Dynamic model of muscle fatigue and recovery considering the roles of slow-twitch and fast-twitch muscles (Validation with a pulling motion)

Abstract

The present paper proposes a new model of muscle fatigue and recovery considering the roles of slow twitch (ST) and fast twitch (FT) muscle fibers. The proposed model can predict the variation in the degree of muscle fatigue because it considers the properties of muscle fatigue and recovery, which have been neglected in previous models. The aim of the present study was to predict not only the progression of muscle fatigue under maximum voluntary contraction (MVC) but also the endurance time for a force maintenance task and the variation in the output force achieved during MVC with regular intervals of rest. To validate the proposed model, a case study were conducted. The parameters of the proposed model, which depend on the anatomical properties of the individual, were determined from the measured variation in the output force under MVC. The endurance time for a force maintenance task with an arbitrary output force and the variation of the output force during MVC with intervals of rest were measured in the case study and compared with those predicted using the proposed model and a previously developed model that does not consider the roles of ST and FT fibers. In the case study, the proposed model showed good agreement with the measurement results and achieved better accuracy than the previous model. Therefore, the proposed model can be applied in cases with a low output force or intervals of rest, which are beyond the scope of the previous model.