Abstract
Valid and reliable methods of assessing exposures to repetitive and forceful activities are needed to address the relationship between work tasks and the development of upper extremity musculoskeletal disorders. The utility of wrist-worn activity monitors for measuring exposure to repetitive activities in hand-intensive work was examined in this study. Twenty-two grocery cashiers and ten noncashier retail workers wore activity monitors on both wrists and the left ankle during their normal work activities. Work activities were periodically observed and recorded on videotape. Data recorded by the monitors were matched against observational data. The results indicated that the monitors were effective in detecting significant work-related variations in physical activity in the three limbs studied. Compared with traditional observational procedures, activity monitoring represents a cost-effective approach to obtaining objective and quantitative information about the frequency and intensity of manual work activities over long time periods. However, observation of job activities is required to provide additional information needed for a complete job analysis (e.g., to identify tasks associated with periods of increased activity). Continuous activity recordings can be used in conjunction with work sampling protocols to examine the relationship between work-related physical activities and musculoskeletal trauma.