the effect of cutaneous mechanical stimulations of lateral plantar surface on the excitability of ipsilateral and contralateral motoneurons

mechanoreceptors of foot sole likely contribute in the reflex regulations. stimulation of these receptors in the lateral aspect of the foot is corresponded to the lateral plantar division of the tibial nerve. therefore, it was hypothesized that repetitive low threshold afferents stimulation would have an inhibitory effect on the soleus h-reflexes. methods: sixteen normal subjects voluntarily participated in this study and were randomly allocated. subjects were remained in prone position. the cutaneous mechanical pressure (cmp) equal to 50% of leg and foot weight was applied to the ipsilateral lateral plantar surface using a special instrument through a square plate (30x30 mm). h reflexes as indicator for excitability of motoneurones was bilaterally elicited before and after the application of the cmp and the hreflex parameters were measured. results: the amplitude of h reflex and h/m ratio showed significant differences before and after the ipsilateral cmp stimulation of the lateral side of the foot (p<0.05 p<0.05, respectively decreased). furthermore, the latencies of h reflexes were also increased (p<0.05). conclusion: our results highlight the modulatory effects of natural stimulation of cutaneous afferents on excitability of ipsilateral and contralateral motoneurones. this in respect may have practical application in the management of muscle tone disorders following brain and spinal cord injuries.