Maximum acceptable work time for the upper limbs tasks and lower limbs tasks. Workload limits

Introduction: The physical workload is a major occupational risk factor for workers. Currently the used methods to assess physical dynamic workload evaluate working with the whole body and do not discriminate the load of the body segments. Objective: Determine the maximum acceptable dynamic work time when the work is involves the whole body, the upper limbs and the lower limbs. Methods: Oxygen consumption measurement by ergospirometry and heart rate were monitored in 30 workers exposed to various loads executed with the whole body, legs and upper limbs. Anaerobic threshold was determined by respiratory quotient. This was used to calculate the acceptable dynamic work time. Results: Statistically significant differences were found between acceptable dynamic work time for upper limbs and lower limbs. Negative exponential correlation was found between the workload time, oxygen consumption and heart rate, so we found that R > 0.9 in all cases. We propose six regression equations to determine the acceptable dynamic work time. Conclusions: The acceptable dynamic work time for lower limbs and whole body is similar. The acceptable dynamic work time for upper limbs was significantly lower than acceptable dynamic whole body work time. The relative heart rate seems to be the best indicator to measure acceptable dynamic work time.