An evaluation of nonlinearities in the motor output response to applied torque perturbations in man.

Nonlinearities present in the motor output response of biceps and triceps muscles in normal human subjects to applied torque perturbations were evaluated quantitatively. When the applied perturbations were relatively continuous, consisting of a pseudo-random train of pulses, the identified nonlinearities were small, never exceeding 20% of the amplitude of the linear component of the response and usually being much less.