This article looks at heart rate variability and COVID-19
What’s the deal?
If your resting heart rate is 60 beats per minute, it doesn’t actually beat once every second. It will likely beat every 0.9 seconds, then 1.1 seconds, then 1.0 seconds etc. This is known as heart rate variability or simply “beat-to-beat differences”. It is an indication of health, where variability is high in fit athletes and can be lower in diseases such as cancer, diabetes, and viral infections. Could heart rate variability be used to indicate a possible COVID-19 infection?
What did they do?
In April 2020 (at the start of the pandemic) 297 US-based healthcare professionals were instructed to wear an Apple Watch Series 4 or 5 during their normal day. Their heart rate variability was measured by the Apple Watch, and their data and COVID-19 status were tracked for up to 5 months.
What happened?
13 of the participants tested positive for COVID-19 during the study and their heart rate variability was up to about 95% lower than normal. Interestingly, their heart rate variability was lower when measured 7 days before a positive COVID-19 test, suggesting that heart rate variability predicted the positive COVID-19 test. This was particularly interesting, since only 4 participants had any symptoms of COVID-19.
What can you tell me about the people?
Participants were a mix of clinical and non-clinical hospital staff and were aged 36 years on average. Nearly 70% of participants were women and there was a mix of ethnicities. The vast majority were non-smokers.
What else should I know?
Heart rate variability refers to beat-to-beat differences, but the amount of “difference” changes during the course of the day in a cyclical pattern. It is typically high during the day (enabling us to be more responsive and adaptive) and is lower at night. In this study, heart rate variability for participants with COVID-19 barely increased during the day and barely decreased at night.
What will I do differently?
My watch doesn’t measure heart rate variability, but it does have a host of heart rate-related data. I have noticed that when I feel tired or unwell, it is almost always reflected in my resting heart rate, stress score, or sleep score. I think there is so much power in wearable health tech, that I predict everyone will be wearing them in the very near future.
Acknowledgements
This research was published in February 2021 by RP Hirten and colleagues from the Icahn School of Medicine at Mount Sinai, New York, USA.
This article highlights our personal take on their research, but there is so much more information available! Check it out here and see what you think!
Abstract Athlete 