How does Fitbit calculate Resting Heart Rate?

[BigHaole]

I'm finding this very frustrating to be sitting at my desk, and see my HR showing as 74, but my Resting HR being 80.  Clearly Fitbit is not using the conventional definition (from Wikipedia):

"The basal or resting heart rate (HRrest) is defined as the heart rate when a person is awake, in a neutrally temperate environment, and has not undergone any recent exertion or stimulation, such as stress or surprise."

This definition would lead me to expect my reported resting heart rate to be the low value reached in the early morning, or at least the low value I reach, during the day.  Instead, it's above both of these.  I would like to know how it is being calculated, so I can know if my Fitbit is reporting anything useful when this number goes up or down.  Over the recent new years holiday, I got more sleep and more exercise, with less stress, so I was expecting this to go down, but it has gone up and I do not understand why.

[jsherman]

i desperately want this answer

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@Ken13thStreet wrote:

Simple question. Is RHR calculated once a day or continuously?

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[MariamV]

Hey there guys! Thanks for taking a break from stepping to visit the Community. 

Please note that your resting heart rate refers to the heart rate measured when you’re awake, calm, comfortable, and have not recently exerted yourself. Therefore, your RHR is continuously calculated if you set your tracker to automatically record your resting heart rate.

Your tracker uses your heart rate data from when you’re awake and asleep to estimate your resting heart rate. For best accuracy, I recommend wearing your tracker to sleep. 

Feel free to post back! 

[StreamingEagle]

Hi MiriamFitbit - I think everyone appreciates your efforts to answer the concern, but the bottom line is that the Fitbit doesn't seem to be calculating resting heart rate properly.  As I sit here, at rest, my heart rate is 73.  My Fitbit app tells me that my resting heart rate today is 89.  My actual resting heart rate is a bit higher than I would like, but not alarming.  The resting heart rate calculated by Fitbit is alarming.  It's clear to any intelligent person that the Fitbit reported/calculated resting heart rate is wrong, and not just by one or two BPM.

If I go through my heart rate charts over the past days, I see resting heart rates in the low 70s.  Fitbit is telling me that my resting heart rates have been in the high 80's.  This is a big problem.  The product isn't functioning as it should.  Resting heart rate is an important indicator of health, and it can be a very useful warning flag of a health problem.  A Fitbit is useless if it can't track and report resting heart rate accurately.  Will Fitbit fix this, or do I need to switch to a different wearable health monitor?

Thanks

[TAK61]

Your statement "your RHR is continuously calculated if you set your tracker to automatically record your resting heart rate." is not correct.  SELDOM does not resting heart rate value change after 8:00 am.  Also, days of similar heart rate values results in very different RHR calculations by Fitbit.  I have note been able to determine why unless the Fitbit is taking prior days of data into consideration.  is it?  After many month of asking, Fitbit users have not been provided any specific answer by Fitbit to the question of "how is Resting Heart Rate calculated?".  Why is this such as hard question to answer?  Does Fitbit not know how the calculation is determined?

[StreamingEagle]

TAK61 - they're claiming that the RHR calculation is a trade secret.  If so, that's a terrible decision, and the product managers should be replaced.  A wearable fitness monitor is a sensor, and the raw data should be available.  The Fitbit firmware and apps process this raw data to generate useful insights, but any Fitbit customer or app developer should be able to do the same thing.  RHR is a universally understood (open source) concept - not a proprietary concept or a trade secret.  Failing to disclose this algorithm just makes a Fitbit less attractive as a wearable health monitor, and it does nothing to build brand value or improve the business results for Fitbit.  The RHR algorithm should be published, and peer reviewed.  It should be customizable.  This would position Fitbit as the most open and extensible platform in the wearable health monitor market.  Fitbit also needs to make the raw heart rate data easily downloadable (add it to the download choices), and they should provide an option to auto-generate emails with CSV or XLS data logs on a regular basis.

[MariamV]

Hey there guys!

@TAK61, @StreamingEagle thanks for getting back to me! I appreciate your inputs and feedback.  As you mentioned: "Resting heart rate is an important indicator of health, and it can be a very useful warning flag of a health problem. A Fitbit is useless if it can't track and report resting heart rate accurately..." please note that Fitbit trackers are designed to provide information on behaviors and patterns; however, they're not meant to be used as medical devices. For more info about this please visit this thread. Also, check out your tracker's Cautions in the product manual here.

Since your Charge HRs are activity trackers and not medical devices, I would suggest you discuss this further with your doctor.

The info on how does your Fitbit calculate resting heart rate is in this article right here. Check it out! Hey, just out of curiosity have you  guys tried to restart your trackers? Also, please let me know if you have followed these tips on how to wear your tracker to get an accurate heart rate reading in general.

