Heart rate inaccurate on Fitbit Sense

[Cameronoates]

Hey 

is anyone else experiencing huge heart rate inaccuracy during exercise with the sense? 

During exercise with the sense it won’t ever get above 120bpm for me 

but if I use my charge 4 during the EXACT same exercise my heart rate is between 145-170bpm in the cardio zone 

It’s extremely disappointing and I don’t want to have to switch to my charge 4 everytime I exercise to ensure accurate heart rate 

defeats the purpose of having the sense 

seriously one of the most frustrating experiences I have ever had.

Moderator Edit: Clarified subject

[opiatedsherpa]

@SilviaFitbit is there any news on any updates?  Your "best answer" in September does say that there is work being done.  There is an acknowledgement of a problem, but that was three months ago.

As much as the heart rate monitor in its current state is okay for some, there are issues with it and an update would be appreciated.

[SunsetRunner]

Hey OpiatedSherpa I am a data guy as well and while zone mins may be hokey it would still be a useful statistic if consistent.

I ride the same routes daily, 30-50 minutes, presumably with similar HR at my 'exertion points' which normally sends me from cardio to peak... but, all too often it goes like this...

Notice that I begin the exertion , HR should (and frequently does) increase, but here it falls out of the zone until I get off the bike... then it jumps. So, it is in there somewhere and I think there is a fix. Unfortunately FitBit won't solve a problem which is already 'solved'.

[UnguruBulan]

@SunsetRunner I'll do an outdoors bicycling exercise (today or tomorrow), and will report back. I wonder if that HR jump is specific to that exercise...

[opiatedsherpa]

@SunsetRunner don't get me wrong, I have only seen the "hokey" argument in this forum, I really like it as a statistic.

I have been a Fitbit user for a long time and the quality has always been there, until the Sense.  If they come out with a new "top of the line" unit, I'll be first in line to get one.  Until then, I really hope they fix whatever needs to be done.

[t.parker]

@obermd for swimmers, it's actually a very poor option when it comes to tracking HR because there is no alternative given to track heart rate (additionally, the Swim feature is really poor and has no OWS support). The majority of sports trackers will connect to BT/Ant+ chest straps which have no difficulties in the water (although may have difficulties with connection but then offline caching comes). Swimming is a bad example if one has seen what's currently in the market.

@UnguruBulan I had two Sense watches and both experienced issues with HR tracking. My issues (as you can see going through my posts) show that Sense can get into higher HR, it's not a problem. The problem is that it's very often not even close to reality (like 170-180bpm when I stay in low-aerobic zones). It is true that lots of users don't really care (or have no reference to check) whether the HR is accurate. Usually, we consider something accurate when it just feels right. If we feel good with what we see then it must be correct, right? 🙂 On average, most of my activities are close within several BPM from real average HR (excluding bouldering or weightlifting - this can go totally random). This will probably work for things like calorie counting. That's the only thing the average HR is really good for. A few BPMs of difference on average won't make much difference in calories. It is impossible however to base the training on HR. True that Fitbit isn't designed for that but it doesn't mean it doesn't need a certain degree of accuracy. Moreover, Sense can be accurate, I've seen that quite a few times (and posted here those comparisons, too), it can follow chest strap really close (which I labeled as acceptable accuracy level in my tests) and this is what baffles me. Why one time it just does a really good job and nine times gives rubbish. It would be easier to accept that Sense always provides inaccurate HR but that's not the case. It can be really accurate just very rarely and I have no idea why (and won't have).

[NazH]

The HR reading is intermittent, sometimes it's spot on, other times not so much. I have raised this issue with Fitbit (they are aware of it), I'm going to pester them until it is fixed. They have asked me to switch off auto tracking for all exercises to test if there's any difference with HR reading. I doubt there will be any difference. 

[UnguruBulan]

@t.parker I totally agree that when it's way off, it's a problem that should not be tolerated. While when it's consistently just "fair enough" (my case so far, but I only have the Sense for 11 days) probably users tend to be ok with it. When it alternates between way off and "fair enough" I can see why users are annoyed. I would be too!

[opiatedsherpa]

@SilviaFitbit @AndreaFitbit @EdsonFitbit I may have found something that could be useful... in my spreadsheet, the good heart rate data with the Ionic did take a turn on 2020-09-03.  The Active Zone minutes went down considerably then, so I suspect there was a change in the coding, if an update was done around then.  A piece of coding that may have transitioned into the Sense.  Very suspicious.

[t.parker]

@UnguruBulan see this:

https://community.fitbit.com/t5/Sense/Heart-rate-inaccurate-on-Fitbit-Sense/m-p/5018621/highlight/tr...

This is exactly the case when accuracy doesn't change much when it comes to average HR and calories burnt. The difference is 11bpm. In that response, I haven't given any details about calories but the difference isn't that big either. It's approximately 86kcal for whole 1hr53min long activity that burned 1300kcal+ then +86 or -86 kcal doesn't matter, it's just an estimate anyway. It could be just a difference between algorithms or anything else. I would consider it insignificant (and each algorithm may under or overestimate energy expenditure). Hence, for the average Fitbit user who just counts steps, calories etc. even HR trashed like this (and there is no doubt looking at charts that Fitbit HR is all over the shop) won't matter at all. Even AZM difference is just 1 minute. Averaging may bring two different datasets to the same (or similar) final result. Yet, in this case, only one dataset is correct.

