The effect of overcommitment and reward on muscle activity, posture, and forces in the arm-hand-wrist region - a field study among computer workers

Objective Office workers with high levels of over commitment and low levels of reward are thought to be more prone to arm-wrist-hand symptoms, possibly through a higher internal physical exposure. The aim of this study was to examine the effects of high over commitment and low reward on (i) forearm muscle activity, (ii) wrist posture and kinematics, and (iii) forces applied to computer input devices during computer work in an actual work setting. Methods We continuously measured wrist extensor muscle activity, wrist posture and kinematics, and forces applied to the keyboard and mouse for two hours during the daily work of 120 office workers with four different levels of over commitment and reward (low-high, high-high, low-low, and high-low). Results Wrist velocities and accelerations in radialulnar direction were higher for workers with high compared to low over commitment, while their wrist range of motion was similar, possibly indicating a higher work pace. Wrist extensor muscle activity and forces applied to the keyboard and mouse were not increased by high over commitment and/or low reward. Conclusion Overall, our findings provide little support for the proposed pathway of high over commitment and low reward in the development of arm-wrist-hand symptoms through a higher internal physical exposure.