Concurrent validity and accuracy of wrist-wearable devices to track heart rate during exercise in sedentary individuals

Background: Heart rate (HR) is commonly used as an indicator to represent a change in oxygen consumption and energy expenditure during activities. Nowadays, HR is easily measured by low-cost wrist-wearable devices, but a few studies examine the validity and accuracy of these devices in sedentary people. Objective: The study aimed to explore the concurrent validity and accuracy of low-cost wrist-wearable HR devices (The GT2e: approx. 4000 THB and Red Mi watch 2 lite: approx. 1000 THB) for measuring HR during exercise on a treadmill in people with a sedentary lifestyle. Materials and methods: Seventy-six sedentary participants (60 female; 78.95%) were instructed to wear a Polar H7 while randomly wearing a watch on each hand. Participants were asked to walk or run on the treadmill for 40 minutes, including free-living activities, exercise, and HR recovery phases. Pearson’s correlation coefficient was utilized to explain the levels of correlation (concurrent validity) of wrist wearable devices with the Polar H7. In contrast, the Bland-Altman method, Concordance correlation coefficient (CCC), and Mean Absolute Percentage Error (MAPE) were then used to determine the accuracy of wrist wearable devices. Results: The GT2e had an excellent agreement with the Polar H7 in free-living activities, exercise sessions, and the HR recovery phase (CCC=0.88, 0.85 & 0.78, respectively) and strong correlation with the criterion measured; Polar H7 (r=0.79 - 0.88; p<0.001). While Red Mi watch 2 lite also had an excellent agreement and correlation in free-living activities and the HR recovery phase (CCC=0.88 - 0.85; r=0.79), but a moderate agreement was found in the exercise phase (CCC=0.55; r=0.61 [p><0.001]). Conclusion: Both the GT2e and Red Mi watch 2 lite wrist-wearable devices could be used as alternative HR-measured devices to detect HR in sedentary people’s daily lives. However, the GT2e wrist-wearable device was more valid and accurate in detecting HR than the Red Mi watch 2 lite.