Equipment for the quantification of motor performance for clinical purposes.

An apparatus is described for the quantitative assessment of important parameters that characterise motor performance in normal subjects and in patients with different types of motor disorders. The apparatus has a handle that can be moved along a straight horizontal track either by the subject (to study voluntary movements) or by a torque motor (to study reflex activity). During voluntary movements the mass and friction of the mechanical part of the equipment are eliminated by feedback of the force exerted at the handle by the subject. The computer program that controls the apparatus gives a choice of four different tests that characterise different aspects of the motor system: the reflex organisation, the regulation of viscoelastic properties mediated in part by reflex activity, the control of fast goal-directed movements, and the performance in a tracking task. The results of a pilot study to the tracking behaviour of clumsy children show that the group of clumsy children differs from a group of normal children in the latency of the tracking response, in the ability to track high-frequency components and in the fact that clumsy children introduce relatively more frequency components in the response that are not present in the tracking signal.