Charge 5 inaccurate heart rate tracking during exercise

[Chuck59]

I recently switched to the Charge 5 after having the face pop off of three Sense devices in a year and a half (this is a well known issue with the Sense that is documented here and elsewhere over and over yet Fitbit never fixed it apparently).  Having a $300 device not glued together adequately to last a year, when I can get a $20 plastic watch at the mall that would last longer, is irritating enough.  Now the Charge I purchased reluctantly only because they wouldn't replace or fix my Sense is wildly inaccurate.  I walk the same distance/path/duration every day and have for a couple years; most days with my Sense I would have anywhere from 0-10 zone minutes which mostly seemed a factor of the weather (hotter = more).  I have had the Charge on for 4 days and every single time it says I am in "fat burn" within half a block of walking out my door and I am on pace to set the world record for zone minutes by the end of the week.  Literally nothing has changed but the device....same distance, path, duration, times of day, etc and there's no discernible difference in resting heart rate.   This is ridiculous....does this company make anything that stays together and works properly?

[Julia_G]

Hi, @Chuck59 , your heart rate levels in Fitbit, including fat burn, are not based on your personal resting heart rate level, but based on an average level for someone your age and sex.  If you are particularly fit for your age (or are on medications such as beta blockers) these HR thresholds during activity - fat burn, cardio, peak - may not be appropriate for you.  In that case you can set custom heart rate thresholds in your app.

[Chuck59]

Hello Julia -- I think you missed my point.   I had a Sense....for reasons I explained above I now have a Charge 5...that is the only difference.  My fitness level, age, medication status, etc. are no different.  So if I wear my Sense and go for a 3 mile walk or wear my Charge and go for a 3 mile walk the numbers should be the same....same person, same fitness level, same weather conditions, etc.  There's no reason why my Charge should be registering 10 to15 BPM higher heart rate other than the Charge is inaccurate for exercise.  Again it's an issue with the DEVICE, not me.  Why is that?

[Julia_G]

Hi, @Chuck59 , do you still have the Sense?  If so could you go for a walk wearing them both and compare?  (Obv you will need to temporarily create a separate account for one of the devices.) Otherwise it is impossible to be certain, your readiness to walk that day, your pace, your body’s responses, all could be different depending on the day.  I can confirm that both devices use the same basic principles/programs/algorithms for detecting your activity and responses; however the Sense has more features including more health related algorithms.  These are not likely to be related to basic stats like heart rate when walking, however, so only a direct, side by side comparison would really give insight.

[Chuck59]

Let me make it simple:  walked Saturday with Sense, 3 miles, average HR 95, no zone minutes;  everything was the same on Sunday except I wore the Charge and average HR was 102 with 18 zone minutes.   This pattern has continued the last three days as well only keeps going up;  Monday with the Charge average HR was 106 and 38 zone minutes.   

Nothing else was different, pace was the same, distance was the same, same amount of sleep the night before, hydration, etc etc.  Clearly something is off with the Charge.  

[Chuck59]

Also worth noting...heartrates at rest and during sleep are the same on both devices....this is only an issue when moving

[Julia_G]

@Chuck59 , as I said, the only way to test this is to do the same walk with both devices, otherwise there are too many potential variables which could explain the discrepancy, especially as you say they appear to match otherwise.  

[Chuck59]

I did the same walk with both devices...that's what I have said repeatedly.  Never mind

[Julia_G]

I mean the same walk at the same time.  You would need to temporarily set up one with a different email address and wear them both at the same time.

Also, if you are so certain that one is wrong, how do you know that it is the Charge 5 and not the Sense?  (I am not arguing, just questioning why, if you are sure one is wrong, why you are certain which one is wrong?)

[Chuck59]

I have manually taken my pulse; that's how I know.  I see on another thread that activating an exercise on Charge seems to elevate the HR recording as opposed to just doing the exercise (i.e., selecting "walk" and "start" results in higher overall measurements than simply walking without activating)...I'll try that and see what happens.  If that is indeed the case then it's clearly a glitch,

[Julia_G]

@Chuck59 and what I keep saying is you have to do the at the same time wearing both watches together.  Otherwise there are too many variables.  

As for what you saw on another question, that is partly correct.  If you activate exercise mode (rather than just passively allow it to track) the HR sampling is slightly different.  Ordinarily your Fitbit measures your HR continuously and averages it over 5 minutes in the graphs.  While in exercise mode it monitors it continuously but averages it over one minute.  So that could certainly make a difference.  For the most accurate report of your HR during exercise it is best to activate exercise mode rather than rely on “smart tracking”.

Perhaps we are getting somewhere with your concern?

[Chuck59]

The Charge simply doesn't work right with movement for some reason.  Today I walked a very short distance within the building from my office to the lunchroom and I happened to look down and I was allegedly in cardio burn at 142 bpm....though when I took my pulse it was actually 75.  I removed the Charge and readded the Sense for my evening walk and the numbers were in line with what they have been for years now.

I guess for now I will have to use the Charge for sleep tracking and the Sense for exercise....though it's a bit of an annoyance to have to delete/add them every day.