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

[Irish57]

So sorry, ongoing problems that seems they won’t or can’t figure out!

[Suz2]

I totally agree with you. My Charge - which the screen all of a sudden went dark- did a much better job at tracking. I spent almost an hour with support on chat- and they were useless... and refused to stand behind their product!

[Frammus]

It would appear that the latest update to my Sense may have fixed HR sensing inaccuracy. Too soon to know for certain but it was dead on accurate for the first time ever after I updated to the new release yesterday. 

[SunsetRunner]

Thanks, @Frammus . Please let us know again in a couple of weeks. I'll do the same. First impressions are sometimes deceptive.

[MarkMM]

In my support case, Fitbit didn't claim to have fixed it in the new update. 

[t.parker]

@SunsetRunner what you said is exactly a perfectly described picture of the current (and probably future) situation. For my last 3 runs, only the result of one is acceptable:

 Blue is Sense and it overlaps quite well with the H10 chest strap. However, there are spikes reaching 180bpm which is probably nothing more but unfiltered noise caused by my cadence (fixed 182spm). Since Fitbit doesn't recognize cadence I don't think there is any correction to eliminate such false heartbeats (cadence taken for heart rate). Yet, this result is quite acceptable. If only little less of those spikes and it would be decent HR monitor for (at least) steady-state activities.

Then my two 5k runs (today's was sort of race).

Yesterday run. My HR elevated barely into the threshold but Fitbit (blue) shows just rubbish (also noisy spikes).

And today (local ParkRun event). In here I was running well over my threshold and stayed in the anaerobic. In other words, I gave almost all I had but Fitbit thinks I'm rather giving up 🤣 

There is no explanation why is that. Sometimes I don't even get those noisy spikes and the overall HR looks very decent. Other times it's like shown above. Interesting is that it's not that Fitbit HR is always lower or higher. It may go either way and the problem isn't only for weights or HIIT but for any kind of activity. Users trying to solve the problem by skewing the big picture and looking for patterns while there are no patterns here (maybe except that cadence thing), there is nothing that we can pinpoint and tell "this is the reason". It is what it is. There is nothing that helps here and Fitbit just keeps people waiting until they can jump onto the next watch (and as usual, customers will run with hype and pre-order because who needs to wait for in-depth testing).

[Irish57]

I agree, completely! Finally back to exercising today and nothing has
changed. My run faired a bit better than the elliptical but not much.
According to my Sense I’m quite the slacker when my body and heart beg to
differ!
I am noting perhaps, again perhaps a better lower HR but it’s far too early
to judge.
I keep hoping but probably to no avail!

[SunsetRunner]

Thanks for your great post, @t.parker .

Your graphs with your description tell all.

I don't work on such high HR, but in the end the conclusions are very similar.

[Tdif]

I know the frustration I know this doesn’t work because today I did not
have it on till after 1:30 but yet it said my heart rate was at 156 how I
wasn’t wearing it and I also notice that if I use that hand a lot or move a
lot it does that I am going back to Apple Watch this sucks and Fitbit has
not gotten back to me … I am just sorry I spent the money my versa was
better than this --

Moderator Edit: Personal info removed

[Tdif]

Also it said my heart rate was 150

• something at 1:30 am but to be honest look at these graphs they don’t make sense or match when I look at my sleeping heart rate at that time it was low 70 almost high 60 but yet on the activity screen it shows 156 ? No sense 

[James.P]

Hi to All, how do you guys be so sure that the heart rate is inaccurate? Because this thread has shakened my belief with Fitbit.

I am from Singapore and bought this watch on 10 Nov. And had installed most recent update that was released on 07 Nov. 

It seemed to me that heart rate seem to be the same as my previous watch, Ionic. 

Lastly, may you all advise or observe that settings on Non-Dominant hand may affect? I am wearing Sense and wore Ionic on left hand and set it as Non-Dominant hand (because I am right-handed person).

I had watched a YouTuber - The Quantitied Scientist - and he explained that fitbit had improved heart rate readings on the update before this Nov patch for Sense. However I am still worry that inaccuracies of Fitbit Sense heart rate readings after reading this thread

If anyone can share such views, this is helpful for me and the rest of us. Thanks in advance.

