I’ve previously discussed how to include HRV in your training plan. Here I’d like to use 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, the best case for HRV in the context of managing training load is to determine when to reduce load (we’ll see below what “reducing load” means). In practical terms, starting from a solid plan, built by you if you are self-coached, or by your coach, we want to use HRV to make small adjustments, reducing load when your body is unlikely to assimilate the stimulus. Without a solid plan, there is no use for HRV as HRV cannot capture important parts of the recovery process (e.g., muscular breakdown).
Keep in mind that while we can do the work, what matters is not as much the work we do as it is the work we can adapt to. In this context, HRV can be a great ally, as multiple studies have shown how doing less total work can lead to improved performance, if we use our body’s physiological response (i.e., a morning HRV measurement) to determine when it is not a good time to apply additional stress.
Here are a few additional aspects to consider when we decide to incorporate HRV into our training load monitoring process:
Do we want to rely on acute or chronic changes?
My preference is chronic changes, as done in more recent scientific literature on HRV-guided training. This means that we are less reactive, and typically give it a few days before we implement a change. Practically speaking, in HRV4Training Pro, you can look at how the Baseline (blue line) behaves with respect to the normal range (shaded area), instead of looking at individual days. See the image below for an example.
Do we reduce volume or intensity?
Early research by Stephen Seiler and colleagues has shown that intensity, more than volume, leads to disruptions in autonomic nervous system activity. No surprise there as the response to low intensity training is typically the opposite, with reduced cortisol levels and increased HRV, something I have discussed here. As such, is intensity the parameter I am careful at managing with the athletes I work with, when using HRV.
I’ve recently started working with James, whose data shows quite well a few important points that I’ve just discussed, and I’d like to recap here:
Stability is the ideal response. This is identified by an HRV baseline within normal range, reduced day-to-day variability, and a stable heart rate as well. In HRV4Training Pro, you can highlight the data using our “detected trend”, which indeed shows “coping well” for the last training block before the marathon and for the recent training block in which we want back to hard training, with added load as we aim to reach new levels of fitness in the upcoming months.
A low HRV score does not indicate that you cannot perform. A low HRV is a sign that the body is unlikely to positively assimilate additional stress. This means that we can go hard, we can perform, etc. - but we are unlikely to get better because of what we did on those days. This obviously means that we should not be worried about a low HRV on race day, something that could be due to changes in sleep, nutrition, race nerves, or more. James had a suppressed HRV the day before the race and the day of the race (May 23rd and 24th), and yet executed perfectly and came home with a better-than-planned time (sub-3 while running only ~45 km/week - all credit to him as I’ve started prescribing training only the day after the race). Anyways, no surprise here, if you know what you are doing and understand what HRV is about.
Intensity is the key parameter to manage. After the marathon, we had planned a transition block of 2 weeks. James has a history of running injuries, hence he was already managing his training with a low volume of running and plenty of cycling. The transition block was also built with this in mind, using the bike most of the week, and limiting running to the second week of the block. We picked up volume again quickly, but there was no intensity until June 11th and 12th, when we started introducing back-to-back hard days (one running, and one cycling). At this point, HRV was well within normal range. Note also that despite the higher intensity of this new training block, HRV remained stable, which gives confidence in the athlete’s ability to assimilate the load and further improve.
During these past few weeks, I didn’t make any changes to James’ plan because of HRV. I had already planned a transition block of 2 weeks, which coincidentally, was exactly what he needed to bounce back and be ready to go again. HRV simply provided confirmation that the plan was a good plan (pat on the back).
Another athlete might have responded differently, and in that case, we could have used the data to, e.g., delay the reintroduction of intensity. Similarly, a drop in HRV after reintroducing intensity might highlight that, despite the rebound, the body is not ready yet for that type of work, and therefore, we might have also adjusted the load again at that point.
Alright, I hope this short case study gave you some useful pointers on when and how to use HRV in the context of athletic performance.
Thank you for reading!
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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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What are the physical symptoms of a low HRV during a run? The data is presented nicely and the argument makes sense, but I have found much more success in running when throwing all wearable metrics out of the window. I'd like to learn how to apply HRV regulation based on body feel as a non-elite runner!