The Apple Watch has been touted as the most accurate wrist-based wearable in a new study from the Cleveland Clinic, published in JAMA Cardiology. The study was performed on 50 healthy adults, who wore an electrocardiogram (EKG), Fitbit Charge HR, Apple Watch, Mio Alpha, Basis Peak, and a chest strap for several hours. See Also: Apple Watch sales more than halved so far this summer Participants performed a variety of exercises to test wearable accuracy during rest, walking, and on a treadmill.