Experimental validation of a subject-specific maximum endurance time model

• Published in: Ergonomics Vol. 61; no. 6; pp. 806 - 817
• Main Authors: Liu, Bin, Ma, Liang, Chen, Chi, Zhang, Zhanwu
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis LLC 01.06.2018
• Subjects: Contraction; Design; Elbow; Elbow (anatomy); Exhaustion; Fatigue; Fatigue tests; Isometric; Mathematical models; Workers; fatigability; elbow flexion; Maximum endurance time (MET); Subject-specific MET model; physical fatigue
• ISSN: 0014-0139; 1366-5847; 1366-5847
• DOI: 10.1080/00140139.2017.1416180

This study aimed at experimentally validating a subject-specific maximum endurance time (MET) model. Thirty health participants (15 males and 15 females; Age: mean = 21.5 years, SD = 1.6 years) volunteered to conduct an isometric elbow flexion task until exhaustion. The endurance times of each participant were measured under relative exertion levels ranging from 30% MVC (Maximum Voluntary Contraction) to 70% MVC at 10% intervals. Assessment of the model showed that the intensity-endurance time relationship for each studied individual could be well fitted by the subject-specific MET model (R  > 0.89). The fatigue rates identified from the model fitting were normally distributed (Mean = 0.96 min , SD = 0.29 min ). In addition, the fatigue rates of the male group were significantly higher than the female group. The subject-specific MET model can be used to predict the MET for individual workers, and further support physical task design, based on the fatigability data of a targeted worker population. Practitioner Summary: Ergonomists have extensively used MET models in physical fatigue assessment and physical task design. A subject-specific MET model could be used to predict the MET at individual levels, and also to support work design for a target worker population, based on the fatigability data distribution obtained from sampled workers.