Effect of skin tone and activity on the performance of wrist-worn optical beat-to-beat heart rate monitoring

Abstract

Wrist-worn reflective photoplethysmography (PPG) has gained popularity as an unobtrusive method for heart rate monitoring, also known as optical heart rate monitoring (OHR). Recently beat-to-beat heart rate information measured with OHR technology has also started to be utilized in heart rate variability analysis as well as in detection of cardiac arrhythmias. However, as an optical method, the quality of the PPG signal and thus the performance of the technology is affected by the skin tone of the measurement subject. In addition, movement and superficial blood perfusion are other relevant factors affecting to OHR monitoring. We evaluated the performance of optical heart rate monitor manufactured by PulseOn company in controlled trial with 36 subjects of varying skin tones. The results show clear dependence between the skin tone and the coverage percentage of good quality beat-to-beat intervals (BBI) as well as improvement of the coverage and the BBI accuracy after physical activity, especially with people with darker skin tone.