Do Ultramarathons Affect Males and Females Differently? | Koopcast Episode 135

trail and ultra runners what is going on what's happening welcome to another episode of the KoopCast as always i am your humble host coach Jason Koop in this episode of the podcast gets back to one of the fundamental and most talked about aspects that we continue to find as coaches and that is how should we train men and women differently based on how they react to different physiological stressors and one of the lenses that we can look at this through is how are they affected differently in races and that is the subject of this particular podcast a recent paper was published in medicine and science and sports and exercise by repeat podcast guest nick tiller the title of that paper is sex specific physiological responses to ultra marathon and what he and his team did for this particular paper is they looked at finishers of the tour de mon blanc time match them between the men and the women ran them through a battery of tests before and afterwards and saw how men and women were affected differently or in sometimes the same way from the particular race the results of which in certain areas are actually quite enlightening and may have training implications

for you ultra runners out there and so to get to the heart of the matter i brought nick on the podcast with one of our stellar coaches coach corinne malcolm to discuss the results and what if any are the practical implementations that you all can take home and implement in your day-to-day training as always i have a lot of fun with nick and corinne this one was a hoot as well because we tend to go off the rails on different pieces of banter but we always bring it back home we always bring it back to the most salient pieces of information that we can get from this research and how it applies to everybody out there so with that as a backdrop i'm getting right out of the way here's my conversation with nick tiller and coach corinne malcolm all about how ultra marathon affects the sexes differently before we talk about ultra running seriously nick you've been killing it lately like i don't know what the secret nick tiller sauce has been but like every time it seems like for like the last like nine months every time i turn around there's something that spans both the scientific literature and the lay literature at the same time and you've been able to weave those together um uh quite uh immaculately i would say so kudos to you for for that and i know it's just getting started i appreciate the the kind the kind words and yeah you ain't seen nothing yet we've got a lot of stuff in the pipeline i've been

working with paddy ekakakis the last 18 months two years on a series of papers and that baseless claims and pseudoscience paper is kind of the spearhead of this uh of this series of articles that we've got and and that's kind of ultimately that's that's our mo is to try and integrate the science stuff with the mainstream applied practice because the the two things don't work they're not mutually exclusive they don't work independently of each other the the mainstream health and wellness stuff influences the science and hopefully you you'd want the science to to impact impact the health and the commercial industry as well so if we if yeah if we're able to unify those two areas then then we've done our jobs properly but no i appreciate it i love it man you're throwing down the gauntlet even when you're even when you're like running at full steam it's beautiful man i appreciate that about you um we're going to talk about your most recent paper and um as you guys can tell if you're watching the youtube video i'm in my van driving back from western state still uh and i actually had a thought this morning when i was trying to like think about how i wanted to articulate the intro this um when i first started coaching ultra runners there was this theory out there that there was a certain distance at which women would outperform men in running and in endurance events and the premise of that was largely a mathematical one they just use a simple regressive analysis they'd look at you know what

the gap was at 100 meters what the gap was at 400 meters what the performance gap was at a mile and a marathon and then 50k and then 100 miles and eventually those time gaps kind of narrowed down and if you just extended the lines on the chart there's some theoretical distance that the women would start outperforming the men but my point with that is is it was based off of race performance and then several several years later and what is still starting to happen is we start to look at the physiological advantages that women might have over men in terms of what physiological traits do they have that could enable them to outperform men at endurance events or in ultra distance events and now we can kind of like take it a step further to see how they were how they are affected from ultra marathon events comparing women to men and we can kind of like alchemize all of those into some interesting theory so with that as a setup nick i'm i'm gonna kind of like turn it over to you for the for the paper specifics but that's exactly what you guys did you took a group of women and time women and men that were all time matched and you looked at how they were affected after the ultra trail de mont blanc yeah and just to preface the discussion of the paper so this is this is a collaboration that i have had it's been ongoing for a couple of years now with the mayo clinic so the team at various

institutes of the mayo clinic across the states and they set up this project many years before i even came on board and they were specifically interested in how there was this interaction this physiological interaction between ultra endurance exercise and hypoxia or altitude and they were specifically interested in the kind of the cardiopulmonary implications of the the intersection of those two things and so before i even came i just wish i'd i'd have met them sooner because uh and i'll tell you very briefly how we met shortly but uh before i came on board they they went to every space camp did a study there they went up kilimanjaro they did a whole bunch of um uh other studies looking at as i said the intersection between these two areas of physiology and just uh it was really just to to make a scientific contribution but because they're interested in it as well the director there bruce johnson who's a legend in in cardiopulmonary physiology at the mayo clinic and he just he was very fortunate got some grant money that he brought in and was able to just do these things that that he was interested in and uh and then i met the the team at the acsm conference in 20 2019 so this is pre-covid and i just at the time i was there presenting a paper that i'd published there was a there was a couple of papers but one of them specifically was a case study on an athlete who had done 100 peaks in the uk and so this is basically

the three peaks challenge but he'd done the the hundred tallest peaks in the united kingdom in i think it was 25 days so it came out that he'd done an on average a marathon every day for 25 days but uh had had just done this phenomenal cumulative ascent and descent over the course of the challenge and we looked at the physiological implications of that and it was it's kind of it was quite novel because that kind of thing had never been done before so and and those guys were there presenting some of their stuff from every space camp and we just got talking and it turns out that they had this project coming up at UTMB and they they needed a um a respiratory physiologist or somebody who understood the respiratory stuff very well and and um six months later i was i was in chamonix doing this um doing this project so it was really kind of an opportunity sample because we had this very big data set we've got 55 athletes from UTMB all together males and females and we're working on separate papers where we're discussing the kind of the more the more general physiological responses to extreme endurance and altitude but i thought this is a wonderful opportunity to try and get some empirical data to answer this question because it goes back decades and it's been talked about and written about ad nauseam as to whether females are more robust for ultra endurance athletes are they going to surpass men in terms of their performances and actually we had some data here where we could at least start to piece the puzzle together it's very preliminary it's a small data set but it is

