Photoplethysmography-based estimation of heart rate recovery using a wrist-worn device

Estimation of pulse rate from photoplethysmogram (PPG) signals has led to a breakthrough in a smart wristband technology. This study introduces a method for estimating heart rate recovery (HRR) using a custom-made wrist-worn device, capable of acquiring instantaneous pulse rate, as well as a consumer smart wristband, which provides pulse rate at intervals of 5 s or longer. The feasibility to estimate HRR parameters using the PPG-based devices was assessed by comparing to the synchronously acquired reference electrocardiogram. Three HRR parameters were studied on pulse rate data, obtained from 22 healthy participants, instructed to perform standardized stair climbing test. Study findings show that HRR parameters, estimated using the wrist-worn device, are associated with twice lower absolute error compared to the consumer smart wristband, emphasizing the importance of an instantaneous pulse rate to ensure a sufficiently accurate parameter estimation.