Modulatory effect of repetitive peripheral magnetic stimulation on skeletal muscle tone in healthy subjects: stabilization of the elbow joint.

To investigate the role of repetitive peripheral magnetic stimulation (RPMS) on the postural component of motor performances, the long-lasting modulatory effect of RPMS on the stabilization of the elbow joint was examined in 13 healthy subjects. The resistance against very slow passive movements in the relaxed state was recorded simultaneously with the electromyogram (EMG) of the forearm extensor and flexor muscles. The experiments show that RPMS performed on the forearm flexor muscles increased the degree of stabilization of the elbow joint, whereas RPMS on the forearm extensor muscles caused a decrease in stabilization. This leads to the assumption that the postural component of motor tasks depends on the motor task itself: motor tasks like manipulation, pointing or grasping which are fine skilled movements require an increase in stabilization while goal-directed movements require a decrease in stabilization. Therefore RPMS is involved in sensorimotor integration and may modulate the motor program at the cortical level.