the first of its kind and and i think we've i'm very pleased with this paper because we've moved the subject on in a in a meaningful way i think even how you know even though it is a small sample and describe for the listeners what things you were looking at after they finished the race because the the setup of the study is athletes go they do the race and then within two hours you start analyzing all of these different parameters why don't we kind of like walk through what each one of those were and maybe some of the highlights that were more impactful in your opinion sure so for the people who haven't read the paper as i said we had 55 total athletes of those only 10 were female so that's roughly in line with what you'd expect in in ultra endurance race of this distance somewhere between 10 and 20 of the field are usually female and so we had 10 female finisher 10 females two of them didn't finish or one of them didn't finish one of them didn't return for their post-race assessment so we had eight and we time matched them with with eight male athletes so we had a group of eight females and eight males they came in the week before the race to do a bunch of physiological assessments and then they came in on average i think it was an hour and 40 minutes after the race to repeat their measures so we looked at a whole bunch of different things we did some basic kind of anthropometry so we looked at body mass we took some vital signs which included resting heart rate and took their blood pressure

more just kind of for the basic health status and we were interested in whether that changed but it was more really just to make sure that they were in reasonable shape and could progress through the study we took some blood samples and we looked at all types of different biomarkers so we looked first at electrolyte concentration sodium potassium chloride and hemoglobin and hematocrit so as an indication of sort of red blood cell count or red blood cell destruction plasma volume as well so we calculated plasma volume from the hemoglobin and hematocrit and then in terms of biomarkers we looked at two markers that were specific more or less specific to cardiac function i don't want to say cardiac damage because it's disputed as to whether these markers actually reflect damage of the myocardium but we but it was um cardiac troponin and uh and bnp and then we looked at muscle damage uh with ckmb and then renal functional kidney function with creatinine so these these are all the markers in the blood and then we did a whole bunch of different cardiopulmonary measures or i guess it was more specific to the respiratory system so we did basic spirometry where we get data on their overall lung function so how much air can they move in and out of the lungs if that is diminished in any way it can uh it can reflect sometimes if there's some kind of airway obstruction or if there is some kind of inflammation in the airway

that is preventing the efficient movement of air in and out of the lungs we look to airway resistance through a special method called impulse oscillometry so that without going into the detail it basically uses sound waves and reverberate sound waves up and down the airways and it gives us a pretty good indication as to whether there's airway an increase or decrease in airway resistance and we look to gas transfer as well so diffusing capacity so obviously the the main function of the respiratory system is to move oxygen from the atmosphere into the blood and when at rest most healthy people can do that pretty efficiently but following exercise particularly extreme exercise the ability to move oxygen through the alveoli in the lungs can be diminished so we were interested to see how the race and the altitude and the interaction between the two affected the athlete's ability to move oxygen through the lungs and then the other key thing that we looked at here was what we call lung comet tails so this is a lung comet tails reflect the amount of fluid accumulation in the lungs or it's more commonly known as pulmonary edema so pulmonary edema is fluid accumulation in the lungs and that in turn can affect lung function and it can have some really major clinical implications as well and we did that using a what we call a transthoracic ultrasound so it was an ultrasound probe that was

looking between the through the rib cage between the between the various ribs and we look specifically at the lungs and we can look at cardiac function as well so what happens to the pumping capacity of the heart pre and post race so that's a very quick whirlwind tour of the things that we looked at there were a few other things that are probably not worth mentioning at this point but it was a really comprehensive kind of physiological assessment and it gives us a pretty good indication as to what's going on especially in terms of the cardiopulmonary function with any within any of those that you just mentioned are there any ones of those that you would describe as like heavier hitters and the other ones in terms of we know when we see dysfunction here and it shows up in a biomarker or the physiological assessment or whatever we know when we see this type of dysfunction we know that that person is going to their performance is going to get impacted more so than anything else yeah good question because a lot of these things a lot of these measures are taken and they're supposed to reflect one thing but actually when you look at the literature it's a little bit dubious to say the least so for example i mentioned earlier that when we look at these markers of cardiac damage quote-unquote damage so cardiac troponin and bmp this seems to be what we saw the really large elevations in markers of cardiac quote-unquote damage

following the race but actually if you look at the literature these markers are increased following almost any type of exercise any high intensity exercise marathon running ultra running there's been a bunch of studies looking at this specifically following western states which we were talking about a few minutes ago and it's quite normal and not necessarily clinically meaningful that you would see increases in these things i don't think it should just be ignored and we shouldn't just assume that it's that there's nothing wrong with it i think we need to do a little bit more research and understanding what the chronic implications are of repeatedly elevating cardiac biomarkers there might be long-term implications of periodically seeing spikes in these but certainly it's not not necessarily clinically meaningful certainly following a race of this type now if somebody who was otherwise healthy came into the emergency room and they had elevated cardiac troponin without any other cause then that could be in that's indication probably of heart damage and there's there's some kind of underlying cardiac issue but in this context it's quite normal for these things to be elevated following an extreme distance race so those things are kind of fairly normal it's obviously expected that you'd see large increases in muscle in markers of muscle damage so ckmb is is always elevated following races but interestingly it seems to be more elevated following ultra running than following marathon running so that there are two things that might increase damage of the skeletal muscles it would be high intensity

