Is the Acute and Short-Term Effect of Whole-Body Vibration the Same on the H-Reflex Recruitment Curve and Agility?

Context: Despite the widespread use of whole-body vibration (WBV), especially in recent years, its neurophysiological mechanism is still unclear and it is yet to be determined whether acute and short-term WBV exposure produce neurogenic enhancement for agility.

Objective: To compare the acute and short-term effects of WBV on the H-reflex-recruitment curve and agility.

Design: Cross-over study.

Setting: Clinical electrophysiology laboratory.

Participants: 20 nonathlete male volunteers (mean age 24.85 ± 3.03 y).

Main Outcome Measures: Subjects were randomly divided into 2 groups, H-reflex and agility. In the sham protocol, subjects stood on the turned-off vibration plate while maintaining the semisquat position, and then, after a 2-wk washout, vibration-training sessions were performed in the same position with a frequency of 30 Hz and an amplitude of 3 mm. H-reflex-recruitment curve was recorded and the agility test of a shuttle run was performed before and after the first session and also 48 h after the 11th session in both sham and vibration-training protocols.

Results: Acute effects of WBV training caused a significant decrease of threshold amplitude and H-max/M-max (P = .01 and P = .04, respectively). Short-term WBV training significantly decreased the threshold intensity of the soleus H-reflex-recruitment curve (P = .01) and caused a decrease and increase respectively, in the threshold intensity and the area under the recruitment curve.

Conclusions: The results suggest an inhibitory effect of acute WBV training on the H-reflex response.