Heart rate inaccurate

[Bluekona]

I have the new blaze and am pretty happy with it overall.  I had an HR prior to the Blaze.  The only thing that I do not like is that I cannot get either FitBit to monitor my heart rate accurately while I exercise intensly.  When I am lifting, I wear a Polar Heart Rate Monitor with a chest strap.  My Blaze does not come close to the Heart rate that the Polar shows.  I have been extremely active for my whole life.  I count my HR manually.    The Fit Bits are dangerously inaccurate.   My average HR while lifting is over 120 with a max of over 160.  The blaze only measures an average of 95 and a max of 120.  The inaccuracy throws off my calorie count for the day.  I slide it up and down my arm trying to find a sweet spot.  But, no matter what I do I cannot get an accurate heart rate until my HR drops below 110.
Strangely, it seems to be fairly accurate when I am hiking intensly.  It comes close when I use the eliptecal cross trainer at a moderate level.  However, if I do HIIT it will not measure correctly.  I really don't know how to get it to work correctly when I am lifing weights or working out hard.

[CambyMan]

I've noticed the same exact thing! I've also been comparing the Blaze HR readings to my Polar H7 Chest Strap and the HR readings for weight lifting or HIIT sessions differ significantly. However, on a steady jog or run, the Polar H7 and Blaze readings are very close (after a a few minutes...the Blaze readings are slower than the H7 at first but seem to "catch up" after a couple of minutes). Maybe a future firmware update will improve the performance & accuracy???

[bbarrera]

Yes, this is a known HR accuracy problem with Fitbit's optical HRM. Has been consistently reported for 14 months, since the Surge and 'PurePulse' were introduced. Unfortunately you can't connect a Bluetooth chest strap to Blaze (or any Fitbit), so there is no workaround. In addition to weight lifting, where my experience is very similar to yours (Surge read 60-80bpm, actually at 120-160bpm), I've also had trouble getting accurate HR when spinning and cycling -- this has been documented in a detailed Blaze review performed by a triathlete well known for testing fitness devices.

[Rich_Laue]

Are you wearing it the two to three finger widths from the wrist joint as Fitbit recomends?

[JeffWski]

I thought the HR monitor was decent on the Blaze until this weekend when I did some interval training.  At times the Blaze's HR would match my chest strap, but then others it was signficantly off. It started to get real bad during the first cool down section.  My HR went from 130 to 100 on my chest strap monitor. My Blaze actually increased from 130 to 160! That's absolutely wrong. Obviously my HR went down during the cool down.  2 out of the 3 cool downs the Blaze HR went up instead of down.  Often during higher intensity the HR would stop reading like I've seen others say. I've tried it all over my arm, loose and tight. 

[CambyMan]

Yes. Tried it at the two-finger and three-finger positions. Same results. 

[Bluekona]

I have moved the blaze up and down my arm so often that it interferes with my exercise.  I am really disappointed that it is not more accurate.  I work out with weights 4+times per week and get on the eliptical for HIIT 2xs per week.  There is no point in even wearing the blaze during these exercises.  I have even had situates where it gives me inaccurate readings during hikes.  If it doesn't work, I am wonderinng why I spent $200 for a watch that I never needed?  I am really considering getting my money back.  Maybe when they get these issues worked out it will be worth it, but $200 for a bad HR monitor is not a good use of money.

[AdamMSC]

It's odd that you say that... so many 'experts' have commented on how much better this hr monitor is than on previous fitbit devices. Those must have just been pointless... Honestly, I have found mine to be accurate enough. Wrist-based hr monitors are generally inaccurate for hight intensity workouts... You have your chest strap for those, and that is great! The blaze is mostly meant for giving you an overall picture of trends, not medical grade accuracy.

[FelixFive]

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@AdamMSC wrote:

It's odd that you say that... so many 'experts' have commented on how much better this hr monitor is than on previous fitbit devices. Those must have just been pointless... Honestly, I have found mine to be accurate enough. Wrist-based hr monitors are generally inaccurate for hight intensity workouts... You have your chest strap for those, and that is great! The blaze is mostly meant for giving you an overall picture of trends, not medical grade accuracy.

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So many people seem satisfied with "accurate enough" on a $200 electronic device from the leading company in the wearable market (vs knockoff vendor product where this would be expected).  That's cool.  But I haven't seen any post wherein someone is asking for "medical grade accuracy" and I'm not sure what that even means in this example.  Technology is technology whether medical, fitness, music, accounting.  If I had, say, an MP3 player (remember those?! lol) that consistently albeit occasionally skipped tracks or a calculator that occasionally but unpredictably produced wrong results I'd be a bit perturbed too. 

If PurePulse heart tracking is advertised as a great way to monitor everyday resting / non-training heart rate, or tracking moderate but consistent motion training or something like that, fine, but PurePulse is advertised as "Check real-time heart rate to ensure you’re giving the right amount of intensity during workouts" and "By measuring how fast your heart is beating, Fitbit trackers with PurePulse technology can more accurately gauge how many calories you’re burning." Intensity is mentioned because PurePulse is supposed to do more than just providing day in / day out trends, and PurePulse is also a feature on the  "performance" device, Surge, without modification.

