Influence of peripheral magnetic stimulation of soleus muscle on H and M waves

• Published in: Journal of Physical Therapy Science 2018, Vol.30 (5), p.716-718
• Main Authors: TADAMITSU MATSUDA, TAICHI KURAYAMA, MIKI TAGAMI, YUJI FUJINO, ATSUSHI MANJI, YASUAKI KUSUMOTO, KAZU AMIMOTO
• Format: Article
• Language: Japanese
• ISSN: 0915-5287

[Abstract.] [Purpose] This study evaluated the effects of repetitive peripheral magnetic stimulation of the soleus muscle on spinal cord and peripheral motor nerve excitability. [Subjects and Methods] Twelve healthy adults (mean age 22 years) who provided written informed consent were administered repetitive peripheral magnetic stimulation for 10 min. Pre-and post-stimulation latencies and amplitudes of H- and M-waves of the soleus muscle were measured using electromyography and compared using paired t-tests. [Results] Pre- and post-stimulation latencies (28.3 +- 3.3 vs. 29.1 +- 1.3 ms, respectively) and amplitudes (35.8 +- 1.3 vs. 35.8 +- 1.1 mV, respectively) of H-waves were similar. Pre-stimulation latencies of M-waves were significantly higher than post-stimulation latencies (6.1 +- 2.2 vs. 5.0 +- 0.9 ms, respectively), although pre- and post-stimulation amplitudes were similar (12.2 +- 1.4 vs. 12.2 +- 1.3 mV, respectively). Motor neuron excitability, based on the excitability of motor nerves and peripheral nerve action, was increased by M-waves following magnetic stimulation. [Conclusion] The lack of effect of magnetic stimulation on the amplitude and latency of the H-reflex suggests that magnetic stimulation did not activate sensory nerve synapses of α motor neurons in the spinal cord. However, because motor nerves were stimulated together with sensory nerves, the increased H-wave amplitude may have reflected changes in peripheral rather than in α motor nerves.