[Lonka2]

As I am considering a purchase of Sense tracker, I am curious if you have tried doing the same exercise with a disabled GPS and perhaps so me other unessential features.. It's possible that due to a limited processing capability, the tracker just can't keep up with the load.

[TommyIzzo]

@Lonka2 I have GPS turned off in all exercises. Notifications off as well, as I only use Fitbits for activity tracking and always have a phone with me anyway. One of my early feelings was being in an exercise mode might be limiting processing, but I just gave up and went back to an older tracker. 

[Tgisele]

As a long time Fitbit user (08 or 09) I have never had a major issue with one of their products until the Sense, as @t.parker had mentioned it inconsistant. I do not expect 100% accuracy, however something in the ballpark would be nice. I do a variety of exercises, swim, walk, circuit, yoga and aerobics, and have not found any heartrate consistancy in any exercise I do. While at the end of a yoga class my heartrate will increase, when just starting an aerobic class I am in my peak and never reach it again during the class, while taking a curcit class I would expect some ups and downs, but the downs are always much lower than they should be and the highs are not as high as they should be.  I do not think we will get an answer from Fitbit, it has been over a year and we still get the same response. "We are aware of the problem and working on it."  I hope I am wrong. Even if they come out with a top of the line product, I have lost faith in the company and wouldn't buy it. I have said this before and will repeat it, @fitbit it would go a long way, if you would admit the problem and give us some kind of answer as to when you will have an answer.  

[UnguruBulan]

@t.parker thank you, yes that makes sense.

We can make a lot of speculations what could be the reason for the HB inconsistencies.

To make a parentheses here, I never had a tracking device until this Sense. Because I never felt the need for such thing. My philosophy as an amateur athlete always was: "exercise freely, and don't think about all that none-sense like calories and all those other stats". That's actually was what everybody did, before the tracking devices were invented.
I got this new Sense because it was pretty much offered to me, for quite a large discount.
I was ok with everything it reports because I really don't want to become now, after I ran for tens of years without any tracking, dependent on and affected by its stats.
Then I saw this forum and one of the big debates is about Sense's HB issues, that made me curious a bit about what's going on.
Considering the users say other Fitbit devices report the HB correctly and Sense doesn't, one speculation that is somehow logical is the problem is specific to Sense: either a hardware, or a software one.
Building on top of that speculation, we could say maybe Fitbit is experimenting some "latest and greatest" HB detection technology on the Sense, without disclosing it to us, the users. And so far the results are not promising, the feature has inconsistencies, yet Fitbit keeps relatively quiet about it. 

[SunsetRunner]

I have a different tracker arriving in a few days and I plan to wear them both simultaneously on each wrist. Will report back in a few days.

But, I just reviewed my activities and there is no way HR is accurate. It literally drops 50 bpm when I start my sprint more often than not (but, when it doesn't I usually go into peak zone, 151, for a few minutes).

It is beyond discouraging that while pushing myself on my 34lb MT bike my heart rate drops from high 130's - mid 140's to low 80s. It basically renders the device useless in my opinion.. In reality I'm heading towards my peak zone, Sense shows an HR similar to sitting at my desk.

Prior to linking FitBit to my Strava account Strava's power output in these segments showed an increase, now that I have linked my Sense they show a dramatic decrease. Clearly inaccurate.

Thankfully I am still in the return window.

Mattie.

[KBaker81]

Same! Super frustrating—I also track via Whoop and my heart rate will be at 174 via that and at 101 via my Sense. Extremely disappointing given the amount of money spent on this and that the Versa was so much better and more accurate!

[UnguruBulan]

@SunsetRunner I've done my bike exercise test today... 11 laps on a ~1.6km road circuit, uneven terrain... unfortunately/fortunately I did not see the issue you're seeing. I've done a sprint on the last km or so, and the bpm, as expected went up and my Sense seemed to record it accordingly.

Here's the details (btw with that occasion I noticed the elevation isn't recorded properly, should've been 11 identical figures)

Bike training 11 laps x 1.6km road circuit

[opiatedsherpa]

I'm not going to claim that I found the solution, but with the way the day has been going for me, I'm very happy with the results and I want to share what I had done.

1. I waited until it notified me about the low battery.
2. When I went to charge it, I did the reset, holding down the left button for the count of ten.
3. I put it on the charger.
4. Charged it to 100%.  The clock face SimpleClockDuo does a good job of the charging process.
5. And took it off.

I slept the night and got to exercising right away and the heart rate monitor was giving me Zone Minutes without too much of an issue and the easy accumulation of the floors came right away.  I've only had it for the morning, but I'm very happy with the results.  I would wager that steps 2 through 4 are important, I'm not sure we have to do it every time it needs a charge, but I will go until it needs that boost again.

I couldn't wait to share, so I'm not too sure how long it will last, but it's definitely worth a try.

[JDubb89]

Thank you for this! I have raised this issue with Fitbit customer service on several occasions. I am on my second Sense. Their response was disappointing to say the least. I have been using the Sense since April 2021 and the HR inaccuracies are the worst. I am going to try this and see how it works for me. 

[SunsetRunner]

@opiatedsherpa ,

I totally miss the tech logic of your suggestion. Can you please tell us:

• What is the rationale behind the sequence of procedures you suggest?
• What is the role of SimpleClockDuo on this? It's just a watchface.
• Is this just a joke?

Thanks.

[MikeyP132]

When doing low intensity cardio on treadmill/xtrainor etc am getting unrealisticly high hr readings from my sense, have cross checked using other monitors which show expected hr levels. Anyone experienced similar problems?