Fitbit Sense heart rate is way off

[MarkLiberman]

Just got a new Sense. When I exercise to raise my heart rate, 3 independent monitoring methods all show (for example) a rate of 140-145 -- the sensor on the elliptical, the readout from my Orange Theory "Burn" device, and a fingertip blood oxygenation monitor. But the (apparently worthless) Sense says "89".

I've tried multiple times, different wrists, different placements -- essentially the same result.

In contrast, my Ionic was pretty good at this -- the only problem was that the battery basically died, would only last a few hours.  Overall, Fitbit seems to be making crappy devices these days.

Moderator edit: format

[KCl94]

Agreed. I mostly do weight lifting, I tried the Sense for the second time today and it did OK, the difference was about +/- 10 bpm (132 average bpm) as compared to the HR sensor on my S9+. But wow did it mess up during my StairMaster session! Sense's Peak average bpm = 116 (lower than the weight lifting!?) vs SM average = 170!

Anyhow, I noticed a difference between the first and second time when I put the sensors facing the inner side of my wrist but, for some reason, this worked only during the weight lifting session, the Sense did just as bad both the first and second time I tried it during my cardio session.

[DavideFitbit]

Hello @Maxinelabutte @KCl94, thank you for sharing all this information about your Sense watches. 

Before considering other options, I would recommend performing a restart and to follow all the instructions in this article to improve the accuracy of heart rate information, this has been useful to other users who have experienced something similar. 

Please keep me posted on the outcome. 

[Kazzy86]

Makes no difference, i have the same issue and did all that, didn’t work. Really disappointed, returned my sense and went back to my iwatch. 

[KCl94]

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@DavideFitbit wrote:

Hello @Maxinelabutte @KCl94, thank you for sharing all this information about your Sense watches. 

Before considering other options, I would recommend performing a restart and to follow all the instructions in this article to improve the accuracy of heart rate information, this has been useful to other users who have experienced something similar. 

Please keep me posted on the outcome. 

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Hi Davide, yeah I did that before my second test. I'll keep testing for the next week or two

[ThatAdamGuy]

Ah, yep, and I thought I just had a defective Sense.

Rode a spin bike today, with heart rate repeatedly (legit) peaking above 170 (as measured both by my Scoche Rhythm+ device and manual counting).

The Sense rarely got about 150, and most of the time was 15-20 (!) BPM lower than my actual heart rate.

If it can't get something this simple right (compared to devices that are 1/5th the cost!), what else is it getting wrong?  How could I trust the ECG or sleep monitoring or anything else?

Unless there's a firmware update in the next couple of weeks that fixes this, I'll be returning the watch.

[Craigside]

Hi

I have tried the Twitter support but am getting nowhere...

Basically, I’ve had a sense for 3 weeks after 3yrs of wearing a Blaze. My Blaze used to report 170+ when I was HIIT training. Sense barely reaches 120bpm same exercise?

Today I did my HIIT workout wearing my Sense and also chest strap HR monitor.
The chest strap HR recorded similar to my Blaze (170bpm), however my Sense is way off too low?

Also, my sense shows HR even when placed on any inanimate surface, (eg on table for 15 mins) is this correct?

Is there is any support it would be appreciated...

My Blaze HR recording;

My Sense HR recording same HIIT workout;

At same time, Chest Strap HR Recording confirms Sense inaccuracy?;

 

[SunsetRunner]

I normally set my watch down with the back side facing down with a sock or something under the bottom. I have found with these sensors, pick up a light source and interpret that as your heart rate when placed on the table at an angle. My Apple watch used to do that. 

[MarkLiberman]

I agree -- I've tried three more times while exercising, and the Sense is
always 30 or so below the rates from other (reliable) devices, which agree
with one another within one or two.

[Banjomanjo]

I have the exact same problem. Basically only correctly tracks my resting heart rate. it basically always wants my heart rate to be between 85 and 110. As soon as I bump up over that it jumps down to 100 ish regardless of weather on not my real heart rate is 120 or 160. Rebooted.

Tight and high in the super awkward location they want it in, tight and at a normal position, loose like a watch should be... all positions produce the same results. Running the latest firmware. Referencing my old Apple watch and manual measurements.

Pretty uninspiring... Is there anything else useful we can try other than the same article telling us to wear our watches halfway up our arm and rebooting?

[Craigside]

Mine still reported changing HR whilst lay on the bed, on the carpet, on wooden table, etc. Perhaps it’s normal for the HR sensor to show a reading for any surface, I don’t know?, but support just say ‘I’ve made a note of that’, which doesn’t help and just adds to the frustration.

Finally after ‘escalating’, Support said ‘it’s working fine’... ha ha ha!

Anyway I’ve now returned it for refund and have orders another Sense. If the new Sense still doesn’t monitor HR in a useful manner I will return it for refund and maybe buy a Versa2 while I wait for the next new Fitbit with a working HR sensor to be released.

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It isn’t how you are wearing it, I’ve found for years with Blaze - comfy on wrist never had an issue...

I’ve read yesterday a men’s magazine review which mentioned the Sense’s HR sensor doesn’t cope with high HR levels and HIIT training, ie up/down HR levels.

I’ve now returned my Sense for refund and have ordered another. If the replacement is also useless with HR monitoring I’ll ditch that one and buy something else.

