A new simple dynamic muscle fatigue model and its validation

Musculoskeletal disorder (MSD) is one of the major health problems that are related to physical labor especially in jobs requiring manual work. In some literature, muscle fatigue is considered to be closely related to MSD, especially for muscle related disorders. In addition to many existing analysis techniques for muscle fatigue assessment and MSD risk analysis, this paper proposes a new muscle fatigue model. The new proposed model reflects the influence of external load, workload history, and individual differences. This model is simple in mathematics and can be easily applied in real time calculation, such as the application in real time virtual work simulation and evaluation. The new model was mathematically validated with 24 existing static models by comparing the calculated METs (Maximum Endurance Times), and qualitatively or quantitatively validated with three existing dynamic models. The proposed model shows high or moderate similarities in predicting the METs with all the 24 static models. Validation results with the three dynamic models were also promising. The main limitation of the model is that it still lacks experimental validation for more dynamic situations. Relevance to industry: Muscle fatigue is one of the main reasons causing MSDs in industry, especially for physical work. Correct evaluation of muscle fatigue is necessary to determine work-rest regimens and reduce the risk of MSD. (c) 2008 Elsevier B.V. All rights reserved.