back to article Got a Fitbit? Thought you were achieving your goals? Better read this

Scientists have tested a pair of wearable fitness gadgets from Fitbit and found they get heart rates wrong by as much as 25 beats per minute. The study (PDF) was commissioned by law firm Lieff Cabraser, which is running a class action against Fitbit over inaccurate heart rate readings. The study didn't use a colossal sample …


    1. d3vy Silver badge

      Re: Not surprised

      The cheapest model is a clip on the belt pedometer... which are not as susceptible to rapid wrist movements as the other. Did they give you a flex (cheapest wrist band)?

      Side note, I ran a mile an a half in the shower once.

      I sold it on eBay because it lost its appeal, thing is I know how active I am during the day, don't need a wrist band to tell me that I didn't walk as far when I've driven to work instead of walking... I can figure that out on my own.

      1. Greg D

        Re: Not surprised

        Aye, it was a flex. Didnt think there was an even cheaper version available - then again, I really dont care. They are pointless.

  1. Dadmin
    Thumb Up

    New El Reg Masthead Menu coming your way! ASAP...


  2. andrewj

    This "news" is of absolutely no surprise whatsoever to virtually anyone who owns a fitbit. Much discussed on forums.

  3. Bob Dole (tm)
    Paris Hilton

    Consumer vs Medical grade

    >>Fitbit's CEO James Park has said that: "People need to use common sense. It’s not a medical-grade device; it’s a consumer device. In that setting, it works incredibly well."

    There's a serious problem with that statement. Usually the difference between a consumer and an industrial product is that the consumer product is made of far cheaper materials and will break much sooner. As opposed to being completely unfit for purpose.

    If the device is supposed to tell me how fast my heart is beating then it should be able to do so within a reasonable deviation. If it can't do that then it shouldn't be used at all.

    1. Anonymous Coward
      Anonymous Coward

      Re: Consumer vs Medical grade

      Define "reasonable deviation". Fitbit will no doubt argue that's exactly what they offer. A "reasonably" accurate, reproducible HR measurement without the inconvenience of a chest strap.

  4. seanradford

    Another similar article

    Reminds me of this similar article:

    (data analysis by start-up TrainAsONE,

  5. Anonymous Coward
    Anonymous Coward

    Nobody ever says

    "I wanna be a photoplethysmographer when I grow up"

  6. ntevanza

    Brachycardia, n.

    "This study will scare the many athletes - serious competitors and weekend warriors alike – who aim to train at certain heart rates. "

    Quick clarification: athletes are not using Fitbits.

    If you are using a serious heart rate monitor and can't get a consistent reading, or have any unexpected weirdness, see a cardiologist. In the UK, you may have to fight your GP, who will have been trained to tell you there's probably nothing wrong with you. He/she will be right only 90% of the time.

    But to get to the real point: the commentariat has done it again: 'brachycardia' is an instant classic and refers henceforth to tachycardia, or the illusion thereof, attributable to masturbation.

  7. Herby Silver badge

    Doing heart rate on an instrument like that...

    Isn't very easy. They have contacts pretty close together to detect EKG pulses (typically R wave) and just count the interval between R waves (the most predominant part of the EKG, and go from there. The math(s) is pretty easy to do (I helped in patient monitoring for anesthesia back in the 70's). The big problem is getting a good signal to the device, and there are lots of ways noise creeps in.

    I'm sure FitBit can put all sorts of disclaimers out there and results might vary all over the map, but the number they display is probably pretty good, considering.

    Not if they can get their FitBit Flex goodie a little more water proof. I used to wear it in the shower (and that was OK), but the trip to Hawaii last year and its encounter with salt water have seemed to foul it up. It blinks nicely (when charging) but it doesn't sense anything. Oh, well...........

    1. Seajay#

      Re: Doing heart rate on an instrument like that...

      They aren't detecting EKG pulses at all, there are no contacts. It's an optical sensor which works by noticing the tiny difference in the redness of your skin as you blood pressure changes within a hearbeat.


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