Dr. Stephen Seiler joins us to talk about his new project developing a breathing frequency measure and why it may match up better with perceived exertion than heart rate or power.
For a long time now, we’ve been trying to figure out how to best measure training load and the stress it places on our bodies. Some athletes live by power while others still like to use heart rate. The truth is that both are decent surrogates, but they have their shortcomings. A bad night of sleep or how well you’re hydrated can affect heart rate. While power is an accurate measure of load, it’s not a measure of the stress on our bodies. One day 250 watts may be the perfect power for a particular interval workout, but the next day it may be too high or too low.
RELATED: Episode 308 How to Navigate a World of Exploding Metrics and Estimates with Dr. Stephen Seiler and Marco Altini
This is what’s led many coaches and athletes to say that oldest metric – perceived exertion or RPE – is still the best. But what if there was a quantifiable and reliable measure that actually matched up with RPE? As it turns out, breathing frequency is controlled by the same part of the brain that controls our perception of exertion. So, the harder we perceive an effort to be, the faster we breath.
This is important because your power may stay steady through a long workout, but as you fatigue, your perception of that effort will get harder and sure enough your breathing frequency goes up as well. Likewise, a set of Tabata’s may feel all out, but heart rate will show a moderate effort because of the frequent rests. Breathing frequency, on the other hand, will also be maxed out.
Long time friend of the show and respected physiologist from the University of Agder, Dr Stephen Seiler, has recognized the value of breathing frequency for a few years now and has been working on developing a measuring device. So far, the results have been promising.
He joins us for today’s episode to talk about the history of breathing frequency as a metric and why it may be the most valuable metric to come around in a while. This includes the fact that it may be a better metric for training stress. We’ll also discuss what drives ventilation and why there may be a value in training it. Finally, we’ll talk about where things are at with breathing frequency devices and what challenges still need to be overcome.
Joining Dr. Seiler, we’ll also hear from coach and physiologist Julie Young, owner of Julie Young Training.
So, slow your breathing – or speed it up if you’re expecting this episode to be an effort – and let’s make you fast!
References:
- (Fitzharris, Hezzell, McConnell, & Allen, 2023; Greco, Innocenti, Massaroni, & Nicolò, 2024; KIPP, LEAHY, & SHEEL, 2024; Nicolò, Bazzucchi, Haxhi, Felici, & Sacchetti, 2014; Nicolò, Marcora, & Sacchetti, 2016; Nicolò, Massaroni, & Passfield, 2017; Nicolò & Sacchetti, 2023)
- Fitzharris, L. E., Hezzell, M. J., McConnell, A. K., & Allen, K. J. (2023). Training the equine respiratory muscles: Ultrasonographic measurement of muscle size. Equine Veterinary Journal, 55(2), 295–305. Retrieved from https://doi.org/10.1111/evj.13598
- Greco, G., Innocenti, L., Massaroni, C., & Nicolò, A. (2024). Validity of a Commercial Wearable Sensor Measuring Respiratory Frequency in Cycling. Journal of Science & Cycling.
- KIPP, S., LEAHY, M. G., & SHEEL, A. W. (2024). Sports Bra Restriction on Respiratory Mechanics during Exercise. Medicine & Science in Sports & Exercise, 56(6), 1168–1176. Retrieved from https://doi.org/10.1249/mss.0000000000003403
- Nicolò, A., Bazzucchi, I., Haxhi, J., Felici, F., & Sacchetti, M. (2014). Comparing Continuous and Intermittent Exercise: An “Isoeffort” and “Isotime” Approach. PLoS ONE, 9(4), e94990. Retrieved from https://doi.org/10.1371/journal.pone.0094990
- Nicolò, A., Marcora, S. M., & Sacchetti, M. (2016). Respiratory frequency is strongly associated with perceived exertion during time trials of different duration. Journal of Sports Sciences, 34(13), 1199–1206. Retrieved from https://doi.org/10.1080/02640414.2015.1102315
- Nicolò, A., Massaroni, C., & Passfield, L. (2017). Respiratory Frequency during Exercise: The Neglected Physiological Measure. Frontiers in Physiology, 8, 922. Retrieved from https://doi.org/10.3389/fphys.2017.00922
- Nicolò, A., & Sacchetti, M. (2023). Differential control of respiratory frequency and tidal volume during exercise. European Journal of Applied Physiology, 123(2), 215–242. Retrieved from https://doi.org/10.1007/s00421-022-05077-0
Episode Transcript
Trevor Connor 00:00
Trevor, hello and welcome to fast talk your source for the science of endurance performance. I’m your host. Trevor Connor, here with Chris case and Dr Griffin McMath. For a long time now, we’ve been trying to figure out how to best measure training load and the stress of places on the body. Some athletes live by power, while others still like to use heart rate. The truth is that both are decent surrogates, but they have their shortcomings, a bad night of sleep or how well you’re hydrated can affect heart rate. While power is an accurate measure of load, it’s not a measure of the stress on our bodies. One day 250 watts may be the perfect power for a particular interval workout, but the next day it may be too high or too low. This is what’s led many coaches and athletes to say that the oldest metric received exertion, or RPE, is still the best. But what if there was a quantifiable and reliable measure that actually matched up with RPE? As it turns out, breathing frequency is controlled by the same part of our brain that controls our perception of exertion, so the harder we perceive the effort to be, the faster we breathe. This is important, because your power may stay steady through a long workout, but as you fatigue, your perception of that effort will get harder, and sure enough, your breathing frequency goes up as well. Likewise, a set of tabatas may feel all out, but heart rate will show a moderate effort because of all the frequent rests. Breathing frequency, on the other hand, will also be maxed out. Long time friend of the show and respected physiologist from the University of Agh, Dr Steven Seiler, has recognized the value of breathing frequency for a few years now and has been working on developing a measuring device. So far, the results have been promising. He joins us for today’s episode to talk about the history of breathing frequency as a metric and why it may be the most valuable metric to come around in a while. This includes the fact that it may be a better metric for training stress. We’ll also discuss what drives ventilation and why there may be a value in training it. Finally, we’ll talk about where things are at with breathing frequency devices and what challenges still need to be overcome. Joining Dr Seiler. We’ll also hear from coach and physiologist Julie young, owner of Julie young training, so slow your breathing or speed it up if you’re expecting this episode to be an effort, and let’s make you fast.
Chris Case 02:12
Hey everybody. This is Chris case, joined with Trevor Connor and Griffin McMath and Dr Steven Seiler over in Christian son this morning, or for us this morning. It’s afternoon. For you, welcome back to the show. Dr Seiler, well,
Dr. Stephen Seiler 02:27
thank you for having me. It’s always fun. When was the last time we had you on the show? I feel like it’s been a bit, been a minute. I think it was maybe not on the show, but did an interview with Andy Pruitt some months ago, back in maybe September, or something like that. So it’s been a while. I’m
Trevor Connor 02:42
still recovering from the hot wings, but that’s going bad. Yeah,
Dr. Stephen Seiler 02:48
we we don’t need to mention all the different things we’ve tried to
Chris Case 02:55
- What’s interesting today is hate to say it, but you and this podcast sort of united together to popularize your reputation as the king of the polarized method. But today, we’re not talking about that at all. We’re talking about a completely different subject. Is that a good feeling to talk about something else
Dr. Stephen Seiler 03:13
up in my brain, it’s all connected, but that we’ll get into that in terms of how to train what we’ve learned about the training process, and then how do you, how do you monitor it? How do you kind of keep, keep control of it, and know when’s enough and when’s too much. And so the breathing part that we’re going to talk about today does, it’s not out in left field, really. It’s, we’re bringing it into the fold to say, Hey, this is maybe a really useful tool for us understanding our own bodies and brains better during exercise. So we’ll get into
Trevor Connor 03:50
- So the connection I see, and actually, this morning, I got to work early, so I read a study that you had written about this concept of ISO effort, and what I’m seeing you get into now, when you talk about polarized training, you came up with the idea by looking at how pros were training, but it wasn’t something that you were seeing in the research. It wasn’t something that they were measuring or studying very well. And I know you’ve been working on figuring out how to study polarized training we’re actually recording later today with one of your students about a study that you and he wrote about the different distribution models. And one of the things I noticed there is the difficulty in measuring these different distribution models. So what I find really interesting now is you are getting into how do we better measure this stuff? So ISO effort. Most research studies, when they compare different training methods, try to match for work, which is not a great way to do it. So you came up with this notion of you want to go as hard as you can in each different protocol, and the work actually isn’t going to be the same, but it’s more. Representation of what they’re doing out on the road, and what I’m finding that we’re going to go into today with this breathing frequency is it does seem like it could be a really good metric for how hard you’re going. So it does all seem to interrelate. We’re trying to find better ways to measure all this.
