Utilizing the Repeated Bout Effect for Downhill Running With Arash Khassetarash | Koopcast Episode 138

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 is inspired by all the runners with smashed quads out there and all the runners that are going to have smashed quads out there stemming from some sort of mountainous ultra that you have done or are going to do this year i feel your pain we have all been through that before and one of the great mysteries of coaching athletes for these types of events is how to prepare them to contend with all the copious amounts of descending the damage that goes along and the loss of control and the loss of technique that happens to go along with all that descending as well and so in order to come up with some science-based explanations on how we could potentially train to ready athletes for this particular demand of trail and ultra running i brought on a researcher in this area in a rosh kazatarash out of the university of calgary i got to know a rosh through his presentation that he put on during a downhill specific running seminar put on by the famed physiologist guillaume mie that i just happened to be a

panelist on the uphill portion of that seminar i'll leave links to both of those in the show notes for those of you that want to deep dive into the science and practice of uphill and downhill running i encourage you all to check it out but i got to know a rosh during this presentation or during this uh during this webinar and i was absolutely captivated by some of the research that he has done in this area because i think that there are very practical takeaways in terms of how frequently how much and how hard you should incorporate downhill running into your sessions to get the most bang for your buck so with that as a bit of a backdrop i'm getting right out of the way here is my conversation with a rosh kazatarash all about how to train for downhill running um but before we get into it dude i was doing some uh some research research on this in in the background and it i had a hard time actually getting to your research because all i could find were uh like lay articles and things like that about pull-ups oh wow yeah so so just as a little bit of a personal story i know you're probably a humble person but i think the audience would like to like to know what's the fascination with pull-ups man and how many first off how many pull-ups could could you do on a normal day uh on a normal day these days i'm not doing many i do a couple hundreds uh but for specifically that event that i was trying

to go for i was gonna go do 8 000 in 24 hours um there's a there's actually a study with it uh three times 2 000 pull-ups i i was a subject on that one and uh it's gonna be published soon so it was interesting the different strategies that we uh we tried to uh uh try to do and actually that study was also led by uh guillaume my supervisor and yeah i i just think that it's uh i was just trying to challenge myself dude but seriously that's like a huge feat and interestingly enough kind of something that you have in common with ultra running because one of the ultra runner characters right that we uh that a lot of people look up to include including myself that i've known for a while is david goggins who had the pull-up record for a long for a long period of time so it's just interesting that all this stuff seems to come full circle man it's just a small group of idiots that keep regurgitating all this stuff that we're trying to do right yeah it's actually very the pull-up uh is quite similar to what you see in the ultra run and in the study that will come soon hopefully we uh try to show um we try to show how the terms of events looks like a 24-hour run so that's that's quite interesting

good like upper body lower body and oh my god so 8 000 in 24 hours would be the record do you have any thoughts on trying to capture that record in the future i i don't think so because i uh lost the fitness and i also gained some weights and so on like it's been it's been two years and then the gyms were close due to covid and then i couldn't work out well so i just lost the fitness oh man well that's a hard thing to do now yeah you got to train a lot for it well we'll have to circle back when that paper comes out more just to talk about it yeah anything else i think that's really cool uh but we're gonna talk about ultra running man and um as we were chatting offline a little bit um i was recently at the hard rock 100 and there there are two primary things that ail the runners out there and everybody talks about it before the race and everybody complains about it afterwards and the first one is the high elevation so there's an average elevation of 11 000 feet it tops out at handy's peak which is over 14 000 feet and that causes a whole host of problems the main one of which just being nausea um and so athletes have come have have kind of undertaken a number of different strategies to combat that using altitude tents and getting out on the course and trying to improve their fitness and things like that and the second one which is more in your wheelhouse is how to how to really combat and to introduce interventions that specifically can help them deal with the

copious amounts of descending that is on the course 33 000 feet of climbing 33 000 feet descending and over the course of 100 miles that's just a lot of wear and tear on your legs and and um as uh as a lot of the research has started to to come out research might might not be the right word but as long as the rate a lot of the race analysis has started to come out we start to see a lot more of the time gaps open up in the latter parts of the race and specifically on the descents as opposed to the earlier parts of the race in the essence and i think a lot of the research that you're doing is is going to illuminate on how we can train ourselves better to to combat to combat that although it's still a big open question at this point uh of the game huh yeah so so so to start to start out with we're gonna have to go back to some fun to some very fundamental to some very fundamental physiology but i want to know initially how you became how like you became curious about eccentric work and the repeated bout effect and how this affects athletes and how they can better prepare for it like what's your kind of like personal interest in this and how did you get involved i'm i'm more of a biomechanist and physiologist and one of the things that i was really interested in to see the difference in two different conditions and uh thinking about

knowing that the the repeated bout effect exists and we know about it and we know that it has a huge training effect that is not uh it's not normal for like a concentric type of contraction i was interested in trying to figure out how the biomechanics of certain tasks would move would change due to this training effect and then the downhill running was a quite uh good example of how people uh can get trained quite fast and so you you mentioned this phenomenon that we've talked about previously on this podcast that a lot of the long-time listeners will recognize and that's going way back to one of my earlier podcasts with roger anoka out of the university of colorado who's one of my undergraduate professors and i remember seeing his class one day and i still have his book it's sitting over my shoulder somewhere and we were going over uh we were going over the inoculation effect i'm going to term it a little bit differently to kind of emphasize it more than anything else and i was sitting in his classroom as a young undergraduate and endurance athlete and he was trying to impress upon us that in most types of adaptation situations whether it's an athletic one or rehabilitative one we're looking at an adaptation that can occur over the course of weeks and months

