Validation of biofeedback wearables for photoplethysmographic heart rate tracking

The purpose of this study was to examine the validity of hr measurements by two commercial-use activity trackers in comparison to ecg. twenty-four healthy participants underwent the same 77-minute protocol during a single visit. each participant completed an initial rest period of 15 minutes followed by 5 minute periods of each of the following activities: 60w and 120w cycling,walking,jogging,running,resisted arm raises,resisted lunges,and isometric plank. in between each exercise task was a 5-minute rest period. each subject wore a basis peak (bpk) on one wrist and a fitbit charge hr (fb) on the opposite wrist. criterion measurement of hr was administered by 12-lead ecg. time synced data from each device and ecg were concurrently and electronically acquired throughout the entire 77-minute protocol. when examining data in aggregate,there was a strong correlation between bpk and ecg for hr (r = 0.92,p < 0.001) with a mean bias of -2.5 bpm (95% loa 19.3,-24.4). the fb demonstrated a moderately strong correlation with ecg for hr (r = 0.83,p < 0.001) with an average mean bias of -8.8 bpm (95% loa 24.2,-41.8). during physical efforts eliciting ecg hr > 116 bpm,the bpk demonstrated an r = 0.77 and mean bias = -4.9 bpm (95% loa 21.3,-31.0) while the fb demonstrated an r = 0.58 and mean bias = -12.7 bpm (95% loa 28.6,-54.0). the bpk satisfied validity criteria for hr monitors,however showed a marginal decline in accuracy with increasing physical effort (ecg hr > 116 bpm). the fb failed to satisfy validity criteria and demonstrated a substantial decrease in accuracy during higher exercise intensities. © journal of sports science and medicine.