Dr. Stephen Seiler 05:16
Yeah, and so, you know, I don’t know where to where we want to begin actually, but all I can say is, if we go back the first or at least, one of the first formal lectures I gave was in France at the European College of Sports Science meeting in 2004 so Exactly, yeah, 20 years ago, and I’m sitting there and I’m giving a lecture about this idea of training intensity distribution, which was kind of a new thing, even as a as a topic, and then trying to describe what we were seeing with high, high performance athletes, and, you know, and how they were distributing their training. And the coaches in the audience, the national team coaches who were at this conference, they’re nicking their head positively, they’re saying, Yep, that’s what we do. And then the scientists in the audience were looking at me like, that’s not right, that can’t, you know, seriously. So I was getting this mixed messaging. And the audience, the people that were me, my people, the scientists, were like, no way that can’t be right, because their background was the body of literature that was basically taking untrained people and training them for eight to 10 weeks and then measuring them again. And a good way to go with those is just have them work at the same threshold intensity every day, three days a week for eight weeks, and yep, they get a nice response. So it didn’t make sense to them that I was basically saying, well, athletes don’t do that too much. Yeah, they do threshold stuff, but they don’t want that to be where everything ends up intensity wise, it’s a great way to just stagnate. So that was that message from 20 years ago, and it was seen as very provocative and everything. And now it’s almost like everybody says, Well, yeah, we’ve always known that, you know, that’s what I hear. You know, I feel like it’s become a cottage industry to talk about either polarized or pure middle or, you know, so things have changed a lot, and we do have a, I think there’s a greater acceptance for at least one aspect of all of it, and that is, you can’t train hard every day. You can’t train in the red zone every day, or even the yellow zone. And so there’s a lot of generalizable acceptance to say, Yeah, most of the total volume, if you’re counting hours or counting sessions, most of those sessions will be working, just doing the work. And zone one or two depends on your model, you know, whether you’re using a three zone model or a five zone model. Okay. So then along the way, when people started to compare this stuff, you know, like you say they were using kilojoules or amount of work as as the calibration, then you would end up with these really bad, really poor, low intensity sessions that lasted maybe 40 minutes, and then they would be compared with a 30 minute interval session, and the interval session would come out on top as being much better. And so then I said, Well, yeah, but that’s not how athletes train. If they train at a low intensity, they’re not training for 40 minutes, they’re training for 90 minutes or two hours, or if they’re cyclists, they may be going for hours. So that’s not, that’s apples and oranges. You’re not, you’re not comparing reasonable workouts. And so that’s when we started saying, well, let’s just when we’re looking at these workouts, let’s base things on effort. What’s the effort of the workout or and we called it maximum session effort. Is it truly maximum? Probably not. If I threw, you know, if I waved some money in their face, or if I, you know, if they were under threat of being eaten by the dog, there’s probably a little bit to go. But it’s mathematically. If you say, do four times six minutes with two minute recovery. I’m giving them some parameters. It’s like algebra training algebra. And I’m giving them some of the known variables, and they’re solving this equation with the output, with the power they manage to hold for each of those work bouts. And then we just would say, try to maintain a power where you don’t fly and die, try to have the highest average power or speed during the workout. And that’s your kind of, your measure of getting it right. But it’s not going to feel stable. You’re trying to hold a stable power or a stable speed with this maximum session effort kind of approach. But trust me, it doesn’t feel stable, because your perceived exertion is getting higher all the time. And then we start sneaking into the breathing issue, and what we see is that, well, by golly sodas, breathing frequency, it increases just. Boom, you know, all the way up as we’re doing these hard sessions and and it is just a very good indicator of effort, of how deep we’re digging to maintain that power or to hold on to that group, you know, and it’s costing more and more and more, even though heart rate may be stable, quasi stable. So that’s what we found. Is breathing is really interesting because it’s telling us something extra. And
Trevor Connor 10:33
that’s a good segue to the topic on Hannah is going to say I would actually love to do an episode with you where we talk about measuring intervals, the particular type of workouts that athletes do by work versus effort, because I think that’s really important. And like I said, I read one of your studies this morning, and it drew very different conclusions from what you were seeing with studies that were based on work. But this episode, yeah, we’re talking about respiration. And glad you made the segue. So let’s talk a little bit about that, and maybe let’s give some background for any of our listeners who are hearing this for the first time. Tell us a little bit about what you mean by respiratory frequency.
Dr. Stephen Seiler 11:14
Look, endurance is about moving oxygen from the atmosphere from the sky into the lungs and out to every working cell. That’s what makes us these aerobic creatures we are, that we can do, that we can move oxygen from the atmosphere. We don’t have to it doesn’t have to be absorbed through the skin or through it. We’ve got this apparatus, and it’s got two parts, and one part is the heart and the circulatory system. So that’s the transport system for blood. And blood transports oxygen and CO two and then the lungs represent this interface, this radiator, this exchange zone, to allow for that handoff from the atmosphere to the blood. And then the blood says, All right, got it, we’re full. And it goes to the working musculature. It goes everywhere, but particularly during exercise, a lot of the total blood flow is going to those muscles that are working rigorously. So that’s the heart without the lungs is useless. The lungs without the heart is useless. They are only useful, and they keep us alive as a duo. Okay, now, all right. So when we breathe, just like with heart, with moving blood, we can kind of think of three variables in the heart. You’ve got the frequency of beating, the heart rate. You have what’s called the stroke volume, which is just how much blood is in each beat in milliliters. It’s, you know, it’ll be some number of milliliters, 70 at rest, and maybe 150 at you know, high intensity or more. So that’s heart rate times stroke volume equals cardiac output, which is a measure in liters per minute. Well, we can do exactly the same with breathing, except this time it’s breathing frequency, which is analogous to heart rate, and then tidal volume, which, as the name suggests, is analogous to stroke volume. So it’s the amount of air in each breath that’s being moved in and out of the lungs. And then we can multiply those two together, just like we do with heart rate and stroke volume, and we get ventilation volume, which is liters per minute. They’re parallels of, you know, the math is, is essentially the same of how we do this. And like, heart rate, breathing frequency, is just easier to measure. You know, heart rate is, was one of those first biometrics we could get a hold of and measure accurately. Well, breathing frequency within the respiratory complex of frequency and stroke and tidal volume and ventilatory volume, breathing frequency is the easiest one to measure accurately and repeatedly. Okay? And not only that, but it’s really, really useful. It’s a truth teller, because it turns out that breathing frequency is tethered to effort. It when the brain is perceiving it’s having to turn on more muscle, for example, as we fatigue, one of the things the brain will do is say, okay, the desired power is 300 watts. I’ve been holding that for 45 minutes. It’s getting really tough, and the brain is turning on additional reinforcements of what’s called motor units, these groups of muscle fibers that are controlled by a single nerve. And so as the brain recruits more muscle because other muscle units motor. Units are dropping out. They’re fatiguing. Well, it also parallel. In parallel will increase breathing. There’s a connection between as the brain is mobilizing reinforcements, as we’re feeling, you know, it’s feeling harder, the breathing frequency is matching that. Here’s what was going on. Is I, one of the key issues for me when I came back after some years in leadership is I said I got to get my head around all the different metrics, all the different terms that are being used on top of each other in in this field I love called sport science, because it’s like the Tower of Babel in the Bible. We’re all using different terms and the languages we’re not understanding each other. And so I’m starting to see a proliferation of metrics, you know, and and including things like Functional Threshold, power and training, stress score and just terms load is getting used. Sometimes people are saying stress, some people are saying load, you know. And so it was confusing. Anybody could have been confused. Because I think we as scientists were confused when I would, you know, look at the literature, I was like, Good grief, we can’t agree on what on the terms we’re using. So I exited. I said, I gotta see if I can find somebody, someone, somewhere, some field that makes more sense of all this. And so I went to engineers. First I went to hon Selig to try to understand what he was thinking and writing when he was talking about stress and and the general adaptation syndrome and so forth. And then I went to the engineers. And it happens, you know, because I kind of like the mechanical engineering, all the geeky technology. So I thought, I wonder what they think. Well, it turned out that the engineers used three terms, very structurally and with and with clear definitions. They used load, stress and strain. And I thought, Oh, wow, and so. And then I looked and I said, Well, my goodness, all right, how they define this and then load was just, very much just the actual physical load, mass times gravity, being put on top of a wooden beam. And the wooden beam, or the steel beam, or whatever they were measuring the tolerance of it would be stressed by the load, the cells of the beam were under stress when the load was applied, and they could measure the relative difference. But then, if the beam started bending in response to the load, that deformation was called strain. And so all of a sudden, I was like, well, that I can see parallels of with biology here. But obviously the biology is different because it’s not linear. It’s, you know, there’s some the same load can be responded to in different ways. And so we started having to work with this, but it the framework worked. And so that’s what I’ve been focusing on, is trying to understand using that framework in a biological context. And then when you do that, now, when I give you a prescription as an athlete, I say, I want you to do four times eight minutes at 90% of your you know, FTP or whatever. It’s a calibrated load, but it is the external load. It’s what you do. It’s not what it does to you. Does that make sense? So load is just what you do, and then stress becomes the response, and intensity means nothing without a duration attached to it. You know, intensity can’t operate in a vacuum. You can only make sense of it if you give it a duration. And what we see is that obviously, when we’re working at high intensities, the minutes count and the minutes change, the perception changes, the cost changes, the amount of muscle recruited changes, the hormonal responses change, the heart rate drifts. Lots of things change, so that whether we’re talking about a short interval session that lasts 30 minutes or a six hour bike ride at low intensity, each unit of time is not the same from a standpoint of what it’s costing to do. And then the question is, well, how do we measure that?
