A study released released last week claims that Fitbit's PurePulse™ Heart Rate Monitors are "highly inaccurate."
The study commissioned by the law firm behind January's class-action lawsuit against Fitbit, found that the device does not "provide a valid measure of the user's heart rate and cannot be used to provide a meaningful estimate of a user's heart rate, particularly during moderate to high intensity exercise."
According to CNBC, researchers tested the heart rates of 43 adults utilzing the PurePulse™ Heart Rate Monitors found on the Fitbit Charge HR and Fitbit Surge. The subjects were monitored using a electrocardiogram to check the data against the Fitbit devices.
The study revealed that the average difference between the Fitbit device and the ECG was approximately 20 beats per minute while exercising.
In a concluding statement, the study suggested:
"Overall, the results of this investigation demonstrate that the PurePulse™ 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. "
Fitbit responded to the study in an email sent to Fortune:
"[The study] was paid for by plaintiffs' lawyers who are suing Fitbit, and was conducted with a consumer-grade electrocardiogram—not a true clinical device, as implied by the plaintiffs' lawyers. Furthermore, there is no evidence the device used in the purported 'study' was tested for accuracy."
The company also noted that Consumer Reports tested the devices and gave them "excellent" ratings.
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