Spinal reflex excitability and homosynaptic depression after a bout of whole-body vibration.

Although whole-body vibration (WBV) affects neuromuscular performance, it remains unclear whether the effects are due to spinal reflex potentiation or inhibition, or differ between muscle groups. This study aimed to identify the effect of WBV on measures of spinal reflex excitability (H-reflex) and homosynaptic depression (HD) in the soleus (SOL) and medial gastrocnemius (MG) muscles. H-reflex and HD measurements were made in the SOL and MG muscle of 20 participants before and after a bout of WBV. H-reflex and HD were measured every 15 seconds for 10 minutes post-WBV and averaged at 1-minute increments. H-reflex amplitude was depressed for the first minute post-vibration, whereas the effect of HD was reduced for the first 2 minutes post-vibration. WBV significantly decreases spinal reflex excitability and HD, but it does so transiently and independent of muscle group.