Blaze resting heart rate absurdly inaccurate?

[WalshDaddy]

I just recently purchased the Blaze to help monitor my heart rate.  I had previously had a fitbit One, but my doctor wanted me to monitor my heart rate because of medication that I am on.  I figured that I might as well kill two birds with one stone and get the Blaze to monitor my steps and keep track of my heart rate at the same time (I find it challenging to try to take my pulse throughout the day and doubt the accuracy of my own readings so I thought an electronic device might be more accurate).

I have read through many posts,  but have not found an answer to my problem.  How does fitbit calculate resting heart rate?

I was under the assumption that it considers your heart rate to be resting over a span of time when you have accrued a minimal amount of steps (especially this is what moderators have responded to other people with).  Example: if you have obtained 20 steps over the course of an hour, your heart rate would accurately be assumed to be in the resting state.

I work at a desk job and move very limitedly throughout the day.  I find it hard to believe the resting heart rate that fitbit claims that I have each day when it thinks that I am in "fat burn" mode for over 12 hours.  If I am sitting at my desk for 2 hours straight, why does it think that my heart rate isn't at the resting heart rate stage and instead claims that I am working out and in fat burning mode?

I believe that fitbit, instead of calculating resting heart rate the sensible way (by measuring your average heartrate when you are resting), instead just ASSumes that if your BPM is over 100 you aren't resting.  Why else would I be in "fat burn" mode while sitting at a computer (I really can't type THAT fast)?

Could someone please enlighten me beyond the canned ambiguous and pointless responses that moderators have been providing to other peoples' questions as to how the resting heart rate is actually calculated by these devices?

[Fosse66]

It isn't a medical device; buy one of those if you want to calculate your heart rate.

Or simply take your pulse for 15 seconds and multiply by 4.

[Lordrobs]

I have to be walking pretty briskly to get into fat burn. Don't forget that your max heart rate (and therefore your zones) are calculated from your age. So the wrong age in your profile will throw it off by quite a bit.

As for resting heart rate, I'm not sure but it does say to wear it in your sleep to maximise the accuracy of your resting heart rate. I wonder therefore if it uses your heart rate just before it detects that you are awake? If you don't wear it in your sleep it probably just takes an average over periods of inactivity throughout the day. This would most likely give a higher reading as things such as sitting up or digesting food can up your pulse rate.

[fudge22 · Accepted solution]

You can manually adjust the heart rate zones if you find they don't work well for you and your personal fitness level. 

My resting heart rate average is usually pretty close to my sleeping resting heart rate. I'd look at that and adjust the heart rate zones accordingly.

Now, given the fact that your resting heart rate is over 100 bpm I have to agree with your doctor that you should keep track of your heart rate on a regular basis. Since your resting heart rate is in the average person's fat burning stage, your heart is working really hard on a constant basis. I would suggest doing moderate exercise on a regular basis to decrease your resting heart rate. This is just my personal suggestion though.

[Anointedrj]

I find when actively working on my computer and doing stressful work, the heart rate is higher.  The blaze calculates your resting heart rate while your resting; siting still, not doing anything-and sleeping.  If you are working at your desk, that is not resting.  It makes sense to me that your heart rate would be in the high nineties or fat burn.

[AdamMSC]

I am pretty sure it calculates your RHR when you are sleeping... I get a new RHR most mornings, mostly in the 40s. My heart rate is not that low during the day; therefore, it wouldn't make sense that it would be an average throughout the day. I think it takes your most consistent, lowest heart rate and calls that RHR. As for accuracy, I am not sure. I think mine is probably a little bit lower than what I get on the Blaze, but it's not too far off. I find that is has a much harder time dealing with extremely high heart rates that elevate quickly (anaerboic exercises).

[shipo · Accepted solution]

---

@AdamMSC wrote:

I am pretty sure it calculates your RHR when you are sleeping... I get a new RHR most mornings, mostly in the 40s. My heart rate is not that low during the day; therefore, it wouldn't make sense that it would be an average throughout the day. I think it takes your most consistent, lowest heart rate and calls that RHR. As for accuracy, I am not sure. I think mine is probably a little bit lower than what I get on the Blaze, but it's not too far off. I find that is has a much harder time dealing with extremely high heart rates that elevate quickly (anaerboic exercises).

