Analysing performances of Heart Rate Variability measurement through a smartwatch

This paper presents the experimental performance assessment of a smartwatch (SW) measuring the heart rate variability (HRV), compared to a multi-parametric chest belt that is considered as a reference sensor. HRV from smartwatch can be extracted with two methods: directly from internal onboard processing of the device or by post-processing data collected from the photoplethysmography signal. To evaluate the uncertainty of both methods, measurements were performed while users were sitting at rest, wearing the SW on the preferred wrist and a chest belt that can collect electrocardiographic signal, used as reference measurement. Measurements from SW and belt were compared turning out to provide that HRV measured with the SW (onboard processing) has an uncertainty of 0.95% with a coverage factor k = 2, corresponding to ± 4 ms; while HRV extracted from the PPG signal has an uncertainty of 1.2%, corresponding to ± 6 ms, indicating that at rest condition the HRV measured directly with the onboard system of the SW can be used to assess correctly the HRV.