Durability in Ultrarunning with Ed Maunder PhD | Koopcast Episode 160

Trail and ultra runners, what is going on? What's happening? Welcome to another episode of the KoopCast. As always, I'm your humble host, Coach Jason Koop. And this episode of the podcast takes the concept of durability, which we normally associate with materials like our shoes and hydration packs and applies it to sports science and physiology. I don't need to tell you that in many cases or in most cases, the end of a race is more difficult than the beginning of a race. And similarly, the end of any workout is harder than the beginning of any workout. When we drill this down even further, standard physiological concepts like lactate threshold or even running economy have durable properties to them, meaning they change from the beginning of exercise to the end of exercise. Yet in most concepts, we measure them in a fresh state.

Take running economy, for example. In this sort of test, you're analyzing oxygen consumption for just a few minutes at sub-maximal speeds when the subject is fresh. And it's well understood that improvements in running economy will lead to improvements in performance in most endurance events under most circumstances. However, in the ultra distance events, this relationship starts to decouple, meaning better running economy does not necessarily correlate as tightly to ultra marathon performance as it does in the more traditional running events. And this is something that I don't think we fully appreciate when designing training interventions and evaluating the practical aspects of scientific literature. With that as a backdrop, today's guest will try to shed some light on what this might mean for ultra runners. Ed Marinder is a lecturer at the Sports Performance Research Institute New Zealand. In his recent paper titled The Importance of Durability in the Physiological Profiling of Endurance Athletes, which appears in the Journal of Sports Medicine, is a thought-provoking take on how the way we currently assess physiology might underserve endurance athletes and in particular ultra athletes as the context of their performance, which includes hours of fatigue, is mismatched from the assessment condition, which is normally in a fresh state.

As a final note, stay tuned to the outro of this podcast and I'll provide some coaches' color commentary on what this might mean for you and how to apply it in your training. All right, so with that intro out of the way, it is time for me to step aside. Here's my conversation with Ed Marinder, all about the concept of durability in endurance sports. Thanks for coming on the podcast. I appreciate it. Why don't we spend a little bit of time first just describing, you know, who you are and what you do just so the audience can become a little bit more familiar with your work before we dive into this paper specifically. Yeah, sure, sure. So yeah, my name's Ed Marinder. I'm originally from the UK, so from Southeast England, but I'm now living and working in New Zealand. So I'm a lecturer and a researcher in exercise physiology at AUT, Auckland University of Technology. I'm in Auckland in New Zealand.

My main teaching and research focus, I guess, is on metabolic responses, mitochondrial adaptations to endurance exercise and also profiling. So physiological profiling of endurance athletes. So those profiles that we use to predict performance and then regulate training and training and monitoring, that sort of thing. So that's my primary research interests. I mean, that's kind of where the paper starts, right? And for those of you listening, the paper that we're going to discuss today, the title of it is, is the importance of durability and the physiological profiling of endurance athletes. And you coming from a, like a physiological profiling kind of perspective, I think that that's the genesis of it. I can kind of give you the coaching observational perspective that we've had on this that I first ran into probably in the early or mid 2000s when we're watching the Tour de France. And, you know, anybody's who's ever watched a mountain stage in the Tour de France, the kind of the same scenario plays out year after year where 20 people go over the first climb or 20 people make it over the first climb into the group. And then 10 people make it over the second climb in the group. And then five people make it over the third climb.

And those five people race to the mountaintop finish. It kind of unfolds like that, where the field gets smaller and smaller and smaller. And I remember what I remember watching, you know, that race for years. And finally, one year, our coaching colleagues kind of looking around saying, why aren't we measuring that instead of the prototypical, uh, lactate threshold VO2 max test that everybody has, they do it fresh. In fact, intentionally, you try to do it very fresh just to try to get like the, like the best numbers. Why aren't we measuring this phenomenon? Like what's happening between climb one and climb five, that this group of, you know, a hundred athletes has kind of gotten whittled down to a few of which they're fairly, they're going to be fairly homogenous on the previous, uh, profiling test or any sort of graded exercise tests that we can, that we can kind of put them through. And the outcome of that, us trying to hack it together as coaches was literally, we took whatever version of WKO plus for the listeners out there, this is just a piece of software that can analyze cycling power files and GPS files and things like that. We took whatever version of that we were using at the time, which is probably like three or four. And I think now they're on version five now. And we started to create, uh, power, we started, started to create, uh, power duration curves after a certain amount of kilojoules. And everybody started to play around with this, with their athletes. What does it look like after 2000 kilojoules after 3000 kilojoules?

