The Importance of Biarticular Torque Generators in Torque-Driven Simulation Models

Forward-dynamics computer simulation models of human movement are typically driven by individual muscle models, or torque generators. In muscle-driven models, muscle parameters are typically determined from experimental data in the literature. While in torque-driven models, subject-specific torque parameters can be determined from torque measurements collected on an isovelocity dynamometer. Such a method avoids some of the errors encountered with individual muscle models by determining strength parameters directly from torque measurements. The disadvantage of existing subject-specific torque generator models over individual muscle models has been that the torque exerted at a joint has been represented by a function of the kinematics of the primary joint. As such torque generator models may not accurately represent the torques exerted by biarticular muscles where the kinematics of a primary and secondary joint may be important.