In light of lawsuit, Consumer Reports revisits, reasserts accuracy of Fitbit heart rate monitoring

By Jonah Comstock
12:03 pm

There’s been much ado lately about Fitbit’s heart rate tracking technology, found in its Fitbit Charge HR and Fitbit Surge trackers. A recent class action lawsuit alleges that the devices are inaccurate and endanger consumers and a second lawsuit says the technology infringes on Valencell’s patents

Now Consumer Reports, which proclaimed the accuracy of the devices when it reviewed them initially, has re-tested them in the wake of the class action suit. Its verdict? Still accurate.

“At Consumer Reports, we were surprised [by the class action suit] because we had tested both of the devices, and found the heart rate readings to be quite accurate,” Associate Editor Paul Austin writes. “We decided to retest these models to confirm that we should continue to recommend them. And to learn more about their performance, we added some elements to our standard fitness-tracker test protocol. The result: Both the Fitbit Charge HR and Fitbit Surge passed our tests handily, accurately recording heart rates at everything from a leisurely walk up to a fast run.”

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The consumer advocate publication tested the devices against a Polar heart rate strap, as they did before, but added a few more variables to account for the specific complaints in the suit. This included incorporating higher intensity workouts than in their original assessment and testing the device both high on the forearm — as Fitbit recommends — and on the wrist. The tests included one male and one female subject.

“In our previous testing, we had captured our data when the subjects were at rest, and when they were undergoing moderate exercise,” Austin writes. “But the problems cited in the lawsuit had allegedly cropped up during harder workouts. For our new test, we recorded our subjects’ heart rates at four levels of intensity: at rest, a walking pace (110 bpm), a jogging pace (130 bpm), and a running pace (150 bpm). All tests were conducted twice. A total of 64 heart rate measurements were recorded.”

The result was a difference of no more than three beats per minute between the Fitbit devices and the Polar strap for every test except one: The device was off by as much as 11 bpm on a high-intensity test of the Charge HR on the female subject. The anomaly was only observed when she wore it on the wrist, not on the forearm.

This is a stark contrast to claims in the lawsuit that the devices were off by 24.34 bpm on average and 75 bpm in extreme cases. 

In other Fitbit legal news, Law360 is reporting that in Jawbone and Fitbit's ongoing lawsuit Jawbone has been ordered to hand over its computers and documents to the court, despite a claim by Jawbone that the presence of trade secrets would protect them from the order.


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