Excitability changes of corticospinal pathways by magnetic brain stimulation during the maximum voluntary muscle contraction

A previous study reported that only three single TMS with the maximum voluntary muscle contraction (MVC) to patients with weakness of thigh muscles transiently, but significantly increased muscle strength compared with TMS with muscle relaxation^ . Nevertheless, the effects of TMS with MVC have never been established, and its mechanism is still unknown. In a preliminary study, we reported the modified protocol of TMS with MVC to induce more prolonged and robust effects on motor neuron function. This result has been reported previously in International Conference on Complex Medical engineering (CME2007) at Beijing and Annual meeting of Japanese Society of Clinical Neurophysiology in 2007. In the present study, we evaluated the effects of magnetic brainstem stimulation at the foramen magnum level during MVC on motor evoked potentials (MEPs) and muscle force, attempting to elucidate the mechanism of TMS with MVC modulating motor neuron function.