running so running quickly or running slowly for a very long period of time and typically you see much higher concentrations of of markers of muscle damage following ultra than you do in marathon than you do in 10ks for example so ultra seems to have but and again that's kind of intuitive to answer your question the the big hitters so to speak for me in this study are the cardiopulmonary measures that we've that we've taken because these things are not haven't been assessed so frequently and typically the studies that have looked at lung function following marathon and ultra marathon running have looked at basic spirometry so how much air can you move in and out of the lungs in a single breath which is interesting and it tells you a little bit about the lung function but in terms of the lungs diffusing capacity so its ability to transfer oxygen that's that's fairly novel following a race of this type and also the transthoracic ultrasound that tells us about pulmonary edema because that's not that's not been commonly looked at following ultra endurance exercise and again the the interaction between ultra endurance and hypoxia because that tells us a little bit about what's going a lot going on in terms of lung inflammation so those are kind of the novel aspects and those are the things that we'd want to focus on more closely well and that's one of the things that the paper pointed out kind of most directly and we'll we'll skip we'll kind of skip directly to the lung diffusing capacity piece which i think is a

really interesting one and this is once this is an aspect that declined more in males than it did in females and also has uh what you would you would you would call a clinically significant outcome but i would call a performance significant outcome if we're looking at how it actually affects people's performance but let's back up a little bit because most of the listeners aren't going to kind of understand how we how you actually assess that so within that particular test just walk through what it looks like before and afterwards and then what the actual results were in terms of what you guys found for these athletes that had just done UTMB okay so measuring it is really simple we measure it using what we call the single breath technique so the the hemoglobin in the blood have this have the main role of carrying oxygen so you you take a breath in your lungs to fuse oxygen if they're working effectively through the alveoli in the lungs and then the oxygen is transported in the blood to the various tissues and muscles of the body so in terms of performance everybody is familiar with vo2 max and vo2 max is primarily determined by how much oxygen you can deliver to the muscles the the ability of the muscles to take in oxygen isn't really a limiting factor that the most kind of limiting factor or the rate limiting step in terms of maximal oxygen uptake for performance is how much oxygen you can deliver so and that's usually cardiac output so it's the pumping capacity

of the heart and how much hemoglobin you have in the blood but if that if something is is reducing the lungs ability to diffuse oxygen into the blood to begin with then that's obviously going to have an impact on performance if there's less drive for oxygen through the lungs into the blood there's less oxygen available to transport to the muscles to begin with so that's why exercising at altitude it typically diminishes your aerobic capacity and diminishes your ability to exercise at a high intensity because there's less drive for oxygen into the blood so so going back to your question so we measure this with the single breath technique and rather than measuring how much oxygen is diffused through the lungs we look at carbon monoxide because the hemoglobin in the blood have a have a very high affinity for carbon monoxide in fact the hemoglobin in your blood would prefer to transport carbon monoxide over transporting oxygen it actually carbon monoxide binds more easily to to hemoglobin in the blood that's why carbon monoxide poisoning is so deadly and and it's so easily um it's so easy for these things to cause so many clinical problems because your your hemoglobin would much would much more readily bind to carbon monoxide and if it's doing that it's not carrying oxygen right so people essentially asphyxiate and so but so we use a very very very tiny concentration of carbon monoxide that doesn't have

any clinical impact on the body and we get the individual to take a deep breath in all the way up to the total lung capacity so they breathe in as deeply as they possibly can and we have a known concentration of carbon monoxide in this breath in so they're breathing through a mouthpiece and they're breathing mostly room air but there's a tiny concentration of carbon monoxide in there they hold their breath for about 10 seconds and then they slowly slowly breathe out and we look at the discrepancy between the carbon monoxide concentration that's that's breathed in and the amount that's breathed out and then that tells us the the gas transfer capacity or the diffusing capacity that the lungs have for carbon monoxide it gives us a pretty good indication as to how effectively the lungs is able to transport gas in this case it's a surrogate for oxygen and so you're comparing before race and after race and seeing what that and seeing what that deterioration is and there's deterioration in both groups but the men deteriorated more than the women and here's what i want to here's what i don't understand that you might be able to eliminate for corinne and i from a clinical standpoint what was that deterioration and can we put that into like a like some sort of context like it is the the deterioration itself is is clinically meaningful or meaningful to performance to what degree is there anything that we can say about that so in terms of what we found there were we looked at dlco so

diffusing capacity of carbon monoxide and dlno diffusing capacity for nitric oxide and females didn't show any statistically significant change pre to post race there was a slight kind of reduction when we look at the the results i'm just looking at the the kind of the spreadsheet that we published here and you know you could say it's approaching something statistically significant but but generally there was no if you live by the sword you die by the sword there was no change in females whereas males did exhibit this large statistically significant reduction in both values and there were large effect sizes as well in the males so the effect size is the magnitude of the change we don't just look at whether it's statistically significant because that's only that only tells you if if it's you know there could be some kind of statistical artifact or statistical noise or chance and something could come out statistically significant but when we look at the magnitude of the change looking at the effect size the males had a pretty large effect size as well so so for dlco so the diffusing capacity for carbon monoxide it was um it dropped from 34 in males pre-race to 29 and that was uh statistically significant and had a large effect size so 0.83 that's a cohen's d so people who understand statistics and effect size that's that's pretty big that's a big drop yeah and we saw that we saw the same for dlno