Griffin McMath 19:20
You made a really great point about terms, and everyone aligning on terms, and I think this is a really great point before we jump in here. Because even in preparing the outline, we’re talking about respiration, we talk about ventilation. You’ve already said ventilation rate, and in the medical field, so often people refer to respiration rate. And so I think we just pause here, understanding that ventilation is the mechanical act. Respiration is that physiological exchange of gasses that you can’t, you know, witness overtly. And then understanding, I think, other things you’ve talked about too, with heart rate as a great segue, what this measurement act? Actually means, and something called a practical proxy. So you might look at someone’s ventilation rate, right, not respiration rate, and go, Oh, okay, this is the information we can grasp from this, but it’s indicative of a rabbit hole to go down, or context to put it in, just like blood pressure, just like BMI has been. So I think I’m really curious now that you’ve really laid out some terms here ventilation, you’ve talked to respiration rate, you’ve talked about load and all these stroke volume, right? How can we dive into this being a really meaningful metric to
Trevor Connor 20:37
Griffin’s point, adding a new metric is going to be a challenge for athletes and coaches alike. Here’s experience coach Julie young talking about her willingness, at this point, to use it as one of her measures.
Julie Young 20:49
I don’t use breathing as a metric. Definitely try to enforce, like, reminder of good breathing and trying to train that off the bike. You know, I think yoga is a great thing for that, like, kind of getting us more aware of how we’re holding our body and maybe how we’re holding our breath. And really do try to work with athletes, like on the bike, like try to maintain that relaxed, deep belly breathing, but I don’t use it as a metric.
Trevor Connor 21:13
Let’s get back to our conversation with Dr Seiler and hear why this new metric may have values we don’t get from heart rate or power. Can I jump in here? Because I think this is really important, where you were going with this, and talking about the load, talking about the internal and external measures. So I just want to throw this out to all our listeners to make sure they understand this. Going back to your whole idea of maximal effort, let’s take two different interval protocols. One that’s continuous. You just tell the athletes, go do a 30 minute time trial so it’s steady. Just go as hard as you can for 30 minutes. And then you have another protocol, which is 3030s and you tell the athletes, same thing, do this as hard as you can. If you measure those with heart rate on that continuous effort, the heart rate is going to match up pretty closely with how hard they are going. You know, when they tell you, I’m going about as hard as I can, and this is really hurt, and their heart rate is going to be very high, and you’re going to see the heart rate go up with their perceived effort. But when you get to those 3030s they’re going to tell you the same thing. This really hurt. I was going as hard as I could, but the heart rate is going to be substantially lower. Heart rates actually going to disassociate from the effort. So heart rate, in that particular case, isn’t a good measure of the intervals you could use power. But the issue with that being an external measure is they could come back and say, Well, I did the 3030s I did them all at 400 watts. And the answer that question is, was that good? Could you have done them at 500 we don’t know, relative to you, whether that was a good effort or not. And what you’re bringing up, and I hope you dive into this more, is the fact that again and again and again in the research, this breathing frequency matches up whether it’s intermittent or continuous, like the 30 minute effort, or, you know, the 3030s breathing frequency matches up with perceived effort every single time it
Dr. Stephen Seiler 23:04
does. And so if we back up a little bit, and I say, you know, I found this load, stress, strain, kind of construct from the engineers. And I said, All right, I want to work with this. And I introduced it to some physiologists, the first ones in Australia, and I, and I kind of stress tested it with other groups. And they said, Yeah, this makes sense. And so I thought, Okay, I’m going to keep going. I’m going to keep working with this, and then I’m working with my colleagues, and you know, we developed our own kind of bespoke analytics, this Endura. And I’m trying to say, Well, how would we quantify the stress response? What do we have? Well, we got heart rate, so we can look at cardiac drift. And we tried to get real fancy with how we measured it, by saying, well, we’re not going to just measure heart rate drift. We’re going to measure a calibrated heart rate drift. We’re going to, you know, look at the drift relative to the heart rate reserve. You know, because we all have a max heart rate, we’ve got a resting heart rate, and those are quite individual, but there’s the number of beats between rest and Max, that’s our reserve. That’s how many beats we have to work with. And then if we take a percentage of that reserve, it matches up quite well with what percentage of vO two Max we’re working at, for example. So we use this, and we started developing metrics, you know, for analyzing the heart rate as a tool or a measure of this increasing stress response, and it it’s when you’re working at low intensity and you go a really long time and you get slow drift because of fatigue. It kind of works. It kind of makes sense. But then when you do interval sessions, it’s like, wait a minute, the heart rate drift is actually less during a hard interval session than it is during a really long ride. Why is that? Well, because of seedling effects. Because if you’re working at 90% heart rate Max, you don’t really have any room to drift very much. Plus, turns out, heart rate is really strongly tethered to the actual oxygen demand. It doesn’t just over supply. I so if I’m just busting my butt during the interval session, and I’m giving everything I got, I, like you say, during that 3030 I may only be at 90% of max heart rate, right? And so what we were seeing was this was just not satisfying. I was I was thinking, I’m not capturing stress reasonably with with heart rate, I’m missing something. But then I was listening to myself, but good grief, I’m always breathing like a horse at the end of these workouts. I wish I could measure that, you know? And so then I started trying to measure my own breathing. And then I realized, well, as soon as I start trying to measure it, it changes, you know, because it just that’s that kind of how it is. So I end up getting connected to a company that was developing a wearable for this, and that company was time where, and we’re still working together, and we’ve been working together now for three years, I guess, and then at the same time, I found the research of a guy named Nicolo, Andrea Nicolo from this kind of the Italian sports university, and he had a couple of nice papers that I read quite early on. One of them was with the late Lewis Passfield from the University of Kent. Some of you will remember Lewis. He did a lot of work in cycling. He had a bad fall, and ultimately died from those injuries, tragically, but Lewis and Andrea wrote an article about breathing frequency as the neglected physiological measure, and I went into that and thought, Oh, my goodness, yes, this matches up so well with what I am feeling. You know, what I’m perceiving as an athlete when I’m doing these hard workouts, is breathing is a truth teller, but we just need a way to measure it, you know, independent of our own heads. And so it was just this alignment of the stars for me, meeting him, seeing in his research, and he says, Look, breathing frequency is being controlled by a different part of the brain than tidal volume. So he was presenting a differential control theory on this whole process. And so that was interesting. And then he says, Hey, this is a one of the Forgotten vital signs in hospitals. What do they do? They measure your heart rate and they check your breathing. Those are the two most important first, you know, if you get wheeled into a hospital unconscious, those are the first two things they’re going to look at, the first two variables. And in endurance exercise, it kind of works the same way as Good grief. They’re powerful tools for me, for monitoring, and they tell us different parts of the story, heart rate and breathing. So then we kept going with this, and I first started testing it on myself. The wearable began as a shirt. It’s no longer a shirt now. It’s now a belt, but it began as a shirt, with the assumption being that the shirt would help stabilize the sensor very specifically on the torso, and that that was really important for accuracy. Turns out that, unfortunately, the shirt transferred a lot of extra noise, bending and moving as the person you know was executing their sport and and so it turns out a well designed belt is actually a better solution. When you say belt, do you mean chest strap? Yeah, it’s a chest strap with a two different sensors. One is a ECG based heart rate monitor, and the other sensor is a stretch it’s a stretch sensor, a very accurate, precise stretch sensor that is coupled to tested textiles that have the properties that they need to have in terms of repeatability. You know that they keep giving the exact same amount of stretch with the amount of force for gazillions of repetitions and all this stuff. Anyway, early days, we test it first with me