Where Can Exercisers Sense Heart Rates Accurately and Comfortably on Their Bodies?

摘要

These days, because of its simplicity, non-invasiveness and unobtrusiveness, photoplethysmography (PPG) has been commonly used for heart rate (HR) sensors. Just placing a light emitting diode (LED) and a photo detector (PD) on the skin surface, PPG can measure HR as the change of light intensity in the PD output, so PPG-based HR sensor can be applied for almost any part of human body under which there is a blood vessel. On the other hand, when applying a PPG-based HR sensor in exercise, human body motion introduces motion artifact (MA) in the PD output, which results in erroneous HR. The degree of motion during exercise depends on the part of human body, so attainable HR and tolerance against MA must depend on the part of human body where HR is sensed. In this paper, we investigate the part of our bodies where we can accurately and comfortably sense our HRs during exercise. We conduct experiments involving ten human subjects, and we evaluate the performance of a PPG-based HR sensor. In the experiments, we select four human body parts such as forearm, wrist, waist and calf, and evaluate the HR at different fastening belt pressures and different exercise intensities. Our results show that the forearm is the best where the HR error can be the lowest with a tight belt pressure.