<prompt> Most common nerve used conduction study in H reflex -Median nerveUlnar nerveTibial nervePeroneal nerve  <response>: The H reflex is basically an electrophysiologically recorded Achilles tendon stretch reflex. It is performed by stimulating the tibial nerve in popliteal fossa. It is recorded over the soleus or gastrocnemius muscle. It is used most commonly to evaluate S1 radiculopathy or to distinguish it from an L5 radiculopathy. REF:Ref: Text book of Neurology p.781 