And it was our way of kind of getting ahead of this concept of durability that eventually is going to get kind of flushed out in the literature. And so I offer that as just a little bit of, of, of, of a springboard to when I see research like this, I'm kind of taken back to that initial, uh, exposure to it and say, yeah, we do, we do need to describe this a lot better, but we haven't to date. Yeah. Yeah. So I guess, I guess I come to the concept in my research in, in, in, in, I guess, similar way, um, to what you've just described. So I have, as long as I've researched some quite a bit of applied experience too. So I'm running a lot of these physiological profiling type assessments, working with triathletes and some ultra and ultra, uh, endurance runners, that sort of thing.

And yeah, seeing, you know, doing our traditional profiles with fresh athletes, measuring the traditional metrics, um, which do a good job of predicting performance in certain events, but, um, you know, often seeing athletes with very, very similar profiles with fresh and then having quite different performance outputs in particularly long duration, um, events and also seeing athletes come back who've gone through period of training and are much better from a performance perspective, but not seeing big shifts in that profile and thinking, Oh, what is it that we're, what is it that we're missing here? So I think hopefully durability and perhaps durability might be, um, one. And I think that ultra marathon is probably a really good playground for this because at the end of the day, we're kind of testing the outer limits of what durability might actually be.

We can build up people's VO two maxes and lactate thresholds. And are they important? Yes, but there's so many other things that go into the ultimate and performance of which could play into this durability concept. But before we go even further, I think we have to like, kind of like settle on the terms because this is one of those terms that starts in everyday language, right? In lay publications and things like that. And you're trying to put a scientific concept around it. Normally it's the other way around. We talk about VO two max, that's a physiological scientific concept. And we're trying to relate it to, you know, lay people or make practice out of it here. It's kind of the opposite. So it gets kind of confusing and you did a really good job in this paper of, of, of trying to set some initial construction around what this definition can be. So can you take the listeners through that so that we are initially all on the same page? Yeah, for sure. And I think it's probably fair to say that in science and in exercise physiology, we do a good job of confusing terms.

So it's good to get on the, good to get on the same page to start with. And I guess probably worth also prefacing that different people might have slightly different definitions, but the definition and the concept that I'm thinking about when I'm thinking about durability is essentially how resilient your exercising physiology is to the overtime during very long duration exercise. So I think about it from a physiological perspective. So I think of the traditional metrics that we use to profile someone's exercise physiology. So you've mentioned VO2 max, we might also think about lactate threshold or critical speed, you know, various other threshold definitions and things like running economy too. So durability is okay. How do those things change from the fresh values that you measure over time during long duration exercise? So a more durable athlete will be resilient to those changes.

So they'll see smaller decrements in those, in those variables over time during long duration exercise, whereas someone who's perhaps less durable will see sharper, greater drop-offs in those variables. And in my earlier example of taking, you know, a cyclist power duration curve and for a runner, you can use, use pace duration, the time component we were essentially replacing with the amount of work that was, that was being done. But the concept I think kind of holds the holds true after a certain amount of time or a certain amount of work, or even you could say an intensity over a certain period of time, because as we'll probably talk about later, this durability concept is probably different depending upon the intensity as well. And just not, not just the duration and then seeing how those different physiological factors essentially play out. And in my earlier example, we're taking the entirety of the power duration curve, which, you know, you could say that's an overly broad lens or not, but you can really take any other physiological component, as you mentioned, whether it's lactate threshold or critical speed or, you know, VO2 max or whatever, and just see how, see how, or if it deteriorates after that point of demarcation that you've kind of determined in some fashion.

