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.

[Julie19]

The daily resting heart rate value appears to be an average over several days.  I say this because I get an elevated resting heart rate after eating foods that I am sensitive/allergic too, which can last for several days.  When my heart rate drops back down to normal, Fitbit will calculate an average resting heart rate value that is higher than every single data point on the chart (and yes, that is after a night of wearing it to sleep).  So my logic is that it must be including data from the previous day(s).  I know the algorithm is a secret formula, but can someone please confirm this and let me know - is this a five day average?  Seven day average?  Thanks!

[Yiran]

I'm wondering if the RHR on the App has anything to do with visits to the dashboard from a computer: i.e., if you visit often, then App RHR changes more often during the day.

[rjas82]

Hi Mariam. Thank you for this helpful response. Would you be able to provide some more details about how the algorithms calculate RHR?  I wear my monitor to sleep and although my sleeping heart rate seems to vary between 44 and 52 on any given night, my app gives me a resting heart rate of 60 at the moment. I would like to know how this number is reached so that I can interpret it and know what it means. E.g. Does the algorithm apply any kind of averaging from historical data or is today's RHR calculated ONLY with HR data from today?  The reason I ask is that in the past I have taken my waking pulse as an indicator of my health. It tells me when I'm getting ill before the other symptoms appear, and when I have recovered. And if I have been over-training etc. So I need to know more about how the RHR on Fitbit is calculated in order to trust and interpret this number as it relates to my health otherwise I will revert to using a simpler measure that like waking HR which I can have confidence in and understand precisely what it it. Many thanks!

[dpayne69]

Anybody who is interested in tracking their resting heart rate is pretty serious about their health and data.  So, unless they understand the basis of the calculation, won't fully trust it - which limits the usefulness for the very people who would find it most useful!

I would strongly advise Fitbit to be more transparent about their approach.  Not necessarily publishing the exact details of the algorithm, but more information than merely "Fitbit  makes use of HR data from both when you're asleep and awake".

Almost every day my reported RHR is significantly higher than my lowest HR recorded both while asleep and while resting (e.g, lying on the sofa watching TV).  So clearly the value reported isn't consistent with the standard definition of RHR.

That said, I'm happy to use a non-standard measure, as long as I understand what's being measured,  And as long as it's consistent, that the trend is still meaningful, and therefore an indication of fitness, illness, stress etc.

Come on Fitbit - a little more transparency would significantly increase customer satisfaction with this feature.

[Yiran]

Somehow my RHR on the iPad App is always lower than the number online, by one. Is that normal?

[Chena]

My RHR during sleep is typically 58-60 and I wear Fitbit to bed so why does it show my RHR to be 69?  

[Babinator]

It must average in the time you  

are not wearing it.

I don't wear my FB. HR when sleeping.
Does this affect my average resting heart rate?

Sent from my iPhone

Moderator edit: merged reply

[jross0427]

That's not true.. I've seen my resting heartrate change during the day. Hours after being awake.

[SunsetRunner]

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@jross0427 wrote:

That's not true.. I've seen my resting heartrate change during the day. Hours after being awake.

What isn't true? It's hard to know what you're disputing as you haven't quoted anything.

If you mean the bit about FitBit using heart rate during sleep as part of its calculation for RHR, the fact that RHR changes throughout the day does not negate that. My RHR also can change a little during the day (obviously only if I sync multiple times) and yet I still don't doubt that it uses some sleep HR as well.

[jross0427]

@SunsetRunner I was referring to your comment " it's not always taking or calculating RHR when you think you are just sitting, resting, not doing anything."

J

[SunsetRunner]

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@jross0427 wrote:

@SunsetRunner I was referring to your comment " it's not always taking or calculating RHR when you think you are just sitting, resting, not doing anything."

J

I still don't understand why this isn't true. Are you telling me your FitBit never measures 'false' steps because I know mine does; not a major issue on the scheme of things but also would suggest (by FB's own statements) that it's not calculating RHR at that point as it thinks you're involved in 'activity'.

Unless there is a time threshold as well in which case maybe it is using that time for RHR.

[jross0427]

@SunsetRunner My fitbit definitely counts false steps. At that time even though the steps are false I suspect they are not using heart rate data at that time. However the moment you have very little movement but are awake, I believe it's continually looking at your resting heartrate. We may be saying the same thing.

