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.

[shipo]

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@greysave wrote:

I have to agree with the original post.  I have the same issue with my Charge 2.  I don't know what algorithms it uses, but I can see my resting heart rate as much as 6-8 points lower at times during the day than what the app shows my rate for the day.  Now obviously I do not know what my resting rate is at night, but if I can see it lower than what the tracker says my daily rate is many times during the day and the sleeping rate should in theory be low as well....Seem like the measurement is flawed....

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Reading between the lines of your post, do you not wear your Charge 2 to bed?  If you don't then the RHR calculation will be totally screwed up; said another way, the Fitbit calculation requires a sleeping heart rate to be factored into the mix.

[greysave]

I should clarify.....I do wear it at night but obviously I am not checking it.  Now I do check it in the morning.  I only learned how to bring up the more detailed graphs and view the overnight data yesterday,
 
As an example....Last night my resting rate went as low as 64 BPM on two occasions and 66 BPM on other occasions. That was from 9:30 PM through 4:30 AM.  Once up I was mobile the entire time other than sitting down for about 15 minutes to eat.  My resting BPM for today (Just checked) is showing as 74 BPM.
 
When I look at yesterday my resting BPM hit 68, 69, and 70 on one or more occasion at night,  During the day I am both mobile and at a desk and at the desk I am not ever "resting," yet I still hit 74 BPM at times.  Resting BPM for the day was 75.3
 
I have to think that the device must obviously average out the numbers throughout the day and even "anticipate" a bit based upon the prior day's number.  That is the only way I can explain why I would have an average resting BPM of 74 at 6:45 AM with the low numbers that I had last night.
 
I know it is not a medical grade device.  I think I am going to look at the graphs and use those low numbers to work off of as they are a more realistic representation of what is going on.

[shipo]

@greysave, as a general rule I've found my RHR is calculated at 9 BPM (plus or minus two) higher than where my sleeping heart rate bottoms out overnight.

[Colmcq]

About the same. Hr min 45 rhr 56

[4362]

A related topic , my heart rate and sleep activity levels are no longer part of my dashboard, why might that be?

[shipo]

It depends upon which dashboard you're referring to; your phone or the one at Fitbit.com.

[CjB929]

What I don't understand is how my resting heart rate will be in the low 50's to high 40's when I sleep, but when I wake up it says my resting heart rate is 60. Makes no sense at all.

[shipo]

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@CjB929 wrote:

What I don't understand is how my resting heart rate will be in the low 50's to high 40's when I sleep, but when I wake up it says my resting heart rate is 60. Makes no sense at all.

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Makes complete sense, Fitbit differentiates Sleeping Heart rate from Resting Heart rate (i.e. awake but inactive).

[Colmcq]

I handed my unit back and got a refund

[shipo]

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@Colmcq wrote:
I handed my unit back and got a refund

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Why?

[CjB929]

Dude, think through your response. If from Midnight to 5 am my heart rate never goes above 59 (avgs low 50's/high 40's), how is it 60 right when I wake up. I get what your saying, but that didn't fit in this example. 

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@shipo wrote:

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@CjB929 wrote:

What I don't understand is how my resting heart rate will be in the low 50's to high 40's when I sleep, but when I wake up it says my resting heart rate is 60. Makes no sense at all.

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Makes complete sense, Fitbit differentiates Sleeping Heart rate from Resting Heart rate (i.e. awake but inactive).

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[shipo]

Dude, it's because the RHR is calculated using data collected over the last 24-48 hours; it makes complete sense your RHR should be represented as 60.

[Colmcq]

It just wasn't accurate

[CjB929]

I train multiple hours every day and track everything to a T with spreadsheets so I'm not just pulling this out of thin air. I also utilize a heart rate monitor so I know what my actual resting heart rate is (when I sleep and throughout the day). My resting heart rate never hits 60, so while your logic would rationalize it by saying its over a 24-48 hrs span, the fact is my resting heart rate never gets that high. I sleep for 8 hrs a night and it ranges from the 40's to low 50's. Throughout the day it never goes above 55, so to say it makes sense because its a combination of 48 hrs is ridiculous. The fact is that Fitbit's are not very accurate when it comes to heart rate, especially on the high end. They are very inconsistent on the high end when you train extremely hard It gives you a decent ball park, but if you want an accurate reading you should utilize a heart rate monitor. I'm just surprised the low end resting heart rate is off as well.

[Colmcq]

that's precisely why I returned it.

Training at perceived exertion of about 90% and it had my HR over 100%
at an HR I hadn't seen since 1994. Err.

And RHR was just nonsense.

[shipo]

@CjB929, that sounds very contrary to my experience of how the Ionic works.

Here is the daily graph for a fairly typical day for me:

Stats for that day:

• Minimum 5-Minute sleeping average heart rate: 34
• Calculated resting heart rate: 42

I'm interested in seeing a daily graph for you.

[SunsetRunner]

Do you not rest when you are asleep? I know I do...

[shipo]

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@SunsetRunner wrote:

Do you not rest when you are asleep? I know I do...

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As I mentioned above, the Fitbit formula differentiates Sleeping Heart Rate from Resting Heart Rate.

[jsherman]

Sorry, but the Fitbit resting heart rate is a bunch of bull. The algorithm doesn't make sense averaging it out throughout the day as that counts when I'm sitting behind my desk not resting but stressing over work with a heart rate and stress rate going through the roof. My resting heart rate is supposed to be what my heart rate is right after I wake up. When I look at my Fitbit or I use a heart rate monitor right after I wake up my heart rate is 55 to 58 on average. However it put bit puts me between 62 63 and even higher. I do not believe that. I do believe my resting heart rate is what the standard industry practice is which is right after I wake up. Fitbit does not explain their algorithm or how they come up with it so how can I trust something like that?!

[shipo]

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@jsherman wrote:

Sorry, but the Fitbit resting heart rate is a bunch of bull. The algorithm doesn't make sense averaging it out throughout the day as that counts when I'm sitting behind my desk not resting but stressing over work with a heart rate and stress rate going through the roof. My resting heart rate is supposed to be what my heart rate is right after I wake up. When I look at my Fitbit or I use a heart rate monitor right after I wake up my heart rate is 55 to 58 on average. However it put bit puts me between 62 63 and even higher. I do not believe that. I do believe my resting heart rate is what the standard industry practice is which is right after I wake up. Fitbit does not explain their algorithm or how they come up with it so how can I trust something like that?!

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Who says it is supposed to be anything?  With the advent of 24x7 heart rate monitoring, we now have the ability to be much more precise with measurements and tracking.  I'm laying odds the entire medical industry evolves to the point where there are several zones associated with times when an individual is relatively inactive (just like there are now zones for activity which didn't used to exist).

To build upon the final point above, I have already seen several authoritative sources clearly differentiate sleeping and resting heart rates.  You may not like it, but that doesn't mean it isn't correct and it certainly doesn't mean the shift isn't going to happen.