Active behavior of skeletal muscle and modeling sarcopenia with a mixture active strain approach based constitutive model

Abstract

Different continuum hyperelastic constitutive models for the contraction of the skeletal muscle exist in literature. In this work, we compare the models developed by Ehret et al (2011) and Riccobelli and Ambrosi (2019). We follow the mixture active strain approach of the latter but employ the strain energy density functions proposed by the former for modeling the contraction. The model excellently recovers the experimental stress–stretch data of a passive and activated rat tibialis anterior muscle. The model is further improved by introducing a decay deformation tensor into the multiplicative decomposition of the deformation gradient, which helps model the geriatric syndrome called sarcopenia. This improved model accurately reproduces the experimental stress–stretch data of passive and activated human type II vastus lateralis muscle fibers of both younger and older adults and suggests that changes in all muscle parameters are responsible for explaining sarcopenia.