Study of the peroneus digiti quarti muscle length effect on a motor unit fractional multi-model

Skeletal muscle models have several applications. In medicine, they can improve the understanding of these organs, and if inverted they can also be used for muscle rehabilitation by functional electrical stimulation. Moreover they are also useful in bio-inspired robotic, because they allow to reproduce accurately natural motion. When they are used for robotic issue, they need to be compact and embeddable. Thus, a multi-model of muscle was identified and presented in previous papers. This model is able to predict the response of a motor unit to an electrical stimulation, considering isometric contractions (that is to say, muscle length is constant). In this paper, muscle length effect on the multi-model is studied and the limitations of the linear multi model are presented.