Yeah, absolutely. So what you explore this a little bit in the, in the paper, and we're going to have to use a little bit of a, like a broad brush stroke to try to, to try to get a better fix on this. But what would be the physiological underpinnings between an athlete that has good durability and athlete that does not have good durability? Do we have enough answers to start to fiddle around with now, or is this still a really big question? Yeah, that's a, that is a good question. And the first, I guess the most succinct answer would be, I don't think we have, from a research perspective, I don't think we have clear answers to that question yet. I'm optimistic and hope that those answers will come over the next little while. We're actually doing some research here at UT, looking into those questions exactly. Now, if you were going to make some hypotheses for why one athlete would be more durable than, than another, again, you'd probably get a different perspective depending on who you spoke to. So I'm interested in muscle physiology. So I'd probably come back with muscle physiology answers. If you spoke to a cardiorespiratory specialist, they'd probably come back with cardiorespiratory answers, et cetera. But sort of things that we're interested in and looking at things like, um, you know, fiber type profiles. So you would probably guess the athletes that are more slow twitch type one dominant, more fatigue resistant

muscle fibers would probably, um, serve to be more durable. Now within a, within a population of high level ultra runners, there's probably not going to be a lot of variation within that. You'd probably guess that most of the athletes had quite a type one dominance. So maybe that doesn't explain the differences between people. So type fiber type profile be one thing we've looked a little bit and there's a little bit of literature on things like glycogen availability. So how well you can preserve your body's carbohydrate stores. So there's some suggestion that that might not relate to durability and that would make, make sense to me. So maybe athletes who are more capable of utilizing their stores to supply the energy that they need to keep moving. Um, they might, they might serve to be more durable. I'm interested in things like, um, heat shock proteins, so heat shock proteins exist inside cells and they help you manage stress that accumulates, um, during exercise and following exercise. So maybe if you've got a bigger reserve of those proteins, those stress managers, they might, then that might serve you to be more durable. But the honest answer is we don't, um, we don't know in that much detail.

Now, one thing we did a study published earlier this year, this was by one of our master students, Julian Stevenson. So he did a durability study where he looked at how the lactate threshold or the first ventilatory threshold changed, you know, before and after from before to after two and a half hours of moderate intensity cycling. So he quantified that it went down by about 10% on average, quite variable between people. Now he was able to see that that reduction in power output associated with that threshold that came from reduced efficiency. So becoming less efficient over time during exercise. So less ability to translate energy expenditure in the body into, in this case, what's on the bikes and mechanical power output. So there was a bit of that. And there was also just reduced ability to do energy expenditure before hitting that threshold. So coming from, um, multiple places. Now that doesn't give you the underlying mechanism, but it might lead us down paths to help us try and, um, isolate and identify those.

And I remember when that study came out and I was trying to translate it to running. And my initial theory on that was that it's probably more the, the economy piece of it, or the efficiency piece of it is, is, as you're describing it, it's probably more pronounced in running because we typically think of cycling economy as a fairly stagnant factor that you, that is not, that doesn't change either over the course of an athlete's lifespan even, but here you're demonstrating that site that what I'm going to say cycling economy, when you're saying efficiency here, here, we're here, you're demonstrating that, that economy essentially does change after a certain amount of time to an appreciable extent, extent, and also varies within the individuals. I would take that as, as it's actually probably more pronounced in running.

Yeah. No, I, uh, I could, I could certainly get on board with that as a hypothesis. I think what you have with running is all that muscle damage that's going to be created, all that eccentric stress, those breaking forces, you know, that, um, you know, might impact metabolic processes and, you know, have an effect later on in an, in a, in an ultra endurance event running. Um, whereas in cycling, you don't have that. So absolutely. I would imagine that this could potentially be more pronounced, um, in running than it's cycling. You know, you spend a decent amount in the paper trying to create a difference between what a lot of people will call aerobic decoupling or cardiac drift and comparing and contrasting it to this con to this concept of durability.

And once again, ultra marathon being kind of a great use case of this, where we actually see cardiac drift happen after a certain amount of time. And then it actually goes in the, it kind of goes the opposite way, right? Which can confound, which trust me, I see athletes who try to, uh, train and also race by heart rate in eight, 10, 15 hours events. And it's a completely befuddling aspect to them because they don't understand this, this natural rise, rise and fall. I want to spend a little bit of time discussing that because I do think that a lot of the audience will, one of the things that they could take away from this, that I don't think that they should is that this heart rate component, it could be a way or could be the way to track if you're more durable or not. It's just simply stable over the course of time.

And we've seen this kind of pop up in a lot of the, um, and a lot of training philosophies where it actually might be one of the more desired outcomes. So let's explain the difference between those two first and then how durability folds into this, this concept of the difference between how the internal load is actually manifesting itself in heart rate and what actually might be going on underneath the hood. Yeah. Yes. No, that's a really good, really good point to talk through. And heart rate is an, is an appealing metric to use during exercise because you can see it, right? That's one of the things that we can do measure routinely whilst we're exercising and we can respond to it because we can see it. So it's, it's a good question. So I guess what we, well, what has been done and cardiovascular drift, cardiac drift is not a new concept.

