Comparison of heart rate measurement accuracy among commercially available photoplethysmography-based wearable devices across exercise intensities

[Purpose] We compared the heart rate (HR) measurement accuracy of commercially available PPG-based wearable devices against an ECG-based reference device across different exercise intensities.[Methods] Forty healthy young adults were recruited, and data from 37 participants were analyzed. HR was simultaneously measured using Polar H10 as the ECG-based reference and four PPG-based devices: Polar Verity Sense, Polar Pacer Pro, Apple Watch SE, and Galaxy Watch 6. Participants completed low-, moderate-, and high-intensity treadmill exercise. Accuracy was assessed using mean absolute error (MAE), mean absolute percentage error (MAPE), Lin’s concordance correlation coefficient (CCC), and Bland-Altman analysis.[Results] MAE and MAPE generally decreased as intensity increased. Significant differences in MAE were observed among the devices across intensities (<i>p</i> = 0.002). The Polar Verity Sense and Apple Watch SE showed significantly lower MAE than the Polar Pacer Pro and Galaxy Watch 6. During low-intensity exercise, the Apple Watch SE showed lower MAE than the Polar Pacer Pro and Galaxy Watch 6, whereas during high-intensity exercise, the Polar Verity Sense showed lower MAE than the Galaxy Watch 6. CCC values increased with exercise intensity and were consistently higher for the Polar Verity Sense and Apple Watch SE. Bland-Altman analysis showed narrower limits of agreement for the Apple Watch SE and Polar Verity Sense.[Conclusion] HR measurement accuracy differed substantially among the PPG-based wearable devices. The Apple Watch SE and Polar Verity Sense showed the highest agreement with the ECG-based reference, suggesting that wearable HR data should be interpreted based on device-specific validation.