Validity and Reliability of the Apple Series 6 and 7 Smartwatches and Polar H-10 Monitor on Heart Rate

A persistent problem with field devices lies in the quality of the data that is obtained through the device. Given that data accuracy, validity, and reliability is currently unknown, errors in the estimation of these variables are often prevalent. Wrist-based monitors may show convenience and comfort in comparison to chest-strap monitors and enable them to be largely used. The purpose of this project is to monitor and compare heart rate data through the use of the Apple Watch Series 6, Apple Watch Series 7, and Polar H-10 chest-strap monitor, in comparison with the gold-standard 12-lead ECG in collegiate level athletes and recreationally active college-age young adults. A single-session cross-sectional study design was implemented. Twenty-five college-age male athletes from the UTEP football team and 20 college-age recreationally trained young adults (n=20; 10 males and 10 females) were recruited for this study. UTEP football subjects were asked to walk (low), jog (moderate), and run (high) intensity at zero incline for 3 minutes at 3 mph, 6 mph, and 9 mph, respectively. Similarly, recreational athletes followed the same protocol except the speed set on the treadmill was lowered to walk (low), jog (moderate), and run (high) intensity at 2.5 mph, 5 mph, and 7.5 mph, respectively. Following the test, subjects were asked to continue walking on the treadmill for 3 minutes for recovery. High association and good to excellent agreement (r = 0.76-0.99, ICC2, k = 0.86-0.99) between ECG and Polar H-10 throughout all stages. However, there were moderate associations and good agreement at walk, jog, and run intensity between the ECG and apple watch 6 (r = 0.57-0.77, ICC2, k = 0.62-0.84), and ECG and Apple watch 7 (r = 0.42-0.74, ICC2, k = 0.49-0.85). These findings indicate that even though there is a good-excellent agreement between the Apple Watch and ECG the accuracy of the Apple Watch tends to diminish with an increase in intensity