Modeling of maximum endurance time for static pulling tasks.

Background: Pallet truck pulling is one of the common manual materials handling tasks which could result in musculoskeletal injuries. The endurance time for sustained truck pulling tasks has been rarely discussed in the literature.

Objective: The objectives of this study were to measure the muscular fatigue after performing a pulling task and to establish models to predict the maximum endurance time for truck pulling tasks.

Methods: A simulated truck pulling experiment was conducted. Ten human participants were recruited. The participants pulled a handle simulating that of a pallet truck under two loading conditions until they could not pull any longer.

Results: The results indicated that hand/wrist and elbow had higher subjective ratings of muscular fatigue than the other body segments. A subjective rating of 5 or more was found on at least two of the body segments for all trials except one. An exponential model and a power model were established to predict the maximum endurance time of the pulling tasks.

Conclusion: Hand/wrist and elbow were the body segments most likely to suffer muscular fatigue for the simulated truck pulling tasks. The endurance time models established may be adopted in job designs for one-handed truck pulling tasks.