[SunsetRunner]

Having owned a FItbit pedometer in the past and a Charge for sleep tracking, I wanted to try the Sense out for myself to get it out of my system and finally say that I tried. Yesterday when I got on the treadmill in the morning, I compared it with my Galaxy Watch 3 reading. The Fitbit was slow to respond when there was an increase like interval training. The Fitbit was reading way too high compared to the Galaxy Watch and I knew the reading was not correct. 

In the afternoon, the Galaxy Watch 3 was the erratic one reading bigger numbers over 30-40 bpm and the Sense was stable and the readings were somewhat reasonable. Granted it did say that I was in zone but for the full 8 minute test but only gave me 4 minutes of Active Time credit. Go figure. However, accessing the data online showed me that I did get credit but not on the app. 

This morning, the Fitbit did well with the morning treadmill. The increase in interval training was a very slow response but overall it did better than the Galaxy Watch 3. The Active Minute was still an issue as it did not give me credit for the 25 minutes I was in the zone. I then decided to clean the sensors on both watches really well. 

In the afternoon, I got on the treadmill once again this time with the Pulse Oximeter. Both the Galaxy Watch and Fitbt were in agreement with each other and the Pulse Oximeter. They were both within a few bpm of each other. When I tried to do interval training it would respond slowly but not as bad as before. The only difference between this time and the other times was cleaning the sensor and wearing the Fitbit Sense for about 10 minutes before I started on the treadmill, therefore waiting for the pulse reading to somewhat stabilize before I started on the treadmill. This time, the app gave me no credit for Active Minutes even though I was in zones for 7 of the 8 minutes which was odd. 

Today seemed to be a good day for the Fitbit Sense except for the message on my phone in the morning about repairing with my Bluetooth and the facf that my sleep tracking ended at 12:30 a.m. But after powering off the Sense and then repairing it, it seemed to operate with some hope. Will I plan on keeping it? Not sure. Seems doubtful considering I have owned this one for a couple of days now and there are too many instabilities. 

[Craigside]

Hi

It certainly is frustrating when you are looking for meaningful HR data from your efforts.

From what I have read, and experienced, it would appear that the Sense is slower to respond to changes in HR, but does reach a level when doing steady work. What I’ve read and experienced suggests that it doesn’t respond well to high/low rapid changes such as you might have during HIIT.

In comparison to my Blaze and Polar chest strap, which both report very similar data, the Sense is 40bpm lower when going flat out on the elliptical trainer.

Also frustrating is the apparent inability by Support to recognise the issue, which could indicate that it’s a hardware issue that can’t be resolved and they aren’t allowed to acknowledge?

It’s a shame because otherwise the Sense is an awesome device!

I hope my new replacement surprises me when it arrives but I shall have to wait and see...

[DavideFitbit]

Hello, thank you for your replies, for the screenshots you've provided and welcome to the new users in the Community. 

Thank you for confirming that you already tried the suggested troubleshooting steps as well. 

@Kazzy86 @KCl94 @ThatAdamGuy @SunsetRunner @MarkLiberman @Banjomanjo, I've gone ahead and sent your information to the Customer Support team for further assistance, so you should be getting a reply soon.

@Craigside, I've sent your information to Customer Support as well, but it seems that you already have a case created or that you already got in touch with them. 

Let me know if you have further questions. 

[Craigside]

Hi

My new Sense has arrived today so I’ll be trying it out at the gym tomorrow. I’ll soon know if it doesn’t report HR in a meaningful manner compared to my other devices, ie my Blaze or Polar chest monitor.

kind regards 

[KCl94]

Keep us posted!

[DavideFitbit]

Thank you for the update @Craigside, let us know how it goes with the new Sense watch.   

[MarkLiberman]

After several more tests, I'm coming to the conclusion that it's a software botch, not a sensor problem.

In two more exercise bouts in which three other devices agreed that my heart rate was between 132 and 150 for ten to twelve minutes, the Sense never showed a rate higher than 109. (132-150 is at the upper end of what I'm supposed to see, since I'm 73)

But today, I maintained the higher heart rate for more than 15 minutes -- and after the 15 minutes, the Sense suddenly started agreeing with the other devices.

This time, the other devices were the HR monitor on the elliptical machine, an Orange Theory sensor and app, and my old Fitbit Ionic -- which tracked the actual heart rate from the start, without a 15-minute delay before it would believe its sensors! :-)...

I should say that I've restarted the Sense each day, with no effect. 

This makes me think that exchanging the device might not have any effect -- we might just have to wait for a firmware update, if one ever comes that fixes this stupidity.

[DavideFitbit]

Thank you for your reply @MarkLiberman, I've sent your information to the Customer Support team for further assistance with this, but it's been taking a bit longer to receive a reply for the last few months. They should be contacting you trough e-mail soon. 

Thank you again for sharing your feedback. 

[BlueMountain]

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@DavideFitbit wrote:

Hello, thank you for your replies, for the screenshots you've provided and welcome to the new users in the Community. 

Thank you for confirming that you already tried the suggested troubleshooting steps as well. 

@Kazzy86 @KCl94 @ThatAdamGuy @SunsetRunner @MarkLiberman @Banjomanjo, I've gone ahead and sent your information to the Customer Support team for further assistance, so you should be getting a reply soon.

@Craigside, I've sent your information to Customer Support as well, but it seems that you already have a case created or that you already got in touch with them. 

Let me know if you have further questions. 

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I too am interested in being on your list. Very frustrating. I have sent my sense back so I do not exceed Amazon's return policy. I am however a big fan of fitbit and want this tracker/smartwatch to work for me. It has many features I love.