Cardiac autonomic response during recovery from a maximal exercise using whole body vibration

Objective: To examine the effect of passive whole-body vibration (WBV) on heart rate (HR) variability (HRV) during the recovery from intense exercise. Design: Randomized, counterbalanced, crossover design. Setting: Laboratory. Interventions: Twenty-three healthy male performed a bicycle exercise test to exhaustion followed by an active recovery period using WBV (25. Hz and peak to peak displacement of 4. mm) or passive recovery period (noWBV; 0. Hz-0. mm) on two separate days in random order. The recovery protocol consisted of six 1-min sets separated by 1-min inter-set rest periods in the seated position with the feet on the vibration platform. ECG recordings were made at baseline and during recovery at min 2, 4, 6, 8, 10 and 12 in both conditions. Frequency-domain measures of HRV were determined via power spectral analysis using fast-Fourier transform. Low frequency (LF; 0.04-0.15. Hz) and high frequency bandwidths (HF; 0.15-0.4. Hz) were determined. Results: HR was increased in both groups (P< 0.01) throughout the recovery. At min 2, HR was lower (P= 0.05) after WVB compared to the noWBV trial. At min 3, the increase (P< 0.05) in total power after WBV was significantly different (P< 0.01) compared to noWBV. Normalized (nu) LF and LF/HF were increased (P< 0.01), whereas HF nu was reduced (P< 0.001) in both conditions without a significant group-by-time interaction (P= 0.08). Conclusion: Passive WBV reduces HR and increases total power during the early recovery of intense exercise, despite no effect on power spectral components of HRV.