Fitbit, other heart-rate wristbands often inaccurate, study finds

Watchlike wristbands that monitor heart rate may not offer true readings during exercise, a small study finds. In a recent study published in JAMA Cardiology, researchers from the Cleveland Clinic tested the accuracy of heart rate monitoring in several popular wearables including the Apple Watch, Fitbit Charge, and Mio Alpha "All worked pretty well at rest," said Dr. Marc Gillinov, the Cleveland Clinic cardiac surgeon who led the experiment. "But as people exercised, the accuracy diminished." None of the four devices achieved the accuracy of a chest strap monitor. In treadmill tests, the Apple Watch and Mio Fuse were the most accurate.