Acute effects of high-frequency microfocal vibratory stimulation on the H reflex of the soleus muscle. A double-blind study in healthy subjects

This study in healthy subjects examined the effects of a system delivering focal microvibrations at high frequency (Equistasi (R)) on tonic vibration stimulus (TVS)-induced inhibition of the soleus muscle H reflex. High-frequency microvibrations significantly increased the inhibitory effect of TVS on the H reflex for up to three minutes. Moreover, Equistasi (R) also significantly reduced alpha-motoneuron excitability, as indicated by the changes in the ratio between the maximum-amplitude H reflex (Hmax reflex) and the maximum-amplitude muscle response (Mmax response); this effect was due to reduction of the amplitude of the H reflex because the amplitude of muscle response remained unchanged. The present findings indicate that Equistasi (R) has a modulatory effect on proprioceptive reflex circuits. Therefore, Equistasi (R) might interfere with some mechanisms involved in both physiological and pathophysiological control of movement and of posture.