Blood flow in the tibialis anterior muscle by photoplethysmography during foot-transmitted vibration

Photoplethysmography (PPG) was used to detect changes in the anterior tibial muscle blood flow (MBF) during foot-transmitted vibration in six healthy subjects. A filter was developed for reducing the vibration-induced artefacts in the PPG signal. The vibration applied was random with constant acceleration power density in the range 5–2,000 Hz with an acceleration of 16–46 m s–2 (rms). The application of the filter technique showed a dramatic reduction in the vibration-induced artefacts and distortion of the PPG signal was negligible. The mean ratio and correlation coefficient of MBF originating from filtered and non-filtered PPG signals was [mean (SD)] 0.89 (0.04) and 0.99, respectively. This made it possible to detect a relative increase in MBF of 20% during an acute vibration exposure. The results suggest that the use of the filter enables MBF to be measured by PPG during vibration, thus extending the range of applications of the PPG technique to include ergonomic conditions.