Crossed spinal soleus muscle communication demonstrated by H‐reflex conditioning

Abstract

A conditioning volley to the ipsilateral tibial nerve (iTN) inhibits contralateral soleus (cSOL) electromyographic activity at latencies of 37-41 ms. This is evidence for spinal muscular communication in opposing limbs. The aim of our study was to determine whether the cSOL H-reflex would be inhibited in a similar manner. Thirteen subjects participated in two experiments: (1) stimuli delivered to the iTN at 85% of the maximal peak-to-peak M-wave (85% M-max) with a pre-contracted cSOL; (2) 510 stimuli delivered at 85% M-max to the iTN with a test volley delivered to the contralateral tibial nerve at interstimulus intervals of -6 to 100 ms. Significant inhibition was observed in the cSOL H-reflex when conditioning stimuli were delivered 3-33 ms before the test H-reflex. The activity of this spinal pathway can be quantified using H-reflex conditioning to provide a controlled model for further studies of this response.