Modeling of maximum endurance time for one‐handed carrying tasks

Abstract

The objective of this study was to establish models to predict maximum endurance time (MET) for one-handed carrying tasks. A one-handed carrying experiment, under three loads and two walking speeds, was performed. The participant carried a dumbbell on the side using either dominant or nondominant hand. His or her arm was straight-down.The MET values were collected. Both power and exponential functions were adopted in establishing simplified MET models considering the relative force (f MVC ) applied. The simplified models were further expanded to full models where body weight and walking speed were also included. It was found that the power models provided better estimates than the exponential models when the f MVC was lower than approximately 0.17 for both the simplified and full models. Considering the effects of the walking speed, the full models are recommended when the f MVC is 0.3 or lower. K E Y W O R D S carrying strength, manual materials handling, maximum voluntary contraction, muscle fatigue, musculoskeletal disorder Hum. Factors Man. 2019;29:319-326. wileyonlinelibrary.com/journal/hfm

Strength Decrease, Perceived Physical Exertion and Endurance Time for Backpacking Tasks

“…The effects of walking speed on the MET were more prominent at low f MVC_back than were at a high one. This was consistent with the findings in the literature [35]. The MET model established in the current study may be used to determine the work/rest allowance for backpacking tasks similar to ours.…”

“…Establishment of MET models has been reported [14,19,25,26,27,28,29,30,31,32,33]. Model development involves establishing a mathematical function with the %MVC, or alternatively the relative force ( f MVC = %MVC/100), as independent variable [23,34,35,36,37].…”

“…However, most tasks involving static contractions for certain body segments in industry are accompanied by dynamic or cyclic activities of other body parts. Li et al [35] conducted a one-handed carrying study and established MET models considering body weight, walking speed, and f MVC . Their results indicated that both body weight and walking speed were important parameters in predicting the MET when walking was considered, especially when the f MVC was 0.3 or lower.…”

“…Muscular fatigue issues for one- and two-handed carrying tasks have been discussed [21,22,35]. Backpacking is also a common manual material handling tasks, being performed, for example, by school students [38], firefighters, polices, and military personnel [39].…”

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

“…The mean absolute deviation (MAD) has been adopted to estimate the fitness of the model in estimating the MET (Li, Peng, et al, 2019;. The MADs of the MET models in the current study and those in the literature are shown in Table 6.…”