From Load to Strain: Dr. Stephen Seiler’s Latest Research

I guess it's a real-time stress detector. It's like an internal training load detector.

Hmm.

is kind of going on, isn't it?

Or training stress detector. guess I, I try to really be careful with my word choices now where load is neutral. Load is just what you do, but stress is has to do with what it does to you.

Hmm.

Hello and welcome to the Athletes Compass podcast where we navigate training, fitness and health for everyday athletes. We are honored today to have a very special guest in the world of endurance sports, Dr. Stephen Seiler. Dr. Seiler is an internationally recognized exercise physiologist, best known for pioneering the concept of polarized training, which has reshaped how endurance athletes structure their training intensity.

With decades of research and collaboration with Olympic federations and elite coaches, he has helped bridge the gap between sports science and practical coaching. If there are rock stars of endurance science, Dr. Seiler will definitely headline the arena tour. Dr. Seiler, you are well known for your work with polarized training and observational studies of elite athletes. Now you've been working on breathing frequency as a proxy for training stress, potentially even

even replacing RPE heart rate or power, what have you learned from this project so far?

wow. There's so much to unpack there. I almost have to back up a little bit and kind of give you, give you a bit of a backstory or genesis for all this. And, and part of the genesis is just when I came, I was in a period of leadership at the university. I was not, I was kind of spinning my wheels, trying to keep the research going, but, not keeping up really well. So then I come back full speed, you know, on the floor as a professor, and I look at all of the metrics that have were just.

Please do.

flourishing because of the digital landscape that we train in and wearables and power meters and so forth. Lots and lots of metrics, some validated, some not. ⁓ You know, it's pretty easy to create a metric with just take this number and multiply it times this number. And so it was a confusing landscape. It is a confusing landscape.

confusing for the scientists, confusing for the athletes. And so in that landscape, I was trying to figure it out and I ended up going to ⁓ engineering and saw that, they use three of these terms that we use sporadically. They use them very specifically. They use the term load, they use the term stress, and they use the term strain.

And so then I started digging in and went back to Celia and what was he trying to get at with his research back in the day when he brought the term stress into the medical literature and into the psychology literature really. And all of that resulted in trying to use this paradigm of load stress strain where load is just what you do. That's pace, power, duration. ⁓

you know, calibrated with intensity, but it's just work. It's the external work that's accomplished. Stress is what happens while you're doing it in the sense of it is, it can be the changes in the body's ⁓ effort, you might say, that both the psychological and the physiological ⁓ effort that is or.

that we use to achieve the power or the pace that we're trying to sustain. that effort tends to increase over time because we fatigue, because we become glycogen depleted, because we start to to ⁓ recruit more muscle fibers and so forth. And then strain is this downstream effect that might happen if we have too much stress over too many days in a row. Strain means that

⁓ man, I can't get my heart rate up or my heart rate's too high or I just don't feel like training. I'm tired. My readiness to train is down or my heart rate variability has gone down. So there's a number of variables that relate to strain. There's variables that relate to this concept of stress. And then we have our tools for measuring load. So that's kind of the framework that I've been working with.

In that framework, one of the big challenges is to get at the stress, to measure it properly and accurately across the entire spectrum of intensities and durations that we work ⁓ at. What's one of the ways we measure stress? Well, we measure it with heart rate drift, for example. But if we do a good job of, if I'm in Norway and I'm drinking properly and I'm well ventilated,

then I don't have very much heart rate drift and heart rate is really well tethered to oxygen demand. It's fairly oblivious to ⁓ how tired I am. It just says, how much oxygen do you need right now? And it delivers that amount and it doesn't over deliver. So heart rate is limited in what it can do for us. Then we have RPE, rating of perceived exertion, Borg scale.

