Recent articles and updates [June 2025]
Heart rate variability (HRV), endurance coaching, training talk, wearables, entrepreneurship, and some ramblings.
Hi there 👋
I hope all is well.
Here’s a new recap of articles, research, and updates from the past month. I hope you’ll find the articles useful, and I would like to take the opportunity to thank you for your support.
Please feel free to comment below or in the articles should you have any questions, and I will follow up soon.
Take care!

Heart rate variability (HRV) 🫀
The Heat and Heart Rate Variability (HRV)
As we head into warmer months here in Italy, I wanted to cover something that is still missing in my blog, i.e., the relationship between The Heat and Heart Rate Variability (HRV).
What happens, physiologically speaking, in response to the heat? How do we adapt over time to this stressor?
Learn more about acute and chronic responses (and how they differ!) here.

Training Talk 🏃🏻
How to Manage Training Load Using HRV
I’ve previously discussed how to include heart rate variability (HRV) in your training plan.
In this new blog, I discuss data collected from an athlete I coach to highlight a few important points, which might help you make better use of HRV data. In particular, we look at race day HRV, post-race recovery, stability in response to high-intensity training, and how to potentially adjust your training plan.
Learn more, here.

Nutrition 🥑
Periodizzazione della dieta nello sport di Endurance
Qualche settimana fa ho fatto una chiaccherata con Marco Perugini, su quello che e’ stato il mio esperimento con la periodizzazione della dieta nel contesto della prestazione nello sport di endurance. Potete trovarla qui.
Grazie mille Marco!
Low-Carb Snacks of the Week
Since I started talking about periodized nutrition, I’ve received quite a few questions about low-carb food options for days in which we train less or at lower intensity, hence this blog with two recipes I tried a few weeks ago.
Metabolic Testing
This is work in progress, but together with Alessandra, I’ve been setting up a Lab in Brisighella which will serve both for Yoga classes and for Metabolic Testing. Last month we have also ordered a metabolic cart from Cosmed - which I can’t wait to have! - to test all things metabolic flexibility, economy, and durability.
I will also be offering this service to the athletes I coach whenever they’d like to visit. We should be set up to start sometime next year.
If you’d like to work with me, please apply here. Thanks!
Building 🛠️
Biofeedback data in HRV4Training Pro
Last year, we moved our HRV4Biofeedback app to the same backend as HRV4Training, in order to allow you to see your data all in one place (which is HRV4Training Pro).
We have just released the first update to start moving in that direction, which allows you to visualize time spent practicing slow breathing exercises with the HRV4Biofeedback app, in relation to your morning resting physiology collected with HRV4Training.
In particular, you can now pick "Biofeedback Time” as a Tag in the Overview page of HRV4Training Pro, as shown in the example below.

To recap, here is how I use the apps:
HRV4Training: morning HRV measurement, while seated (see reasons behind this protocol here) + analysis with respect to my normal range to assess my response to acute and chronic stressors (see article above about how to use this data in the context of managing training load).
HRV4Biofeedback: slow breathing exercises, which could possibly impact recovery, e.g. by quickening a return to normal in terms of nervous system activity after high-intensity exercise, apart from the various benefits that have been shown in the scientific literature (e.g. reduced anxiety, better sleep, etc.). While I measure with the iPhone camera in HRV4Training for my morning assessment (see data and validation here), I prefer to use a Polar H10 for longer, biofeedback sessions.
Please see my other articles below if you are new to biofeedback and interested in learning more:
I hope you’ll find the update in HRV4Training Pro useful. Thank you again for supporting my work.

That’s a wrap for this month. Thank you for reading!
Recent Updates:
Endurance Coaching for Runners
If you are interested in working with me, please learn more here, and fill in the athlete intake form, here.
How to Show Your Support
No paywalls here. All my content is and will remain free.
As a HRV4Training user, the best way to help is to sign up for HRV4Training Pro.
Thank you for supporting my work.
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 Endurance Coaching, advisor at Oura, guest lecturer at VU Amsterdam, and editor for IEEE Pervasive Computing Magazine. He loves running.
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