How accurate is HRV?

[SunsetRunner]

How accurate is the HRV in the health metrics?

Moderator edit: updated subject for clarity

[Tlinlo7don]

Thanks for your response. You are with the majority on this subject

[IronChuck]

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@alison.p wrote:

Anyway, all this is to say, the Fitbit HRV metric should be done away with until they can give you at least semi reliable data/readings. What’s the point?? There’s no way, that I logically have the HRV of a 70 year old man…. It can’t be. 

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Whoop has a ton of data about HRV, and they say "Rather than worrying about what is “normal” or using other athletes’ heart rate variability as a barometer, it can be much more valuable to track your own trends in HRV."

https://www.whoop.com/thelocker/average-hrv-normal-heart-rate-variability/

Looking for an app that gives you higher numbers doesn't actually tell you anything about the Fitbit's HRV measurement.  They're measuring in different ways at different times of the day.

[IronChuck]

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@Tlinlo7don wrote:
What chart or scale do you use to determine what is normal for your HRV?

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There is no "normal". If you want a measurement that you can compare with others use resting heart rate.

[alison.p]

Looking for an app that can give you more realistic measurements is useful if you’re actually going to track your HRV and learn from the trends. 

[IronChuck]

As far as I can tell, Welltory's numbers are just higher - they're not more realistic when compared to a HRV captured while sleeping.  EliteHRV just gave me a 64ms HRV from a chest strap, and Welltory thinks I have a 102ms HRV.  If you think that Fitbit's bad - Welltory looks to be just as bad but in the other direction.

[Bangkokrunner]

… you just should have gone to a cardiologist for cross checking. Would have been saved a lot of time:).

😉

[Nicollette27]

Thank you for your post! I feel the very same ... irresponsible on fitbit's
part to continue to call this HRV, which has known formulas, values, and
aspects that define it. They should RELABEL this attribute, standardize
whatever data they are collecting and have us focus on the change values
... because it is NOT true HRV. Appreciate your feedback.

[Tlinlo7don]

Thank you.

[Bangkokrunner]

Just forget the fitbit hrv figure based on 3 hours sleeping solely. You need to have an average over 24 or 48 hours. A cardiologist is the only solution when you want to know your hrv. Just make an ECG by a cardiologist if you dont want a 24 hour monitoring. Works also.

Your mood becomes bad with this gimick from „fitbit young IT programmers“ who lack behind in the market with additional working modules as part of a so called unique selling position on the market.

Its common knowledge that they also have issues with blood pressure tools in their tracker:).

Use the tracker for distance, sport tracking, pulse and be happy😀

[IronChuck]

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@Bangkokrunner wrote:

You need to have an average over 24 or 48 hours. A cardiologist is the only solution when you want to know your hrv. Just make an ECG by a cardiologist if you dont want a 24 hour monitoring. Works also.

Please cite the study which used 24 or more hours to measure HRV.  You can't, because nobody did that.  A longer HRV measurement is just a different measurement, it's not intrinsically more accurate, and it's useless if you're trying to compare based on other measurements taken over 5 minutes while awake or to HRV values taken while supine or sleeping.

[Bangkokrunner]

Sorry for my bad English. Ask a cardiologist how he measures. Of course you can measure hrv not limited after sleeping:). No study needed when a ECG tells you that as a side result:). I did it. Again I am not a native English speaker. Sorry when I am unclear.

[IronChuck]

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@Nicollette27 wrote:
Thank you for your post! I feel the very same ... irresponsible on fitbit's
part to continue to call this HRV, which has known formulas, values, and
aspects that define it. They should RELABEL this attribute, standardize
whatever data they are collecting and have us focus on the change values
... because it is NOT true HRV. 

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Say what? I just pointed out that HRV measurements don't have any standard (awake / sleeping; supine / standing; 60 seconds / 2.5 minutes, etc.) and you turn around and complain that the Fitbit HRV isn't standard?  I also shared readings from multiple devices (including a $400+ Frontier X2 chest strap) and show that the HRV measurements are not the same on any two.

But sure, I'll bite.  Where is the standard, and whose devices do a good job of measuring it?

[Bangkokrunner]

To the Recovery Runner:

Well you act little bit aggressive but no offence from my side.

Probably you should accept a comparison of different methods by one and the same person.

Fitbit vs. Cardiologist results.

At the end I believe my cardiologist.:) And his words were: „Dont interpret too much in these results from your watch.“ His machine is better:). His knowledge too:).

You are right in your statement in term of „what is normal“. Calm down.

[IronChuck]

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@Bangkokrunner wrote:

Its common knowledge that they also have issues with blood pressure tools in their tracker:).

There's no realistic way to optically measure BP without at least calibration from a pressure cuff, and the only people who know how do it appears to be Aktiia. Fitbit it trying to build the data to correlate PAT with BP, but you can't do that without electronically detecting the heartbeat, which it appears only the Fitbit Sense can do. 

Whoop measures HRV just fine from an optical sensor, so there's no reason to believe there's a technical limitation with the Fitbit that keeps it from doing the same. 

[Bangkokrunner]

She wrote focus on „change values“ and made a suggestion.

You dont read twice before you answer:). Of course it is not a standard:).

Conclusion: If someone is concerned go to a cardiologist. I myself did and I do know the limits of these trackers now. All the best to all.

[IronChuck]

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@Bangkokrunner wrote:

Sorry for my bad English. Ask a cardiologist how he measures. Of course you can measure hrv not limited after sleeping:). No study needed when a ECG tells you that as a side result:). I did it. Again I am not a native English speaker. Sorry when I am unclear.

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That is my point - the cardiologist's 24 hour HRV is just an HRV measured with a different technique.  My waking HRV is about 20-30ms faster than my sleeping HRV. What does that mean? Absolutely nothing. If I look at a study of HRV and health impacts I need to see what techniques they used to measure HRV so that I can capture my HRV in the same way or the number I have can't be compared to the numbers in their graph.

Just because the cardiologist's number is higher doesn't mean it can be used to compare to other HRVs to tell you that you are or aren't healthy. If the other HRVs were measured using 2.5 minutes while supine and sleeping then your cardiologist's HRV value is useless to you.

[Tlinlo7don]

Same with my cardiologist appointment. Not sure what the value is of this
information or the collection criteria, and really didn't care. That is
where I'm at with this fitbit feature. If you really want this information,
you should use another method to obtain it. Then figure out what is it's
significance and impact on your health.

[IronChuck]

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@Bangkokrunner wrote:

She wrote focus on „change values“ and made a suggestion.

You dont read twice before you answer:). Of course it is not a standard:).

She also wrote "irresponsible on fitbit's part to continue to call this HRV, which has known formulas, values, and aspects that define it" and "because it is NOT true HRV". 

If she's just going to focus on the change in values all it matters is that Fitbit's consistent from night to night in it's technique of measuring HRV, which means that the Fitbit HRV works as well as anything else.

[Bangkokrunner]

Correct, Iron Chuck. Dont be so iron:).

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 :).

Many users are not familiar with detail background like you after one year.

Further on the algorithm is a secret and fitbit did not reveal or not published how they calculate the result in detail and on which parameters (some might be forgotten).

Comparison with different method statements are less useful. Right. 

The interpretation from cardiologist on basis of his examination is the right way.

The interpretation from fitbit excludes of course such expert knowledge of a cardiologist.

Thats the point!

At least for me. 

Result fitbit: Unhealthy, result cardiologist: in the range of my age etc.

[Tlinlo7don]

Can't say it any better than that.