J

[MariamV]

Greetings Fitbitters!

I'd like to step into this thread to let you guys know that your trackers calculate your Resting Heart Rate when you’re awake, calm, comfortable, and have not recently exerted yourself including your heart rate data from when you’re awake and asleep. I recommend wearing your trackers to sleep, for best accuracy.

Please note, that your resting heart rate is usually higher than your heart rate while you are asleep, so don’t be surprised if your resting heart rate is higher than the lowest number that you see in your heart rate graphs.

Also, your heart rate may be affected by a number of factors at any given moment. Movement, temperature, humidity, stress level, physical body position, caffeine intake, and medication use are just a few things that can affect your heart rate. Different medical conditions and medications can impact your heart rate too.

Hope this makes sense. Let me know if you have any other question!  

[TAK61]

Unfortunately this description does not add any details or specifics to prior statements. Basically Fitbit is saying, resting heart rate is calculated based on available data. Not super helpful. Here are some very specific questions that would be great to know.

Is today's resting heart rate value based only upon today's data? Or is data from prior days taken into consideration?
Can resting hear rate change over the course of the day? Or is it fixed once it is calculated sometime each morning?
If resting hear rate is higher than the heart rate displayed while resting, then what is the resting heart rate calculation?

Thanks

[dsr1]

What a load of total clap trap. A solution indeed!

So FitBit has a new method of calculating resting heart rate? Do they have a new metre and centimetre too?

Time to stop pretending and give the user the option to enter their own resting heart rate or snapshot a current reading. It is not within the capability of the device to determine resting heart rate without guess work. So why make a pretty good device look like a clown with nonsense algorithms?

[klez42]

I think it's a little confused here - this is mid-afternoon after my third coffee and my 'resting' heart-rate is _still_ higher than my current heart-rate.  And my heart-rate actually went up when I grabbed my phone to take this screenshot 😛

Charge HR, latest app version and device firmware.  Sitting and typing - not very active but clearly not sleeping...

[SunsetRunner]

The responses from FitBit "staff" as well as the calculation are not acceptable.

A major point of contention is being told how to live one's life to get (limited) use of their (FitBit's) product - wearing a rather large watch while sleeping is not ideal and presumably many do not do so. (Sounds rather like the "you're holding it wrong" excuse).

RHR is mostly stipulated as being taken when awake, some definitions specifically include "awake but at rest" (e.g. Wikipedia which is where most searching for it would end up / take as authoritative) so the sleeping rate is not, and should not be, a necessity and definitely not a predominant part of the calculation.

After much effort to get hold of the logged heartrate data (thanks FitBit for making that so difficult) that was compared to the reported RHR (multiple days over a 2 month period compared, these are examples):

Reported 75; Minimum (daytime, at rest) 64

Reported 78; Minimum (daytime, at rest) 65

Reported 75; Minimum (daytime, at rest) 63

(Device reading is usually within 4bpm of a manual reading so accuracy of device is not in question)

Fitbit staff on the forum also indicate that sleeping heart rate would be even lower than what is considered "standard"  RHR so this data is indicating a huge problem. For months I have been accepting that the reported RHR was the actual situation .... which was a concern as it was not going down with increasing exercise and only noticed this discrepancy as happened to be watching the current HR while being aware of the RHR.

Along with the requirement to beg and plead and usually restart either the phone or the Fitbit just to get a sync (standard Nexus device, so pretty much as standard as android gets) and exceptionally slow sync times and failure if no internet connection ... this current dubious nature of the reported data makes me regret getting a Fitbit even more. And also calls into question all the other data I have blindly accepted as being "at least nearly accurate".

[jsherman]

How do you see the graph of sleeping heart rate? I'm over all frustrated with Fitbit algorithm as I know when I flip over my watch when I wake up in the morning I'm at 55-57, but Fitbit usually calculates me at 61-63.

Everything I've read says I should be the 55 through 57 that I see when I look at my heart rate first thing in the morning.

And using these periods of rest seems to be BS to me as I spend my entire day sitting down working at a computer under high tension and if that is calculated into my resting heart rate of course it's going to be higher

[Styrski]

I'm noticing the danger thing.   My heartrate went up by 7 when sick last week, had remained elevated.   Suspect fitbit is using a 7 day or longer average.    Very frustrating that they are not answering the question!  

[Ken13thStreet]

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