Modulation of the ipsilateral and contralateral H reflexes following ipsilateral mechanical pressure of the foot in normal subjects
Bastani, A.; Hadian, M.R.; Talebian, S.; Bagheri, H.; Olyaie, G.R.
Electromyography and Clinical Neurophysiology 50(5): 251-256
2010
ISSN/ISBN: 0301-150X PMID: 20718337 Document Number: 642036
Mechanoreceptors from the foot sole likely contribute in the reflex regulations. Therefore, it was hypothesized that repetitive low threshold afferents stimulation would have an inhibitory effect on the soleus H-reflexes. Sixteen normal subjects voluntarily, participated in the 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 and Medial plantar surface by a designed instrument through a square plate (30 x 30 mm). H reflex as an indicator for excitability of motoneurones was bilaterally elicited before and after the application of the CMP. The H-reflex parameters were estimated. Mechanical pressure significantly depressed soleus H-reflex excitability in ipsilateral and contralateral feet in all subjects. The demonstration of a decrease in H-reflex excitability as a result of applied pressure to the foot sole suggests that the change in reflex excitability is the result of a common spinal mechanism. The results highlight the modulatory effects that natural stimulation of afferents can have on reflex excitability. The placement of a small flat plate, in order to apply pressure to the plantar eminence, may be useful for modulation of muscle tone. In addition, these findings might be useful for reducing spasticity; because spasticity is at least partially caused by hyperexcitability of the motorneuron pool.