LOAD PATTERN AND PRESSURE PAIN THRESHOLD IN THE UPPER TRAPEZIUS MUSCLE AND PSYCHOSOCIAL FACTORS IN MEDICAL SECRETARIES WITH AND WITHOUT SHOULDER NECK DISORDERS/

Object: A current hypothesis for the genesis of muscular complaints in the shoulder/neck region postulates that short periods with a complet ely relaxed muscle are essential to avoid complaints. Another hypothes is is that these disorders are related to psychosocial conditions at w ork. In order to test these hypotheses, 23 medical secretaries were in vestigated. Methods: The load pattern during work in the upper trapezi us muscle bilaterally was assessed with electromyographic (EMG) techni que and exposure variation analysis (EVA). In addition, pressure pain threshold (PPT) was measured on the trapezius muscle bilaterally and o n the sternum. Psychosocial conditions at work were assessed with a qu estionnaire. Results: The medical secretaries with complaints had sign ificantly fewer episodes with totally or close to totally relaxed musc le compared with the healthy group. The group with complaints tended t o have a more monotonous load pattern at low load levels (approx. 1%-5 % maximum voluntary contraction) while the healthy group had more freq uent pauses but also somewhat more frequent short load peaks. The grou p with complaints showed lower PPT readings compared with the healthy group. However, the whole group had considerably lower PPTs than is us ually reported in the literature. Of the 12 questions in the psychosoc ial questionnaire only one regarding work task satisfaction showed a s ignificant difference between the two groups. Conclusion: Support is f ound for the hypothesis that secretaries without complaints have more frequent episodes with totally relaxed muscle. A significant differenc e is found regarding work task satisfaction.