Frequency dependent response of cardio-vascular system to foot based vibration while in the seated position

The objective of this study was to determine the frequency dependent response of heart rate variability (HRV) to mechanical vibration, applied at the feet with the subject in the seated position. Ten female volunteers in the age group of 22 to 70 were exposed to the vibration stimulus at each of 6 different frequencies (0, 15, 22, 44, 60, 88 Hz, 0.2g) for 20 minutes, with only one frequency per day being tested. Tests were carried out in a randomized manner for 6 weeks and blood pressure and continuous heart rate were recorded. Frequency analysis by FFT was used to evaluate HRV. Initial results suggest that both blood pressure and HRV can be affected by vibration at frequencies of 40 Hz and above.