The apparent thixotropic properties of limb motion in totally relaxed subjects

Continuing work with the leg drop pendulum test under general anesthesia reports that the nonlinear model presented last year (2001) for limbs with spasticity is equally accurate in normal limb. The nonlinearities included powers of position and velocity respectively in stiffness and damping terms. An additional damping term, based on the inverse product of velocity and acceleration brings the limb model to rest in a more accurate fashion. This paper also demonstrates that the further addition of an initial limit on the acceleration, using the jerk, provides further improvements in the model. The paper speculates on the nature of these two additional terms