and um and and i think it's it's worth mentioning the the the pulmonary edema that we saw here as well because it's there's a good indication that when we see pulmonary edema or fluid accumulation in the lungs that could in turn affect diffusing capacity and and again in this case we saw a very small decrease um in in um sorry a small increase in uh pulmonary edema in the females but a very large increase in the males and again that the effect size in in females was 0.96 which is which is pretty big in the males it was 2.4 which is colossal so that so we see this not just statistically significant but a very big effect size in the males so so we're seeing a much more prominent fluid accumulation in the lungs with the male athletes so it in terms of clinically whether it's clinically meaningful or whether it affects performance that's a difficult question to answer because probably in this case in in most individuals it wasn't clinically meaningful nobody had to be hospitalized because of this nobody needed any kind of medical intervention following the race even though these are quite novel findings we've not seen this before there's a good chance that it would impact performance because if if it's reducing your ability to transfer gas across the lungs or if it's causing some kind of respiratory symptoms that's going to affect race performance so in the athletes that

we typically see and we've got a couple of case studies that we're going to pull from the data set a couple of athletes that we see who have the biggest increases in fluid accumulation on the lungs they have this kind of crackling noise when they breathe they have this really marked marked increase in respiratory symptoms they feel breathless and all kinds of distressing respiratory symptoms and that in turn is going to affect performance and in in a couple of these athletes we do see clinically meaningful decreases in lung function that that would suggest to us actually we need to monitor these guys and i don't know when you get to the point where you pull them from the race and i'm not sure if um if there's kind of a threshold that you'd have to cross but certainly yeah it can be clinically meaningful and almost certainly affects race performance can i pose a question just because i'm really curious here about um you know the simpler the simpler mode of examining this which doesn't really get to doesn't get to the heart of what you guys were able to see is that is that forced expiratory volume and you note that that seemed to decrease more in women which which makes sense to me women have even in size matched individuals women would have smaller smaller total lung capacity smaller lungs from an anatomical standpoint they like at the same rate of exertion they have to breathe more because they have smaller lungs and so i'm like just kind of baffled that while we see a drop there in women that seems to be larger than in their male cohorts like how does that not translate to women ending up with more pulmonary edema in a in a time matched

race setting like this like that to me is just like very curious and i don't know that we have an answer but that's like exactly like where my where my brain is going with it yeah super interesting question and you rightly point out that that in general what we saw is that when we look at the what we call them this the spirometry measures so again for people who are not familiar with the measures you get your athlete to take a deep breath in and then they breathe out as hard and as fast as they can for as long as they can and it gives us an indication as to not just how much air they can move in and out of the lungs so their lung capacity but how quickly they can do it so it gives us an idea as to the flow rate if the flow rate is reduced then it could be because there's some kind of airway obstruction that's limiting airflow in the same way that if you if you get a hose that's spraying out water and you compress the if you squeeze the hose somewhere up the line then the water is going to start trickling out at a slower rate it's exactly the same with airflow and so and in fact airflow is considered to be you know when you study airflow it's fluid dynamics it's all kind of the same physical principles and as you you're absolutely right kareen that women tend to have smaller lungs they have slightly narrower airways and they tend to be more predisposed to airflow limitation for various reasons than males and that's kind of what we saw here in terms of uh so so we see this decrease in lung capacity pre and post race in in women but not men and when we look at things like flow rates

the decrease in peak flow the amount of airflow that could be generated pre to post race there was a bigger drop in females but again going back to my point about whether this was clinically meaningful it wasn't even though that the decrease was bigger in women actually there wasn't there was no meaningful change there was no clinically meaningful change in either group and um that this it probably wasn't because of some kind of airway obstruction because the advantages or the advantage of looking at these more mechanistic measures uh that we have here is that we can get to the root of what's causing the change in lung function and we can say with some confidence that there wasn't any airway obstruction there wasn't um you know anything that was obstructing airflow in either group and so we can almost consider the change in lung function and the change in diffusing capacity as two separate entities now what's causing the diffusing capacity we can only speculate it might be something to do with um the capillary recruitment in the lungs so pulmonary capillary recruitment there might be a difference between males and females there but really we you know we don't know what kind of phenotype is specific to males and females that would cause the males to have much more pronounced decreases in diffusing capacity and we don't know what may be protecting females against this kind of pre to post race decrease in diffusing capacity it's really sort

of up in the air we need more research to look at the you know genetic determinants of that yeah that's exactly what i was going to ask is what sort of sex specific physiology would you theorize is responsible for the discrepancy that you're seeing and you know it seems like this is just one of those things where it might be left up to theory at this point yeah it's all theory because you know when you look at something that we've that we know a little bit more about like the musculoskeletal responses we we see that females i'm saying females rather than women for i don't know if the reasons are necessarily obvious but but females are the correct term here when we look at the the female responses in terms of the muscular musculoskeletal markers there is a smaller increase in ckmb so we can say that females experience less muscle damage and that might be intuitive because there's plenty of data showing that females actually tend to be more fatigue resistant in the in the skeletal muscles and lots of great research done by our good friend guy mille from university of saint etienne and you know that his lab has shown a bunch of different times that that females are probably more fatigue resistant over long long periods of time and that might have some kind of role in protecting females from large increases in in markers of muscle damage but in terms of the lung function stuff we we really

