Determining subject specific torque parameters for use in a torque driven simulation model of dynamic jumping

This paper describes a method for defining the maximum torque which can be produced at a joint from isovelocity torque measurements on an individual. The method is applied to an elite male gymnast in order to calculate subject specific joint torque parameters for the knee joint. Isovelocity knee extension torque data were collected for the gymnast using a two repetition concentric-eccentric protocol over a 75◦ range of crank motion at preset crank angular velocities ranging from 20◦s-1 to 250◦s-1. During these isovelocity movements, differences of up to 35◦ were found between the angle of the dynamometer crank and the knee joint angle of the subject. In addition faster preset crank angular velocities gave smaller ranges of isovelocity motion for both the crank and joint. The simulation of an isovelocity movement at a joint angular velocity of 150◦s-1 showed that, for realistic series elastic component extensions, the angular velocity of the joint can be assumed to be the same as the angular velocity of the contractile component during the majority of the isovelocity trial. Fitting an 18 parameter exponential function to experimental isovelocity joint torque / angle / angular velocity data resulted in a surface which was well-behaved over the complete range of angular velocities and within the specified range of joint angles used to calculate the surface.