I like the six to 20 scale, there's others that use the one to 10. Same idea. How's this feeling right now? How hard are you digging? You how hard is this right now? So it's an acute measure and, and perceived exertion we've had, you know, you might think, well, that's the easiest metric around to measure. Well, it turns out it's not so easy to measure when you're training. It's not so easy to put a number to

How do I feel right now for the first, you don't have anything to write down. You're, you know, you, you're not in a situation where you can easily chart your, your, your RPE. And the other issue is that as athletes, we game the system big time. And so RPE is tricky for the first thing. If, if I ask an athlete or I tell an athlete, all right, what's your RP right now? And they'll say, well, what, did I say last time?

Mm-hmm.

That so there, so there's.

there's an auto correlation problem, meaning that they're paying attention. I said 14 last time. Okay, 15. So that's a problem. RP is not as simple to use as you would think it would be ⁓ because of number one, we're afraid to tell the coach that we're actually suffering. Number two, we tend to auto correlate. We kind of want to get the answer right and so forth. And then out in the field, it's not so easy to record that. We've even worked with Garmin to try to

develop a dedicated channel on the Garmin device so that the athletes could just push a button and punch in their RPE. So it's doable, but it's tricky. So anyway, so those are two of our tools that we have. And now I was training myself and I was thinking, heart rate just doesn't always tell, it doesn't seem to...

tell me what I feel because for example, if I'm doing intervals and I'm already at 90 % of heart rate, there's really not that far for heart rate to drift. So it's kind of the, might call it their ceiling effects in using heart rate as a stress tool. And so I thought, man, I just wish I could measure breathing because I'm breathing out my ears right now. And that was my mental state is I was just saying I can feel, I can hear myself breathing harder, faster.

towards the end of the interval session compared to the beginning of the session, how can I measure that? Because when I try to measure it, when I think about it, it changes, right? So anyway, so that was the start of all this. And just by chance, I got connected to ⁓ two very important resources. One was Andrea Nicolo, who was doing research on this topic of breathing regulation and the things that he...

Revealed in some papers. I read it was this neglected Vital sign and I thought man that that makes sense, you know, and I need to investigate this further And he did some work with the late Louis Passfield who was at? ⁓ In the UK and and so It was it was really interesting and so I took contact with him And then the other was was this startup company and you guys know about startups or you do Paul?

University of Calgary.

you know, just a group of people trying to get it right, trying to develop a new technology, ⁓ you know, and, and it was time where, ⁓ and so I've been working with this particular company for three years with absolutely zero economic connection or financial connection, but just purely fascinated with, ⁓ as a sports scientist, trying to understand technology development from the developer side.

you

And, be part of a development process because I do believe that being able to measure ventilation in the field has significant upside, significant potential to help us get a better understanding of where our athletes are in training sessions. Perhaps a better understanding of when enough is enough in a workout, you know, because when you're having a good day.

Sometimes you can stretch a workout, you may do an extra repeat in an interval. When you're not having a great day, maybe you contract the workout a little bit. And we're finding that breathing data really informs that decision or potentially where that athlete is. So that's the background.

That's beautiful. ⁓ if I can come in there for, for moment team there, I can actually remember Stephen, the podcast that you and I did on the training science podcast. Gosh, it's, it's probably over two years ago now, but you, you, kind of, gave us the framework, and you were talking about ventilation back then. And I can remember after the podcast, we, we'd done it kind of at a similar time of day, my morning and, you know, I needed to eat after that. So I ate, but.

probably ate too much. ⁓ My stomach was a little bit upset and I needed my ride and I went and did my sort of my standard ride. And I was thinking about things whilst I was riding up my hill as my gut was kind of unsettled. And I was noticing how my overall stress was higher because my gut was uncomfortable. And I noticed, and maybe it was placebo at that point, because you had mentioned it to me.

but I noticed that my ventilation was heightened. And I was like, hmm, I wonder maybe Stephen's got something here that he's, pathway is going down. Fast forward two years here and ⁓ MJ and I kind of getting prepared for this interview. MJ is like, you should really get the latest Garmin device, ⁓ Garmin ⁓ heart rate monitor strap because it measures ventilation frequency. Now just the frequency.