don't know it's it's it's it's pure speculation at this point we're seeing all we can say really with our study and again it's a small study and it's one of the i think it's pretty much the only study of its kind at the moment in this kind of uh looking at sex differences in this kind of event we can say that females experienced no significant changes in lung diffusing capacity whereas males absolutely did and it was a not just significant but it was a large change as well and we can say that males had a much uh greater uh increase in in pulmonary edema but we don't really know what's causing it that there are there are some kind of um there's some kind of male there's some kind of sex difference in the phenotype that needs to be studied uh more closely but we can only speculate as to what that might be here's what i extrapolate a little bit from it when when i kind of like look at it through a performance lens is when i see the kind of the insults that the males displayed across the entire range of them i can look at that and say okay if we were to do like a graded exercise test before and afterwards and just isolate those variables that's probably worth several points you know somebody has a vo2 max of 60 it's reduced to 52 or 50 or something like that set several points when i look at it on the female side it's it's kind of trivial it's maybe a few points right

and you see that play out maybe mainly in like clinical populations right where they have some sort of pulmonary edema they do a bruise protocol graded exercise test before and afterwards you see that you know that that what i'm calling a performance deterioration kind of show up now we know that ultramarathon performance and if your colleague has really done a good job at anything he's done a good job illustrating this we know that ultramarathon performance is more multifactorial but at least on the cardiopulmonary side when i try to bring it out into like realistic very pragmatic terms that end function or that end performance function i really do boil it down to something that would that would show up on something like a performance test a graded exercise test or a time to exhaustion test where you can actually see those see those differences play out yeah and if you were to one of the limitations of our study is that we weren't able to quantify kind of cardiorespiratory fitness or any kind of performance measures i know geese done some stuff on on this in in the past and actually it's funny because when we were when we were doing our data collection geese in his in his lab were actually in an adjacent room so we were we had two different projects going on at the same time in the same facility um and and it was fascinating seeing the kind of stuff that they were doing as well and he was getting his his subjects they finished the race and they had to do these maximal sprint efforts so he was so mean i don't know how he recruited any any i mean he did he did he's he's i mean he

knows the race very well he knows the race directors and he probably knows the athletes well so i think that kind of works in his in his favor but uh he was getting to do these maximal exercise protocols and i just i can't imagine i had trouble getting people to stay conscious just doing lung function tests literally one of these guys breathed into a tube and then was on the floor and i and uh i had to you know coax him round and i got him through the the the test which is one of my prouder moments but yeah so we weren't able to quantify cardiorespiratory fitness and if we were able to do that that some kind of performance test all of these things that i've described differences in lung diffusing capacity the skeletal marker the skeletal muscle uh biomarkers and certainly the pulmonary edema would would would if it's affecting gas transfer would affect their ability to take in and utilize oxygen but i think what what we need to try and move towards and i think we're a long way away from doing it there are there are some models that have tried to do this but we need to try and create some kind of fully integrated holistic model of ultra endurance performance where we have these different factors we try and get an understanding of the magnitude of each kind of physiological system and how that might influence performance and we can you know if we could plug in all of these different factors and and um it's probably going to be different for males and females which is which is an added complication and it's probably and and i think that's more so in ultra than in other types of sports so i think we're a long

way from doing that but hopefully having an understanding of the kind of physiological changes that we've seen in this study we might be at some point plug in some of these numbers into that some kind of uh comprehensive model when you were doing some of the um some of the research to kind of get ready for this project were you aware of anything similar at some shorter distances even in other sports that took kind of the same these these same things that you were comparing across and if you found those could you kind of like generalize what the differences were in those shorter you know those shorter events versus what you actually see in ultra marathon there's quite a lot of stuff done in marathon running and the problem is that as we know ultra is such a unique sport it's not just long marathon there are so many additional things to think about it's so so multifactorial and dynamic there are so many things so many physiological systems that are affected in ultra that are not necessarily affected in marathon and i think the the danger is that we're too ready to extrapolate the studies from marathon and and that marathon is the closest comparator we have right and and it really doesn't tell us almost anything about ultra endurance physiology and so i think if anything extrapolating research from marathon running or shorter distance races or even triathlon it hinders rather than helps our understanding of ultra we've got to look at this

with a fresh set of eyes we've got to empty our cups so to speak to quote a bruce lee term and so that i mean a bunch of stuff has been done looking at you know changes in cardiac functions and looking specifically at skeletal muscle function contractile fatigue in the skeletal muscles but i'm just i'm not sure how much it really informs our understanding of of ultra endurance physiology which is why we we've got so much research in ultra and yet there's still so much we don't know because it's really difficult to try and get this integrated model um because it's really it's only been studied for the last couple of decades and i've alluded to this before unfortunately i would say the majority of research that's done in ultra is research for the sake of research it's big data staff or it's not very mechanistic let's really move our understanding forward in any meaningful way this is the first study that's been done on this area and i would say that this is one of the most impactful studies looking at sex differences and yet this is at best this is preliminary data of two groups of eight people you know and and i i we fully acknowledge the limitations of this study and yet it's probably the the most meaningful study we have in this area um or that's been published in a long time so that can that tells you about the state of the literature here well we're a long way off from that integrated model i don't want to sound like a party pooper or anything like that because i'm i'm going to be the first one that you know starts to adopt pieces of that integrated model is something that i very first wanted when or i wanted something close to that at least when i very first started coaching just to give me a little bit of framework

um i wanted to ask more as a cheeky question than anything else have you had anybody reach out to you and start like spiking the football in terms of you know women are better than men in this just because of this study or is that just something that we've gotten so used to that people aren't so quick to jump to that conclusion yet yeah a bunch of people have reached out recently more for mainstream media stuff i mean this has been written about so many times right in the mainstream media that when we wrote a review paper a year or so ago it was published in sports medicine called um do sex differences in physiology confer a female advantage in ultra endurance sport and within that we cited i think six different media outlets that have basically published the same they've all they've all written about the same thing that they've posed the question do do women make better ultra endurance athletes than men but of course they're not approaching it as an open question they've already that they they it's a it's pretty much a close-ended question they already know what they're going to write about and they go into it with this narrative of well yes and and then some of them one of them was um the title was why women are better ultra marathon runners than men yeah yeah and then it did this very cursory overview a very simplistic analysis and so that one of the things that's that inspired me to write that paper was because it's been written about so many times in in the media and they've done such a rubbish job of doing it so this is something that has been

