Maximum endurance time modeling for push and pull tasks considering gender and handle height

Abstract

The strengths of both push and pull using both hands at handle heights of 75, 90, and 135 cm were measured for 11 female and 8 male participants. In addition, simulated push and pull tasks were performed on one of the three heights as in the strength measurements. In these tasks, the participants either pushed or pulled a swing suspended with one of the two loads (32.5 and 42.5 kg) until they could no longer do so. Then, the strength of push or pull was measured again. The participants also reported bodily discomfort on their body parts on a CR-10 rating scale. It was found that hands and leading leg had the highest CR-10 scores among the body parts and were the bottleneck body parts for the push and pull tasks, respectively. Models of maximum endurance time incorporating gender and handle height, in addition to force ratio, were developed. These models may be adopted in predicting the endurance time in job design concerning work/rest arrangement.

Fatigue and Recovery of Muscles for Pulling Tasks

“…In the current study, the participants grabbed the handle and pulled and walked on a treadmill. The only difference between the static pulling task in the literature [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ] and our study was that the participants in our study needed to walk. The participants might need more effort to pull and walk than those in the static pulling tasks.…”

“…In the literature, the MET models were often established using the relative load f MVC ( f MVC = forceful exertion/ MVC ) or %MVC ( %MVC = f MVC × 100) as the independent variable [ 21 , 39 , 49 , 50 ]. In dynamic force exertion tasks, such as carrying and pulling tasks, the development of muscle fatigue was usually evaluated by walking velocity, f MVC , and BMI [ 27 , 45 , 50 , 51 ].…”

“…A summary of existing static MET models revealed [ 21 , 39 , 49 , 50 ] that exponential and power functions have been adopted to fit the MET – f MVC relation. Similar to those MET models in the literature [ 21 , 39 , 49 , 50 ], the MET for pulling tasks may be fitted using these two mathematic functions: …”

“…Pulling tasks involving both static [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ] and dynamic [ 13 , 23 , 24 , 25 , 26 , 27 ] postures have been reported. The difference between those two approaches was whether the participants needed to walk when they were pulling.…”

“…The development of muscle fatigue for pulling tasks was generally assessed by measuring the pull force, electromyography (EMG) signal of muscle groups, joint stress, or maximum endurance time ( MET ). The MET models are often constructed to predict the maximum time an operator can persist at a worksite [ 19 , 20 , 21 , 27 ]. They provide a way to determine the work allowance for workers.…”