Can you tell us a little bit about that? Why RPE?

RPE?Yeah, yeah, that's right.

Um, so I would say there's different sides of it.

One, I think that in the long term as athletes, I think one of our goals should be to be in good tune with our body and understand what effort means and how long can we sustain an effort, and that can help us in, you know, in racing, but also in training so that we make the right choices and, you know, we don't burn too many matches too early, but at the same also we don't underperform, right? There's always two sides of it.

So I think being in tune with our body is key, and to get there, training by perceived effort is a useful tool because we start to pay more attention to how different things feel, and then we develop a bit that skill.

At the same time, I think being overly prescriptive with other metrics, um, fails a bit to recognize that there is a lot of variability in the day-to-day into what easy means, for example, right? So if we go for an easy run or an easy ride, even if our power or our pace for an easy run is a certain intensity typically, it could be that we are just more sore or less sore, or it's warmer, or there is anything else that is happening that makes that feeling actually hard if we were to try to maintain a certain external load that comes from, you know, zones or whatever is our frame of reference.

While if we pay attention to how we feel, then we just naturally slow down and, and take it super easy, and I think that's also how many of the good athletes that are out there train because, you know, you need to pay attention to how you feel.

Really?

So maybe you can explain to us about the difference in the measurement protocols, how you can track your HRV, and what the difference in the quality of the tracking method is, let's say.

Yeah, for sure.

So I would say there are two ways in which we can measure our resting physiology in a way that is accurate and reflects what we care about, which is our stress response.

And that can be done either measuring throughout the night, which is what you would get typically with a wearable, or first thing in the morning using a nap as you do.

So, these two options, they're both valid, but there are some differences.

I think the most obvious one is that, of course, the night comes before the morning.

So, typically, night data is a bit more reflective of our behavior the previous night, especially if maybe we have a late dinner or we drink some alcohol or we have some stressful events.

And then a lot of devices and apps will give you a kind of a proprietary algorithm number to say whether the HRV is high or low, right? So what is the difference? What do these numbers mean? RMSSD, SDNN, which one is, if an athlete only had to look at one single metric on their data sheet, which one should it be? And just a bonus question is, what do you think about the wearables of the Garmin or the Suunto or whatever it is, them having their own algorithm to determine the recommendations?

Yeah, for

sure.

I think one of the main ones probably is that it needs to be higher, right? The highest possible.

Higher is better.

This is quite common as messaging.

Many of the tools available also still interpret the data that way.

I think that is a bit naive and it's not necessarily how physiology works.

Is there a best practice?

Could you talk us through in your mind what is the gold standard for capturing heart rate variability?

Yeah, I would say that we have two protocols that I would consider accepted, and that is first thing in the morning and through the night.

So we just need to be aware of the differences when we use this data for ourselves or if we work with other people, athletes or whoever, because there are differences.

And I think it's just important to understand, for example, that obviously the night comes before the morning.

So typically night data might be more tightly coupled to your behavior, what you did in the evening prior to measure.

Because for example, if you drink some alcohol or if you eat quite late, or if you're out with your friends, it could be that it just takes some hours for your physiology to renormalize.

So if you measure in the night, that might be captured as a suppression or slightly more elevated heart rate.

So how do you in your own training and how do you recommend other athletes interpret and use heart rate variability to make training decisions?

So is it just important that you're reliable in how you're measuring it or is there a more ideal time to measure it over this longer timeframe?

Yeah, so I think that first we need to think about why we are measuring it and what we are trying to capture.

So in this context, what we want to look at is really our stress response.

That means how we respond to the various stressors that we face.

that we have faced, let's say in the past 24, 48 hours.

So the ones that have a bit of a stronger impact on our physiology, while we don't want to capture all the almost irrelevant stressors that we face during the day and that impact our physiology, but not in a way that if we're looking at it would represent our overall state.

And to simplify, I could say, if I have coffee and then I measure, I will just see the effect of that coffee, that excitement, but that is really not representative, you know, my state as a stressed person or my inability to capture, you know, yesterday's workout and things like that.

So what are the key metrics that we should be really concerned about?