Can a rheological muscle model predict force depression/enhancement?
A new phenomenological model of activated muscle is presented. The model is based on a combination of a contractile element, an elastic element that engages upon activation, a linear dashpot and a linear spring. Analytical solutions for a few selected experiments are provided. This model is able to reproduce the response of cat soleus muscle to ramp shortening and stretching and, unlike standard Hill-type models, computations are stable on the descending limb of the force-length relation and force enhancement (depression) following stretching (shortening) is predicted correctly. In its linear version, the model is consistent with a linear force-velocity law, which in this model is a consequence rather than a fundamental characteristic of the material. Results show that the mechanical response of activated muscle can be mimicked by a viscoelastic system. Conceptual differences between this model and standard Hill-type models are analyzed and the advantages of the present model are discussed.
Forcinito
M
M
Department of Mechanical Engineering, The University of Calgary, Alberta, Canada.
Epstein
M
M
Herzog
W
W
D000465:Algorithms; D000818:Animals; D002415:Cats; D004548:Elasticity; D005544:Forecasting; D007537:Isometric Contraction / Q000502:physiology*; D016014:Linear Models; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure; D009126:Muscle Relaxation / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D012212:Rheology; D013314:Stress, Mechanical; D013997:Time Factors; D014783:Viscosity