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.”

  • William Noah

    yepper, my thoughts exactly!

  • Michael

    It sounds like opportunism to me. These devices are not medical equipment.

    If it’s crap at measuring heartrate, put it in the box and send it back to amazon or wherever for a refund, but don’t start waffling that you’ll die because your heart is beating too fast.

    There’s really no such thing as a “safe heart rate for your age” nor the idea that you need to exercise under this rate or risk some terrible thing happening to you.

    If you hit your max heart rate you might pass out, but you’d know without a device telling you if you were getting close to pushing this hard because your legs would be screaming too and your muscles and lungs burning. You don’t hit your max heart rate by accident. And, for most mere mortals, they’ll slow down or give up long before killing themselves.

    Of course max heart rate and things like lactate threshold heart rate vary between individuals, but the 160 quoted in the article is not particularly high. It’s about low zone 4 for me so, it’s the kind of effort you should be able to do for an hour or more.

    You jeopardize your health and safety by not exercising regularly and raising your heart rate than you do by the small risk of having a heart issue during exercise. It’s a bit of a misnomer to imagine that you’re going to drop down dead because you get off the sofa. The reverse is far more common.

    Of course, if you’re ill and you’ve been given specific medical advice to not exercise with an elevated heart rate then you should heed that advice. You need some equipment to reliably measure your pulse (which can be as simple as a clock and a couple of fingers)

  • Rich Wake

    Well abnormal heart rhythms play havoc with medical equipment such as Oxiometers especially when they are so far to the extremities of the body. Nursing staff often need to do a full ECG, and manual heart rate check to get a accurate measure.

    If the lady in question had such a heart rhythm than no wonder the machine got confused and surely if she was starting to feel ill she should be listening to her body and not her watch?

  • Butty

    Quote from Charge HR blurb:

    “Let your heart be your guide with Charge HR. Monitor heart rate automatically and continuously right on your wrist to accurately track calorie burn, maintain workout intensity, maximize training and optimize health—all without an uncomfortable chest strap”

    Does “accurately track” mean accuracy as imagined by the marketing dept and not the scientific dept?

  • J1

    I’d guess that chest HRMs will always be more accurate. I think that’s why the Garmin Forerunners still use them.

  • Gazzaputt

    Strangely my new Garmin Vivosmart does the exact same. I have had to switch back to using a chest strap as the Vivosmart was wildly inaccurate when riding the bike.