Phase-dependent modulation of cutaneous reflexes of tibialis anterior muscle during hopping.

During human gait, the amplitude of cutaneous reflexes in the leg is modulated as a function of the phase of the step cycle. In tibialis anterior (TA) the responses to sural nerve stimulation are facilitatory at end stance while they are suppressive at end swing. To investigate in how far this modulation is specifically related to alternating locomotion, the modulation of such reflexes was studied during a symmetric rhythmic movement, namely hopping (as equivalent of galloping). The end-stance facilitation was present during hopping while the end-swing suppression was absent. It is concluded that the end-stance facilitation is not specific for alternating gait. The absence of the end-swing suppressive reflexes may be related to the absence of heel strike in hopping.