Isokinetic elbow flexion and coactivation following eccentric training

Abstract

The influence of an eccentric training on torque/angular velocity relationships and coactivation level during maximal voluntary isokinetic elbow flexion was examined. Seventeen subjects divided into two groups (Eccentric Group EG, n=9 Control Group CG, n=8) performed on an isokinetic dynamometer, before and after training, maximal isokinetic elbow flexions at eight angular velocities (from −120° s −1 under eccentric conditions to 240° s −1 under concentric conditions), and held maximal and submaximal isometric actions. Under all conditions, the myoelectric activities (EMG) of the biceps and the triceps brachii muscles were recorded and quantified as the RMS value. Eccentric training of the EG consisted of 5x6 eccentric muscle actions at 100 and 120% of one maximal repetition (1RM) for 21 sessions and lasted 7 weeks. In the EG after training, torque was significantly increased at all angular velocities tested (ranging from 11.4% at 30° s −1 to 45.5% at −120° s −1) ( p<0.05). These changes were accompanied by an increase in the RMS activities of the BB muscle under eccentric conditions (from −120 to −30° s −1) and at the highest concentric angular velocities (180 and 240° s −1) ( p<0.05). The RMS activity of the TB muscle was not affected by the angular velocity in either group for all action modes. The influence of eccentric training on the torque gains under eccentric conditions and for the highest velocities was attributed essentially to neural adaptations.