# Muscle Fatigue Analysis Using OpenSim

## TL;DR

This paper presents a method to analyze muscle fatigue during arbitrary motions using OpenSim, a digital human modeling platform, by developing a plug-in based on a muscle fatigue model and testing it on running data.

## Contribution

A novel plug-in for OpenSim that calculates muscle force decline over time during arbitrary motions, validated on a running scenario with detailed muscle fatigue analysis.

## Key findings

- Muscle force output declines to 60-70% after 10 minutes of running.
- Erector spinae muscle loses 39.2% of its maximal capability.
- Subject attributes influence fatigue levels and are discussed.

## Abstract

In this research, attempts are made to conduct concrete muscle fatigue analysis of arbitrary motions on OpenSim, a digital human modeling platform. A plug-in is written on the base of a muscle fatigue model, which makes it possible to calculate the decline of force-output capability of each muscle along time. The plug-in is tested on a three-dimensional, 29 degree-of-freedom human model. Motion data is obtained by motion capturing during an arbitrary running at a speed of 3.96 m/s. Ten muscles are selected for concrete analysis. As a result, the force-output capability of these muscles reduced to 60%-70% after 10 minutes' running, on a general basis. Erector spinae, which loses 39.2% of its maximal capability, is found to be more fatigue-exposed than the others. The influence of subject attributes (fatigability) is evaluated and discussed.