Possible Fix for inaccurate heart rate

[SunsetRunner]

So I have been toying with the Sense and it's HR monitor the last few days and think I have found a fix 

It seems their is a bug in the software in terms of how it auto generates custom min and max heart rates that cause the sensor to bug out and lag hence inaccuracies in HR, especially exercise.

I have found the following steps improved the Sense greatly:

1. Open Fitbit app

2. Scroll down to the Heart Rate tile and tap it (the one with the heart that shows your heart rate)

3. Tap the gear in the upper right hand corner of the graph.

4. Tap Heart Health listed under the exercise heading 

5. Check the box that says "Custom Max Heart Rate" 

6. Set the Custom Max Heart Rate to 200

7. Check the box that says " Custom Heart Zone"

8. Set upper limit to 200

9. Ser lower limit to 40

10 tap done in upper right hand corner.

11. Return to main screen and sync Sense.

12. After sync is complete hold down side button for 8 seconds until you see fitbit logo to reboot device.

13. After device reboots sync Sense one more time with the app.

You should notice the HR monitor is much more responsive to changes even at rest. You may have to play with those numbers a bit, but they are not your actual Max rates, they are just numbers used to calculate your Max rates.

It's my experience the auto generated numbers do not work and cause the HR sensor to lag. This appears to fix the heart rate issues with my spinning exercises. 

I hope this information helps others who are having issues.

[t.parker]

@SunsetRunner I use PolarOH1 and, as for the armband optical sensor, it is very accurate. My model is quite old and I know Polar released a recently updated version (I haven't had a chance to test it yet).

It is true that most manufacturers recommend using external sensors due to the limitations of optical wrist HR. The thing is, they can do that because their devices can connect to the external sensors. Fitbit can't. As I said, it would solve lots of issues in the world of Fitbit if they developed such a feature. When I bought Suunto Spartan and found out how bad wrist HR was there, if not for external HR connection, I would probably return it. I must say that Spartan could be even worse than Sense (in fact, I turned off on-wrist HR because it was pointless to use it and drain the battery for nothing - it was that bad!). For training, I was using external sensors (and to be honest, only then I was interested in HR so I was ok with that). Interesting is that this feature was a reason I kept Spartan so I'm really sure Fitbit could keep more customers happy (or at least semi-happy) if only they provided an alternative to the optical HR.

[SunsetRunner]

@t.parker 

Thank you for your thoughts! Certainly is very helpful. I'm new to running and has recently gotten into HR training zones since I think it is the most objective way to train. Thing is, I have yet to determine my true max HR. Fitbit uses 220 - age and in some books i've read, that is only predictive and not personalized to the individual. This also ties in to the personalized HR zones in the fitbit app being somewhat of an estimate and may or may not be suited to the individual since the max HR is based on a predictive formula. 

Since the armband also uses light sensors against the skin to detect blood in our capilaries, maybe that's the reason Fitbit recommends wearing the Sense during exercise 2 finger widths above the wrist bone where there is more flesh thereby more capilaries available to the sensors to get a more accurate reading. Armband placements that I've seen in various manufacturers recommend placing these monitors in the forearms and somewhere near the biceps....more flesh/capliaries available to get a reading. One armband manufacturer touts a third light sensor that is colored yellow in order to compensate for dark skin! 

Anyway, thanks for all the informative insights on HR accuracy. Fortunately/Unfortunately my Sense is behaving well and no issues that are present that are being discussed in the forums....except...floor count! LOL! I gave up on that since it has no relevance in my usage of the Sense. 

Who knows, maybe someone in fitbit might get the inkling to have external HR sensors available in the Sense via firmware update (highly unlikely). Maybe most of Fitbit's resources are now geared towards the next wearable that would feature Wear OS hence the perceived lack of support for the Sense. 