Of course, this is a longstanding phenomenon that exists in, in exercising, uh, endurance exercise. Um, so cardiac drift being for a given work output. So for a given running speed, for a given power output, requiring a higher heart rate over time. So maybe you're running at 12 Ks an hour initially and your heart rate's 140 and then a couple of hours into exercise, that same speed, 12 kilometers an hour, your heart rate's 155. So you've had a drift in heart with drift in heart rate of 15 beats per minute. So I guess the next, so that happens. And you're, and also you rightly mentioned that with very long duration exercise, you can start to see that relationship coming, coming back down again. So the question then is what is that actually telling you?

So if we focus on the, um, less extreme long duration events. So when we're only seeing the wood and decoupling the upward cardiovascular drift, what is causing that increase, um, in heart rate in order to sustain the same running speed, the same power output? What is that telling you? Well, the internal stress is probably a little bit higher because it's driven the heart rate up. So that could come from, there's probably lots of different, uh, factors, you know, the inputs to controlling your heart rate are broad. Um, so there's probably lots of different factors that could explain that. So for example, just the classic one that you'd see in a physiology textbook would be dehydration. So if you become dehydrated during exercise, your plasma volume, your blood volume decreases.

So that drives your heart rate, um, in order to supply the same amount of cardiac output to the body. There's probably lots of other reasons too. If you're becoming less efficient, so if you're becoming less efficient, if you're running economy decreases over time, you might be running at the same speed, but you're requiring more energy expenditure in order to do it. So, you know, you would expect that that would necessitate a higher heart rate because you'd need more cardiac output to supply more oxygen, um, to the working muscles. So I guess we looked at it kind of from that perspective. So in that paper, we sort of characterize different athletes. So some, some had a low, lower amounts of decoupling over time between heart rate and then it was cyclists and, um, and also runners too.

Um, and others had much greater decoupling. So what is that telling you? And again, we didn't answer it in that, in, in that paper. So we certainly didn't say, you know, we certainly couldn't say that this, you know, is explaining one particular phenomenon or another, but sort of hypothesis that you might have is that those athletes who decouple more, so they have large amounts of cardiovascular drift. That's indicating that there's larger changes going on in their physiology. So perhaps that means that they're less durable than others. Now, one thing that was quite interesting that we followed on since then. So in that study that I mentioned, the, um, Julian led with the cyclists where we measured the lactate threshold before and after two and a half hours of, um, cycling exercise.

We measured the power output at that lactate threshold and it decreased by about 10% on average, but the heart rate associated with that threshold. So the heart rate at lactate threshold went up and that was consistent across almost everyone in the sample. So when fresh, your lactate threshold might've been 200 watts and 140 beats per minute. And then at the end of the experimental session, after two and a half hours of exercise, it might have been dropped down to 180 watts, but a higher heart rate. So 150 beats per minute, say. So what that tells us is that as some cardio, some of the cardiovascular drift that's going on during exercise, isn't telling you that you've jumped into a different intensity domain.

So maybe it's not telling us as much about durability, um, as we might like, given that it's a very practical appealing metric. Yeah. And I think the way you described it in the paper is some of that drift is just totally benign and there's no consequence to it. And some of it might be deleterious, but we don't quite know how to divide and conquer those two areas. Yeah, absolutely. Yeah. That's that, that, that to me was one of the first times I've heard somebody kind of describe it in a way that actually made sense to me. Because like you said, we have been, we've recognized cardiac drift as a physiological phenomenon for a long time. It is not a new concept, but in terms of saying, yes, this is absolutely deleterious at this level.

That's what, that's what I think really gets to the heart of the matter because I've seen a lot of people that, that try to kind of like aim their training at or interpret training from the standpoint of you want to minimize it as much as possible. And that's typically not even possible, but might not even be an advantage because you should expect a certain amount just as a by-product of everything else that's going on. And it's doesn't matter one way or the other. Yeah. I mean, absolutely. And from a practical perspective, I mean, it's not uncommon and it's certainly something that I've done working with athletes. You know, you said going out to do a long run at the weekend, your long training run, and you want to keep the intensity low. You want to keep the stress low. So you might say you're running for 30 Ks, a couple of whatever it is that you're doing your long session.

