Human soleus H-reflex excitability is decreased by dynamic head-and-body tilts

Abstract

The modulation of soleus (SO) H-reflex excitability during dynamic whole head-and-body tilts (WHBT) was investigated in normal healthy subjects. Between 30 and 70 ms, and 151 and 190 ms after head acceleration onset, the H-reflex amplitude was smaller than during quiet standing by 7.6% ( $\mathit{p}\mathrm{<}0.01$ ) and 15.4% ( $\mathit{p}=0.06$ ) respectively. This finding suggested that dynamic WHBT reduced the excitability of the predominantly monosynaptic stretch reflex arc in the majority of the subjects studied.