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.

[SunsetRunner]

Some basics on fitbit and heart rate....

https://help.fitbit.com/articles/en_US/Help_article/Heart-rate-FAQs/?q=resting+heart+rate&l=en_US&fs...

[BigHaole]

@SunsetRunner, I've read it a few times, but it doesn't actually tell us how Fitbit actually calculates Base Heart Rate.  

[gateswood]

I've been advised to not pay attention to it because it's wrong.

[norandalex]

In what way is it wrong and how do you know? 🙂

What I do not understand is how my average resting heart rate for a day is below the lowest rate of the day...

[kbmm]

What matters most is your heart rate while sleeping. There are very few periods during the day when you are considered "resting". If you're typing or talking with your arms etc etc it's not going to count as resting. The easiest way to see that Fitbit is fairly accurate with this is to look at your graph of sleeping heart rate. It will average that very effectively and THAT will be your resting heart rate. It generally will not recaculate until the following morning, because the sleeping time is when it's calculating resting.

[shipo]

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@kbmm wrote:

What matters most is your heart rate while sleeping. There are very few periods during the day when you are considered "resting". If you're typing or talking with your arms etc etc it's not going to count as resting. The easiest way to see that Fitbit is fairly accurate with this is to look at your graph of sleeping heart rate. It will average that very effectively and THAT will be your resting heart rate. It generally will not recaculate until the following morning, because the sleeping time is when it's calculating resting.

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I disagree; one's sleeping heart rate is just that, their "sleeping heart rate".  A resting heart rate is taken when one is awake and has not been recently active; a very different metric.  As for which one is more important when taken as a specific measurement; in the grand scheme of things, neither is all that important (unless unusually high), and one isn't more important than the other.  That said, what is important is the trend of both metrics.

[kbmm]

Perhaps, but that's not how FitBit calculates it -- FB uses primarily the sleeping heart rate in its calculation. You can check yourself -- your resting heart rate will only change in the morning, and it's based on your heart rate while you're sleeping (you can average it out and it'll work nearly 100 percent of the time). Your heart rate the rest of the day is not generally included in the FitBit calculation. Perhaps the movement sensors are too sensitive and it doesn't count much of your day's sitting etc. as resting. I don't know how it's calculated for medical or scientific purposes - I'm commenting only on FitBit's method because someone was asking about it. (I've been looking at my sleeping heart rate graph in the morning and then I guess what the resting rate will be and I'm nearly always right - I can guess whether it'll be a beat higher or lower than the previous day). And then it stays the same all day. What it means? Probably not much 🙂

[gateswood]

I've gotten to the point I pay very little attention to fitbit data because it's so goofy. For example, I looked at my dashboard to check my HR graph as you suggest. The first thing that made me laugh was it said  I went to sleep at 6:19 AM and got up at 8:12 AM. Actually, I got up at 6:19 AM and sat down to watch the news and eat my breakfast. Here's an even funnier thing... my fitbit graph said my HR was in the fat burn zone all night, sometimes reading over 100. When I actually got up, the HR went down to 67.

A little different than the night before when this silly thing said I slept 9 hr 30 min with a HR in the 50's and 60's when I was actually sleeping.

[HeydyF]

Hey guys! @kbmm, @shipo and @gateswood! Let me give you a little explanation of how the Charge HR calculates your resting heart rate. 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. 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. For best accuracy, 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.

If you have comments, let me know! 

[TAK61]

If sleeping average is the basis my Fitbit is still reporting values for resting heart rate that are high and inconsistent. Resting heart rate is an important measure of fitness.  I want a consistent and accurate value from my Fitbit. 

[all9685]

Straight from searching on the support search...

• How is resting heart rate measured?

[BigHaole]

That's a definition of resting heart rate, but it doesn't tell how Fitbit actually calculates it.  This is frustrating, because I've had the experience of sitting quietly, at work, and noticing that my fitbit displayed heartrate is well below the reported resting heart rate.  I understand that my lowest while asleep may be below their calculation, but I have a problem with my actual heart rate at rest being well below the calculated Resting Heart Rate.

[all9685]

It says, "we use your heart rate data from when you’re awake and asleep to estimate your resting heart rate."

[MariamV · Accepted solution]

@TAK61 @all9685 @BigHaole @all9685 thanks for joining us in the Community guys! Actually, your Charge HR calculates your resting heart rate by measuring your heart rate when it detects sleep, and by measuring it throughout the day while you are awake but inactive (no steps detected). If you don't wear your trackers to bed, it will only be able to measure awake but inactive periods during the day. In that case you may find that your RHR is reported a little higher than it would be otherwise. I also recommend for the most accurate RHR to wear the trackers while you sleep. This is calculated by Fitbit algorithms (it's like the secret recipe ). Let me know if you have any other question guys, I'll be around! 

[BigHaole]

@MariamV, thank you. That was a helpful answer. Do you know if Fitbit tries to filter out the time immediately after movement.  For example, I'm walking around, my heart rate is elivated. I stop for 10 minutes. My heart rate is still elivated from earlier activity, but my Fitbit would view it as no movement. Would that be included in the calculation of my resting heart rate? That could explain why my reported RHR is highter than I think it should be.

Also, do you know if the algorythm used by Fitbit is "stable" or has it been changing, over the last year? If the alogrythm changes, then results could sharply differ, for no reason that is visible to us.  Again, thank you for the answer.

[MariamV]

@BigHaole thank you for getting back to me! Thanks for your questions. You know I'm not that techie; however I can assure you that your resting heart rate refers to the heart rate measured when you’re awake, calm, comfortable, and have not recently exerted yourself. Fitbit uses your heart rate data from when you’re awake and asleep to estimate your resting heart rate. For best accuracy, 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 this makes sense! 

[TAK61]

Thanks for the information. Each day, I wake up and check my heart rate information on my Fitbit App. My experience is that this value never changes for that day. It does not seem to matter how low the heart rate goes the rest of the day, the stated value does not change. If the data from the day is used to calculate the bpm resting, why does it never change throughout the day? Previously I thought the value might be the value calculated for yesterday. But the documentation and notes on this forum indicate that it is in fact the value for the current date. Like many others that have shared here, I do not see any real correlation between the bpm graphs in the App and the stated bpm resting value. This is very frustrating.

Todd

Moderator edit: format

[BigHaole]

@TAK61, I have definitely seen my resting heart rate number change, during the day. One thing to keep in mind, is that this value is calculated at the Fitbit servers, and not on your device or in the app. So you have to let the app connect to your Fitbit to get the data (continuous data pull still seems to work inconsistently), then it gets analyzed, then you get the result. This is similar to how your sleep data is calculated.  It has to finish the sync, then a few seconds later the sleep data is displayed. As I said, I have definitely seen my RHR change during the day.

[Craig1]

My day time HR is regularly well below, and for long periods, lower than my stated resting HR. I wear the charge 2 for sleep. How can it still hold the higher figure as the resting heart rate?