A study of the accuracy of Fitbit's heart rate monitoring found the wearables are highly inaccurate, especially during moderate to high intensity exercise.
Researchers tested the heart rate monitoring technology in two Fitbit models, the Charge HR and the Surge, by comparing their heart rate readings to electrocardiograms for 43 "healthy" subjects.
The study found the Fitbit Charge HR reported a heart rate that differed from the ECG by an average of 15.5 beats per minute during moderate to high intensity exercise. The Fitbit Surge differentiated from the ECG by an average of 22.8 beats per minute during moderate to high intensity exercise.
"The results of this investigation demonstrate that the…technology integrated in Fitbit's heart rate monitoring devices is not a valid method for heart rate measurement, and cannot be used to provide a meaningful estimate of a user's heart rate," the authors conclude.
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