There is evidence that precision work is associated with musculoskeletal disorders of the upper extremities, particularly the shoulders. A logical series of factorial experiments will show whether precision acts alone or interactively with other task factors to elicit musculoskeletal stress. It may not be possible to modify the precision demands of industrial work. However, understanding how more controllable factors, such as task layout or organizational factors interact with precision, will provide pointers as to which ergonomic interventions would best mitigate the impact of precision. The study will also provide simultaneous information about movement time and musculoskeletal stress. Several indices of musculoskeletal stress will be used including; muscle activation patterns, discomfort ratings, postural measures, and counts of the number of non-task related postural shifts. Indices of movement time will be determined from the coefficients found from fitting data on the time it takes to make movements to an equation; that breaks movement time into the time required to move particular distances, and the time required to close in on precision targets. Such information will show whether musculoskeletal stress and movement time are correlated, and whether they coexist or whether one precedes the other in time. Information about the - association of movement time with stress would give agronomists another tool to assess somatic fatigue or stress. The repeated measures experiments will last one to two hours and will provide information about whether the deleterious effects of precision accumulate with task duration, and whether those effects are different for different combinations of precision and task layout. In the early experiments, this would give predictors for when work should stop and when should begin. In the later experiments, that info-nation would provide a means to evaluate the effectiveness of work/ rest cycles.
