Evaluation of photoplethysmography-based monitoring of pulse rate, interbeat-intervals, and oxygen saturation during high-intensity interval training.

Background: Heart disease patients necessitate precise monitoring to ensure the safety and efficacy of their physical activities when managing conditions such as hypertension or heart failure. This study, therefore, aimed to evaluate the accuracy of photoplethysmography (PPG)-based monitoring of pulse rate (PR), interbeat-intervals (IB-I) and oxygen saturation (SpO2) during high-intensity interval training (HIIT).

Methods: Between January and March 2024, healthy volunteers were subjected to a cycling HIIT workout with bike resistance increments to evaluate performance within different heart rate ranges. To determine the accuracy of PPG-based measurements for PR, IB-I, and SpO2 using the CardioWatch 287-2 (Corsano Health, the Netherlands), measurements throughout these ranges were compared to paired reference values from the Covidien Nellcor pulse oximeter (PM10N) and Vivalink's wearable ECG patch monitor. Subgroups were defined for Fitzpatrick skin type and gender.

Results: In total, 35 healthy individuals participated, resulting in 7183 paired measurements for PR, 22,713 for IB-I, and 41,817 for SpO2. The PR algorithm showed an average root mean square (Arms) of 2.51 beats per minute (bpm), bias at 0.05 bpm, and limits of agreement (LoA) from -4.87 to 4.97 bpm. The IB-I algorithm achieved an Arms of 23.00 ms, a bias of 1.00 ms, and LoA from -43.82 to 46.21 ms. Finally, the SpO2 algorithm showed an Arms of 1.28%, a bias of 0.13%, and LoA from -2.37% to 2.62%. The results were consistent across different demographic subgroups.

Conclusions: This study demonstrates that the PPG-based CardioWatch 287-2 can accurately monitor PR, IB-I, and SpO2 during HIIT. However, further research is recommended to evaluate the algorithm's performance in heart disease patients during demanding exercise.