---

The RHR is calculated by looking at your sleeping heart rate as well as your "inactive" but awake heart rate and then applying those rates to their proprietary formula.

FWIW, my RHR (as calculated by my Fitbit) hovers a point or two on either side of 42, however, my sleeping heart rate (as shown on my overnight heart rate graph) typically hovers a point or two on either side of 37.

[Colinm39]

@WalshDaddy How did you go with the solution from @shipo. ?

My RHR is jumping around at the moment because it is getting colder here in Melbourne and I'm experimenting with extra blankets.  It is moving from 50 to 54 and back again. The HR goes down to 41 while asleep.

[shipo]

@Colinm39, I find my sleeping heart rate is the lowest during the part of the year where I sleep the coolest (i.e. spring and fall).  In the winter I wear too many blankets to stay real cool, and in the summer, well, it just ain't very cool around here.

I'm not entirely sure why my sleeping heart rate is so low when I'm cool, but the data seems to bear this out.

[CMichelle]

A normal resting heart rate is anywhere between 60 - 100 bpm so this doesn't sound completely out of line.  It will be lower depending on how physically fit/active you are.  Those of you talking about resting rates in the 30s and 40s - not saying it's not possible but tough to believe it would ever be THAT low.  Maybe for some people but man, not many unless you are a long distance runner or something.

I would consider myself active, work out 5 - 6 days a week but I am definitely no runner and mine falls usually between 68 - 74.  I too have a desk job and checking it throughout the day, it runs in the 70s, maybe 80s up to 90 and 100s when I walk around the office.

Hope that helps!

[Rich_Laue]

If your interested in how the testing heart rate is calculated, it would be best to see what Fitbit says. Scroll to the bottom of the page - click Help - type in ",heart rate". You'll see a link to the heart rate FAQ

[shipo]

@CMichelle,

In my case, I am in fact a long distance runner, and have been off and on since the early 1970s. Back "in the day" I had several doctors try to hospitalize me because my RHR was typically in the mid 30s, and even as I got older it remained slow and strong.

Funny story about a slow heart rate; back in something like 1976 I bought my first waterbed, it was of the type which was nothing more than a huge bladder in a frame, no baffles, no cushions, no nuthin', and I would routinely get woken up because the wave action in the bed rocking in time with my slow heart as it thumped along in the high 20s.

Here is a screen shot from my phone of yesterday's heart rate graph (yesterday was a pretty easy going day with the exception of visiting my mom in the hospital and nearly 400 miles of driving), my calculated RHR was 43 for the day.  As you can see, even at my advanced age of 59 (that's a joke), I am still sleeping with my heart rate dipping into the low to mid 30s:

[Colinm39]

---

@shipo wrote:

@Colinm39, I find my sleeping heart rate is the lowest during the part of the year where I sleep the coolest (i.e. spring and fall).  In the winter I wear too many blankets to stay real cool, and in the summer, well, it just ain't very cool around here.

I'm not entirely sure why my sleeping heart rate is so low when I'm cool, but the data seems to bear this out.

---

@shipoExactly the same here and when my RHR goes up a few beats it is sometimes a precursor to a cold or infection.. When I had my total hip replacement last year my RHR got to 74 and took a month to come down to normal. The specialist wasn't worried, just the normal body reaction, medication and anaesthetic  Our body is an amazing thing when we "listen" to it..

[CMichelle]

That is amazing, @shipo - keep it up!  That's why I am active here in the Fitbit Community, you never know when you will find inspiration to step up your game.  I have tried many times to run but my heart rate shoots up way too fast to maintain for a long period of time so I've been working on intervals as well as fast walking for longer distances and times.  I'm in my early 40s so still plenty of time for me - always a goal to strive for!  Thanks for sharing!

[shipo]

---

@CMichelle wrote:

That is amazing, @shipo - keep it up!  That's why I am active here in the Fitbit Community, you never know when you will find inspiration to step up your game.  I have tried many times to run but my heart rate shoots up way too fast to maintain for a long period of time so I've been working on intervals as well as fast walking for longer distances and times.  I'm in my early 40s so still plenty of time for me - always a goal to strive for!  Thanks for sharing!

---

Hey @CMichelle, I coach a lot of beginning runners (company running club and local running club) who experience the same almost instant spike in their heart rate; in most cases, even though they *think* they're running slow enough, they aren't.

