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Fitbit HR Inaccurate

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  • ubermofishubermofish Posts: 102Member Member Posts: 102Member Member
    My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm
  • Need2Exerc1seNeed2Exerc1se Posts: 13,589Member Member Posts: 13,589Member Member
    ubermofish wrote: »
    My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm

    The instructions say to do this during exercise but I have a hard time getting mine to stay up there. It naturally wants to slip down to my wrist because the wrist is smaller. I usually get tired of pushing it back up and just let it go where it wants to go.
  • ubermofishubermofish Posts: 102Member Member Posts: 102Member Member
    ubermofish wrote: »
    My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm

    The instructions say to do this during exercise but I have a hard time getting mine to stay up there. It naturally wants to slip down to my wrist because the wrist is smaller. I usually get tired of pushing it back up and just let it go where it wants to go.

    You gotta make it pretty tight
  • Need2Exerc1seNeed2Exerc1se Posts: 13,589Member Member Posts: 13,589Member Member
    ubermofish wrote: »
    ubermofish wrote: »
    My Charge HR was doing a pretty bad job until I stopped wearing it on my actual wrist, you need to move it up your arm a bit and tighten it so it stays. Now its pretty much +- 5bpm

    The instructions say to do this during exercise but I have a hard time getting mine to stay up there. It naturally wants to slip down to my wrist because the wrist is smaller. I usually get tired of pushing it back up and just let it go where it wants to go.

    You gotta make it pretty tight

    Making it tight just makes it want to slip to the smaller more, especially when I get sweaty. Unless you mean so tight that it actually creates a bulge on the lower side like a tourniquet, which sounds incredibly uncomfortable and maybe a little dangerous.
  • MeanderingMammalMeanderingMammal Posts: 7,870Member Member Posts: 7,870Member Member
    MandaB9780 wrote: »
    It really doesn't matter what wrist-based device you're talking about - none are as accurate as a chest strap that is actually detecting your heart rate straight from the source.

    It's not quite that simple.

    Both electrical and optical measurement has some error, and both have a greater level of error at the higher range. At normal range the difference in relative accuracy is pretty negligible, and at the top end that goes from negligible to not very significant.

    Factors that affect accuracy include device fit and placement, sampling frequency and with opticals they become vulnerable to skin tone and hair growth as well.

    I think the materiality is that for the vast majority of people optical measurement is good enough. That said, the FitBit range do seem to come off worst in most tests I've seen results for.

    If, on the other hand, you're interested in rate variation, recovery time, cumulative fatigue and sports performance, then undoubtedly an electrical measurement is superior. For that stuff you're spending 4-5 times the amount of money on a device though.
    edited May 2016
  • EvgeniZyntxEvgeniZyntx Posts: 24,424Member Member Posts: 24,424Member Member
    MandaB9780 wrote: »
    It really doesn't matter what wrist-based device you're talking about - none are as accurate as a chest strap that is actually detecting your heart rate straight from the source.

    It's not quite that simple.

    Both electrical and optical measurement has some error, and both have a greater level of error at the higher range. At normal range the difference in relative accuracy is pretty negligible, and at the top end that goes from negligible to not very significant.

    Factors that affect accuracy include device fit and placement, sampling frequency and with opticals they become vulnerable to skin tone and hair growth as well.

    I think the materiality is that for the vast majority of people optical measurement is good enough. That said, the FitBit range do seem to come off worst in most tests I've seen results for.

    If, on the other hand, you're interested in rate variation, recovery time, cumulative fatigue and sports performance, then undoubtedly an electrical measurement is superior. For that stuff you're spending 4-5 times the amount of money on a device though.

    Good enough is correct.
    This study was commissioned by lawyers with the interest of demonstrating what exactly? That these devices are inaccurate. Lawyers will then get paid when they sue FitBit. Conflict of interest? A bit.

    Yet, if people bothered to actually read the study (and understand the math) they'd see a correlation of R=0.70-=0.85 and an error of about 10%. Damn better than the TDEE estimator equations.

    In this study, these devices had an error of less than 8 beats at rest and about twice that during exercise. If you are doing HR training, they are not that useful (a 15+ beat error is a HR zone) but for general use they are good enough. It is unclear that these users had properly positioned the device tightly on the arm.

