The organisation of a simple voluntary movement as analysed from its kinematic properties

Abstract

The object of the study was to ascertain from the kinematic tracings, the extent to which the strategy of movement was influenced by the verbal instructions which the subject received. Results showed that the kinematics of the movement are determined solely by the instructions given to the subject. Of these, the critical instruction appears to be that of speed. Once chosen, the speed appears to predetermine the initial component of the acceleration curve. Furthermore, the mutual interdependence between the various components of this curve suggests a fine coordination of agonist and antagonist forces, as confirmed by the EMG tracings of these muscles. Finally, the correspondence of the movement performed with the instructions given to the subject, independently of the inertia condition obtained, suggests that the neuromuscular system functions as an adaptive system.