We know that your lactate threshold heart rate is 140. So, you know, keep your, aim to keep your heart rate below 135 and you'll know that you're below your lactate threshold. Now, what the data that we collected would maybe suggest is that you can tolerate a bit of cardiovascular drift in order to remain at that same level of physiological stress, if you like. So, yes, separating what's deleterious, what is, you know, this upward drift that is telling you that the exercise is taxing you much, much more versus what is sort of benign that we can happily accept during exercise. Because that's, that's a tricky balance to find in a practical perspective.

But I think we should acknowledge that it's there. A hundred percent. And, you know, there's a related, there's a related tangent to this that ties together the concept of durability with another one of like the holy grails of endurance training. And that's how to quantify training load. I mean, we've been trying to do this for years. You can go back to the old trim scores, which your paper touches on a little bit. And particularly with athletes who have very high singles, very, very long in duration, single session training activities. So four or five, six, seven hours, which is not that uncommon across a whole host of different endurance disciplines. The quantification of how, how stressful that load is actually relatively complicated.

Yet we take this linear approach with it. And the way that, the way that I've always explained it to athletes, and I want to get your perspective on this for how we can probably do it better in the future using some aspect of durability. But the way that I've described it to athletes is, is, you know, that if you go out on a four hour run and you do eight minute pace the whole time, same pace the entire time, the last hour of that is way harder than the first hour. And you can extrapolate that into any situation that you want to, any duration or whatever. The last part is always harder in the first part. Yet when we, when we use these, when we use these training stress quantification, quantification metrics, whatever one you want to use, training stress score, trims or whatever, it doesn't typically take that, that nonlinear stress into account.

We tend, we tend to just add it all up as, as the, as the same thing, but we know that it is in fact not the case. So I'm wondering, I wanted to get your opinion on that and how we might be able to use some of these initial, uh, these, these initial attempts at trying to better describe durability to in essence, try to find a better quantification for training stress itself. Because I have a tough time wrapping my head around it. We know that an increase from just from a gross standpoint, from like 20 hours to 22 hours of, of, of load per week, it's not a 10% increase in stress. It's like likely a little bit more likely, a lot more than that. So I'm wondering if you can describe that a little bit further in, in what you think that we can learn from some of these initial durability findings to just help us just to help us describe it better.

Yeah, no, absolutely. And that, yeah, that, as you, as you say, is one of the holy grails of this domain of research and activity is being able to do that better. Because of course, as you say, same speed, the same power in the third, fourth, fifth hour of exercise is completely different from not only a perceptual standpoint, how it feels, but also from a physiological standpoint, you know, how the exercise manifests in the body is different. So how you actually would go about doing that based on the data that we have at the moment, I, I'm not sure. I mean, what we've demonstrated and has been demonstrated by multiple groups in different ways, you know, is that the parameters that we use at the individual level to quantify intensity at any moment in time, you know, depreciate change over time.

And not only sort of making it more complicated is that there is in into individual variability. So it's not like everyone at a given intensity, their lactate threshold decreases by 10% every two hours, you know, that would make things easy. But because it's, it's variable between people, we can't apply some sort of uniform direction to those training loads and calculations. So one of the, you know, one of the, one of the reasons that we looked at that heart rate data in Julian's study was because it would have been great if the heart rate, the threshold remained constant over time, because then that could, we could use to say, okay, in the fifth hour of exercise, the powers dropped from 200 to 160. But Adam, we know what the stress we can quantify stress at a heart rate of 150 beats per minute, because we know what that looks like.

But the data didn't give us that the data said, no, actually, this, this value is drifting too. So how you go about factoring that in without having an incredibly detailed profile of the athlete that you're working with, remembering as we, as you sort of alluded to in the opening gambit that, you know, the effect of prolonged exercise on these variables will probably also vary with the intensity of the exercise that you've done. So it's not as if we can say, oh, this athlete depreciates at this rate, because all of the training that they do might impact it slightly differently. And I think another lens that you can look at this through is, is when you're actually looking at either training design, or even trying to analyze training intervention that you see pop up in the literature, how the architecture of that actually unfolds, you have to apply this durability lens.

