Comparison between heart rate estimated by single-lead ECG and optical-based wearable systems during outdoor running

Monitoring physiological variables, especially heart rate (HR), is beneficial during physical activities due to its responsiveness to exertion and fatigue levels. Research has extensively explored wearable devices for HR estimation, particularly wearable ECG devices and optical-based wristbands.This pilot study compares the HR values estimated by two differently designed wearable systems (i.e., a fitness watch with an optical sensor and a single-lead ECG chest belt) during an outdoor running session. The session consisted of various stages, including warm-up, active running, and recovery.Our findings reveal good agreement among HR data collected by the two devices during the running phase, with an average Mean Absolute Percentage Error (MAPE) of 1.5% and a Mean Absolute Error (MAE) of 3 beats per minute. Higher differences among HR values collected by the two wearable devices were observed during the warm-up phase, with an average MAPE of 16.7 % ± 5.5 %, while the running phase had the lowest (1.5 % ± 0.8 %).