How accurate is HRV?

[SunsetRunner]

How accurate is the HRV in the health metrics?

Moderator edit: updated subject for clarity

[IronChuck]

---

@Bangkokrunner wrote:

But fitbit tells you what it means when under 20. Fitbit says: „Unhealthy“ in one word and leaves you alone with some sentences. What follows is a „study case“ in the internet from people :).

---

Interesting that you only ever get 18ms from your Fitbit as your HRV.  My HRV varies, and it matches my Whoop strap pretty well.  (Except for last night - and my Whoop HRV is so high I'm questioning it more than the Fitbit.)

Further, you're wrong that Fitbit simply says an HRV is unhealthy. It grades your HRV relative to your range - in my case last night's 28 is considered "average", and I got a blue bar, even though my HRV is low compared to most of the population. 

Whoop HRV for past weekFitbit HRV for past week

Why don't you share a screen shot to show me what you're talking about?

[Bangkokrunner]

My ECG is with my cardiologist:). I anyway cant read the waves and points from the ECG:). Important to me is the cardiologists consultation and conclusion. Above a screenshot from last three days from fitbit. Weeks before I dont have anymore. Readings below 20 were the issue. This is my last posting. All the best. I am not here too feel forced in answering. You give me that feeling. All the best.

[Shelly0872]

Thank you for posting 

my HRV is very low too and I workout all the time 

I’m 59 and it said I was in dangerous zone with low HRV !!

heck I might after this

😱 me 

[TRRN]

At least you are all getting some sort of number. I have been wearing mine for over 3 weeks now and it keeps telling me to wear it to bed to get HRV. I wear it every night and it tracks everything but that. Very disappointed in the versa 2. 

[Shelly0872]

I’ve had mine for 12 years every brand of Fitbit
I just started tracking HRV and I’m
Very disappointed
I workout 5 plus times every week for almost 15 years


Sent from my iPhone

[Shelly0872]

I read where it takes 30 days of wearing your Fitbit to bed also to get HRV reading 

[Tlinlo7don]

The major medical services available on line and my cardiologist says only
a electrocardiogram will give you a true reading over a finger or wrist
monitor. A chest strap works better. An example last night fitbit gave me
an 18 (considered very unhealthy) and sleepnumber gave me a 99 (way over
average for my age). If your concerned about this stat call your Doctor. I
did and am not paying attention to a number of fitbit reports.

[petew4]

Why do you think it takes so long. In any case, I’ve been wearing it to bed for many months and it still gives me 14-16. I use a wrist strap and I get 50, which is reasonable for my age.

What does fitbit measure? I guess it measures the beats but that cannot be used to measure HRV unless you digitize at a fine scale, which fitbit does not. I trust the resting heart rate for example but I do not trust the HRV. I am surprised they claim to be able to measure it. If you know of a scientific paper where they describe the measurement, post it and I will certainly read it!

Sent from my iPads

[Shelly0872]

Thank you very much
It’s really has done a number on me thinking something might be wrong bc my friends says 75

Sent from my iPhone

[IronChuck]

---

@petew4 wrote:
In any case, I’ve been wearing it to bed for many months and it still gives me 14-16. I use a wrist strap and I get 50, which is reasonable for my age.

---

(I assume you mean chest, not wrist strap) Are you using the chest strap to measure your HRV while sleeping?  Because as I've pointed out elsewhere in this discussion, HRV measurements taken during the day are very different from overnight measurements.  From app to app you can get wildly different measurements.

[petew4]

This paper states that your heartbeat slows 20-30 percent while sleeping and so I guess hrv would slow as well by a similar amount. In my case, my waking hrv is 50 and would go down to 35 at the extreme end of sleep. It would not go down to 15.
And the paper says that hrv goes UP during rem sleep.
Fitbit should say how they are measuring hrv. If they are sampling at nyquist, then they are good. Otherwise bad.

https://amerisleep.com/blog/heart-rate-variability-and-sleep/

[Solutiongirl]

Thank you! Ya I figured 😉 still I need to get it higher 😉

[zerocool6687]

Thanks for this… I’ve been hovering around 40-50 for awhile, which isn’t bad based on age but based on activity it felt low. Used another optical scanner and got a reading of 94 last night. Which makes more sense based on current health. I caution I don’t know the algorithm used for this other scanner but the one thing I really liked about the article was to comment around HRV being personal and they refrained from the “this is a healthy range” comment which is what I think sent most people here.

[Shelly0872]

Guess I should get one

Sent from my iPhone

[Tlinlo7don]

I believe you are right. Kind of irresponsible to set guidelines based on
age and not knowing how their averages are determined or how they
determined their overall averages to determine health.