And I'll give a great like running example that everybody can kind of think of. And that's the progression run, right? So if you use a progression run where you're gradually increasing your speed, if you flip that run on its head and just do the opposite, right, you're running fast at the beginning versus slow at the end. The first example of the progression run is actually going to be more stressful and probably apples to apples produces superior adaptation. As long as you're, you know, as long as you're trying to make the two workouts time and pace equivalent, right? They might be time and pace equivalent, but they're not stress equivalent. And usually the higher stress one is going to produce a superior adaptation. But, but when you're really at the limits, you all of your, of your training load and how much you can actually handle, you have to appreciate and recognize that, that increase in stress from the way that you're actually lay from the way that you're actually laying it out.

So I think as, as practitioners, this becomes an incredibly important concept to understand because we tend to use a lot of linear math when we're applying training load and it doesn't manifest itself that way in the body in actual reality. There's not a linear relationship between these two. Yeah, absolutely. So in a training at a training session design perspective, I think it's a really useful concept to consider like exactly as you've just described. You've applied that concept in that way. And then just, you know, came to the conclusion, which I think is a good one, that that particular type of session is going to be more stressful than the other one, despite the fact that they are work match. If you put it into your training load calculator, it would give you the same training stress score.

I mean, here's how you could literally make this unfold, right? If you had an athlete that was somehow injury limited by volume, right? And you wanted to supercharge the stress that they're getting, placing more of that stress later in a run or even later in a kind of an overall training cycle, if you wanted to think about it like that could be one way that you could cheat the whole stress proposition as opposed to just increasing everything, which is what we tend to do, right? We want to get more adaptation. We just add volume or we add volume of intensity or something like that. Another way that you can manipulate it in a safer way. And it might produce a different adaptation. That's a discussion for a later day. But another way that you could increase total stress without increasing total volume would be to just change where the stress is so that it's later in the session.

Yep. Yeah, absolutely. Yeah. That's why this is fascinating to me because you can have two things that look exactly the same on paper and yet they produce completely, not completely, but different adaptations, but also are differently stressful. And I stress this not to use that word too much. A lot with our coaches when we're looking at training design is you not only have to look at the total amount of time, the time and intensity, but you have to look at where those are occurring relative within each session in order to get a handle on everything that's going on. Yeah, exactly. No, I think that that's right. And that's probably the most immediate way we can apply this concept is that the level of the individual session and session design.

I just don't think we're there yet. We don't have the right marker, the right biomarker that we can see live or that maybe we can track throughout exercise in order to quantify that in numbers and then put into our training week, training load score. So what's going to be the next extension of Julian's research? I mean, you already talked about it. Like, I think that's a relatively simple and elegant design to start to test this concept of durability. Where do you take it next from a lab setting? Because ultimately that's what we're going to take into the field. So, you know, one of our, one of the studies that we have ongoing at the moment that is built on the back of that work is to, like I sort of alluded to at the beginning, look at the mechanisms. So I take some more invasive physiological measures.

So we're taking muscle samples and looking at what is it that's distinguishing those athletes who are less durable from those that are more durable. Now that's it. I think, I think interesting from a physiological standpoint, but also might help us direct us to the types of interventions, the types of things that we might do in order to improve or manipulate durability when we're working in practice. So that's one of the directions that we're going. The other is to look at how that relates to performance late on in an event. So call your lactate threshold decreases over time during long duration exercise. And some people see a 25% reduction after a couple of hours. And some people see a 5% reduction. Does that actually matter from a performance perspective? So we're running a similar trial where we've got performance measures when fresh and when fatigued too.

So that's quite nice in a road cycling model where you see high density exercise early and late on. I mean, exercise. And so that's another sort of angle that we're looking at that from. I want everybody to appreciate the last part of that where you're trying to tie it to performance because that is we can't. I mentioned the Holy Grail is workload. The Holy Grail is really performance. Right. And we can measure physiological attributes six ways from Sunday under 10 different conditions every single day of the week, every single day of the month. But if it doesn't actually tie to performance, it's probably not going to matter. And so the natural extension of Julian's research is to see, okay, does that actually matter? Does that actually matter in a performance context? Or can we look at people that perform better?

Do they have these attributes of durability? And can we create a correlation from there? And then the final extension is how do you actually train it? Yeah, yeah. Absolutely. Yeah. And that's it. You want to, I think we're trying to do research in order to guide where those training interventions come from. So what's the, well, you know, what's the mechanism there for what type of training interventions are most likely to work? But also, yes, absolutely. Fundamentally, does it actually matter from a performance perspective? That's, that's, that's critical. Okay. So riddle me this. I know, you know, you deal in science and most of the eggheads that I bring on, on this program, they always hate to start to forecast things, but I always put everybody on the spot. So you're not getting any, any special treatment. What do you think from a training intervention perspective would improve any concept of durability that we just, that we just talked about?

