Claim relates to the Charge HR activity tracker that was launched in August

When Fitbit announced its Charge HR activity tracker back in August, the slogan that accompanied the launch was “every beat counts”. However this claim is now the subject of the lawsuit in the USA, which claims that the device’s pulse sensor delivers inaccurate and potentially dangerous readings.

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The three plaintiffs in the case claim that “the PurePulse Trackers [the heart rate monitor built into the Charge HR] consistently mis-record heart rates by a very significant margin.” This is said to be particularly the case during exercise, when the heart rate shown on the device would significantly underestimate the user’s actual heart rate.


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One of the plaintiffs, Teresa Black, claimed that this could cause a danger to her health, with the device giving a reading of 82 bpm when her actual heart rate was 160 bpm. According to the lawsuit, this was “approaching the maximum recommended heart rate for her age, and if she had continued to rely on her inaccurate PurePulse Tracker, she may well have exceeded it, thereby jeopardizing her health and safety.”

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In response, Fitbit has defended its devices, saying that they are not designed to give scientific accuracy.

“We do not believe this case has merit. Fitbit stands behind our heart rate technology and strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit. Fitbit is committed to making the best clip and wrist-based activity trackers on the market. Our team has performed and continues to perform internal studies to validate our products’ performance.

“PurePulse provides better overall heart rate tracking than cardio machines at the gym, as it tracks your heart rate continuously — even while you’re not at the gym or working out. But it’s also important to note that Fitbit trackers are designed to provide meaningful data to our users to help them reach their health and fitness goals, and are not intended to be scientific or medical devices.”