  Musculoskeletal disorder (MSD) is one of the major health problems in
physical work especially in manual handling jobs. In several literatures,
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, in this paper, a new muscle
fatigue model was proposed. 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 realtime calculation, such
as the application in realtime virtual work simulation and evaluation. The new
model was mathematically validated with 24 existing static models by comparing
the calculated METs, and qualitatively or quantitatively validated with 3
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 risks of MSD.
