Effects of Muscle Length and Physiological Cross Sectional Area on Muscle Force Production: a Comparative Study

Abstract

The estimation of muscular forces is useful in several areas such as biomedical or rehabilitation engineering. The analysis of the forces that produce a given movement (inverse dynamics, ID) or the movement induced by a set of muscle forces or activations (forward dynamics, FD) are typical problems that need the description of muscle mechanical properties. Moreover, to solve the indeterminacy problem in the ID analysis, optimization schemes are required. Several optimization methods (static optimization, dynamic optimization, augmented static optimization) and optimization criteria (minimum metabolical cost of transport, minimum sum of muscle stresses, time-integral cost of activations, torque-tracking) are available in the literature to that end. In all the aforementioned problems muscle properties, such as muscle length or physiological cross sectional area (PCSA), play a key role in the development of consistent models to perform specific tests. In this work, a comparative study of the effects on muscle force production in muscles with different ratios between length and PCSA is presented. Its relevance in the traditional problems faced in biomechanics is also studied.