argued for decades it's going to be continued uh it's going to continue to be argued and i think it's important to stress here that we didn't go into this with any kind of pre-existing expectation i didn't want to find a specific outcome i didn't know what i was going to find it was just an opportunity to look at the data and at least try and fit one of the puzzle pieces into place let's look at the data let's see what we find the statistics here are as robust as we can get the statistics given our small sample sizes and um and the data show what they show overall when we look at all of these different variables males have more frequent physiological perturbations pre to post race and the magnitude of the change is bigger in males as well so when you look at the effect size they pull the effect size it's 0.86 for for men and 0.63 for women so this is a moderate effect of the the race on physiology in women and a large effect in men that's it that's what we found as i said the statistics are robust i'm i'm pleased with the way it's put together and that's that's all we can say about it so it is what it is stop there yeah it is what it is and you could just like stop it there i don't know what you want to say it is what it is corinne i kind of these are so this is something where i have a hard honestly not to like diminish the study nick it's freaking awesome but i have a hard time pulling out the

practical points from a from a coaching perspective that's my role not in life so i'm going to lean on corinne and kind of put her on the spot since i can't come up with something very good for it is there anything that you pull from this corinne where you're like okay from a coaching perspective or in the way that we um kind of manage athletes during or after a race where you look at this and go oh okay i i might think about this little i might think about this a little bit differently or something that you can pass on to athletes i don't know that we have any like this is a try and true guideline that can that's coming out of this data right now right maybe with more like longitudinal studies down the road like i think that what was highlighted here is that we don't know the extent of what an acute what acute damage is done from you know one big UTMB style race right like we don't we don't understand those implications yet and and maybe there's nothing there but you know you could you could look at this edema issue for example and even if it's not they're not presenting clinical symptoms um what does that look like over time like what does that acute race damage look like over time and does that give us a i don't know does that provide more caution to to us as coaches who have athletes that really want to do 600s this year for example and like maybe that's not a good thing and maybe we can use this as a cautionary tale to say hey we don't know like maybe like let's try to meter the excitement there whatever it is but i don't think it's like okay this is what we know

happens and this is this is you know what the data is showing i think we we hear stories i mean tahoe 200 is a example of this from the respiratory side of things like they had a lot of athletes drop out of tahoe 200 this year it's really dusty it was super cold overnight citing respiratory issues they were having issues breathing it was kind of that acute acute um restriction more than likely or obstruction um with some of these athletes but we see that at hard rock actually medical doctors at hard rock they call it the hard rock hack these high altitude generally overnight um or higher altitude i'll say overnight races seem to elicit this respiratory issue in athletes who might have no clinical past with asthma or exercise induced bronchial constriction or some other sort of laryngeal obstruction issue and so to me it's like okay maybe that means when i have an athlete going into a race like that we talk about that medical history we make sure that there's nothing there that we want to be that we're concerned about um i've got another athlete who just went and like is seeing his physician to maybe have a rescue inhaler prescribed because this has happened at a couple races now and in an acute sense and so i don't think we're getting instruction out of the out of the research yet but i do think if anything it provides a a we're less naive about potential outcomes from like a clinical and medical sense and i think that that maybe is the take-home message for people is like we love this sport but you know there there's a dose response here to certain things and maybe that can meter some of

our excitement of uh how many how many of these uh acute i don't know body slams we're willing to take each season um to keep athletes in the sport longer yeah how many times you want to get kicked yeah i was gonna say gold star take her and nick you go ahead well i just i agree 100 and there were just two things that i wanted to add on to that that the first is that the one thing that we absolutely can't do with this paper is say anything to the effect of uh females uh are um less likely to have you know negative clinical responses following ultra so focus on them on the males that would be the you know an extreme take and it's not helpful because as i've said we've got to understand the limitations of these data and every athlete is different as we know some people are more susceptible to acute physiological changes so every athlete has to be managed on on an individual basis and i don't think that we should be anticipating uh more serious or less serious responses based on sex i think that would be very very unhelpful the other thing that corina mentioned was that i think this should be used as a as a platform if it is a springboard to consider the long-term effects so so we've known for a while that that running ultra marathons particularly if you're going to do like a hundred miler or something it has this acute physiological effect on the body people seem to recover within a couple of weeks most of their values return to baseline within a week or so but what are the long-term effects of periodically

slamming the body in this way i don't think we there's enough data now to say i'm pretty confident that extreme exercise training probably isn't bad for you and we spoke about this before i think in that exercising for you know 20 25 30 hours a week doesn't seem to have any increased risk of cardiovascular disease or increased risk of mortality but what i'm concerned about is that going out and running for 24 hours 48 hours two three four five six times a year i'm worried about what that effect on the body will be so you know if we had good athletes here and the average finish time was uh you know 30 hours or something uh UTMB i mean the winners are like low 20s but good athletes are going to take a lot longer than 24 hours and doing that three four five times a year and i and i just think we've got to be a little bit more careful about that but you know the one thing that i want to mention before i forget is is the elephant in the room that a lot of people have not even noticed the invisible elephant in the room is that the data that we have here and the data that we look at with regards to sex differences in ultra endurance responses is not necessarily representative of the average human because 80 to 90 percent of the people who run ultra marathons and the people who are studied are male now that doesn't mean that the 10 percent of female athletes necessarily represent

