NEUROMUSCULAR CONTROL FOLLOWING MAXIMAL ECCENTRIC EXERCISE

Kinematic and electromyographic (EMG) analysis of a target-directed, m aximal velocity movement was used to investigate the effects of high-f orce eccentric exercise on the neuromuscular control of elbow flexion. Ten non-weight-trained females [19.6 (1.6) years old] performed 50 ma ximal velocity elbow flexion movements from 0 to 1.58 rad (90 degrees) , as rapidly as possible in response to a light stimulus, while kinema tic and triphasic EMG parameters were measured. This was done three ti mes pre-exercise, immediately and 1, 2, 3, 3, and 5 days following the 50 maximal eccentric elbow flexion actions. The eccentric exercise ca used lengthening of kinematic parameters including total movement time and time to peak velocity. The EMG elements of the biceps brachii (b. ) motor time, time to peak EMG, biceps b. burst duration, and the late ncy period between biceps b. and triceps b. bursts were lengthened pos texercise. These changes persisted for up to 5 days postexercise. The exercise also caused a large increase in serum creatine kinase (CK) ac tivity. It was concluded that high-force eccentric exercise in this po pulation caused prolonged changes in neuromuscular control that were a function of exercise-induced disruption of the skeletal muscle. Compe nsation in the central motor program was such that the components of t he triphasic EMG pattern were systematically lengthened.