Thanks.

So I did that, I followed up on her advice. I know she's been doing that too. ⁓ I've been watching this variable, just the ventilation, just the respiratory rate, number of times I'm breathing in a minute. And it's just a fun new metric that I'm now measuring it. And maybe I'll pass the baton over to Marjaana and any thoughts Marjaana on your tinkering with ⁓ ventilation in the last month or so.

Thank

Yeah, the last two months, I guess I've been on a road trip from Houston, Texas, which you're probably very familiar with Dr. Seiler. ⁓ Very flat, very humid, very hot. So we escaped to cool Canada and ⁓ I spent first month in Vancouver Island, run uphill. had this same uphill. was 200 meters elevation up.

you

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And I was like determined that this is the summer that I learned how to climb hills. However, I got quickly really frustrated with my Garmin device who was complaining that my fitness is going down. And in my mind, I'm getting stronger, right? And I can feel it. My whole body is, I have that strain for days because I go from flat to this. ⁓ So I'm flat to hills.

on runs and bikes and at the same time my estimated VO2 max score on Garmin device plummets. So I'm like, this makes no sense whatsoever. And I started to looking at my data and I got, because when you go uphill, you start breathing a lot harder, right? So I'm like, this makes no sense. I'm muscly fatigued for days and I'm...

you

something like 2.5 K, so 2,500 meter elevation. I'm breathing hard and I'm looking at the power data and heart rate data and it looks like a regular ride, but it doesn't count for breathing rate. I was preparing for this podcast all summer long doing my own experiments.

That's great.

So you're finding that the breathing data you get from the watch is reasonable, or it seems reasonable.

Well,

I don't know what the validity is actually. And I'd be ⁓ interested to know what the difference is between the time wear and the Garmin strap is actually. But ⁓ definitely the RPE was higher on those rides and runs going uphill. And it wasn't detected by the traditional metrics like, know, pace or power.

heart rate.

But

was ventilations, like was respiratory rate higher MJ? Yeah, well that's kind of cool. So there could be something there. Now I think the advantage of the timeware system probably, Stephen, you're gonna tell us is that you're not just getting the rate, but you're also getting the depth of each breath. Is that correct?

Yeah.

It is, that's one of the advantages. And the other is, is that we just have to be clear that trying to capture the respiratory frequency from the, you might call it the embedded signal that is happening in heart rate or our intervals is tricky. And as intensity goes up, then you're losing, you know, have parasympathetic withdrawal.

So essentially you have no heart rate variability at high intensity. if we're depending on that to measure respiratory frequency, then what's going to end up happening is those respiratory frequency values get less and less valid with increasing intensity. So that would be my concern. And that's why Timeware or that's a reason why Timeware has followed in the footsteps of a big review by Nicole and colleagues around

Hmm.

all of the different ways you can measure breathing frequency. You can use it, do it acoustically. You can do temperature. You can do a lot of things in a laboratory, but as soon as you go out in the field, most of those methods fall apart because of ambient noise, because of temperature, because of wind, because of talking, all that stuff. Well, what doesn't fall apart is just actually measuring the torso, measuring the expansion and contraction of the rib cage. And, but you have to do it with a

you

really good sensor, you have to control for some different variables like the textile that's transmitting the signal. And so it's not, it's not trivial to do this, but good engineers are getting it right, I think. And so we're plus minus one breath per minute across the range. ⁓ And that's, that's very solid on the, on the validity and the reliability of the breathing frequency signal. And then some of the things they've done.

with the strap or I think, or I would almost say revolutionary in how they're achieving a very consistent placement and stretch characteristics and so forth to allow the tidal volume measurement to also be ⁓ valid. Now, not directly in liters per minute, but in a linearly kind of an arbitrary units that can be calibrated against the actual metrics if we so desire.