in my home lab, and I get enough of a good response, I’m getting good measurements, I’m thinking, Okay, let’s move this into the lab. So then we start testing it in the lab, and it looks pretty good. And so then I have a master student that is going to be going and testing something with the UNO X cycling team at the time. And I said, You know what, while you’re there, I want to put this shirt on some of the riders and get a feel for it, see what’s happening. I feel good enough about it. I want to at least test it out. And I knew the coach, Espen aerosol, who now is with visma, and you’ve interviewed him, he’s been on the show, as I recall. So we started testing it out, and it was a mess. I mean, the battery life wasn’t good enough, you know, it was just enough of a success that we said, All right, this is going to get better, you know, and so, but there was something there. They were just not prepared for cycling with the hours and the mountains and, you know, the issues around the signals and stuff. But they learned really fast. The iteration process was exciting, you know, the. Technology, the software was just being iterated in real time, you know, and fixing problems and and I thought, all right, I’m gonna keep working with these group, because they are on it, and it just has gotten better and better. And so now fast forward three years later, and espionage showed the coach that I was been working with. He went to visma, visma, Lisa bike, and then I was asked to speak with them, and then we had a meeting down in Rome and and so I can say, you know, and visma is testing these straps, the belt and the breathing measurements on the entire team. And they do things very professionally. They’re very careful in terms of their approach to examining a new technology and seeing whether or not it is a useful tool. And the jury will see how that goes and what they decide. But we are doing a full scale evaluation of that, and we’re collecting data on all the riders with, you know, ventilation. Okay, so that’s the background. Is the stars align. I started working with a startup at the same time, I interacted with this academic resource in Italy, Nicolo and his colleagues, and it all kind of came together for me into thinking, all right, this is interesting, but then now, here’s the deal. Here’s what makes breathing interesting. Because if it just behaved like heart rate, there wouldn’t be any point to it. If it told us what heart rate tells us, that would just be waste of money and waste of time, you know, and athletes don’t need another sensor on their bodies if it doesn’t give them added value. But what we found was that, interestingly, just as we learn in physiology, the lungs, you might say, are over developed or over dimensioned, or it seems like for exercise compared to heart rate, compared to cardiac function, but that’s a truth with own with modifications. So when you if you have athletes at low intensity, you know exercising it below their first lactate turn point, and then you quantify breathing, just like you quantify heart rate as a percentage of the reserve. So you figure out what’s their maximum functional breathing frequency, and it can be 80 in cyclists. I mean, they can they hit some pretty high frequencies. I even hit 80 sometimes in my old age. So it’s not crazy for that to happen, and then you have a resting frequency that is somewhere around 12 to 15 breaths per minute. So you can do the same math and say, Well, you’ve hit 80 repeatedly at some of your toughest workouts and races. You’re we’re going to just assume your resting is around 15, and now we’ve got your breathing frequency reserve, and then we can take what percentage of that are you using, right? So what we found was, is that under normal conditions, the human body is using a much lower percentage of the breathing frequency reserve than the heart frequency reserve. So we’ve got a bigger reserve in breathing than we do for heart rate from the get go, okay? And so then you think, well, then that, what good is that going to be to measure? Well, here’s the deal, as the athlete works either a tough workout that goes many hours or particularly a threshold plus intensity situation. You know that 30 minute or one hour time trial, or that, you know six times five minutes, or those 3030s or 4020s or, you know, all of those, what we’ll see is that initially, breathing frequency seems to be well under control. It’s lower as a percentage of reserve than heart rate. But what happens is the breathing frequency increases faster than the heart rate drifts, and so it catches up with the heart rate. And so what we have seen time after time with national champions, World Champions, goofball, sports scientists, it doesn’t matter, is that when the cyclist or the athlete, when their breathing frequency reserve hits the same relative percentage as their heart frequency reserve, what that they’re at, whether it’s 85% or 90 or 95% when they overlap, that athlete is eminently about to lose the group. They’re about to fail. They are at their limit. It’s a truth teller, and so we’ve seen it time after time after time, and it’s not a function of ability or, you know, again, I’ve done a lot of this on myself, and I thought, well, maybe I’m different. No, when we’ve looked at these top athletes, they’re at very much different powers, but the physiology is the same. And so that’s what got the interest of, you know, the teams, is that they say, Okay, this is interesting. I want to look at this because they don’t have to measure it doesn’t have to be a super. Fancy measurement, if we can just accurately measure frequency, breathing frequency, and we can now, we think we’re also going to be able to get tidal volume, and then, by extension, ventilatory volume, so we’re going to get even more out of these measurements. But just being able to measure frequency itself get tells us a lot. And so that’s where we’re at right now. In addition with wearable technology, I believe what we’re seeing will be able to, in a way, replace the lactate threshold measurements in the field with ventilatory threshold measurements and make them less invasive, less problematic. Because, you know, doing a good lactate profile is not it’s not simple, it’s not technically trivial, and coaches don’t always do it really well. It’s tough. It’s doesn’t take much to make a little tiny mistake and and so if we could move over to ventilatory thresholds and get the same quality of information, then that would be a practical win in the field. So that’s another issue that we’re working with. I’m
Trevor Connor 36:01
going to say, I think one of the values that I got really excited about here is what we talked about earlier, which is they’ve looked at all the different metrics that we have and breathing frequency, and this is in multiple studies. And thank you for mentioning those authors. You were kind enough to send us a bunch of studies, and we’ll put those in the show notes for anybody who’s interested. But those studies showed again and again and again. Of all the metrics, breathing frequency is the only one that matches up with RPE again and again and again and sorry, I’m sure you’ll talk more about this, but they’re both have have a central command, and it’s the same mechanism in the brain that seems to control both. There is a neuro physiological link between the two. When you feel you are going harder, your brain says, start breathing harder. So they are literally linked. There is a physiological link between the two, but I find that really important, because we’ve had coach come on the show again and again and again. When you say, what is the best measure when you’re out on the road, for doing your work, for racing, for doing time trialing, for doing intervals, and they always go effort, perceived effort. You need to train by perceived effort. We literally now have a metric that matches up with perceived effort. So you can now measure perceived effort. I like
Dr. Stephen Seiler 37:22
the way you said that, because you give me the opportunity to ask a question that I had immediately, and I thought, well, if it just goes in parallel with perceived effort, and we already have the Borg scale, why can’t we just use the Borg scale? But it turns out that measuring perceived effort in that kind of way in the heat of the battle. It’s not so easy to do
Trevor Connor 37:42
in the middle of the race go, what number am I right now? Yeah, nobody,
Dr. Stephen Seiler 37:46
nobody does that. And so it turns out, in fact, we’ve worked with Garmin to clear up a channel so that the athletes could actually punch in their RPE during workouts to get a more quantified RPE response. So RPE is seemingly the easiest metric in the world to measure, but it’s not trivial to do in actual training, you know. And the other thing about RPE perceived exertion is that there is a tendency to game the answer in the sense that the athlete says, Well, what did I answer last time? 14? Okay, well, 15, you know. So they tend to reflexively want to know what was the previous answer. And so they’re not totally untethered giving you the response of, where am I right now, necessarily, whereas with breathing, it’s free of that bias.
Trevor Connor 38:37
It’s also easy in a lab, when you’re being tested, when a researcher says, What’s your RPE right now? To give an honest answer, when you’re in a race, emotions play in, and you might start thinking you’re hurting a lot more than you are, or you might convince yourself you’re not hurting nearly as much as you are based
Chris Case 38:53
on who’s around you, what they’re doing, yeah. Well, there’s a lot of factors. It’s very subjective in that way.
