Extinction of the Hoffmann reflex by antidromic conduction.

We have shown that one cause of the extinction of the Hoffmann reflex by antidromic conduction in the alpha motor axons must be a relative refractoriness of the motoneuron pool. A hypothesized collision between the H-wave and the antidromic M-wave component is not disproved but it (and the incumbent assumptions about relative afferent and efferent conduction velocities) is shown to be unnecessary. A montonic variation of the M-wave with tonic soleus contraction (M-wave increasing with contraction) is observed but not explained.