What would you, if you were prescribing this for an athlete, let's just say you said, listen, I've got this athlete. I know that durability is important. We want to improve durability specifically for this event. What would that look, what would that look like as a, just a practical take home for the athletes? Yeah. So you're right. I will have to, as a scientist preface to say that I don't have the data to, to, to, to back this opinion up. But my take would be, if you press me on it would be, they, there has to be an element of specificity in training, right? So there has to be some, something about the training has to appear similar to the thing that you're trying to train for. So to me, from a durability standpoint, particularly if you're looking at ultra runners, that means that you're going to have to do some really long duration training and that's nothing, that's nothing new.

So getting out for your long runs, getting out for your long rides, pushing the duration element of those individual sessions, I would guess would drive adaptations in durability because you're stressing it, because you're putting yourself in a position where your physiology degrades over time because of the long duration exercise. Now we can do that and particularly with, um, that's easier to do with professional athletes than amateurs, right? Because, you know, work, work, you know, working full time makes it difficult to go out for five, six hours during the week. So what can we do with those time limited sessions in order to make them more prolonged in nature or in, in appearance? So perhaps it's creating stress earlier on in a one hour, two hour long midweek workout such that the last 30 minutes of that session are more similar to the last 30 minutes of a five or six hour long, um, training session.

So that's probably the perspective that I would look at, create some stress early on and then, um, push your body, push your exercising physiology to manage that stress. Um, subsequently. That's interesting. So it's a preloading type of strategy as opposed to actually stacking it out on the back half, like the progression run analogy that I, that I was using earlier. And I mean, you know, not to toot my own horn, that's the way I design a lot of interval workouts where I'll have them do the high intensity, high quality stuff early in a run, and then just extend the endurance component later. It's kind of a ultra marathon scenario where they have to run at endurance intensity for kind of, kind of long periods of time. You know, there's always been this like yin and yang, uh, between these two different philosophies of you want to use architecture that maximizes the performance of the actual workout, or these aren't, these aren't strictly competing, but I'm going to present it as such just to make the point or you put the workout on the end because as we mentioned earlier, it's kind of more stressful.

And I think one of the things that we're finding is, is you can use both of those as long as you realize that they might elicit different adaptations and have different end goals. Yeah. And I think also the circumstances, the logistical circumstances that you're working with might inform that. So if you, if you've got an athlete who on a Wednesday night after work has only got an hour and 15 minutes to do their training session and the, the interval high quality component of that is going to be the last 40 minutes, then they've only really done 30, 40 minutes or so beforehand. So it's not really much of a preload. It's just a slightly longer warmups than you might do. So in that situation, I think maybe putting the intervals at the beginning, creating all that stress and then running off it, you know, producing decent output whilst under the stress that you've just created, that might be the way that you would go.

Whereas in, in a different setting, maybe you could apply it slightly differently if you had longer to play with. And I think, as you say, there probably is a place for both. Well, and with the situation that you're presenting to try to encapsulate that a little bit further for the listeners, you're trying what you, what you, what you're presenting is, is there's probably a minimum viable amount of fatigue that you have to place on the athlete first before this durability component can be trained. And I'm kind of the same opinion. I mean, back to my very original example, that's why we were using two or 3000 kilojoules worth of work to start to separate the power durations curve. We weren't, we weren't just using 500 or a thousand kilojoules of work. I mean, that's a big, that's, that's a lot, that's a, you know, a few hours essentially of, of writing in advance of creating a whole new power duration curve.

So I guess my point with that is, is we're kind of recognizing this concept that you're, that you're mentioning that you can't just like, you're probably getting the worst of both worlds. If you kind of like half-ass it on either side, on either side, if you don't create enough fatigue to actually take advantage of this durability training, and then you're pre-fatiguing so much that you're probably compromising the workout. I'm of the same opinion where I think it's worth it. If you really want to do this, you kind of got to do it right and place a medium to a significant amount of stress first before you start to introduce the intervention. Yeah, no, yeah, absolutely. We'd go on board with that in that practical setting. Yeah. Working out, are you getting enough to actually justify putting it at the end, enough of a preload to justify putting it at the end? Or would you be better to do it upfront where you're going to get all of the strong performance component of those, those, that workout and that will, that will have a larger effect on the subsequent sort of moderate type intensity work that you're going to do.

