Modulation of H-reflex excitability by tetanic stimulation.

OBJECTIVE: This study investigated a strategy to elicit reversible facilitation of the soleus monosynaptic H-reflex in humans using a modified tetanic stimulation technique. METHODS: Interventional tetanic stimulation (ITS) was applied to the tibial nerve in the popliteal fossa, and soleus H-reflexes were recorded before and after stimulation in 15 healthy volunteers. RESULTS: ITS resulted in significantly increased soleus H-reflex amplitudes that outlasted the stimulation period by approximately 16 min. The effect of ITS on soleus motor evoked potentials to transcranial magnetic stimulation and on somatosensory evoked potentials to tibial nerve stimulation was also investigated; no significant changes were found. CONCLUSIONS: ITS produced a reversible increase in H-reflexes in the absence of changes in motor evoked potential or somatosensory evoked potential that outlasted the intervention period for up to 16 min. SIGNIFICANCE: This technique may be used in future studies to investigate whether the induced increased H-reflex excitability influences locomotion.