<qa>  What is the H reflex?- Hoffman reflex H reflex: the H reflex will be elicited by a percutaneous electrical stimulation on tibial nerve delivered on popliteal fossae and recorded the electromyographic responses from the soleus muscle. The values of maximal H reflex, M wave and maximal H reflex and maximal M wave ratio HM ratio will be obtained through a recruitment curve. The recruitment curve will start with a stimulus intensity delivered from 2 milliampere mA and increasing on steps of 1 mA until to M wave curve stabilization no increasing of the M wave amplitude. 