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

• Published in: Journal of Physical Therapy Science Vol. 30; no. 5; pp. 716 - 718
• Main Authors: Matsuda, Tadamitsu, Kurayama, Taichi, Tagami, Miki, Fujino, Yuji, Manji, Atsushi, Kusumoto, Yasuaki, Amimoto, Kazu
• Format: Journal Article
• Language: English
• Published: Japan The Society of Physical Therapy Science 01.01.2018; Japan Science and Technology Agency
• Subjects: H wave; M wave; Original; Repetitive peripheral magnetic stimulation; Spinal cord; H wave; Repetitive peripheral magnetic stimulation; M wave
• ISSN: 0915-5287; 2187-5626
• DOI: 10.1589/jpts.30.716

[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.