Week 32: Sickness and HRV
Hi there 👋
I hope you are doing well.
A study caught my attention last week, looking at HRV and sickness.
In particular, Koulla Parpa and co-authors looked at morning HRV measurements taken with the HRV4Training app in relation to COVID-19 positive tests in a cohort of elite female soccer players.
The data shows large suppressions in HRV already 2 days before a positive test, as well as a re-normalization within a few days (you can find the full text here).
Here is the data:
No wearables, no continuous monitoring, no distractions. Just a simple and effective protocol, 1 minute each morning.
Unsurprisingly, sickness is one of the strongest stressors, as we had shown in our paper (“What Is behind Changes in Resting Heart Rate and Heart Rate Variability? A Large-Scale Analysis of Longitudinal Measurements Acquired in Free-Living“, see here), typically showing suppressions that are 3-5 times larger than what we can see with training.
While many people have anecdotally reported seeing in their data suppressions associated to sickness before they noticed symptoms, not much research has shown support for this so far, as it is always tricky to find a reliable reference point or perform a systematic analysis of something that cannot be properly controlled (such as sickness, for obvious ethical reasons).
Yet, this study does show how HRV data can help in detecting sickness a bit in advance. Needless to say, this is not a “prediction” as it is often branded, but simply a detection: for HRV to be suppressed, the body must be already sick and fighting an infection (or else), even though we have not noticed it yet (at times!).
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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 is a certified Ultrarunning Coach.
Marco has published more than 50 papers and patents at the intersection between physiology, health, technology, and human performance.
He is co-founder of HRV4Training, Endurance Coach at Destination Unknown, advisor at Oura, guest lecturer at VU Amsterdam, and editor for IEEE Pervasive Computing Magazine. He loves running.
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Interesting! On a somewhat related note can it detect Afib? I have Afib and there are some mornings when my HRV app keeps telling me to adjust my finger placement and gets a poor reading - could Afib cause that?