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How does Fitbit calculate Resting Heart Rate?

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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.

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So frustrated with HR tracker on the versa. At rest the tracker shows 67-71 and fitbit versa app shows it 74-80. It is very inaccurate. 

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What is the actual algorithm that fitbit uses to calculate the resting heart rate. I'm sure the equation is complicated so if you can also include a simple explanation of what each part does and what each constant (if any) is for would be helpful.

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Only Fitbit know the answer to that.
I have asked the same question but no reply.
It’s clear their algorithm differs from standard definitions.

 

Moderator Edit: Personal Info Removed

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There doesn't seem to be much excuse for not explaining how they calculate the RHR. Like StephB17 said RHR was a selling feature.

 

They don’t have to give away the numerical formula, which was described as a “secret recipe” by MariamV over a year ago. A simple English explanation would do. For example, "HR at rest is defined as HR below 50% of maximum. RHR is a weighted average of all the HR at rest time with more emphasis placed on HR during sleep.” I just made this up, like every other customer I’m in the dark about how they do it.

 

It just seems like they could describe their algorithm in plain English without giving away the “secret recipe.” Customers have been asking in this forum alone for more than a year.

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Yeah, it does seem a little strange the my resting hr is higher than my he during the day. You would assume your rh would be measured when you first wake up and not based on an average during the day.

I’ll go with what iv always done.
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My resting heart rate was 56 today.  The highest it was while i was sleeping was 51. So i feel that is wrong

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Is this fixed? I am wearing the latest iconic and my hugest sleeping HR is still lower than the calculated rating HR .

 

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Hi everyone! Good to see you in the Fitbit Community Forums! 🙂

 

When it comes how the resting heart rate is calculated, resting heart rate measures your heart beats when you are still, and it can be an important indicator of the health of your heart. According to the American Heart Association website, “the average resting heart rate is 60-80 beats per minute, but it’s usually lower for physically fit people.” This is because “active people often have lower heart rates because their heart muscle is in better condition and doesn’t need to work as hard.” Also, the average resting heart rate rises with age.

 

You can find more information about this on this help article. Anything else you need, let me know!

Ferdin | Community Moderator, Fitbit

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Answering the question would be a good starting point. Repeated below:

 

There doesn't seem to be much excuse for not explaining how they calculate the RHR. Like StephB17 said RHR was a selling feature.

 

They don’t have to give away the numerical formula, which was described as a “secret recipe” by MariamV over a year ago. A simple English explanation would do. For example, "HR at rest is defined as HR below 50% of maximum. RHR is a weighted average of all the HR at rest time with more emphasis placed on HR during sleep.” I just made this up, like every other customer I’m in the dark about how they do it.

 

It just seems like they could describe their algorithm in plain English without giving away the “secret recipe.” Customers have been asking in this forum alone for more than a year.

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Crystalclear - you are indeed crystal clear!!  I thought the same (although with more swear words)

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Indeed.

 

I still don't understand how my resting heart rate is higher than the maximum heart rate all night long. I look at it in the morning and the resting heart rate is higher than any reading since about 7pm the previous day.

I do notice that previous readings seem to change at random, the last few DAYS change, that is the entire weeks resting rate will suddenly jump from about 73 to 76 . To make this clearer, on Friday, the resting heart rate for the previous seven days will suddenly change. That is the reading for 5 days ago will suddenly rise from 73 to 76.

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It is perfectly normal for your resting heart rate to exceed the overnight average or minimum.

This is simply a matter of how ‘resting heart rate’ is *defined*.

The normal accepted definition is that resting heart rate is at rest but *awake*. This definition obviously comes from when you took it yourself, or a nurse took it (and in doing so woke you up!) it is in fact poorly defined - how long at rest, sitting, lying down?

So it’s normal for it to exceed sleeping rate.

However the moderator who compared the Fitbit values to published numbers *is making a scientific error*. You can not compare numbers measured using different methods without great care. Fitbit uses overnight information; the standard method does not. You CANNOT then validly compare these figures without a careful examination of the effects of that! (I’m a professional scientist and edit a scientific Journal; this would unquestionably be *REJECTED* from a scientific journal, it is invalid.)

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Hi guys, thanks for getting back and great to see you all around!

 

Answering your question in a more specific way, resting heart rate refers to the heart rate measured when you’re awake, calm, comfortable, and have not recently exerted yourself. Fitbit use your heart rate data from when you’re awake and asleep to estimate your resting heart rate. For best accuracy, you should wear your tracker to sleep. 

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.

 

Hope you find this answer a little clearer. Any other doubt you may have, let me know!

Ferdin | Community Moderator, Fitbit

Help others by giving votes and marking helpful solutions as Accepted

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Hi there, a question about resting heart rate, I got my Fitbit Alta HR a couple of weeks ago and have been wearing it day and night ever since. I’ve kept an eye on my daily resting heart rate - which I believe is supposed to stay roughly the same value - however it has decreased dramatically and is now starting to increase. For example, the values from day to day go like this: 84, 80, 78, 76, 74, 73, 76, 75, 73, 72, 72, 70, 69, 69, 72, 73, 75. Why is my heart rate varying by such a large degree? Is it a fault with the tracker? As I said before, I believe the resting heart rate value is supposed to stay within a relatively short range with only small increases/decreases over a longer period of time, not a matter of days. Thank you for your help.

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The resting heart rate is the DAILY resting heart rate not your overall resting heart rate. So with the values you provided your general resting heart rate is about 74 and that should stay about the same over time.

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It 7am on Sunday. Sunday started at midnight 7 hours ago. My highest heart rate in those 7 Sunday hours was 73. But fitbit claims my Sunday resting rate was 74, at 7am when no heart rate was above 73. Why is that so hard to understand?

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It is pretty meaningless to look at one days resting heart rate and compare it to the next. It can fluctuate a fair bit due to exercise, what you eat, and in the Fitbit case how well you sleep. Because Fitbit use an undeclared algorithm which incorporates overnight measurement, it cannot validly be compared to *anything* else.

Your resting heart rate can change slowly with time. If you start exercising vigorously and regularly, it should slowly drop. This could take several months to show up clearly. But you need to compare averages over say a month, not day to say changes.

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