Is peak exposure to computer use a risk factor for neck and upper-extremity symptoms?

OBJECTIVES Epidemiologic studies on physical exposure during computer use have mainly focused on average exposure duration. In this study, we aimed to relate periods of high peak exposure during computer use with the occurrence of neck-shoulder (NS) and arm-wrist-hand (AWH) symptoms. METHODS A prospective cohort study among 1951 office workers was carried out for two years, with periodical questionnaires and continuous measurements of computer input use. To define peak exposure, a distinction was made between peak days and weeks. Peak days were defined as days with a long duration of computer (ie, ≥4 hours) or mouse use (ie, ≥2.5 hours) or days with high frequency of mouse (ie, ≥20 clicks per minute) or keyboard use (ie, ≥160 keystrokes per minute). Weeks containing ≥3 peak days were considered peak weeks. Independent variables were numbers of peak days and peak weeks during a 3-month measurement period; dependent variables were self-reported NS and AWH symptoms during the following 3-month measurement period. RESULTS Valid data were available for 2116 measurements of 774 office workers. No relation was found between any of the peak exposure parameters and AWH symptoms or with peak exposure in duration and NS symptoms. Most parameters referring to high frequency-related peak exposure were associated with less NS symptoms, but the effect estimates were very small and the confidence intervals close to the null. CONCLUSION In this study, we found no indication that high peaks in computer use were related to the occurrence of NS or AWH symptoms.