Fitbit even provides tips and tricks to get better accuracy during intense exercise, so certainly Fitbit is selling Blaze as a capable activity heart rate tracker whatever the fitness intent. Unfortunately, the data accuracy becomes more compromised because if HR is inaccurate, or for that matter, step count, then calorie assessment will be inaccurate, too - bad data in means bad data out - so "accurate enough" spirals into less and less accurate correlated data like calorie counts.

For me, the biggest issue, the most frustrating issue, is the unpredictability of the PurePulse performance l leading me to spend more time trying to make it work, or validate it's accuracy, or troubleshoot it's functionality, or scout out tips and tricks, than I spend exercising. I sure hope they find a way to fix their technology or at least come out and say what it is for and what it is not for, more than in a FAQ stating optical HR limitations, because that is *not* what I see on their cool commercials and colorful advertising.

[SunsetRunner]

Most wrist HR devices do not do well when lifting weights. I have seen it on the Apple Watch, too.

[AdamMSC]

I mentioned the medical-grade accuracy as a standard of comparison. Wrist-based wearables are not going to be nearly as accurate as an EKG, for example, and they are known for being off when pushing the body to its limit... I agree that the advertising can be misleading, and fitbit has had lawsuits filed against it because of that. But I guess I am not as dissapointed in the watch because I did my homework beforehand and knew what to expect. Wrist-based wearables are not to the point where they can be reliably depended on for HIIT; however, generally speaking, they do a good enough job at tracking trends. And people are satisfied with that because that is what practically all wrist-based tech does at this time, save a few examples (mio and maybe one or two more, but they have to be worn so tight that they leave marks indented in the skin). With that said, I have checked its (blaze) accuracy while working out and found it to be within 5-10 beats directly after jumping rope and directly after lifting weights... I am surprised to see the complaints about the wild inaccuracies. I can honestly say I have not experienced that yet...

[Tyler91]

I have the same issue.  Blaze heart rate is way low during intense tennis singles.  I have been using Surge to track the same activity over the last 8 months.  So, that is my point of reference.  I'm sure my Blaze is way off.... Frustrating... $200 for tracker plus $220 for leather and metal bands...

Location and tightness on my wrist seems to have no effect.

[Tyler91]

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@Tyler91 wrote:

I have the same issue.  Blaze heart rate is way low during intense tennis singles.  I have been using Surge to track the same activity over the last 8 months.  So, that is my point of reference.  I'm sure my Blaze is way off.... Frustrating... $200 for tracker plus $220 for leather and metal bands...

Location and tightness on my wrist seems to have no effect.

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I should add that the resting heart rate tracking seems to be accurate.  It's only during high intenstity activity where the heart rate seems to be tracking very low.  

I know that my average HR should be around 150 during my normal tennis workout.  I'm consistently getting a 110 average over the past 6 or 8 workouts with the Blaze.  Way off...

[AdamMSC]

So weird... can you get it to go past that point at all? I think there may be some faulty devices out there...  I've done some tests on my device to see if it would react quickly to changes in heart rate, and it did very well... I am attaching two workouts to show the variation in my heart rate while I do different exercises. I check my pulse manually and compare it to the watch. I have a polar h7 chest strap coming in for more specific detail and will post comparison graphs this coming week..

[Tyler91]

Adam,

Yep.  Today during 2.5 hours of tennis singles, the tracker showed two spikes to about 170 (which is accurate).  But, only for about 1 minute...should have been closer to 60 minutes of peak.

[Tyler91]

Here's a better size...

[AdamMSC]

I've definitely not done anything that labor intensive, nor have I used it for tracking any sort of sport. Mine has all been controlled weight lifting and gym work outs. That is a bummer... Do you have a chest strap? I started researching them once I realized that wrist wearables aren't accurate for high intensity workouts; they are cheaper and smaller than I thought they'd be (chest straps). Something to keep in mind if you want something more accurate than what the blaze is going to give you.

[Tyler91]

Here's the activity detail from last month with my Surge...nearly identical activity wth my regular hitting partner.  The Blaze seems to have an issue...

[AdamMSC]

I forgot about the dashboard on the laptop. It's easier to interpet the numbers. From the Blaze.

[AdamMSC]

Yeah there's definitely a big difference between that 137 and 112 average that you posted... Mine was right in the 130 avg for today, and I was working pretty hard. There must be something wrong with your watch! I hope you can get a new one that works better if that's what you decide to do.. Fitbit has a 45 day return policy, so you have some more time to mess around with it if you want to! Oh yeah, if you haven't tried it yet, you should hard reset your watch! Press and hold the left button and bottom right for 10 seconds. That helped me with some problems that I was having, but I am not sure if it'll make any difference on the monitor.