Thanks.

Don't want to go too deep down the, you know, we'll see what that means. But for right now, if you can just get at breathing frequency and do it well, that's telling us quite a lot. ⁓ and, we see cyclists, you know, and athletes that their breathing frequencies as they're at the, you know, at the upper end of their performance during intervals or climbs, they can be hitting 80, even 85 breaths per minute. Which, kind of breaks the rules that we were taught Paul.

Wow.

You know, we were told, well, once you get over 60, you're done. That's your toast. That's a sign that you've hit your VO2 max. You know, that's not true. It may be kind of true with a mask on because masks and mouthpieces change the way the brain solves breathing. But out in the field, we see some pretty big respiratory frequencies.

Yeah.

Yeah.

So

Dr. Seiler, when you're talking about the breathing rates, are we going to end up with essentially zones? I mean, how are we, how is that going to help us? I mean, I just got a, ⁓ a breath strap from a different company to try out and it's like, okay, no, what do I do with all this information? You know, and where, so where's it leading us?

Yeah, I really, think that's where we'll go where we'll end up is, is that it's individual just like heart rate. You know, we all have, we've learned that you can't use 220 minus age or whatever you've got. If you want to actually know maximum heart rate, have to put in some effort and get a, get your individual heart rate and, and you probably have an individual max or peak heart rate for different modalities. If you're a triathlete, we, we see evidence of the same thing in breathing.

breathing frequency is, maximum breathing frequency is probably sports modality specific. ⁓ Cycling is probably going to give you, cycling we don't really see much of it in the way of what's called entrainment where the breathing gets connected to the cadence or the movement of the body. Whereas in other movements like cross country skiing or rowing, there's a really tight connection between breathing, how the brain solves the breathing and the movement pattern.

You

So that constrains frequency, breathing frequency, which is just to say it's going to be individual. It's going to depend on what sport you're doing and just how you breathe and how you solve breathing and so forth. So it'll be like heart rate. And what we've been using is I just said, well, okay, I'm going to go back to the Carvonen formula, which you'll remember is just saying.

If I know my max heart rate and I know my resting heart rate, then what's in between is my reserve. It's the beats I have to work with. And when you use heart rate reserve, ends up being, you know, the percentage of heart rate reserve you're at correlates pretty darn well with the percentage of your oxygen, maximum oxygen consumption. So it, kind of corrects for differences in resting heart rate and max heart rate. Well, we can do exactly the same with breathing. And so we.

Mm-hmm.

We've over time, we get data from the athletes and we start to say, okay, professional cyclist, John, you're looks like your breathing frequency hits about 80 peak values, resting values about 15. So now we know what your heart rate, your breathing frequency range is. And so then we can compare during a workout during an interval session, what we'll see consistently is that in the first, at the start of that interval session.

the athlete is under utilizing their breathing frequency, meaning they're at a lower percentage of their breathing rate reserve compared to their heart rate reserve. But as the workout progresses, what ends up happening is that that changes the breathing frequency reserve. It starts going up, up, up at a faster rate than the heart rate change. Does that make sense?

So breathing is telling us something different. Just like you experienced ⁓ MJ is that breathing was telling you a story that was, that said, I'm working hard here. Whereas heart rate was not heart rate was true to just your demand, your oxygen consumption. And it wasn't telling the story that, this is getting more and more challenging as I continue to climb.

You know, and it was getting more and more challenging for two reasons. One, you're fatiguing and two, the altitude is increasing. So that was double jeopardy and breathing was capturing both of those changes and you were experiencing that. Heart rate was just saying, what's my oxygen demand? And it wasn't changing in the same way. And this is very consistent with what we see.

That's

cool, Stephen. Can you go just a little bit of a geek out for us? Are there centers in the brain that are regulating this or interpreting this that are feeding back into the respiratory system to tell us that? How is the mind taking that in and that's getting feedback?

