INFLUENCE OF THE PARAMETERS OF A HUMAN TRICEPS SURAE MUSCLE MODEL ON THE ISOMETRIC TORQUE-ANGLE RELATIONSHIP

This study investigates the influence of parameter values of the human triceps surae muscle on the torque-angle relationship. The model used consisted of three units, each containing a contractile, a series ela stic and a parallel elastic element. Parameter values were based on mo rphological characteristics, which made it possible to model individua l units. However, for a number of parameters the values reported in th e literature vary considerably. It was investigated how sensitive mode l results were for variation of these parameters. Slack length of the series elastic element, mean moment arm, maximum force, and length of the contractile element appeared to be the most important determinants of the behavior. For mean moment arm and contractile element length, morphology-based methods of estimation could be recommended. Slack len gth and maximum force were obtained through optimization. It was concl uded that the model does not contain parameters on which its output de pends strongly and which are difficult to estimate as well, with two e xceptions: slack length of the series elastic element and maximum forc e.