    Other optical devices like the Mio or Scosche are intended to fit tightly on the mid arm and do not seem to have the same issues. My own testing (Scosche) and dcrainmakers (neither of which are valid as research but then neither is an unpublished lawyer paid article) show much smaller variance with a strap HRM.

  • abatonfanabatonfan Posts: 1,123Member Member Posts: 1,123Member Member
    But when does it cross into personal responsibility? If one has a medical condition that requires them to very closely monitor their pulse (the first thing that's coming into my mind is someone on digoxin who would need to hold their dose if their resting HR is below 60BPM), then it would be rather foolish for them to rely on a more inaccurate piece of technology. If I used a continuous glucose monitor to track my blood sugar (imagine it like how a fitbit measures HR), it would still be my personal responsibility to do a true blood glucose test (pricking my finger and checking it with my meter versus reading what the CGM thinks I am) if I am going to be making a diabetes decision that is highly dependent on my blood sugar (such as determining how much insulin to take to correct for a high blood sugar reading).

    I was looking at some stats from my last workout at my university's gym. The elliptical machine I used said my average HR was 144 (3.1 mile distance, about 300kcals burned, 35 min duration, though my hands weren't on the HR bar the entire duration of the workout), while my charge HR says that my average HR was 135 (260kcals burned).
  • lemurcat12lemurcat12 Posts: 30,886Member Member Posts: 30,886Member Member
    I've noticed in the last year that the machines in my gym have a disclaimer about the heart rate that it's not necessarily accurate.

    On the other hand, I've been wearing my Apple Watch (which I never trusted for HR), my Garmin (which I do -- chest strap), and occasionally checking on the machine, and for me the numbers have been identical. (I don't use machines that often, so this is just a spot check, but I was impressed with how much better the Apple Watch did than I expected.)
  • tomtebodatomteboda Posts: 2,176Member Member Posts: 2,176Member Member
    Useful information here. I am thinking about getting a hrm because my resting pulse has gotten super low (high 30s, low 40s consistently) , and my rate during activity has also dropped significantly, just to get more data before seeing a cardiologist.
  • jbrooks222jbrooks222 Posts: 1Member, Premium Member Posts: 1Member, Premium Member
    I have a FitBit Blaze. When I am exercising I put the band on a looser setting, slide it up my arm a few inches, and use a terry cloth tennis wristband to hold it in place. I also try not to swing my arms too much.
    Overall I have found that if I baby it, the Blaze seems pretty accurate. If I don't, it loses contact with my arm and gets crazy heart rate readings that are way too high.
    I still like my Blaze but expect a lot of people (quite reasonably) wouldn't have that much patience.
    edited May 2016
  • emmafulfordemmafulford Posts: 10Member Member Posts: 10Member Member
    I find if I wear my Fitbit hr three finger widths above my wrist bone like the instructions say it's pretty accurate.
  • canary_girlcanary_girl Posts: 366Member Member Posts: 366Member Member
    I find the FitBit overrated in general. It's lacking in monitoring heart rate; my chest strap is far superior. The step function, if worn on the wrist csn be misleading. I can get a few hundred steps just folding laundry. I thought the sleep tracking function would be interesting, but it simply tells me what time I got into bed.

    I'm ready to get rid of mine.
  • Christine_72Christine_72 Posts: 16,074Member Member Posts: 16,074Member Member
    I find the FitBit overrated in general. It's lacking in monitoring heart rate; my chest strap is far superior. The step function, if worn on the wrist csn be misleading. I can get a few hundred steps just folding laundry. I thought the sleep tracking function would be interesting, but it simply tells me what time I got into bed.

    I'm ready to get rid of mine.

    My fitbit tells me how many times I was awake or restless throughout the night, and how many hours of sleep I had. It also has automatic sleep recognition , in other words i don't have to press a button when i go to bed or get up in the morning.

  • Need2Exerc1seNeed2Exerc1se Posts: 13,589Member Member Posts: 13,589Member Member
    I find the FitBit overrated in general. It's lacking in monitoring heart rate; my chest strap is far superior. The step function, if worn on the wrist csn be misleading. I can get a few hundred steps just folding laundry. I thought the sleep tracking function would be interesting, but it simply tells me what time I got into bed.

    I'm ready to get rid of mine.