Right. this is a great question.

And this is where the connection to Rome and Andrea Nicola comes in because that's specifically what he has been dedicated to is trying to understand that. And what he has shown is that breathing frequency seems to be controlled by, you might say, a different part of the brain than tidal volume. And you can kind of

Roughly say that breathing frequency is feed-forward control meaning when the brain Activates muscle when the brain turns on activity There's there are parallel signals to to the breathing frequency center. You might say so there is a strong relationship between breathing frequency and ⁓ Mobilization or effort

So that's the breathing frequency side. And then when breathing frequency goes up, well, that puts constraints on tidal volume. So the working hypothesis for Nicolo is that it's breathing frequency that kind of drives the, it's the driver or the orchestra leader. And then tidal volume will have to adapt to a given frequency. Now, as frequency goes up, when it starts to get really high, you just don't have enough time

to get in a big tidal volume. So tidal volume will tend to go down. Okay, initially tidal volume will hold or even go, both will go up. But as you start really hitting those higher breathing frequencies, really fatiguing, then tidal volume will also go down. Well, now this this creates an interesting problem because now the cost of breathing is getting higher.

Right? Because we've only got so much oxygen, you know, the heart delivers oxygen. if normally at low intensities, the cost of breathing is quite low, 8, 10 % of VO2 max. So it, you know, that's the, it's a small tax, but once we get it really high intensities, that gets closer to 20%, 18, 20%. So now that breathing is costing a lot more.

And it's a bigger percentage of the total available oxygen. Well, that has to come from somewhere. So there's competition between breathing cost and the working muscles. And Jerome Dempsey, who's kind of the legend of ventilation control, has talked about this issue that there's crosstalk between the ventilatory musculature, the muscles between the ribs and...

The working musculature. So if the ventilatory musculature is struggling, that will tend to inhibit the working musculature in the leg. So there's this feedback that's going on. That's a really fascinating aspect of this, ⁓ which then raises the question of, can we make the respiratory or the intercostal muscles more bulletproof so that they

handle breathing better? Should we be training, doing respiratory muscle training? know, and the question, the answer then is based on the reviews, probably it depends. Again, it's probably individual. There are probably athletes that would benefit. They have some constriction in their upper body. They, you know, they've got some of that. Their shoulders are kind of forward. They're, not able to expand their rib cage. They might benefit.

Yes.

you

Mm-hmm.

from RMT, whereas other athletes would not. So I think a lot of the stuff that you and I talk about these days is, the answer is it depends and it's very individual. And that's where we need tools to be able to help the individual athletes solve how their body works, if that makes sense.

Yeah,

completely. I couldn't agree more. that's again, it's just, you know, you've kind of alluded to it throughout the podcast already. It's kind of why we've gone down to the Athletica roadmap with our startup. Cause we could see that this is, we need to solve problems that athletes have at the individual level out in the field and tools like Timeware and maybe integration centers ⁓ like Athletica.

can help solve these individual problems. yeah, I just love that ⁓ conversation you just gave us there, Stephen, on all of the cool little intricacies. And it's so fascinating that we're still learning. ⁓ this new, I guess it's a real-time stress detector. It's like an internal training load detector.

Thank

Hmm.

is kind of going on, isn't it?

Or training stress detector. guess I, I try to really be careful with my word choices now where load is neutral. Load is just what you do, but stress is has to do with what it does to you. The cost of achieving that load. I, and, that cost of a workout, if we get even more medical metaphysical here, that cost not only depends on your fitness that day.

Hmm.

But it may depend on the environmental conditions that day, like you're either on a mountain or you're in the heat of Texas or so forth. But it can also depend on things like, Hey, ⁓ my, my mother got is sick. Is she seriously sick? I just found out about this and this, this is, I'm really stressed out. Well, that's going to potentially impact how your body responds to that workout.

Yes.