the female athletic population they're probably self-selecting this is speculation i don't know this but i suspect that the type of women who are entering 100 mile races knowing full well what the risks are how extreme it is knowing full well that 80 to 90 percent of the field feel the male they're probably self-selecting as the toughest most robust most um you know most badass females among female athletes they're not just they probably don't represent female athletes they're they're they're i suspect that they're exceptionally tough female athletes so i think we've got to be very careful looking at data sets like this you know when only 10 percent of the field are female and saying that that this group represents female athletes because they probably don't now it's different when you look at marathon running because 45 to 50 50 percent of marathon runners are female right it's a developed field yeah it's a developed field here any given ultra marathon race is only 10 10 15 percent female they probably don't represent female athletes as a whole so we've got to be very careful about how we extrapolate these kind of data yeah you could probably get closer with like 100k or a 50 miler because as we it's as you go up in distance that you see less female participation and part of that is like the the selecting in of like if i think i can finish it under the cutoff time i am more likely to start the race

and you see that more so in the female field than you do in the in the male field and so i mean it tracks it makes sense to me what why that 10 percent might be selective you even think anecdotally and i hate to bring an anecdote because the plural of anecdote is not data but every you know i know a lot of male ultra marathon runners who are like in decent shape and can get around an ultra and then maybe carrying a bit of extra weight and you know whatever every female ultra runner i know is a badass you know what i mean like maybe that's just i know that's that's only my own perception but like you don't you very rarely see like uh you know an out of shape not very robust not very determined female ultra marathon runner i'm like is that just me no that's not just you i was thinking the same thing i the the the percentage of like the really badass females compared to like the total pool of females is way way way way higher than it is on the men's side way higher so this self-selection nick i i've never thought about that but i'm totally with you and i'll also throw in that the that cohort right females running ultra marathons is likely to change dramatically over the course of the next few and several years and when you have that expanding you know population you're going to get a more diverse that you're going to get a more diverse user group and so your point of not necessarily extrapolating it i think is really is really well taken because as that user group gets more and more diverse the results that you

will likely find are probably going to be less homogenous yeah and we we know right now that like like we we follow this kind of every time there's a big race i haven't i haven't crunched the numbers yet for western states but overwhelmingly men will pull themselves and the the the participants in the women's race get either timed out if they if they dnf or have a medical dnf and it's so there's this interesting psychology there between the two fields where men will be like i think i'm good actually like i'm gonna stop now and women are like i missed the cutoff by a minute and that's why i didn't get to continue so there's this interesting like how do they select into the dnf pool is very very different across the fields and even looking at a race like western states which is you know one of one of the toughest the oldest and one of the toughest 100 miles you can do you have to qualify so even those even that athlete group are self-selecting as as the best ultra runners in the world so that that's even less uh that's even more homogenous less heterogeneous so again we've got to consider all of these things when we're weighing up the the data that we have on this sport well and once again i think that's kind of why why UTMB presents one of the one of the best opportunities to gather those athletes because you typically have a more diversified set of athletes um you can do it across multiple races kind of in a similar or the same type of uh type of environment and there's just

more people i mean let's face it you know there's 2 000 people in each of the races there's 10 000 athletes out there total and you know when you're looking at you know western states or kind of whatever it is you and you move from a few hundred to several thousand that's not trivial that's why you and gee can be like in adjacent rooms and still have you know successful you know research studies being done because there's just such a there's just such a huge core cohort of people to pull from there was a little bit of tugging of jerseys in our room coming up but uh for the most part we got on we got on and uh yeah we were able to split the cohort yeah so are you gonna are you going to in the future nick are you going to expand upon this in a little bit more of a robust fashion to you mentioned this is the kind of a first of its kind deal what do you want to look at next so we have a bunch of data from that particular study that we that is that is in the works so we have a series of papers looking at different aspects of pulmonary function with the larger data set as i said at the start we have 55 athletes in total and we have a bunch of data also from the hong kong 100 as well and we're sort of going to merge the data sets and look and try and pick out to see if there's a difference in the athletes who were exposed to the altitude um and and and try and get to the the bottom of some of those questions so we have a series of studies in in that area in terms of trying to develop this

study looking at sex differences there are no plans to do that at the moment because this study was the data were collected over two years of the race so that the group attended UTMB in 2018 and 2019 but pre-covid obviously and and we were able to get 55 athletes through our testing protocol and when it came down to it we had eight females only so so and and that you know this was a costly trip we were out we were in chamonix for three weeks we were all physically exhausted at the end uh it was it was a real kind of uh it was a gargantuan effort to get this data set together over two years of the race and we still only got eight female athletes so how we are going to expand on this kind of study i don't know there are no plans to at the moment if an opportunity presents itself or if somebody is listening who wants to give us some funding to to look at this then hey that that that would be wonderful but um this as i said this is kind of the the the biggest data set of its kind at the moment given all of its limitations so yeah how how we move forward from here we don't know but but but in terms of the larger data set we've got a series of different physiological systems that we're going to try and isolate and contribute to our understanding of ultra endurance physiology i always appreciate your context that you put things in like sometimes you