I really hope this helps. Feel free to post back! 

[StreamingEagle]

Thanks for your reply Mariam.  The article says "How is resting heart rate measured?  Resting heart rate refers to the heart rate measured when you’re awake, calm, comfortable, and have not recently exerted yourself. We use your heart rate data from when you’re awake and asleep to estimate your resting heart rate."

That's a contradiction.  Resting heart rate must be measured when you're awake.  Why would Fitbit use heart rate data from when I'm asleep?  When I see the daily heart rate graph, I see many periods where my resting heart rate is a reasonably low number.  But the resting heart rate that Fitbit reports is disturbingly higher.  It just doesn't make sense.

[Babinator]

That's why I originally asked the question about how? I don't wear it sleeping so what I'm supposedly getting is the bPm at it's lowest average for a preset amount of time? I guess.

Sent from my iPhone

[SunsetRunner]

I'm very surprised you're still in these forums - presumably as an "ex" user - given that you've been rubbishing Fitbit products for well over a year.

[gateswood]

I still get great enjoyment from the idiosyncrasies of my fitbit. It never fails to amaze me with antics like awarding me with 46 floors for mixing 25 gallons of fertilizer solution and bottom watering 31 large container plants last Wednesday.

PS: I've enjoyed laughing at my fitbits for more than a year and a half now.

[MaryPinPhilly]

Today when I awoke my heart rate was 60. I took a catnap this afternoon and when I awoke my rate was 56. But somehow my Fitbit resting heart rate says 67. I think I am going to ignore the 67 number since I haven't seen a good explanation of how that number is derived. Note that I wear my Fitbit while sleeping 

[Babinator]

Not rubbishing just one question a year ago and enjoying both my Fitbit though I can't read the face while exercising, and the response.

Sent from my iPhone

[Gregg42]

I've had my Charge HR for more than two years now, so I have some conclusions about the thing and resting heart rate:

1. Fitbit isn't going to tell us how they specifically calculate it.

2. A large portion of the calculation is dependent on using it while sleeping.

3. Sleeping heart rate is much lower than what it calculates as resting heart rate.

4. What it calculates as resting heart rate tends to be higher then what I consider to be resting heart rate (calculated by taking pulse, or looking at the Fitbit display, while lying in bed soon after I wake up in the morning).

5. Although it will calculate a new resting upon syncing after waking in the morning, this number is NOT the final one for the day. There's a 50% chance it will change after moving around a bit an hour or two later (maybe even the next day!), and I can usually guess whether it will go up or down by comparing my sleep HR graph with the night prior.

Much like body fat scale percentages, since we don't know exactly how it's calculating this, it's the trend that matters, rather than the specific number. When I'm exercising regularly, it tends to go down. After hard workout days, when it shows my sleeping heart rate is higher than normal, the resting will also go up the next day. When I'm sick (or about to get sick), it tends to go up. It also seems to average the number across a a few days, because it only goes up or down by 1 (at most 2) bpm each subsequent day.

So my advice? Watch the trend from day-to-day to see how you're doing, and get a much more sophisticated device if the exact number is important to you.

[MaryPinPhilly]

Makes sense. I've decided that it isn't really my resting heart rate because it's never the same as what I can see for myself. So it's some other undefined measure and as you suggest, I'll just look at the trend. Thanks for replying!!

[StreamingEagle]

gateswood - oh yeah, I got 30,000 steps one day for riding my motorcycle for 4 hours.  I'm surprised that an accelerometer-based system couldn't tell that I was moving at 70 mph, so it would be unlikely that I was actually walking or running.

[Tintin1977]

I too find that the resting heart rate seems a bit high...For example, today my RHR is 76. My sleep varies between 66 and 76 with a average 71 (based only on visual because i cant extract the actual data), during the day it varies between 74 and 98 with an average of 85 (again visual average). So the RHR looks to be the max of the sleeping HR because it's higher than the lower during the day... I'm no expert but it doesn't feel right. Looking at the data i would guestimate an RHR around 70.

[Seanpmo]

Why does the resting heart rate graph on my fitbit charge 2 app say that a higher resting heart rate is better?  A lower resting heart rate is better because it means your heart is stronger and doesn't have to pump blood as often.

[Dawnc7679]

So why is my resting heart rate lower than some of the readings I have been getting while sleeping?? I most have readings in the mid 70s asleep and my resting heart rate states 68.

[Holland.W]

Apparently, I have **ahem** sleep, I'm sitting at my desk seeing a resting heart rate of 54BPM (lowest BPM 47 early morning) but have a reported RHR of 61 BPM.

[sgalant]

Workouts help to lower the FitBit RHR during the same day as well, before some of my track workouts I sometimes sit at about 54 and after doing some sets and reps I am at about 52 or 51.