So this is, and then this kind of connects brain and body. This idea of the stress bucket model that we, you know, we have one stress response essentially to all kinds of different stressors, such as financial challenges, medical issues, you know, my child is sick, all of these different things can then influence how our body physically responds.

to the same training session. So this is that individual aspect. It's even more complicated than we maybe have imagined. And so it certainly tells us that the idea of writing a training plan for the next 30 days and then just pushing the button and executing that plan and everything's going to go great, forget about it. That's utopic because humans are just too complicated.

you

for that to be true. It's like the weather. tell my students, said, look, folks, there is essentially no phenomena on the planet that is there is more computational power used to try to predict than the weather, the daily weather, wherever you live on the globe. And yet we are almost, it's almost impossible to make any predictions that have even a

No.

modicum of accuracy beyond 10 days out. By the time you get 10 days out, it's already just barely better than guessing. But that's the issue of complexity. Right? Well, it's the same for our bodies. I would argue that as coaches, you make your plans, but how often are they working exactly as expected beyond 10 days?

Thank you.

Because stuff happens and you adjust and that's what good coaching and good, you know, understanding your body is all about is, is dealing with the realities of life as you follow your plan.

Totally.

Mm-hmm.

Mm-hmm.

Mm-hmm.

Totally.

Oh, man,

that is so good. And I really appreciate the correction in my own mental models around the, you you corrected me right away. It's like, no, Paul, it's not actually an internal load marker, I would say. I would say it's an internal stress marker. And I see it now. It's taken my, it's taken me a long time, but it's yeah, it's in the moment. It's you're over, it's everything, it's,

Mm-hmm.

It's almost a little bit like HRV and how HRV is telling you just a little bit more than heart rate, right, in the morning.

Right. And I would, I would classify HRV as a really good tool for assessing strain that, that next step, which is, okay, you've, you've stressed your body maybe several days in a row. And the consequence of that now is a strain response, which is this, and strain in engineering terms means that that wouldn't beam bends. gets deformed under the load. gets bent. Well,

That has a nice analogy in the training situation is the athlete says, coach, I don't know what it is. I can't get my heart rate up. Right. So the normal response pattern is, is changed or they they're using their hour of ring and it's saying their heart rate variability has gone down. You know, what, or whether it's whatever tool you might be using. So, so that would, that would be in my mind, a strain response, if that makes sense.

Totally. Totally.

Stress is

happening during the session. Strain is a downstream result that we try to, you know, I don't think we ever want to, we try to get rid of it, but we try to manage it because we're trying to get the most signal with a very manageable amount of strain.

Yeah. So, Stephen, this is just phenomenal. I know we have lots of other questions around ventilation, but I'm also mindful that we've had an incredible response to knowledge that we're going to be interviewing you on from our forum. We have a lot of ⁓ listener questions. And Paul, I'm just wondering, in the interest of time, do we want to get to some of those here in the podcast?

Sure, did you have a question MJ? Yeah, let's.

I did. I did have a question.

I want to go back to, ⁓ you mentioned ⁓ the competition between the working muscle and intercostal, the ventilation muscles. Have you ever experienced, I have a runner that I've coached who after a hard, or she's running marathons. So at the end of a marathon, somewhere around 30 K mark, she starts to get this

gagging reflex. Have you ever experienced ⁓ an athlete where, you know, after 30K on marathon, the stress is pretty high, right? And she's getting fatigued and then she gets this gagging reflex and it only goes away by walking, stopping or walking and then she just kind of struggles through. ⁓

Mmm.

Well, that sounds more like a, my first thought is that sounds like some type of either an aloe response or a, a, or a bronchial restriction, kind of a exercise induced asthma response. When you say gagging, meaning you're feeling like you can't breathe or some kind of, and in the two big terms now are, know, that we're distinguishing between, ⁓ exercise induced asthma, which is a bronchial constriction issue versus aloe, which is that.

