Research we're watching
Earlier studies have shown that wrist-worn activity trackers can accurately record the number of steps a wearer takes. However, few studies have determined how well they monitor heart rate.
Researchers at the University of Wisconsin in Madison studied four wrist-worn activity trackers — Basis Peak, Fitbit Surge, Fitbit Charge, and Mio Fuse — to determine the accuracy of their heart rate monitoring in 40 healthy women and men ages 30 to 65. The researchers fitted each participant with four trackers—two on each wrist. Using the trackers as well as an ECG machine, the researchers measured the wearers' heart rates at one-minute intervals for 10 minutes while they were sitting. They then repeated the measurements while the participants walked on a treadmill for 10 minutes. When they compared the readings from the ECGs and the trackers, they found that all of the readings were more consistent when the participants were resting than when they exercised.
Although the results, published online April 11, 2016, by Annals of Internal Medicine, indicate that activity trackers may not be as accurate in monitoring heart rate as they are in recording steps, the devices are becoming more accurate as new models appear. However, for now, basic step counters may be a wiser investment than costlier trackers with pulse monitors.