and qualitative interviews were used to describe the tension concept. Tension was scored on a visual analogue scale (VAS) every hour, and trapezius muscle activity and heart rate were recorded. Ninety-four female workers from four service occupations participated.
Results: Tension was described as a musculoskeletal activation response involving the upper body regions, but also autonomic activation responses were described. The cause of elevated tension comprised a variety of situational demands; however, contact with other people causing negative emotions was a common factor. Averaged muscular activity and heart rate responses did not correlate with prolonged perceived tension, but the differential tension score between high- and low-tension periods correlated with the corresponding differential trapezius activity responses. The regression line indicated no effect of short-term variation in perceived tension on median muscle activity for differential VAS scores of < or = 2 cm. An increase of 2% of maximal electromyographic activity for a differential VAS score of 4-5 cm was indicated.
Conclusions: This study identifies work exposures that cause tension, and it demonstrates a physiological correlate with the subjective perception of tension in the short term. The low recorded muscle activationresponse does not represent a risk factor for pain by the traditional standards used for recording and evaluating muscle activity responses, but it may point to underlying pain-inducing mechanisms, such as low-threshold overexertion of motor units.