A Hill-Type Submaximally-Activated Musculotendon Model and Its Simulation

Hill-type models are ubiquitous in biomechanical simulations because of their computational simplicity and efficiency. But these models are designed to describe the maximally activated muscles and muscle properties are linearly scaled when they are applied to sub maximally activated conditions. This scaling approach should be based on the independence of muscle activation and force-length properties, which has not been proven yet. Actually, muscles in vivo are unlikely to be often maximally activated during daily life. Therefore, effective methods should be taken to modify the existing Hill-type model to insure the accuracy of their applications. This paper analyzed the sub maximal activation conditions, developed a sub maximally-activated musculotendon model on the basis of Millard damped equilibrium model and implemented the benchmark experiments to verify effectiveness of the modified model.