My coaching philosophy is toward LSD running (long slow distance), errr, with a slight twist, and away from what I call TFFFS (Too Fast, too Far, too Frequently, too Soon).  I don't know what your current level of conditioning is, but it might make sense for you to look up one of the many C25K (Couch to 5K) programs out there and give it a try, slowly.  If you a little more advanced than the initial workouts, skip a few weeks.  Once folks work their way through C25K, I recommend they avoid running faster at all cost (unless they're running in a race) until they can run at least an hour non-stop; once to that point, say five to six miles, start stepping up the speed for the last half mile, then the last mile, then more.  This should allow you to build the endurance to run longer distances without injury and without pushing your heart too hard until you've gotten in more conditioning.

A few key points:

• As a general rule, muscles, breathing, and cardio fitness developes fairly rapidly.
• As a general rule, joints, bones, and connective tissue take a long time (as in months and years) to develop.
• Keeping thing slow and long allows your body to develop in synch with all of its parts and systems and avoid injury.
• You do not have to train fast to run fast; most of my runners who are relatively new to running train in the ten to twelve minute per mile zone, however, almost all of them have been able to break the 30 minute 5K threshold within a year of starting C25K.
• In my case, I train in the nine to ten minute per mile pace, and yet my pace when I race a 5K is just under seven minutes per mile and my half marathon pace is just under eight minutes per mile.

[CMichelle]

Ha ha, you are SO nice, thanks for the tips but I actually did a C25K program starting Feb 1st, got to week 7 and couldn't finish. I did week 7, day 1 for maybe 3 weeks and gave up. I run super slow, only 4.2 mph so can't much slower without just walking fast and I could never get up to a full 25 minutes straight without my heart blowing up.

Downside is, I don't love running. I never did, it was just a new physical challenge I wanted to tackle but in the end, I hate every minute of it. I feel so awkward, all the jarring, pounding motion is just so unnatural to me and I am so temperature sensitive, once my body gets too hot, I'm pretty much done for. Now, my typical workouts are to fast walk a 5k, 30 to 40 minutes of Crossfit or a nice bike ride. But, I will always have a deep admiration for runners!

[Corvettekid]

Some of these heartbeats you folks have during sleeping seem WAY too low.  Normal heartbeat while sleeping is 55-70 give-or-take.

Mine is usually low-60's, high-50's.

If your sleep hearbeat is that low, it might explain why your other readings are off.  Adjust how you are wearing the Blaze or adjust your settings.

[silentium]

I think the sleep tracking is extremely accurate most of the time. I had my heart rate measured by a medical device a while ago which indicated my lowest HR as 37.xx bpm. The Fitbit regularly shows me around 40 and sometimes even 38 bpm.

I think it's just different for everyone.

[shipo]

---

@Corvettekid wrote:

Some of these heartbeats you folks have during sleeping seem WAY too low.  Normal heartbeat while sleeping is 55-70 give-or-take.

Mine is usually low-60's, high-50's.

If your sleep hearbeat is that low, it might explain why your other readings are off.  Adjust how you are wearing the Blaze or adjust your settings.

---

Check your facts, and please, don't confuse "Average" with "Normal".  The fact is, a combination of genetics and over four decades of distance running have left me with a sleeping heart rate down in the low to mid 30s and a resting heart rate in the low 40s.  For every one of us with a low heart rate, there are a commensurate number of folks with a high heart rate; hence the average you quoted above.

To take this one step further, the variance in Sleeping/Resting heart rate is not really different than the poorly formed 220-Age formula for maximum heart rate; per the formula my maximum is 161, and yet I can go for a long run where my average rate for the full 90 minute run can be that exact rate.

[bbarrera]

Agree, endurance atheletes generally develop lower heart rates over time. RHRs in 40s and 50s are common with triathletes, long distance runners, and cyclists.

MaxHR calculation used by Fitbit is just a rule of thumb, similar to @shipo I can ride for 30 minutes at my 220-age rate - and I've only been cycling vigorously for a year! If you really want to know your MaxHR then it needs to be measured (either field tested or clinically tested). For example I'd like to do a couple of these tests: http://www.athleticamps.com/performance-testing/phytesting.html and started doing (free) field tests late last year. Other (non-Fitbit) devices and training sites will automatically review recorded data and alert you to detected changes in threshhold values.