Dr. Stephen Seiler 38:58
Yeah, if I just got dropped, my RPE is higher than if I’m hanging on. That’s
Chris Case 39:03
right, that’s right. Yeah, there’s a psychological aspect to it, for sure, right? So
Dr. Stephen Seiler 39:07
there’s a lot of issues so, but yes, and here’s the thing is, look, I studied exercise physiology as a student my PhD work, we learned about ventilation, of course, but what we basically said was, Well, if your lungs are healthy, they’re over dimensioned. They’re not the limiting issue. Just let’s focus on other stuff. And so short of having asthma or some other condition, we basically said the lungs are not a problem. But here’s the thing, and let me to say one more thing. The way they would build evidence for that assumption of over dimensioned capacity for the lungs was to have people do what’s called Maximum voluntary ventilation tests, where they’d say, All right, I want you to breathe as deep and as fast as you can for the next 30 seconds or the next 60 seconds. And sometimes you get busy doing that. But. It. Let’s Let’s assume you do it right, and you you get a number in liters per minute of what’s your maximum ability to just move air in and out of your lungs. And let’s say you get a value of 150 liters per minute. And then you do a vo two max test, and then you only got to 120 liters per minute when you were at max, right? Your ventilation at maximum. At the o2 Max was 120 and you have 150 as your maximum voluntary ventilation. So then they say, see, lungs are over dimensioned. You with me, lungs aren’t a problem. Here’s the deal. If we then compare the o2 consumption, let’s say it’s four liters a minute. But in that last minute when you were at that maximum consumption of 4000 liters, 4000 milliliters in a minute of oxygen consumed, you may have been at 4400 or even closer to 4800 milliliters of CO two removed, because the lungs are also getting rid of CO two and the at high intensity. We know the physiology tells us that this, the respiratory exchange ratio can be well above one, meaning there’s more CO two getting pushed out than there is o2 coming in. This is because of some chemistry around buffering and different aspects of that physiology. So I would argue that it’s better to think of it the lungs or dimension for CO two removal. That was literally one of the questions
Trevor Connor 41:31
I was going to ask you, because that goes back to an episode that we did where we talked about oxygen delivery and removal of CO two, and that’s something I remember learning in physiology classes, which is breathing in oxygen is not the driver of breathing rate. It’s actually the exhalation of CO two That’s right, because arterial
Dr. Stephen Seiler 41:50
oxygen concentration, just to get all geeky, is maintained super well. So it’s not really the driver, but it’s CO two concentration, to be honest, breathing and respiration, respiratory control, or ventilatory control, is super complex. The engineers would love it, because it’s there’s all kinds of redundancies in the systems. There’s redundancies in the control mechanisms. And I guess evolution has said, Look, breathing is really darn important. So we’re going to build in a bunch of different ways to get to the same place, which is we’re going to be able to increase ventilation when it’s needed. The brain’s not going to forget to breathe. The brain’s not going to forget to increase frequency, because there are redundant mechanisms that are there. And so you talk to some of the great breathing physiologists, like Jerome Dempsey, you know this. It is one of the most complicated aspects of our physiology, you know. So anything I say to you is a simplification, okay, but as a simplification, I will say that CO two is the driver. CO two is regulating CO two, because folks, CO two is a poison for the body, for the cells. So if CO two accumulates in your body, you die, and you die quickly. It is a very lethal poison from that perspective. So it is incumbent upon us, on our bodies, to control CO two concentration in the body, and it does so beautifully, but, but CO two is, is the main driver, and there’s multiple mechanisms for that, both feed forward and feedback mechanisms. You know, feedback means there’s sensors out in the in the you know, on the carotid, there’s sensors different places, mechanical sensors in the joints, but there’s also this feed forward mechanism in the brain, and so clearly, the body has invested a lot of neurocircuitry to make sure we get breathing right most of the time, more than anything else I know, more than any other kind of control mechanism I’m aware of.
Trevor Connor 43:58
So here’s the question that I had for you, because we said Carbon dioxide is the driver of breathing. We need to get the carbon dioxide out of our system. Yet we just said, and what we saw in the research that you sent us is that breathing frequency is coupled to perceived exertion in the brain, not to necessarily sensors of carbon dioxide levels. So why is that? Is that because the body’s basically saying it’s so important to get rid of carbon dioxide, we’re going to watch how hard you’re going and just increase the breathing frequency and get that carbon dioxide out of there before it starts becoming a problem. Or what’s the reason here?
Dr. Stephen Seiler 44:39
I’m not going to second guess the evolutionary mechanism. I don’t know exactly what came first. You know, this is this issue of what comes first, chicken or the egg? What comes first, the increase in breathing frequency, or what we also tend to see is that there’s a decrease in tidal volume as you fatigue. Okay, so. At least over a fairly big scope you’ll see, and I have examples on myself, the ventilatory volume is held almost beautifully constant, and breathing frequency is going up, but tidal volume is going down. And sorry for our listeners, explain tidal volume. Tidal volume is that amount of air in each breath. Okay, so now this is really important, because now we come back to some of the mechanics of all this, because so far, we’ve just been talking about the brain and all these sensors. But there’s also a mechanical process to breathing that we need to be aware of, and that is that every time we breathe, there are muscles around our ribs, the intercostal muscles, and there are even some muscles that up in our the stain lateral mastoid, the muscles that can help lift a little bit of the this collarbone and the diaphragm, which is a muscle, okay, so there’s this set of musculature that is designed to expand and contract that torso or that almost like a bell jar that is the lungs are placed in? Does that make sense? And so mechanically now, when I’m as we’re sitting here talking, those muscles are not working very hard at all, and basically all that’s happening is we’re doing a little bit of a lift of the rib cage, and it creates a bit of a relative vacuum. The pressure inside that cavity goes down compared to the pressure out in the atmosphere. And air rushes in through our mouth and into the lungs, through these bronchioles now. And that costs very little. In fact, the only thing it really costs is that inspiration. Because all I have to do is just turn off the inspiration and the expiration at rest, meaning the return and pushing the air back out the mouth. We get that for free, because now we’ve we’ve built up. It’s like some elasticity in that, in that rib cage, and so then it does the pushing passively at rest. If you sit here all the audience, I want you to do a little exercise now. I want you to be conscious of your breathing and feel that you there’s a certain active process in the inspiration, but then the the expiration is passive. You just let go and it just comes back to starting point. But at higher intensities, then it becomes we have to work harder. We have to do a more of an effort in those intercostal muscles and the diaphragm. The intercostal muscles pull the rib cage up, the diaphragm pulls down. So between the two, we get a volume change in that cavity, and that helps move that air in, but then, because the frequency is going up, we have to start pushing the air out, because we got to keep things moving fast. And so to achieve frequency, you have to start doing not only active work on the inspiration, but you have to do active work on the expiration as well. So at higher intensities, the cost of breathing, as we call it, the metabolic cost of breathing, goes up. And that has to come from somewhere that cost, meaning the lungs, and that all that working apparatus around moving air in and out that steals some of the oxygen from our vo two Max. They’re working muscles. And so at low intensities, it only maybe is 10% of the total cost of or total vo two. But at high intensities, it may be 18% it may be it’s a bigger fraction of our total so that’s a tax, you might say. Attacks on doing that work is that the cost of moving air in and out of the lungs, it becomes pretty darn significant in the total scheme of things. So that’s an issue. And certain physiologists have said that maybe that there are is almost communication between the intercostal muscles and the working muscles that the intercostal muscles, if they are having to work extra hard, that will tend to inhibit blood flow to the working muscles. So there’s a lot of complexity here in terms of how the fine tuning is happening, how the body is regulating where the blood goes and where the oxygen goes and and makes decisions along the way, you know, to optimize the situation, optimize the delivery of oxygen. So, I mean, you could get confused. Trust me, we’ve
Chris Case 49:35
been focusing on breathing as a metric. I don’t know if you’re well versed in the trainability of breathing, and if we want to speak to that at all in terms of, would it be beneficial for somebody at a high intensity exercise to reduce the frequency so tidal volume doesn’t reduce in the same way? Is there something to be said for this bit of an. Industry that has developed around breathing training in terms of exercise,
Dr. Stephen Seiler 50:03
absolutely. And the answer is, probably, it depends.
Chris Case 50:09
There have been heard that one before? Yeah,
Dr. Stephen Seiler 50:12
I know it’s like the worst ever answer from a scientist, but we say it all the time. But the inspiratory muscle, breath muscle training. IMT, you know, these, or respiratory muscle training, I guess, is the term RMT, you know, I had a company contact me just two weeks ago around this and they want to send me a device and have me test it and everything. And so at this stage, I’m saying, Yeah, I think I want to do that because I’m interested, and I don’t think it’s a blank check kind of deal where everybody will benefit from some kind of respiratory muscle training. I don’t think that’s true. And in fact, the data, there’s been a lot of studies on various kinds of respiratory muscle training, and the results have been mixed, and I suspect that’s because there’s a lot of individual variation. I think there are probably athletes that have thoracic stiffness, they they have poor posture, and they don’t breathe very efficiently, and maybe they would benefit from more attentive attention to their breathing, but also with training. And then you have other athletes that just Just breathe beautifully and have lungs like a horse, and they don’t, they wouldn’t benefit at all. It’s a waste of time for them to do that kind of thing. It’s kind of the same as strength training for for endurance. You know, we see some athletes respond, and it really cures up, cleans up some weak links, and improves their overall efficiency, and then other athletes, doesn’t make a difference, right? So those are some of those edge cases where we need to individually assess and try to make determinations. And I that’s fair. You know, that’s not to say that respiratory muscle training has no value. It’s just it’s probably needs to be seen as a an individual optimization issue. First
Trevor Connor 52:02
study I was ever a subject in was a study on a respiratory training device, and I took it very seriously. And for six weeks, I had to, twice a day, sit there on that device, and you
Chris Case 52:15
took it very seriously.