Mm-hmm.

esophageal restriction here, you know, actually around where the, where the voice box is basically, ⁓ I'm no expert on it, but, but we're, we're at least able to distinguish those two. And, you gotta remember your athlete almost certainly is breathing at a higher frequency. Like we were just discussing, she's, she's working harder and harder and that may trigger.

that she may have respiratory muscle fatigue. So there's a number of things that could kind of all play in, but a gagging reflex doesn't sound like a normal, that sounds like something else besides typical ⁓ respiratory muscle fatigue, if that makes sense. I would probably want to look at some issues around just is she, ⁓

Mm-hmm. Yeah.

Is she having some type of exercise induced bronchial restriction or ALO response? The other might be just, is she getting sick to her stomach? Because obviously nowadays athletes are trying to consume, you know, a lot of carbs. They're trying to do all the things right on the, on the, on the fluids and the, and the electrolytes and the glucose. But as the athlete is fatiguing, as the sympathetic load is getting higher.

The gut is, having more and more trouble with handling the intake. And I've talked to professional cyclists and they talk about this is that they, they start to struggle with those big carbohydrate intake regimes as the race wears on because of the intensity. And, and, and so you're, you're getting more and more of a sympathetic push, which means you have less blood flow to the intestinal region, which means that.

Yeah.

it's more likely that you're going to have issues with your gut. that could play in as well.

Sounds like a perfect storm.

Hmm.

Yeah,

that's good way of describing it.

So Dr. Seller, we did have a lot of questions about breathing. ⁓ Giuseppe from the forum asks this question, can the greatest performance gains through breathing be achieved through a specific workout like AeroFit or PowerBreathe? And what do you think of these devices? Or should we be focusing on relaxation with methods to strengthen the parasympathetic nervous system? What should an ⁓ amateur athlete invest in?

it's it's a great question. And it brings us back to this issue that of it. know everybody who listens is going to say, I hate this when he says that, it depends. Yeah. Because, because you're a unique individual, your magic, know, and we want to understand you. ⁓ but it is, it is that issue is that, yeah, you know, I've seen some athletes, even in the tour de France, you'll see them and you think, my goodness, it looks like their shoulders are permanently.

It depends.

screwed forward, you know, that they might benefit from some kind of, you know, yoga or something to stretch out and to give themselves some, literally some breathing room ⁓ versus other athletes. Breathing is just not a problem. ⁓ So I do think that we have to do a bit of triage with our athletes to see where breathing may play a role and not overthink it. Don't make it a problem if it's not a problem.

You know, that's, that's a typical issue is just because we can measure something that we start to say, ⁓ you know, now I've got to, I've got to make this better. ⁓ however, if let's take a scenario, one of the things this, this was secret. This was a secret weapon in Norway, what I'm going to teach you now. ⁓ and I know the guy who invented it and it was up at training camps. were seeing that when the cross country skiers would come to a

a short hill that if they had a PO2 sensor on them, they would often see that as they started climbing up the hill, the O2 saturation would drop in those first meters because breathing wasn't keeping up. There was a lag time between the increased work of the musculature, the increased oxygen demand and oxygen utilization and the ventilatory adjustments. Right? There was some 20

second lag time. So he said, all right, what happens if we just anticipate this and start breathing harder at the bottom of that short hill? Does that make sense? Instead of waiting for it to happen reflexively, we feed forward, drive it and try to minimize that oxygen deficit that we generate at the bottom of hill. And it worked.

Yes.

Mm-hmm.

for them. started seeing the athletes said, okay, this is helping me come up over the top of the hill, push over the top. And I, and I've got less, I feel like I've got less of a breathing deficit. You know, I've accumulated less of a deficit. So if you look at some of the Norwegian athletes in that period, like Olaf Tufte, who won two gold medals in the single and rowing, they would take off from the blocks. Just, he would be breathing like a horse.