    I think it's supposed to track steps for things other than walking. It's counting step equivalents. No idea if it's accurate but I'm pretty sure that's what it's supposed to do.
  • The_EnginerdThe_Enginerd Posts: 3,933Member Member Posts: 3,933Member Member
    Other optical devices like the Mio or Scosche are intended to fit tightly on the mid arm and do not seem to have the same issues. My own testing (Scosche) and dcrainmakers (neither of which are valid as research but then neither is an unpublished lawyer paid article) show much smaller variance with a strap HRM.

    To add my own experience, I've use a Scosche one on my upper arm for 4-5 months now. Other than some glitches where it would read 10-20 bpm too high for about a mile before suddenly settling down to the correct HR, it has been within a couple of BPM of my Garmin and/or Polar chest strap HRM. I wear it on my upper arm as the readings seem to be better from there. I'm also quite pale.
    edited June 2016
  • Sabine_StroehmSabine_Stroehm Posts: 19,426Member Member Posts: 19,426Member Member
    I test mine regularly. It's usually within 2 beats of my finger tip monitor. Good enough for me.
  • srecupidsrecupid Posts: 660Member Member Posts: 660Member Member
    I find the FitBit overrated in general. It's lacking in monitoring heart rate; my chest strap is far superior. The step function, if worn on the wrist csn be misleading. I can get a few hundred steps just folding laundry. I thought the sleep tracking function would be interesting, but it simply tells me what time I got into bed.

    I'm ready to get rid of mine.

    I went to the doctor yesterday. My pulse was 88 and i was a little nervous. As of right now my charge hr is reporting 76bpm. I'd rather underestimate calorie burn than overestimate it. That being said I am on day 2 and it's adjusted my mfp by 585 calories after walking 9700 steps. The most my vivofit 2 ever gave me back was 439 on monday when i recorded 20,000 steps. I have been making more of an effort to walk uphill instead of flat surfaces now that I have the HR but, it still seems rather high. I guess I really need to test it to find out though. I have a chest strap monitor (2 of them actually) but, they are kinda useless if you don't feel like putting them on. Walking is a leisurely activity to me and I don't want to take the time to make sure everything is ajusted properly before leaving. The charge HR may be inaccurate but, it encourages me to move more (while if i'm putting on a chest strap i had already planned on exercising). If i need to put on a chest strap before exercise that is one more obstacle in the way of me actually doing it. Where as I just put the charge hr on and forget about it. Yes it may just be a glorified pedometer but, I like to know what time it is while i'm at work (not supposed to have a phone on the sales floor) and it's about the same price as a decent watch (and much more useful than a dumb watch) imo. Plus it's more comfortable than any watch I ever wore (hairy arms). That being said I can't wait until android wear watches can do everything that the fitbit can and more. Edit just did a random non scientific test. My polar h7 and my charge hr reported the same heart rate at the same time. But, it adjusts at a slower rate than the chest strap.
    edited June 2016
  • MeanderingMammalMeanderingMammal Posts: 7,870Member Member Posts: 7,870Member Member
    srecupid wrote: »
    I'd rather underestimate calorie burn than overestimate it.

    The issues in the original post relate to discrepancies between actual and recorded HR, not differences between actual and device guestimated calorie expenditure.

    That said, at the levels you're citing the correlation between HR and calorie expediture is very weak. Essentially it's not an indicator of calorie expenditure at the lower end of the range.
    Walking is a leisurely activity to me and I don't want to take the time to make sure everything is ajusted properly before leaving.

    Walking shouldn't raise your HR to the level that it becomes a reliable indicator of calorie expenditure, particularly if that's leisurely. It wouldn't matter whether it was an optical or electrical pick up taking the measurements, the calorie expenditure would be overinflated.
    hairy arms

    That'll contribute to your reading discrepancy as well. Optical pick up is badly affected by body hair
  • srecupidsrecupid Posts: 660Member Member Posts: 660Member Member
    Fair enough. I just live in a rather hilly neighborhood so I assumed I would burn more calories going up said hills than if I was to take the flat route. Even if it's not particularly accurate it still encourages me to not take the path of least resistance. I paid less for it than a decent watch so I'm not complaining. Pretty sure calorie adjustment is way off though.
  • NorthCascadesNorthCascades Posts: 9,532Member Member Posts: 9,532Member Member
    I test mine regularly. It's usually within 2 beats of my finger tip monitor. Good enough for me.

    In what context? Do you test it while you're sitting on the couch, or while you're running?
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