A method for developing biomechanical profiles of hand-intensive tasks

Objective. To develop a methodology for generic, comprehensive biomechanical profiling of hand-intensive tasks. Design. Based on a multifactorial model of work-related musculoskeletal disorder development, a method was developed for continuous, simultaneous measurement of relevant variables (wrist and finger joint position, force, muscle activity, and carpal tunnel pressure). Joint dynamics and tendon travel were derived. Background. Few generic dose-response relationships have been identified for work-related musculoskeletal disorders. This may improve if methodologies are developed that quantify multiple factors along several dimensions (means, cumulative exposure, etc.). This requires continuous, simultaneous measurements, and facilitates examination of interactions. Methods. Five touch-typists were instrumented to quantify their biomechanical profiles using the methodology, and to evaluate the sensitivity of the method to various work organization/design conditions. Results. The method captured individual and group responses to design conditions and revealed interactions and trade-offs between response variables. Carpal tunnel pressure was found to be sensitive to radial-ulnar wrist posture. Conclusions. Multi-variable biomechanical profiling can provide insight into effects of work design on workers; however, to achieve statistical significance large numbers of subjects are needed.