Determining Endurance Limit Under Intermittent Physical Operations Based on a Combined Fatigue-Recovery Model.

Intermittent physical tasks are prevalent in physical manual operations, and engineers must be provided with effective guidelines for intermittent job design to reduce work-related musculoskeletal disorders (WMSDs) resulting from repetitive intermittent operations. In this paper, we combine a local muscle fatigue and a recovery model to determine the endurance limit under intermittent operations. We preliminarily validated the endurance limit model by comparing the predicted endurance limits and the endurance limits measured in a 50% MVC intermittent task. The endurance limit under intermittent isometric operations could be determined using a muscle fatigue-recovery model and individual fatigue attributes. Estimation of the WMSD risk associated with spectrum loadings in a series of intermittent tasks using the proposed endurance limit model is a promising approach.