[Shelly0872]

Yes very frustrating when you spend a lot of $$$

Sent from my iPhone

[AFP-IA]

Glad I found this thread. After seeing a cardiologist, I bought a Sense specifically to track heart health. Two brothers under 56 had heart attacks or open heart surgery and my initial calcium score scan was very bad. I’m 56. I’m in a 3-month wait for ECG and other tests and have been paranoid during this time. My super low HRV numbers have made me more anxious that I’m about to drop dead. Typical week below. Irritating that the device isn’t tracking accurately and makes me upset with my choice of tracker.
Is Apple Watch better? 

[Tlinlo7don]

I don't know what is a better choice. My cardiologist understands HRV but
isn't sure how the numbers equate to heart health. Also, it seems every
manufacturer uses different sample pulls and algorithms in determining
their results. You can buy something that gives you numbers you like or
your cardiologist will tell you your heart health, which is important to
people in our category.

[alison.p]

My son has a newer Apple Watch and he is a long distance runner with no bad habits except moderate junk food intake time to time.
His HRV readings look a lot more sensible for his age/weight, health stats and activity level. What’s cool is that you can take a measurement any time, besides the auto ones. The way he can interact with that data isn’t as extremely limited as Fitbit.

He can easily track patterns through the week based on his training and workout processes as well as sleep, and diet/hydration.

His readings have a very broad spectrum depending on when they are taken, and what stress his body is under. The point is that it’s very broad, anywhere from 38ms-148ms. It accounts for health and stress/recovery. My understanding is that both Apple and Fitbit use similar technology and the readings are given in ms. I would suspect that Apple works to give more reliable data though based on our comparisons. My range is generally between 28-35ms, and I am a healthy, active, moderately fit 37 year old female with no notable bad habits such as drinking or smoking. When I’ve used apps such as Wellatory, I’ve gotten readings that I find more acceptable given my activity, health, and habits. The problem with those is that you have to be awake and the best time to take a reading would be in a deep sleep cycle. The most accurate products will have a chest strap or something similar to give you more accurate results (I haven’t tried these myself).

If you can, find a friend who won’t mind letting you borrow an Apple Watch for a couple days, wear them both, and see how the data differs. My son is obsessed with his data so I won’t be able to do this experiment but maybe you can.


I can’t reliably depend on Fitbit for any of the HRV data measurements. I also thought I must be dying because I blindly trusted that Fitbit wouldn’t offer data on an insightful variable like HRV for which it simply couldn’t. Why bother? It’s really ticked me off with Fitbit because I spent a long time believing I had to be in terrible health which stressed me out a lot… I focused heavily on improving that “score”, leading to overthinking, and overdoing it in a panic to “get in better shape”…stress, which we all know, takes away from your overall health. With more research on the topic and FINALLY questioning fitbit’s ability to offer reliable data, I realized I was panicked for nothing and have since come to terms with simply not using fitbit for that purpose.

I’ll be switching products when this watch becomes obsolete in its other features/software/lifespan.

[alison.p]

Long reply, sorry…

My son has a newer Apple Watch and he is a long distance runner with no bad habits except moderate junk food intake time to time.
His HRV readings look a lot more sensible for his age/weight, health stats  and activity level. What’s cool is that you can take a measurement any time, besides the auto ones. The way he can interact with that data isn’t as extremely limited as Fitbit.

He can easily track patterns through the week based on his training and workout processes as well as sleep, and diet/hydration.

His readings have a very broad spectrum depending on when they are taken, and what stress his body is under. The point is that it’s very broad, anywhere from 38ms-148ms. It accounts for health and stress/recovery. My understanding is that both Apple and Fitbit use similar technology and the readings are given in ms. I would suspect that Apple works to give more reliable data though based on our comparisons. My range is generally between 28-35ms, and I am a healthy, active,  moderately fit 37 year old female with no notable bad habits such as drinking or smoking. When I’ve used apps such as Wellatory, I’ve gotten readings that I find more acceptable given my activity, health, and habits. The problem with those is that you have to be awake and the best time to take a reading would be in a deep sleep cycle. The most accurate products will have a chest strap or something similar to give you more accurate results (I haven’t tried these myself).

If you can, find a friend who won’t mind letting you borrow an Apple Watch for a couple days, wear them both, and see how the data differs. My son is obsessed with his data so I won’t be able to do this experiment but maybe you can.


I can’t reliably depend on Fitbit for any of the HRV data measurements. I also thought I must be dying because I blindly trusted that Fitbit wouldn’t offer data on an insightful variable like HRV for which it simply couldn’t. Why bother? It’s really ticked me off with Fitbit because I spent a long time believing I had to be in terrible health which stressed me out a lot… I focused heavily on improving that “score”, leading to overthinking, and overdoing it in a panic to “get in better shape”…stress, which we all know, takes away from your overall health. With more research on the topic and FINALLY questioning fitbit’s ability to offer reliable data, I realized I was panicked for nothing and have since come to terms with simply not using fitbit for that purpose.

I’ll be switching products when this watch becomes obsolete in its other features/software/lifespan.