A novel approach for determining fatigue resistances of different muscle groups in static cases

TL;DR

This paper introduces a theoretical maximum endurance time (MET) model for static muscle fatigue, validated against empirical models, and proposes a method to calculate fatigue resistance of muscle groups for ergonomic applications.

Contribution

A new theoretical MET model for static muscle fatigue is developed and validated, enabling efficient prediction and calculation of fatigue resistance across different muscle groups.

Findings

The extended MET model shows high correlation with 24 empirical models.

Mathematical regression effectively estimates fatigue resistance parameters.

The model facilitates population-level fatigue prediction in static tasks.

Abstract

In ergonomics and biomechanics, muscle fatigue models based on maximum endurance time (MET) models are often used to integrate fatigue effect into ergonomic and biomechanical application. However, due to the empirical principle of those MET models, the disadvantages of this method are: 1) the MET models cannot reveal the muscle physiology background very well; 2) there is no general formation for those MET models to predict MET. In this paper, a theoretical MET model is extended from a simple muscle fatigue model with consideration of the external load and maximum voluntary contraction in passive static exertion cases. The universal availability of the extended MET model is analyzed in comparison to 24 existing empirical MET models. Using mathematical regression method, 21 of the 24 MET models have intraclass correlations over 0.9, which means the extended MET model could replace the existing MET models in a general and computationally efficient way. In addition, an important parameter, fatigability (or fatigue resistance) of different muscle groups, could be calculated via the mathematical regression approach. Its mean value and its standard deviation are useful for predicting MET values of a given population during static operations. The possible reasons influencing the fatigue resistance were classified and discussed, and it is still a very challenging work to find out the quantitative relationship between the fatigue resistance and the influencing factors.