There's just so many components of it, right? And that's what kind of fascinates with me with this is, is that we have a hard enough time defining lactate threshold. Come on, let's get it right. I was reading it. I was bringing up a paper in our coaching group the other day that had like 12 different definitions of lactate threshold. And there's probably more that, you know, this paper didn't even, didn't, didn't want to, didn't even want to build up. Um, but this layers on components on components on components. But I honestly think that in an endurance of it and much less an ultra marathon event, kind of understanding how everything interplays is one of the keys to training design first and foremost, but also unraveling this entire mystery of how to actually create better performance with athletes, because you're to start out with the initial construction and going back to the paper to kind of bring it all back home. We're testing physiological variables underneath conditions that really might not be all that impactful during a race. Yes, we see these correlations, but at the end of the day, races, you can go to any marathon, any cycling events, races are always determined in the last 20 to 10 to 20% of them, maybe the last 5%, not in the first five or 10%, which is how you're testing the physiology from the onset. So initially there's just this mismatch between how we're trying to set training ranges and define who can perform better or worse and what is actually happening in the field of battle. And your work is trying

to mend those two ends in some fashion. Yeah, absolutely. Absolutely. That's where the sort of money is made, isn't it? At the end of the race. So, you know, carrying it with you, being able to carry that bit more of your fresh profile with you into those last 10 Ks, 10%, whatever it might be. That's surely going to, our hypothesis is that's going to, you know, lend itself to better performance outcomes. 100%. This has been really insightful. I could go on all day. I want to bring in some of your colleagues that are working on this as well, because I really think this is imperative in the endurance space as a whole, but also an ultra marathon very specifically. We're going to let you go before we let you go. Where can people find more about this work? I'm going to have links to your profile and everything in the show notes, but where can people go if they're curious about this stuff? Yeah. In, I guess, to find my work, I always tweet it out. So maunder underscore ed. And then, you know, the works on research gate and Google scholar and all those, all those places. Awesome, man. Well, thank you. Appreciate your time on the podcast and I appreciate your work. I can't wait to see what comes out of this area because I think I really do think it's the next frontier in terms of how we start to unravel this great performance mystery and how we quantify training. We've got both ends of it right here.

Yeah. All right. Thanks very much. And thanks for having me. All right, folks, there you have it. There you go. Much thanks to Ed for coming on the podcast today. And I have two big takeaways after this conversation with Ed. The first one has to do with how we interpret some of the training intervention literature. Most of the times we're doing when we're looking at this, it is one intervention pitted against another. I want to do these intervals and I'm going to compare and contrast them with these other types of intervals. And one of the ways that we evaluate the effectiveness of those training intervention protocols is to have them do a standard physiological test when they are fresh. That can tell us certain things about how effective those interventions are specifically on one's capacity and their physiology, but they might not be as insightful towards this concept of durability that we talked about throughout the course of this podcast.

Second thing I take away from this is something that we mentioned about the training structure. I do think that the way we structure intervals and the way that we structure hard workouts within a session within a week is extremely impactful to the athlete at the end of the day. And there are a couple of schools of thoughts on this. You can arrange the intervals such that they are done in a fresh state at the beginning of a workout, therefore maximizing the total amount of workload that the athlete can handle, or you can arrange those intervals somewhere down the line and essentially pre-fatigue the athlete. The fundamental trade-off that you're looking at between those two scenarios is the first one, when the athlete is fresh and doing the intervals, that is primarily going to be focused on expanding the athlete's capacity, predominantly their cardiopulmonary capacity. The latter of which, where you're doing intervals in a more fatigued state, could be, because this hasn't been studied all that much, could be a good intervention to expand on durability. However, Ed's comments that durability probably has a specificity to it is actually quite poignant. And for my dollar, for my coaching buck, for the time that my athletes spend training, I think I'm going to favor the first scenario more than the second scenario, where I'm designing interval training programs such that they are doing the intervals in as fresh a state as possible. And we're extending the workout by doing endurance miles or endurance

running after that set of intervals in order to take advantage of any sort of durability training that we want to. Those are the two big things I take away from this podcast. I hope you guys found it insightful as well. As always, links are in the show notes, and I appreciate everybody out there listening. If you like this podcast, please share it with your friends, share the insights with your training partners and your running buddies. And as always, we'll see you out on the trails.