Cardiologists regularly get calls from people who are freaked out by the fitness tracker on their wrist.
Typically, the caller is young and healthy, maybe even a half-marathoner, says Cleveland Clinic heart surgeon Dr. Marc Gillinov, who hears such tales from his cardiologist colleagues.
But when they were merely taking a stroll, their fitness tracker said their heart rate was 190 beats per minute—the average maximum heart rate for a 30-year-old, according to the American Heart Association.
