CONSTANT-VELOCITY CONTRACTIONS IN SKELETAL-MUSCLE BY SEQUENTIAL STIMULATION OF MUSCLE EFFERENTS

Experiments are described that quantify the relationship between the contraction velocity, the recruitment of motor units and the electrical activity in the medial gastrocnemius muscle of the cat. The results of these experiments showed that, with differing degrees of activation, the force/velocity relationship closely followed that described by Hill. The electrical activity in the muscle was directly related to recruitment and was also linearly related to the load at any constant velocity of contraction. With progressively higher velocities of contraction, however, for any given load, the electrical activity was also increased. From the above database a computer program and the associated hardware were developed to stimulate muscle and cause it to maintain constant velocity contractions irrespective of the load imposed on the muscle. The applications of this type of stimulation to the restoration of mobility to the paralysed are discussed. © 1979 IFMBE.