  Human muscle fatigue is considered to be one of the main reasons for
Musculoskeletal Disorder (MSD). Recent models have been introduced to define
muscle fatigue for static postures. However, the main drawbacks of these models
are that the dynamic effect of the human and the external load are not taken
into account. In this paper, each human joint is assumed to be controlled by
two muscle groups to generate motions such as push/pull. The joint torques are
computed using Lagrange's formulation to evaluate the dynamic factors of the
muscle fatigue model. An experiment is defined to validate this assumption and
the result for one person confirms its feasibility. The evaluation of this
model can predict the fatigue and MSD risk in industry production quickly.