Dr. Stephen Seiler 52:19
Why am I not surprised?
Griffin McMath 52:20
Like, how many studies have you been in? First?
Trevor Connor 52:23
Been in many. But that was my first. And six weeks later, when I came back, they first did the measurements on my breathing ability now, and they’re like, Wow, that you you have changed. Like, I really, I take as I said, I took it seriously, and then they did all the testing on me. They’re like, yeah, you’re not any stronger. It was, it was disappointing. Like you can breathe. You can breathe really well, but,
Dr. Stephen Seiler 52:48
but here’s another, here’s a poor person’s respiratory muscle training, maybe, and that’s just to close your mouth during exercise, you know, nasal breathing, and this has become a thing, you know, and I’ve done two hour workouts just breathing through my nose. Now, don’t laugh. You say, Well, yeah, but Steven, you have a big nose, so that wouldn’t be a big problem.
Chris Case 53:10
Whoops, I’m not supposed to laugh. I’m sorry, no,
Dr. Stephen Seiler 53:13
but, but, yeah, I get it, but it is clearly trainable. I have a couple of master students in my lab now, and one of them is has been doing nasal only breathing for years, and his vo two Max is almost the same. His vo two peak, or vo two Max, is almost the same. Without ever opening his mouth. He has such Wow, he gets Yeah, it’s amazing to me, the efficiency that he’s achieved, there’s almost no difference. So there’s a trainability aspect to it. And certainly my thought has been, well, you know, one of the things if I can breathe through my nose and open up those passages and it leads to me being less of a mouth breather at night, that’s a good thing, because sleep apnea, a lot of these issues. It starts with that we’re breathing through an open mouth, because snoring doesn’t happen very easily if your mouth is closed, right? So there’s some interesting aspects to this. And I do know I actually did a little survey on X during the holidays, one of several surveys, and it was related to breathing. About 340, people responded, and you know, a fairly significant number one people, they are very aware of breathing. And they’re particularly aware athletes are particularly aware of breathing. Number one, they says whenever they’re doing high intensity work. And number two, they says whenever they get tired, when fatigue, when they start fatiguing, they become more aware of breathing. So I thought, Well, my goodness, yep, that’s exactly consistent with the research you know, which we have been talking about. So athletes are aware of breathing, and many have tried various things like respiratory. Muscle training. Most have tried it and abandoned it, but some, a percentage, say, Yep, and it helps me, which is, again, consistent with it. It’s individual. So, you know, I found that the people who responded to the breathing questions, a lot of them had extra things to write, because it was something they thought about a lot. It was something that they used in their own way, or they had tried, or they had experimented with, and about 20% had issues with breathing, either asthma or either childhood asthma or exercise induced asthma, or I low. You know, the exercise induced laryngo obstruction. So fairly significant percentage of endurance athletes seem to have issues with breathing, just so we’re clear.
Trevor Connor 55:50
So I’m going to shift gears here a little bit because I have a question that I want to ask you, and I’m actually right now looking at the time where website, I know you’ve been working with them, and I’m a little disappointed that they had this giant picture of two researchers that was so clearly pulled out of some stock photography, as opposed to putting you up there. But it says coming soon, so it’s not available yet. But the key point here is soon. And I remember my first heart rate monitor, being so excited, putting it on, and then going out for a ride and looking at the numbers and going, I don’t know what does that mean. And then my first power meter, same thing. Really excited about it. And then I discovered that your power is going all over the map every half second. And kind of went, what does that mean? So we’re probably going to have some of the same thing here, where people are going to get excited. They’re going to get this device. I’m going to get one. I mean, I’m convinced. But what should they be looking for? How do you use this? How do you avoid that same thing and looking at those numbers and going, No, no,
Dr. Stephen Seiler 56:51
well, and this is why we’re really trying to do this kind of slowly, to get it right. And with this team, this professional cycling team, that is testing them. We sat in Rome, I sat with the lead coaches, the head of performance, and we talked about, all right, how do we do this in a way that doesn’t just result in a bunch of people saying, well, what’s this? What’s this? Crap? Mean what? You know, just confusion. And so we initially have been collecting the data without opening up the interface, so that the athletes don’t get a bunch of numbers to start talking about. They’re curious, and some of the best athletes on that team are super interested in that. I’ll just say it that way, but we’re trying to avoid some of the problems you’re talking about is just throw in a bunch of numbers up on their heads up display that they don’t have enough information to interpret. So that’s a pedagogical issue is, how do we make sure we get the technology working? We get the interface, you know, is really reliable and simple, and then the teaching process is aligned with all that so super important question, I can say, you know, even the timeline for time where I’ve used this guy who runs the the company, he started the company, he he teaches a course for me, or he teaches a he gives a lecture on startups And on technology development. And this, this gentleman, as many he was, he did some beautiful work for DARPA as a student the defense research, you know, the Skunk Works of research in the military and, and it was about exoskeletons and, and his team was the first to actually achieve a an increased efficiency with an exoskeleton. Most exoskeletons have actually increased the cost of work because they’re so darn heavy, but he they achieved it. But along the way, he learned, he got so interested in the physiology that he said, All right, I’m either going to start a company or I’m going to do a PhD. And he ended up starting a company. So he teach, he talks to my students about that process. And he talks about how you have to send something out. You have to send a version of your technology out to the public when you know it still sucks. And that’s a quote that you have to give it an opportunity for that rapid iteration, because there will be this first responder group of people that will use the technology and will give feedback, and they’ll say, hey, it’s not good enough, but I’m still using it, and here’s how you make it better. And so they’ve been in that phase, and they’ve got hundreds and hundreds of 1000s of some few 1000s of users, but that’s not going to pay the bills, right? And so he talked about how that you but you’ve got to go through that phase. And they’ve been in it, and they’ve been really fortunate to get such great feedback from these athletes, you know, and the teams and the coaches and that. So, so it’s, it’s accelerated their growth curve, and it looks like that the big launch will probably be middle of. 25 meaning June, July, something like that, that they’ll be, they’ll be on sale for the public. They have been in China, and they’ve been in different, you know, looking at the manufacturing process, and there’s so much around developing a new technology, it’s fascinating. I don’t have the guts to be an entrepreneur like that. I like my paycheck to come rolling in every month, you know. But I have super respect for the people who do it, you know, and the people who do it with passion and want to get it right.
Trevor Connor 1:00:30
So here’s the question I have for you, because we did do an episode about all the new metrics that are coming out, and then the conclusion of that episode was, some of these metrics might be great, but the cycle is too fast. They’re developing the devices in six months. They don’t really do research. Often they’ll go there’s studies behind this, and you find out it was just an undergrad doing a abstract and really nothing else. So want to make sure this isn’t the same thing here and preparing for this episode. I mean, I’ve read three studies that research this to look at reliability, to look at validity. How many do you think there’s been? It does seem like the research is being done. Yeah,
Dr. Stephen Seiler 1:01:09
and we’re finishing up one in the lab now, and it gets more busy. You know, cycling is one of the friendliest movements to do breathing measurement with. So just so we’re clear, because you don’t have this problem that’s called entrainment. Just to add a little caveat to all this, is that breathing is often connected to some aspect of cadence, whether if you’re a rower, if you’re a rower, you have to connect your breathing to the stroke rate. You just have to, because you have to stabilize the upper body when you catch when the or takes grip of the water. For example, cross country skiing, we see some of the same issues with double polling. Running, also running is trickier, but there will be often runners will entrain on some different ratio of their stride frequency. So for example, the other night, I tested this on myself, and I, you guys, I’m trying to learn trying to do high rocks, the newest that’s fad, and it’s like CrossFit for old people or for people that don’t want to be jacked on steroids, you know? And so anyway, so I’m doing high rocks. I’m trying to my daughter wants us to do it together, so, and I’m trying to start running a little bit. And so then I go ahead and put on the breathing belt, just to check it out. And I’m being attentive to my breathing. And I breathe initially when I’m just barely jogging, and I breathe in a three, three ratio, meaning, on the inspiration, I’m taking three steps, and on the expiration, I’m taking three steps, and that’s below my threshold, super low. And then get a little warmed up, get a little faster, and it goes to two, three. Now I’m two steps on the inspiration, three steps on the expiration, and then I go up a hill, and it goes to two, two. You with me. So it’s this quantum changes that are connected to my stride frequency. Now this is called entrainment, so we don’t see much of this in cycling, but we see a lot of it in a different movement modality. So we asked, we also have to take that into account. How do we measure breathing? Does it give us the same information and so forth, but, but certainly cycling, which many of your listeners are cyclists, cycling is very conducive to using this variable, this breathing measurement. So that’s good news for the cyclists.