[t.parker]

@James.P I do test it against other devices like PolarH10 or OH1. PolarH10 is the best the market has currently to offer and it uses electrodes, isn't opitcal. I verify my data (and PolarH10 data can be verified with power meter, too). I can create comparison files with HR data even for non-GPS activities so activities like Spin, Workout etc. can be tested, too. One thing is data (and data don't lie, what you see is what you get) and another are body responses. For example. This is individual thing but trained body follows individual patterns. I know exactly how to lower or raise my heart rate within a scope of particular activity. The responses are quite predictable so I can "shape" my heart rate almost on demand (this is what HR zone based training is for). I don't test a single HR reading by looking at two watch screens whether they match 🙂 that makes no sense. I work with full set of data from various inputs and I apply analysis to that and results are what I have shown before (I posted plenty of comparisons here). I don't expect Sense to be 100% accurate with ECG reading but I don't expect it to be all rubbish either 😁 So answering your question - I am sure the Sense HR isn't fit for purpose (unless the purpose is drawing random lottery numbers).

[James.P]

Oh no. What did I spend my money for? And it wasn't quite cheap for my personal budget... no wonder the many negative comments here.

[Tdif]

Hi
The heart rate is inaccurate for me anyways I have worn it on dominant and
non dominant hand but it shows spikes where it shouldn’t I also wore
another heart monitor device at the same time and it was a medical one so I
know the readings from sense is incorrect
Also it reads heart rate even when I don’t wear it very strange ans wrong
--

Moderator Edit: Personal info removed

[Tdif]

I know expensive after a long time on line with Fitbit I am getting a
replacement but I have lost faith in them I will go back to the Apple Watch
other than the heart rate it is a lovely watch but I mainly use it for
that --

Moderator Edit: Personal info removed

[t.parker]

One more comparison. 10k race, pretty much all out. Sense registered just some random HR not even close to reality.

Blue -Sense, Orange - PolarH10

There are differences of 40+ bpm. I post those comparisons only for fun as it is laughable how bad Sense HR is 😛 Good that more reliable devices do the real job and Sense is just a toy.

[James.P]

This is like watching horror movies.. the gap is wide and hugely inconsistent

[SunsetRunner]

@t.parker , now you said it all, again. I also think, since the Summer firmware updates, that Sense is now mostly a toy for grown ups (yes, I probably took longer than you to reach that conclusion).

Remember those kids who liked to play doctors and nurses? There we are, playing with Sense and looking serious.

This new graph of yours tells a lot, in case anybody still had any doubt. As it happens, I have some even more terrible graphs on the low HR range during calm walks. Just didn't think it was worth the work to export them and make a good graphic like yours (I have not that routined), as most Sense users are more interested on higher HR during serious workouts.

[MarkMM]

@SunsetRunner Are those calm walks in exercise mode? I was at 110 BPM just moving around the house. Making coffee,  rinsing vegetables in the sink, etc. While in actual walk exercise mode, I couldn't hit 90 BPM walking as hard as I could. Was very frustrating and I gave up. I try to start every day with a hard walk, and was getting 0 results other than steps and stairs (ha) during morning walks. All I got was angry. 

[SunsetRunner]

@MarkMM , some of them are, others are not. I admit that since using my Polar H10 band I don't pay much attention anymore to Sense HR during walks. But the values of both devices are often quite different. Sometimes it happens Sense HR goes really well and that always makes me smile - that's the best part 😂. You know, I have a heart condition and sometimes I just can't take the risk of having sudden high HR while Sense keeps nicely (and wrongly) telling me that everything is OK with my HR. The opposite also happened many times, so... there isn't even a consistent pattern from Sense that can guide me. As @t.parker said, it's like a roulette.

As for the HR while doing in house chores, those are usually the worst by far. I can "gain" plenty of fake Active Zone Minutes just by preparing a dinner, with all those hand movements.

I read once in some forum how a user "worked out quite hard", according to her tracker, while she was knitting 😆

I don't knit, but believe Sense would do the same.