Is the Mmax/Hmax ratio a reliable index of the monosynaptic excitability in man? Recruitment curves for H- and M-responses using monopolar and bipolar recording techniques.

The amplitude changes of M- and H-potentials, recorded monopolarly and bipolarly from different leading-off areas on the surface of m. triceps surae upon varying the stimulus intensity from threshold to supramaximal values, in a state of rest and fixed muscle length, are investigated. It is shown that: a) the Mmax/Hmax amplitude ratio cannot serve as a reliable index for a quantitative evaluation of the monosynaptic reflex excitability of the motoneurone pool and b) recording along the medial line of m. soleus in the region from 1.5 to 8.0 cm under the distal insertion of the two gastrocnemii into the Achilles tendon in a state of rest and submaximal values of the stimulus intensity, both mono- and bipolar recording techniques can equivalently be used in studying the changes in the monosynaptic reflex excitability.