PPG-based heart rate monitors demonstrated excellent validity (ICC > 0.90) but showed increased error at higher intensities, particularly during HIIT sessions.
Does the use of commercial PPG-based wearable heart rate monitors accurately measure heart rate compared to a reference chest strap in well-trained male endurance athletes across various exercise intensities?
Commercial PPG-based heart rate monitors show device-dependent accuracy that decreases at higher exercise intensities, suggesting caution when interpreting data during intense training.
The validity and accuracy of photoplethysmography (PPG)-based wearable heart rate (HR) monitors remain debatable. This study aimed to determine the concurrent validity of HR records from a wide range of contemporary PPG monitors across the full spectrum of exercise intensities and running conditions. Ten well-trained male endurance athletes performed several incremental maximal aerobic (IMA) tests and high-intensity interval training (HIIT) sessions while wearing a Polar H9 chest strap, as the reference criterion; 16 PPG-based heart rate monitors were tested (Amazfit Fit5; Apple Ultra and SE; Garmin 35, 45, 235, and 935; Polar M200, M430, OH1, Vantage M, Vantage V, Vantage V3, and Verity Sense; Galaxy Watch 5, Suunto 3 Fitness). The results showed excellent ICC (>0.90) versus the reference device across IMA and HIIT tests. Overall, the ICC decreased, and magnitudes of error increased (BIAS, SEM, and CV) as the intensity increased. Moreover, lower ICC values and greater BIAS, SEM, and CV were observed during the HIIT compared to the IMA test. Nevertheless, notable differences between devices were observed in magnitude of errors, accuracy, data loss, and read failures. In conclusion, PPG-based HR monitor validity is device-dependent and therefore exercise data from running training and competitions should be interpreted with caution.
Oropesa et al. (2025) studied this question. PPG-based heart rate monitors demonstrated excellent validity (ICC > 0.90) but showed increased error at higher intensities, particularly during HIIT sessions.