Effect of load perturbations on EMG activity and trajectories of pointing movements

Force perturbations were applied to the upper arm during pointing movements to a target. Following the perturbation, the trajectories of shoulder and elbow angular velocities converged on those obtained during trials in which no perturbation was imposed, but with a temporal offset. Changes in EMG activity in shoulder and elbow flexors evoked by the perturbation were similar to those observed previously under quasi-static conditions, the change in a given muscle depending on shoulder and elbow motion.