Harvard Heart Letter
Are wristwatch-style heart rate monitors accurate?
Research we’re watching Those popular fitness trackers you wear on your wrist estimate your heart rate with a sensor that measures changes in blood flow through your skin. But just how accurate are they? To find out, researchers tested four popular commercial wrist-worn monitors on 50 young, healthy adults. Participants were hooked up to an ECG machine, which records the heart’s electrical activity and provides the “gold standard” measure of heart rate.