Recent articles and updates [December 2024]
Heart rate variability, wearables, entrepreneurship, training talk and some ramblings
hi there 👋
I hope all is well.
Here is my last newsletter of the year, including articles and updates from this past month. Below you’ll find links to articles covering caloric deficit, higher HRV, measurements before training, research, wearables, training periodization, and prescription.
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) 🫀
Higher HRV: Is It Always Better? Recently, I had the pleasure of exchanging thoughts with Fuminori Takayama, a coach, scientist, and HRV4Training ambassador from Japan, about a study investigating the effects of wearing magnetic garments during sleep on recovery and HRV after a hard workout (30 km run). The study claims that these garments improve recovery, as HRV was reported higher when using them, together with increased deep sleep. However, as is often the case with HRV research, the reality might not be as straightforward as the conclusions suggest. Here I report some of the considerations of my exchange with Fuminori.
Caloric Deficit and Heart Rate Variability. A week of caloric deficit - a classic Christmas project for me - gave me the opportunity to discuss some poorly understood physiological responses to reduced caloric intake. Check out this blog to see how AI gets it wrong, what's really behind your resting heart rate and variability, and how to use the data more effectively with Normalized HRV.
Should I measure my HRV before training? A common question when getting started with HRV measurements is whether one should be measuring before training instead of first thing in the morning. The rationale is that we are about to train, and therefore there is no better time to capture our “readiness to train” than that moment. While the reasoning makes intuitive sense and would be correct if we were able to “capture our readiness to perform anytime”, this is not what we can do with HRV. It’s a limitation of the tool (and the physiology). Let’s see why and how we can make appropriate use of the technology given the limitations, in this blog post.
On The Limits of HRV Research in Sport Science. I’ve been working with heart rate variability (HRV) for many years, and one thing I’ve learned is that things can get quite difficult to interpret in the long term, beyond rather simple acute stressors (or major lifestyle or health-related changes). While HRV can be a useful tool, there are many challenges when it comes to research and its practical use. A recent study comparing morning and night HRV measurements gives us a good opportunity to explore one of the main difficulties, i.e. the lack of a reference. Learn more, here.
Wearables ⌚️
Trusting the Right Tool for the Job. I’ve updated this blog with more considerations and additional data from wearables showing how they are getting worse - not better - at measuring HRV (e.g. Fitbit, Garmin, the Apple Watch). Maybe it’s time to switch to morning measurements.
Issues in HRV measurement when comparing a Fitbit to a Polar H10 chest strap. Figure from this paper. What are your current thoughts on DFA (HRV during exercise), e.g. in Suunto's ZoneSense? A few weeks ago I had a nice chat with Suunto and MoniCardi about their DDFA algorithm for exercise intensity estimation. Here is an updated blog where I added a few important pointers about this method, which seems to provide a meaningful improvement with respect to the standard DFA, when it comes to individualization. I am currently testing this in my own training.
Building 🛠️
I’ve added normalized HRV to HRV4Training Pro, so that you can also verify by yourself if this is something that helps you using your data, as I cover in my caloric deficit article above. You can use code MORNINGISBEST for 30% off HRV4Training Pro until the end of the year.
Training Talk 🏃🏻♂️🚴
CoachCorner: How I Prescribe Training. CoachCorner is a new series of blogs in which I share information that is mostly relevant to the runners I coach. The first blog is about training prescription, intensity, zones, and defining a common language. Check it out, here.
TrainingTalk: Macro and Micro-Periodization, Health, Performance, and more. I wrote about changing my periodization about a year and a half ago, with the goal of staying healthier while still trying to push my limits. Since enough time has passed, in this blog I assess how that went, and discuss a few additional changes I am going to implement in the next months, motivated by my past year’s health and performance.
Training log. As the name states, this is just my training diary for this year.
Passive heat acclimation. No article here, just some data to share. Below is what adapting to a stressor looks like. These are 7 weeks of a passive heat protocol, which means 20-25 minutes in a hot bath at about 42C (down to 40C typically). The protocol helps performance in the heat but can also bring additional benefits such as increased hemoglobin mass, and potentially improve performance in temperate conditions. This is the fourth time I have done this protocol, and I tend to see the same response, which means it takes me 3-4 weeks to see a marked and consistent change with respect to the first week. Have you tried something similar for your endurance performance, and how did it go?
A few weeks of passive heat acclimation.
That’s a wrap for this month.
Thank you for reading, and see you next month!
Recent newsletters:
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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