Signal processing quantification of changes in the blood volume pulse (BVP) waveform due to exercise

Observations made in the past by our group confirmed that the blood volume pulse (BVP) waveform recorded using an infrared finger photoplethysmograph (PPG) undergoes changes as the subject performs physical exercise. In particular, the Dicrotic Notch of the BVP waveform has been observed to become less prominent in connection with the performance of exercise. There is an interest in characterizing those changes through a single parameter to measure the level of exercise the subject has reached, at any time during an exercise session. This paper reports on the comparison of three Digital Signal Processing approaches designed to reflect the BVP waveform changes through a single parameter, which could be obtained automatically from the digitized BVP signal. For this study BVP measurements were taken from 10 subjects, as they engaged in upper-body exercises and rested afterwards.