Chris Case 1:03:44
Is there a imperative here to tie this with heart rate on your head unit, so that you can see the your breaking point? You say how the I was thinking?
Dr. Stephen Seiler 1:03:55
That’s what we’re doing. Yeah, I’ve, I’ve introduced this metric. We just call it the mobilization index. And all it is is the percentage of the breathing rate reserve that’s being used at any given moment divided by the percentage of the heart rate reserve. And initially that may be 50% and then it ends up being 100% you know, or a ratio of one, a one, right? And when you get close to one, you’re cooked. Yeah, you don’t need Eve. And the reason I say, and you say, well, is that so big deal? Well, it shows that you’re cooked often at a heart rate that’s not indicative of being cooked. Your heart rate’s not at max. You’re at 90% or you’re at 87% or but, but your breathing frequency is so high relative to that it tells us this person is glycogen depleted, this person is fatigued. This person is doing everything they can to mobilize to achieve that oxygen consumption, even though it looks like they should have more. To give. They don’t have more to give. So
Trevor Connor 1:05:01
the thing that immediately came to mind, we’ve had the conversation multiple times, that one of the issues with TSS. So if you go out and do a six hour bike ride and you do the whole let’s say you just did the whole ride at 180 watts, you’re generating the same TSS at the end of that ride as you are at the beginning. But in reality, it’s a much bigger stressor on your body. So I was wondering if this is something that we could come up with a new TSS measure on so that you’re better representing when you’re struggling at the end of the ride, you’re generating more TSS.
Dr. Stephen Seiler 1:05:34
That’s what we’re working on. And so I I know dear, can those guys and Joe Friel, and so anything I say is in no way a disparagement to training peaks or any of those metrics, but the TSS is not a TSS. It’s not a stress score, it’s a load score. It’s a measure of what you did, but it’s not a measure of what it does to you. To put it in the simplest terms, I know, yeah, doesn’t measure the impact. It doesn’t measure the cost, the hormonal the stress cost. And if we go back to that original issue of silers polarization, you know, polarized model, and people have said, well, it’s not really polarized. It’s pure middle or maybe it’s polarized for certain events and pyramidal for others. What it comes down to that I believe, after 25 years that we’re, we’re actually polarizing. It’s not heart rate. We’re polarizing stress. We’re polarizing the stress. Man. We’re managing stress from day to day. And so basically, I would say we’re, we’re managing the distribution of stress, high stress days and low stress days. And so that’s where I see that it’s useful to think in terms of load, load, stress and strain. Is because then we have a framework for managing and saying, all right, you like you say, You did six hours, you know, and heart rate wasn’t that high, but by the end of that six hours, you were cooked. You were like you were glycogen depleted. Your RPE was elevated. You wanted off the darn bike. Your breathing was elevated. Your if we’d measured cortisol, if we measured a number of different variables, we would see, yes, we pushed you that six hours was costly for you and different athletes. If, if you take me, I’m, let’s say I’m used to 90 minutes workouts. 90 minutes is kind of my normal value for my my long rides, or my just endurance rides, all right, and I extend to two hours, that’s not too bad. I can handle that. If I extend to three, I am feeling that if I try to do four hours, I’m cooked, because that is well beyond my normal load that I can tolerate, and the stress associated with mobilizing that long for me, because I don’t do I’m not adapted to that long of a, you know, low intensity session. It’s huge, and that means that it’s going to cost me. I’m not going to feel good the next day, even though that wasn’t high intensity session. So stress, that stress response, can come in different disguises. It can come as a result of a really long, low intensity session. It can come as a result of a tough threshold session, and it can also come as a result of a really tough interval session, or, you know, high intensity session. So all three of those, if the duration is long enough, all three of them can become very stressful for athletes. So that’s part of the management process, is knowing when to say, now it’s enough. Now it’s enough. We gotta and what do we wanna? What’s the enough? Well, we wanna generate a signal for adaptation, a strong signal for adaptation at a manageable level of stress. So basically, I would say that my whole understanding of training intensity distribution and training monitoring and potentially the use of breathing is it’s all, all of those things are about or connected to optimizing that relationship signal, which is a cellular level thing, and stress, which is a systemic level thing, signal to stress, if we can manage that from day to day, week to week, month to month, and across seasons, our athletes stay healthy more. They have better overall development.
Griffin McMath 1:09:37
There’s a couple times earlier in the episode where you mentioned something that I think was such a great visual for athletes and coaches. You’re like when this is happening, this is what the athletes experience is, and they’re about to fail. You’re talking about heart rate drift.
Dr. Stephen Seiler 1:09:52
Do you guys want me to show you, just so you see visually what I’m talking about? I’m
Griffin McMath 1:09:57
more curious about if you can. Give an application like, if this is happening, here’s an adjustment to make before failure.
Dr. Stephen Seiler 1:10:06
That’s an interesting, really interesting question is whether or not we can adjust breathing and make it cost less. It’s kind of the same question as, can I adjust my stride length and running and become more efficient. Can I take longer steps? Doesn’t work. Can I take shorter steps and increase my frequency and go faster? Now that didn’t work either. So it’s almost like if you try to just change it voluntarily, it’s not an efficient it doesn’t improve efficiency. But if you have the physical background, the appropriate fitness to then that change happens automatically. If you get fitter, your stride length goes up. For example, I’m
Chris Case 1:10:51
curious though, that if we’re talking about when it reaches the one to one, is it a predictable, catastrophic failure, or do you just say, Oh, they’re approaching one to one, I have to back off, or else I’m going to blow up
Dr. Stephen Seiler 1:11:03
often. That’s when you’ll get dropped in the group. You’re in this group, you know, and you’re hanging on by the by your skin of your teeth, and you get dropped, or you’re about to get dropped, or you have to drop power in an interval session, you fatigue, you know. You You had a four times eight minute plan, and you wanted to have the same power at all four work bouts, bouts, 1234, go as you know you you wanted to hold 350 watts, and you do, and then the fourth one, yeah, you fail. So I would call it’s a failure in the sense that often you’re forced to reduce power output. We do see with certain athletes, and I’ve felt it with myself that you’re coming over the top of the hill and you are in almost a panic, High Breathing frequency. And there does seem to be some value of being attentive to trying to kind of take a couple of deep breaths as you come over the top. You know that you can be attentive to your breathing and kind of pull yourself out of what is almost like this panic mode where the frequency just gets you start breathing like a rabbit. Yeah, you’re hyperventilating at that point. Yeah, I mean, you’re hyperventilating, but you’re hyperventilating or in a really inefficient way. And so that maybe is interesting. Now, another issue that nor a Norwegian physiologist, or kind of the test leader for the Olympic Federation, and is was named Aaron ham, and he was at altitude camps. He’s probably been at altitude camps a significant percentage of his life, years of his life in total. And so he was always measuring the athletes, you know, looking at them. And way before we could measure ventilation out in the field, he was telling athletes. He says, Look, if you’re a cross country skier and you’re coming into the start of a steep climb, you know, a short, steep climb, just start breathing harder. Don’t wait. Don’t wait for the reflexive increase in breathing. Just attack it and start breathing heavier, because then you reduce the Mao D, the accumulated oxygen deficit. You’re priming the system well. You’re just anticipating. You’re saying, I’m not going to wait for those signals from the periphery. I’m going to feed forward, turn it up. I’m just going to turn it up. And therefore, and what they they published a couple of studies that showed that, yeah, in certain in short, high intensity efforts, this is performance enhancing. So we had, like, one of our gold medal athletes was a guy named Olaf Tufte who won the gold medal in the single skulls and rowing in 2004 and 2008 when he’s leaving the starting line for rowing, he is just breathing like a horse from the get go, because he’s been taught to do that. He’s been taught to use this kind of anticipatory hyperventilation as a tool to at least a little bit reduce that, that debt that you accumulate while your weight, while your breathing is catching up to the demand. So anyway, so there are some small tricks that have been, you know, that coaches and athletes and support staff have seen for years and they’ve been doing but now we’ve got a little bit better tools for measuring things.