And it was because he was taught to overventilate initially, if that makes sense, to just anticipate it and get in front of it in those first 20 seconds. And, and I could name other athletes and also in, in, these really stochastic situations where you have really short climbs, like in, in, cycling, that can be a strategy to just be, be cognizant of the fact that, Hey,

Breathing really matters here and don't be afraid to anticipate the demand and get in front of it. Does that make sense? And practice that a bit. So that's not a, that's just to learn how ⁓ to get the most out of ventilation. Cause what are we trying to do? We're trying to, ventilation has three functions, right? It's creating this interface with the blood.

Mm-hmm.

at the lungs, the alveoli to one, deliver oxygen out, right? Two, take CO2 that's produced in the muscle and get rid of it. So we send oxygen to the muscles. We exchange that with CO2 and get it out of the muscles and back into the atmosphere. And three is to control pH, pH balance.

Because we use VO2, we use ventilation as a buffering system to help get rid of those hydrogen protons that, you know, the acid that gets us, you know, it's part of one of the fatigue mechanisms in the muscle. So, so ventilation is hugely important. Number one, and, and those of us who had physiology, we were kind of taught, well, if, if, you know, ventilation is over-dimensioned for the need.

because when we measure maximum voluntary ventilation, it's usually higher than the ventilation that we have at VO2 max. So there seems to be a buffer. But I think that's misunderstood because then you're connecting the demand for ventilation to the oxygen demand. But really, I would say our lungs are designed to respond to the CO2 removal demand. Does that make sense? Because

Mm-hmm.

Those of us who know a little our physiology, we know that there's as the intensity goes up, the amount of CO2 that you got to get rid of exceeds the amount of oxygen that you deliver and it can exceed it by 20%. That would be an RER of 1.2, right? know, so, so, so the lungs are dimension for CO2 removal. The heart is dimension for O2 delivery. And those are different. Does that make sense?

you.

Yeah, love it. Love it. Just for a little more context too, Stephen, so know who you're talking to. So Marjaana, when I was over ⁓ at Olympotoben and walking around there and all excited and taking photos and stuff and sending them back to MJ, she was like, yep, that's where I trained. So MJ's an old, she was in the center there and whatnot. So she knows exactly the people you're talking about.

really?

And

yeah.

Well

then you probably know Erlen Hemm.

I love this guy. He's the best. Yeah. Yeah.

Yeah, that's the guy. He's

retiring now, but there's probably no, there's almost no human that has done more VO2 testing on the planet than that, that person. So,

He's a true legend.

⁓ I took my bachelor's and master's in Norwegian School Sports Sciences.

Okay. Okay. wow.

Yep. So the guy is Erlen Ham. And I asked him, said, Erlen, why didn't you publish this stuff? I was just a few weeks ago talking with him and he said, man, it was our secret weapon.

You

you

That's great. Well, some of the secret weapons are coming up because MJ is collaborating with our colleague, Stephen Oyvind Sandback, and on the cross-country ski plans that are being embedded into Athletica as we speak. so, yeah, so congratulations with those two on the great work that are coming out, hopefully, this winter.

Yeah, yeah.

Okay, yeah, Nobody knows,

yeah, well, Avin, there's nobody that knows skiing better than Avin among the sports scientists, so he's great.

from the Athletica standpoint, Stephen, we're doing some heavy work right now on our coaching platform, just so that Athletica becomes a tool for coaches, not a replacement for them. So just put that out there. MJ is collaborating with me right now on the interface and whatnot that we know needs to be better. we're completely aligned with what you just said there.

Thank you for listening today to the Athletes Compass podcast. Take a moment now, subscribe, share, and let's keep navigating this endurance adventure together. Improve your training with the science-based training platform, Athletica, and join the conversation at the Athletica Forum. For Dr. Stephen Seiler, Marjaana Rakai, and Dr. Paul Laursen I'm Paul Warloski and this has been the Athletes Compass podcast. Thank you so much for listening.