[SunsetRunner]

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@t.parker wrote:

@SunsetRunner I disagree, the reference sensor should be as close to 100% of accuracy as possible, hence using PolarH10 because then I can tell whether the Sense or any other device (I test all the devices I get against H10 and OH1) is close enough to be acceptable for a) average use like estimating calorie burn, b) training with HR zones in mind, c) be used for HRV d) any other accuracy-related purpose. FDA is only in the USA so I couldn't care less about that (Fitbit sells devices also outside the USA). Wristwatches will never be 100% accurate as the wrist is pretty much the worst possible place to wear such a sensor but the accuracy can be measured with data and you can do all the analysis to find the best use of a particular sensor could be. When you do your analysis what is your data sample? For me, the snapshot of the roughly sketched chart isn't enough. It may be that I need very high accuracy on the go rather than average HR, and mind that average is rather meaningless without knowing standard deviation (two watches may come up with the same average HR but the output may be still very different - then are both of them accurate or none of them or one of them? Can't tell without std.dev.). What I mean is that if something is promoted as a fix and requires factory reset (it isn't unusual for Fitbit that factory reset may brick the device) then I'd rather see proper evidence based on actual data showing the improvement. I don't think developers will even consider that as any sort of useful input without backing up results with proof (although, Fitbit developers wouldn't do anything even if the proof would hit them in the face).

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@t.parker I am not trying to argue with you, so please don;t take it as such. I think maybe you just misunderstood me.

A chest strap will always be more accurate than a wrist based monitor. This is because a chest strap goes "On your Chest" and is in very close proximity to your actual heart. Therefore its able to get a much more accurate reading. This is why wrist based devices are not approved for medical use and are not used by Dr or hospitals. Taking your pulse even with two fingers and listening is just a "rough approximation" As long as your numbers are not way high or low above whats considered normal, this approximation is considered acceptable.

The HR monitor on the Sense is only supposed to be accurate "Within the Fat Burn, Cardio, And Peak Heart Rate Zone" Its acceptable for this HR monitor to be off by 10-15 BPM from a Chest strap because the wrist based monitor is only estimating what Heart Rate Zone you are in not actual pulse rate. Does this make sense? For example, if your Sense is reading a Heart Rate of 137 BPM, and your Polar Chest Strap is reading a HR of 150 BPM, for most people both of these numbers are within what would be classified as "the Cardio Zone" Therefore the Sense is doing what is designed to which is telling you waht Heart Rate zone your in.

The Strap will always be more accurate because its placed over your chest and is  much closer to your heart than a wrist based sensor. If you end up in the hospital with some sort of medical problem  they are going to use a strap or multiple sensors on your chest close to your heart to get accurate precise readings to get a better idea of your medical condition and will not use pulse rate from the wrist or wrist based sensors.

For good estimations of what Heart Zone your in, the Sense does this well as designed, as a precise accurate indicator of heart rate, no wrist based sensor will compare to a chest strap such as the polar. 🙂

[juostu]

Sadly changes has no effect.

Did reset my sense, updated to latest firmware, changed Heart Rate settings to custom numbers and restarted and synced several times. No SPO2 face app as suggested.

Zone minutes chart numbers dropped drastically

In comparison active minutes one week with Ionic and with Sense, activity and number of workouts are very similar

Toughest workout of the week - legs, 7 day apart on the same time. Coincidence that even workout duration is the same

Elliptical cardio workout numbers are better but still not satisfactory, Sense delays increased HR up to 10 minutes. Resistance levels are identical and workouts occurred on the same time less than a week apart

So Sense goes on the shelf again and I am losing hope that Fitbit will fix this critical functionality 😞

[IgorR11]

Good Morning. You could make a step-by-step tutorial from the beginning and share it with us via google drive or youtube. I think it would help a lot the fitbit community that suffers from the inaccuracy of the heart monitor. Thank you!

[K-SINGH]

Is this fix still working out?

[K-SINGH]

is this fix still working for you and for all types of exercise? 

[Mel-M]

I tried all the above suggested fixes over the past few days and none of them worked for me.

I did have success with getting reasonably accurate heart rate tracking by not turning on exercise mode on my Sense. I made mental note of my exercise start time, did my workout, and made mental note of my stop time.  I went to the Fitbit app on my phone and my exercise session had auto recognized a partial workout in my account (which, for the amount of time it recorded, seemed reasonably accurate). I deleted the auto recognized workout and manually logged my workout.  The heart rate tracking it generated seemed surprisingly accurate.

What a pain to have to figure out how to get this expensive device to record workouts!

UPDATE:  My suggestion above does not provide consistently accurate results.

There was a recent software update to the Fitbit app which seemed to improve  the stability of some of the issues with the Sense but unfortunately the heart rate monitoring is not one of the issues it improved.  The Sense has many features that I love, however since the heart rate monitoring is one of the key reasons I wear a tracker I'm abandoning my Sense and going back to my Versa Lite.