always run the risk of like presenting a nothing burger you know when you do that because they can be so benign and you add all the caveats and things like that but you know it's always made way better than over sensationalizing what the what the results are so i do hope that you get an opportunity to continue to explore this because at the end of the day i think both on the clinical side and on the performance side of things we all serve to have a little bit more knowledge in this area because it is so new and it's so novel and we're in a lot of ways we were off air we were talking about some of the medical practices that we've seen at uh some of these ultra marathons that's going to continue to evolve as well just because you know for all with all due respect to those early practitioners they're just kind of guessing and making up what they think the best run a show should be and things like this help tailor those practices down to the ones that are going to be the most helpful for athletes both from a performance perspective and then also for a from a health and wellness perspective i think that's really important because one study very rarely changes practice you know it's an accumulation of studies and you know it takes a lot of research to reach a scientific consensus on anything what we can say is that our study is novel it's interesting and it adds you know as i've said another piece to the puzzle but it's a big puzzle and there are a lot of pieces to fill in and the worst thing that we can do is overstate our findings everybody wants answers everybody wants to understand you

know humans need answers to things but the worst thing that we can do is fill in the blanks with you know made up data or or um you know pure speculation all that does is hold us back so we've got to be we've got to be honest and say look the data is here it says this and let's see what else we can find and then over time we'll we'll get it we'll improve our understanding but overstating your results it's just that doesn't help anyone yeah this was fun you guys corinne do you have anything to tack on before we say goodbye you had the best take by the way you always say no i'm just i'm upset that in the show notes you said that we could start talking about when i was gonna start beating you in races and we never never got to talk to that oh okay here we go when are you gonna start but you already can't beat me in races so that debate is already settled i think what's gonna happen is that we're gonna end up at a race because i think you and i try to avoid racing when our athletes are racing and so we're gonna end up at some really weird race together and then we'll get to finally because i don't think we've been we've done the same races but not the same years i think at this point and so it's gonna it's gonna all line up and we're gonna actually have a part to put a wager on the line when it does happen we definitely will and then nick can stop doing research because that will definitively solve all of all all of our questions answer everything just just in that n of one experience right no pressure it'll be yeah who is more dominant the history of all ultra marathon research will be contingent upon the results of that singular

probably it's gonna take something very minor and very obscure for one of you to get an edge like you know it'll rain the night before and the one who's better at running in the mud you know typically in in in uh like in california that people are just not very good at running when it rains and i did the the ray miller 50 a few years ago and it had been uh it had been raining the week before the race and typically californians are not good at running on anything other than dry dirt and the course was muddy and i'm like from england this is my wheelhouse this is this is where i shine everyone else is slipping over and i'm just like flying along i think i'm sick in that race yeah for sure i was overtaking people who were slipping over and i finished sick in that race um just just purely as a as a byproduct of it being wet on the course it was brilliant yeah it's like how i'm the only person that was upset in 2019 when western states was cooler than average i was like no no no crank the heat make it as unbearable as possible this is my wheelhouse yeah all right nick thanks for coming on the podcast again man you're definitely a serial offender and there's a reason for that all the guests appreciate when you uh come on how uh first off i'll leave links in the show notes to the paper itself but how can the listeners find more of your work we alluded to this at the very beginning of the podcast you're kind of like everywhere now and i'm losing track so i'm gonna have to take notes and put them in the show notes as well but where can they find more of your work yeah i've got a lot going on but you can find all of my work in ultra in in uh critical thinking

skepticism science research on my website which is nbtiller.com you can find me on twitter at nbtiller tweet about all of that stuff and yeah watch this space we've got a lot of cool stuff going on so um maybe i can come back on the podcast sometime soon and discuss it with you i can't wait because that's the juicy stuff that everybody gets so fired up about and i get all the angry emails afterwards so we'll we'll definitely we'll definitely do that when we come back on you probably get it more than me but still hey this is fun as fun as always thanks for having me oh awesome man thanks you guys all right folks there you have it there you go much thanks to nick for coming back on the podcast explaining his research and what it might mean for athletes but more importantly nick thank you for all the incredible content that you have produced over the last several months it has been amazing as we talked about from the onset of this podcast everybody listening right now go to the show notes find all the links where you can follow nick tiller and go and follow him you will be well served in your training and racing will be better because of it thank you to corinne malcolm for coming back on the podcast and as you always do helping to explain what the results and what the meaning is of some of the scientific research is in terms of how athletes can apply it day to day you have an incredible gift of doing that and you just get better and better at doing it every time i have an interaction with you most importantly thank you to the listeners out there and this is a very this is a very special most

importantly on this one i know i always say that this one has particular meaning that is because the KoopCast has surpassed 1 million downloads recently in fact i have a sneaking suspicion that while we were recording this very podcast that 1 million download mark got obliterated and i am humbled and i am absolutely honored that so many people have spent so much time listening to this podcast and i hope that it is better informed everybody's training and everybody's racing and if you happen to be a coach you're coaching practice as well and so to celebrate that to give something back to all of the listeners and particularly the hardcore listeners that are out there that are listening to this long rambling outro i'm just going to give stuff away for free what i'm going to do is if you go to my website jasoncoop.com forward slash book and you choose either the hardback version or the paperback version i will send you a free copy with the promo code KoopCast it's coop spelled with a k all in caps that is my gift to you i'm not going to spam you afterwards i'm not going to charge you for shipping i'm not going to charge you for anything just go to the website click on the book link order a book send it to yourself send it to a friend send it to family send it to one of your training partners send it to somebody as a stocking stuffer for christmas it's got to be a big stocking because the book's pretty big no matter how you want to use it i just want to give it away for free to people just as a thank you for everybody out there listening and for all the awesome comments that i receive

on social media and in person like i said i'm absolutely humbled that this podcast has seen this much success so that is my gift to you guys giving my book away for free i'll sign every single one of them go to the website and find it promo code KoopCast all one word all in caps that is it for today folks here's to the first million downloads and here's to several million more in the future as always we will see you out on the trails