Study: Fitness trackers’ accuracy varies

Tuesday, November 22, 2016

By: Jeff Ash

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If you wear a fitness tracker on your wrist, don’t take its heart rate readings as gospel.


That’s what a team of Ohio researchers found when they studied 50 healthy adults using a variety of wrist monitors.


The 50 adults wore Fitbit Charge HR, Apple Watch, Mio Alpha or Basis Peak wrist monitors. They also wore a Polar H7 chest strap monitor and standard electrocardiographic limb leads.


Their heart rates were measured as they walked and ran on a treadmill for 3 minutes each at 2 mph, 3 mph, 4 mph, 5 mph and 6 mph, then as they rested for 30, 60 and 90 seconds after that workout.


Heart rate readings from wrist monitors varied, and none was as accurate as the chest monitor, according to the study published in JAMA Cardiology in October 2016.


Matched against an electrocardiogram, the chest monitor was 99 percent accurate, but the wrist monitors were from 83 percent to 91 percent accurate. The adults’ age, gender and body mass index did not influence the accuracy of the readings.


“Fitness trackers have become popular with many people, and although the information gained from them may be useful, it’s wise to keep in mind that they do have an error rate, as this study has found,” says Dr. Matthew A. Schmidt, an interventional cardiologist with Aurora BayCare Cardiology in Green Bay.


Generally speaking, wrist monitors were most accurate while the adults rested, and their accuracy diminished as the adults exercised, the Cleveland Clinic researchers found.


Dr. Matthew A. Schmidt sees patients at Aurora BayCare Medical Center in Green Bay. For information, call 920-288-8300.

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BayCare Clinic,, is the largest physician-owned specialty-care clinic in northeastern Wisconsin and Michigan’s Upper Peninsula. It is based in Green Bay, Wisconsin. BayCare Clinic offers expertise in more than 20 specialties, with more than 100 physicians serving in 16 area communities. BayCare Clinic is a joint partner in Aurora BayCare Medical Center, a 167-bed, full-service hospital. Follow BayCare Clinic on Facebook and Twitter.