Chris Case 1:14:18
And speaking of those tools, they’re still in the development stage. What are the challenges that you still have to overcome in terms of this product coming to market and being useful perfect? I’m sure it’s not the only one that’s being developed,
Trevor Connor 1:14:32
and along with that, what are some of the challenges you’re seeing out on the road? Every metric has its challenges, like heart rate. You have cardiac drift, and you might have sympathetic fatigue, yeah,
Dr. Stephen Seiler 1:14:41
and you have hardware challenges, and then you have software challenges. You have the hardware challenges with heart rate. The manufacturers don’t want to produce a belt anymore. They would prefer to do everything on the watch, you know, on this main unit, because that means they can just iterate software and not keep having to develop hardware. Hardware is expensive to further develop, so that’s why companies like Garmin and polar, they sell you the PPG units, but the athletes tend to use the old fashioned EKG units because they’re more reliable. So the problem with heart rate has been that for many people, the wrist is too bony and they don’t get a really good signal, they don’t get nice that, that green light that goes down, and you’re measuring the absorption of that, and you’re capturing heart rate, there’s light leakage, there’s issues there. So that’s the challenge of PPG. But they they keep with the PPG, because then they can just keep selling that same hardware. All right, so what’s going to be the problem with breathing? I think it’s probably going to be some it’s the interface between the textile and the sensor, you know, because I already know that there are companies that want to build shirts, that want to generate, create textiles, you know, with an integrated sensor in the kit, right? And so then you’re going to have to make decisions on the the qualities of the fabric. And if the fabric changes, if it gets stretched out, if it changes its characteristics, then that changes the characteristics of the sensor, right? Because they’re, it’s, they’re linked. And that’s going to be the challenge with this breathing frequency is not a problem. It’s going to be going beyond and being able to then capture tidal volume and total volume and so forth like that. Then you’ve got to have even more quality in the sensors that were they’re getting there. But that’s going to be the challenge. And will it be time where I’m not trying to sell anything. I I love these guys just because we’ve been working together for three years. But you’re right. I suspect there are others that are working on the same stuff, you know. So I think this technology is going to become mature. It’s going to become a tool, and it’s just a matter of how well we use it in the daily practice.
Chris Case 1:17:00
So what are the interpretation challenges that we might face once this does become readily available in terms of the metric,
Dr. Stephen Seiler 1:17:07
it’ll be some of the same issues that we have with heart rate in the sense that, you know, you’re going to have, see people start developing equations like 220 minus age, and they’ll figure out one for breathing frequency, and it’ll be wrong. It’ll be right for a, you know, right? Yeah, yeah. It’ll be, you know, you know what I mean. It’ll be that generalizable versus the individual. And we’ll find that now, if you’re really going to use breathing, and you need to understand how that person breathes, and what is their maximum breathing frequency, or their maximum functional frequency in that movement modality, because that’s going to be a very different you know, the swim, swimming versus running versus cycling, for the same athlete, they will have different peak breathing frequencies, just like they have different peak heart rates. So I guess it’s always going to come down to the individualization aspect. How good are we at individualizing our interpretation of the data? So
Trevor Connor 1:18:05
last thing I have to bring up before we round this out. I don’t know if you noticed me, but a little over a week ago, it was a Sunday, I jumped into a group ride on Zwift, and sure enough, you were on the ride, and somehow I kept ending up behind you, like right behind you on the ride, because I’m so strong. Yep, yep, no, I was hanging on. I get it. You’re always on my tail. But I got a comment. I liked your avatar’s hair because it looks kind of like your hair, but done in these, like little, tiny dreads dreadlocks. It’s cooler, yeah, it’s like the cool version of me that I will never be.
Dr. Stephen Seiler 1:18:50
So so that’s that’s very much intentional, is that I said on on Swift, I get to wear dreadlocks. Get to
Chris Case 1:18:59
be a different person, interesting, and no helmet.
Dr. Stephen Seiler 1:19:04
It was, was it the cycling nation group ride? Yes, it was. I just finished the week
Trevor Connor 1:19:11
another hour, so I was like, I’ll jump in. And there you were.
Dr. Stephen Seiler 1:19:14
Yeah, that, and that’s the thing I learned from Trevor, is he learns. He taught me how to do multiple rides and kind of sequence them and then. But then part of I want to say, Guys, this is my third ride. That’s why I’m struggling. So, you know, you know, I want to tell the world, you know, but I, whereas Trevor would never do that, he’s going to just suffer quietly. You know it’s true,
Chris Case 1:19:41
he’s gonna take it very seriously right
Trevor Connor 1:19:44
behind you, staring at the dreads.
Dr. Stephen Seiler 1:19:48
I didn’t know you were in that ride, but I like that group. It’s a fun group. It was a good group. And with that,
Trevor Connor 1:19:56
I think it’s time for our forum. Question, please go to our forum. Forum@fasttalklabs.com this should be right at the top of the main forum page and share your thoughts. Here’s the question, What’s your thoughts on using breathing frequency as a metric? Is it just one more measure to complicate things, or potential revolution in how we train? Really interesting your thoughts? Well, I think it’s time, guys, everybody knows where we finish up time for take homes. I guess it always comes down to that we want to be in control of our monitoring process and not have it take control of us. So with care, we should choose tools that we feel give us a better picture of our training process and the fewest possible as a general rule, and so I am not a person who’s advocating just use every new device that comes down the pike. Absolutely not, given that I do believe that being able to measure breathing is a useful tool, we will find it to be a useful tool that will give us added information that might, I think can help us individualize, can help us monitor and get that signal to stress management process right. So I’m optimistic. My
Chris Case 1:21:14
take home is very simple. I’m excited that Dr Seiler is excited because I don’t use any metrics, so I don’t care about breathing frequency at all.
Dr. Stephen Seiler 1:21:26
He doesn’t need them.
Trevor Connor 1:21:29
I’ll go next and like Griffin, finish us out. My take home is it feels like we have forever been on this quest for the perfect metric. You know how I feel about heart rate. I think it has a lot of value, but it has his issues. Power is good, but it also has his issues. I always thought the metric that we were ultimately going to land on as that is the perfect metric is when we somehow figure out an on the road lactate measure. So this one for me, kind of came out of left field, but the fact that it so perfectly correlates with RPE, and we’re always telling athletes the best training is done by perceived effort. Gets me excited to see how this works out. I will definitely be trying it once it’s available, and I really do want to see if this gets us closer to that perfect metric that can tell you, here’s what’s going on with your body.
Griffin McMath 1:22:21
I think this is a good segue with Trevor talking about our constant search for the perfect metric. Recently, we had an episode on HRV and speaking of wrists that are problematic, we did talk about Chris’s problematic risks on that episode, but once again, and I said this at the beginning of the episode of this metric as almost a practical proxy, right? It might be easy to grab this metric from just watching someone, but how we put that in context and how we’re able to make a change that immediately makes a difference using this metric, I think about other episodes where we’ve done a deep dive on a particular metric, and this one just kind of seems the same. It cannot be a standalone. And just listening to you for a while, I have a great appreciation for this now and the nuance more so than I had as someone who used to take some of these measurements in different settings. But once again, standalone, it just immediately more questions than answers. At least for me, I almost
Dr. Stephen Seiler 1:23:24
have to comment on that, and you can do what you will with it, but I don’t think there is a perfect metric, and I’ve always that’s why I’m always using that triangle and saying, We have to triangulate that. It’s useful to have some measure of what’s actually being done the external load, and it’s useful to have some physiology in some form or fashion, and it’s useful to have some perceptual data to ask people how they feel, you know. And you don’t have to do all three every day, but they offer this kind of a checks and balances system. So I agree with you 100% Griffin, there is no perfect variable. And if I was going to, you know, say one more thing in the load, stress, strain conceptualization, heart rate variability, is a measure of strain, you know, there’s a deformation to the system in the form of reduced heart rate variability, you know. So it fits into that framework, but as a strain indicator, not as a stress indicator.
Trevor Connor 1:24:22
Well, Dr Sadler, has been too long, but always a real pleasure having you on the show. This was a fun conversation.
Dr. Stephen Seiler 1:24:28
Thank you. Yeah. Me too. Thanks. That
Trevor Connor 1:24:30
was another episode of fast talk. The thoughts and opinions expressed in fast talk are those of the individual subscribe to fast talk wherever you prefer to find your favorite podcasts, be sure to leave us a radiant review. As always, we love your feedback. Tweet us at at fast talk labs, join the conversation at forums dot fast talk labs.com or learn from our experts at fast talk labs.com for Dr Steven Seiler, Julie young, Chris case and Dr Griffin McMath, I’m Trevor Connor. Thanks for listening. You.
