Photophlethysmography Evaluation of Pulse Waveform

The proposed study will first investigate whether a novel PPG device will be able to measure the harmonic-analysis indexes of the blood pressure waveform (BPWs) to provide information about arterial pulse transmission (by monitoring arterial pulse waveform, Cn) and cardiovascular regulatory activities (by monitoring coefficients of variation, CVn).

Secondarily, data on Cn and CVn could be useful for detecting the arterial elastic properties induced by external stimulation such as exercise, cold stimulation, mental stress, acupuncture, medications such as antihypertensive drugs, or pathological factors such as metabolic syndrome, and breast cancer. The collected data may thus provide information about underlying health.

Photoplethysmography (PPG) is a non-invasive optical technique for evaluating the pulse and hemodynamic changes in frequency. The device obtains a volumetric measurement of an organ via optical illumination (e.g LED). PPG has been used to determine the PaO2, heart rate, and blood pressure (systolic blood pressure, SBP and diastolic blood pressure, DBP) at fingertip and harmonic proportion at fingertip or from the radial artery waveform at the wrist.

However, to the investigator's knowledge, this is the first preliminary study to determine the effects of physical activity on harmonic proportion evaluating by PPG at fingertip. Ultimately, this data may help to develop a non-invasive, external device that could rapidly detect information about cardiovascular and underlying health.

• Inclusion criteria:

• Ability to understand consent (no proxy consent) in English or Chinese.
• Self-Reported ability to undertake a 20 minute cycling activity at 60-70% exercise intensity.
• Ability and willingness to abstain from use of medications for three days preceding cycling activity, smoking/intense exercise/alcohol for 12 hours preceding cycling activity, and caffeine intake for 4 hours preceding cycling.

• Exclusion criteria:

• Inability to finish a 20 min cycling activity in 60-70% exercise intensity.
• Adverse reaction to adhesive tape.
• Raynaud's phenomenon
• Angina or recent myocardial infarction (previous 6 months)