Newsletter #26: HRV numbers, what do they mean?
plus one year of data, wearables, and periodization
hi there 👋
I hope everything is well.
This week I have written about HRV numbers. When measuring HRV, we end up with a number, that we normally call an HRV feature.
An HRV feature is a mathematical way to translate a series of beat-to-beat intervals collected in a certain amount of time into a single number.
Some of these features are more useful than others, and you can learn more in this blog.
I hope you’ll find it useful.

One year of HRV data
Below is my past year of measurements. I have added a few annotations and training load for context. All data was collected first thing in the morning, while sitting, using HRV4Training's camera-based measurement, typically after a trip to the bathroom.
These are only some of the aspects we can capture using a simple measurement of resting physiology.
Wearables
When it comes to wearables, I often see either blindly embracing a device (i.e. fanboy kind of attitude), or dismissing it entirely because of e.g. an inaccuracy in a metric provided.
Unfortunately, we need to be much more nuanced about these devices and their use.
See my thread on Twitter, for some tips on how to better navigate the space.
Periodization
After a good training year, I have changed my periodization aiming for better health and hoping to maintain or slightly improve performance.
You can find my thoughts here.
How are you planning your long-term training? Please feel free to comment below or in the blog.
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You can find examples and case studies showcasing how the platform can be used to better understand the effect of training and lifestyle stressors at this link
Try HRV4Training Pro for free at HRV4T.com or use promo code SCIENCE for 20% offÂ
In the app, Pro brings the normal values view, which can help contextualizing longer-term changes, as well as rMSSD on the homepage, see an example below:
see you next week!
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.
Twitter: @altini_marco, Personal Substack.