hi there š
I hope everything is well.
I have recently received a question about the possibility of measuring HRV when we have an arrhythmia. I am addressing the question here as well, since this is quite a common concern, maybe even more so for endurance athletes who seem to be at higher risk of arrhythmia. Keep in mind that the prevalence of ectopic beats is really high even in the regular population (keep reading for references and implications).
Can we still use HRV?
Eventually, it all comes down to the frequency of the arrhythmia.
I also experience ectopic beats, but I can measure my HRV, as the ectopic beats are not very frequent. Basically, if you get them once in a while, it is typically not a problem (more info below).
If you get ectopic beats every minute, it is important to try to take a measurement while you do not get them (you can probably feel them, or if you cannot feel them, you can probably see them in the data, as it would look a bit different when a beat is anticipated or delayed, for example in the PPG waveform you can see two peaks very close).
The HRV4Training app has a good artifact removal system (in fact, in a recent validation we performed better than other tools even when linked to the exact same chest strap, see here), and we can easily remove one or two extra beats from a 1-minute recording. Hence even if something happens, normally it is removed so that the HRV number is not impacted and you don't have to worry about it.
A good heuristic here is to look at the HRV number, if it is very high above your normal range, then it can be a good idea to re-measure, as artifacts can only lead to abnormally high HRV. It is not possible for an artifact to lead to a low HRV, as it creates a disruption in the otherwise quite regular beat-to-beat timeseries, which is mostly modulated by breathing.
If you do experience many ectopic beats per minute, then it might simply not be possible to remove all the artifacts and measure your HRV. In these cases, heart rate is typically still reliable, and I would use heart rate as a stress marker as opposed to HRV.
In all cases, I would recommend a morning measurement as with this protocol you are in control, you can feel if you have ectopic beats, you can see the data, etc. - while with night measurements, you will just get "a great HRV", which is mostly artifacted (the same happened to me, with wearables data providing very high HRV while in the morning it was quite suppressed, see the data here). I suspect most people having very high night HRV, simply have an arrhythmia.
Keep in mind that 40-75% of the population has premature ventricular contractions when monitored for 24-48 hours with a Holter monitor (reference here).
It's pretty common.
If you have any doubts beyond what are the implications for HRV measurement, the best thing to do is of course to consult a cardiologist.
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Marco holds a PhD cum laude in applied machine learning, a M.Sc. cum laude in computer science engineering, and a M.Sc. cum laude in human movement sciences and high-performance coaching.
He has published more than 50 papers and patents at the intersection between physiology, health, technology, and human performance.
He is co-founder of HRV4Training, advisor at Oura, guest lecturer at VU Amsterdam, and editor for IEEE Pervasive Computing Magazine. He loves running.
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Great to hear re arrhythmia and that they are noticed as artifact. Thanks for spreading the word about how common they can be. Folk may notice that increased āstressā as monitored on HRV4 due to training can also be due to chronic or acute ANS activation and increase arrhythmia activity. Using the app is useful over time to take control of overactive sympathetic responses.
Thanks Marco!
I visited the reference on comparison of hr and hrv comparison and now am really confused. I have been using hrv4 for some time and use the iPhone camera measurement for 1 minute. I also have an Oura ring and tried importing its data a few times and after it failed to download a few times I went back to iPhone. I run daily with a Garmin FR965. I also have a Polar H10 strap as well as a polar arm band. I have settled on the arm band for every day running. Which should be the preferred method for hrv4. Also the article suggested that at least a 5 minute test was needed for best accuracy. How did the researchers evaluate the Oura ring. I am not aware that there is any other way than using overnight average? How do you suggest I measure my hrv?
My background. Iām an 80 yr old former marathoner. Who only runs 2miles every day. My program is a maintenance one which I think is fine for my age. The reason i have so many devices is I had trouble finding a device that would not give me crazy data on occasion. Gave up on running with Apple Watch. Garmin was good until it wasnāt. Garmin strap was not consistent so tried polar strap and eventually that gave me erroneous data. Have been using Polar Verity sense armband for several weeks and all is good. None of my inaccurate events had associated symptoms. When this stuff first happened I got an ekg which identified a left bundle branch block. I subsequently had echo and chemical stress echo and was told to keep doing what I am doing.