and the audience that that is listening to this is going to be a lot of endurance athletes and they recognize this they put in training for weeks upon weeks upon weeks upon weeks upon months sometimes even up to a year even four years that all that that all accumulates in some sort of apex race that they're training for and for professor anoka to kind of like turn this on its head and to say that one bout of exercise offers some sort of adaptation or protective effect the inoculation being the protective effect again subsequent bouts of exercise to me was kind of mind was kind of mind blowing and also almost unbelievable at that point because we're so used to this paradigm this endurance training paradigm where adaptation takes weeks if not months not one single dose of it yet that's what we find with eccentric exercise and i want you to try to explain that a little bit further for the audience because it is a very novel concept and one that i think a lot of athletes as we're preparing for these events we have to kind of like shift our paradigm around in order to fully understand it yeah so the eccentric exercise is kind of uh very much different in terms of in in many terms it's very different than concentric exercise or whatever people call it isometric exercise which is also um another mode but in

eccentric exercises there are many theories that at some point people looked at eccentric exercise they did a uh one bout of leg extension for example eccentric leg extension and uh to uh explain in a better term eccentric exercise would be the one that we uh uh but that the muscles are lengthening uh instead of shortening and while this lengthening is occurring and they're kind of the muscles are kind of uh trying to withstand the force in that in that in that time there seems to be a uh sort of a damage to the muscle or the contractile uh system or the neural system as well and that kind of triggers some some uh subsequent events that helps to regain strength and even get it become more stronger and we know that this uh we realized like 30 40 years ago we realized that this effect exists and uh they become stronger the second time they tried it they realized that they they're much more uh resilient to this damage and that that was something that very new at that time and uh then different uh researchers looked at different perspective of it to see how this mechanism

is working and over the past 30 years researchers come out with uh different uh mechanism that could that could contribute to this effect and uh you can you can think of many things uh many different uh possibility uh but there are four uh four possibilities that is considered to be uh a reason for this but eventually what is happening is that uh i think for an athlete it would be more important to know that the outcome is that the neural muscular tendon unit becomes stronger and uh that is and becomes more resilient to muscle damage and that is what an athlete wants especially in such a long event of an ultra um ultra endurance or ultra marathon running well and you mentioned some of the original context of this which was to take a very simple exercise a leg extension or sometimes even just lowering the weight from like a bicep curl people to you know people always recognize a bicep curl because it's a vanity type of exercise and lowering the weight back down is the eccentric component of that but how how one bout of that can provide some sort of protective effect for future bouts what the endurance community kind of really

wants to know is is okay how can we take how can we take some of these lessons and how can we learn from this phenomenon learn from this phenomenon to specifically apply it to an ultra marathon situation where there's a lot of climbing a lot of climbing a lot of descending and the descending becomes quite problematic particularly in the latter course of the race and you decided to study just that where you put subjects on a treadmill you made them run downhill and then you examined how this repeated about how this repeated bout effect played out throughout the core throughout the course of the intervention so why don't we start with that study and then we can kind of move into maybe what some learning lessons would be or maybe what some what they could also teach us about the trainability of this particular aspect but let's just kind of start with the study design and what you were actually doing so the the study design was to make sure that we will have repeated bout effect and knowing that downhill running also has a lot of this eccentric contraction and that could basically damage the muscles the first bout and if we do it the second bout we will have this strong effect that we are hoping to figure out what is going on i was mostly interested in the biomechanics but i know that uh many people many uh most researchers are also interested in the uh physiology part of it as well

so what we did was to bring the athletes and they ran on the treadmill for half an hour on a pretty steep descent 11 degrees or 20 percent and running on a treadmill is a little bit different than uh running on a trail because when you run on a treadmill you have to you have to uh kind of break because you can't go further yeah right you're running downhill uh and that would even that 10 11 degrees um um descent would be even more compared to a simple trail running so that was decent enough that uh that uh slope was enough to damage them completely in terms of the their uh muscle let me hold on wait wait but you're intentionally let me i don't want the the the the gravity excuse the pun of the study design to get lost on the listeners this is an a it's an extremely steep slope that you're having them run downhill but you're intentionally setting it up to induce a lot of damage that's the whole design like you want to see a lot of fatigue and a lot of damage just from this from this one bout and so you're designing the condition to be almost as steep as possible i don't even know how you get the treadmill to decline that much so why don't you paint that picture as well to help like solidify it in the listeners minds yes we we have this

instrumented treadmill that can go go i think i'm not quite sure it should be close to 30 degrees that can go down like it's it's very very steep treadmill like it can it can go even lower than that but for our purposes we were just trying to make sure first the athletes will be okay at the end of the run and the second that the athletes will be damaged enough and knowing from the many years of research we knew that this specific duration and this specific slope would incur enough damage for us to be able to see the effect and then in the second part three weeks later we brought them again i asked them specifically and i logged that everything to make sure that they they're not doing anything else during the three weeks which is a very difficult thing for athletes not to work out but three weeks later we brought them again to the to the lab and they did the same exact same thing 30 minutes downhill run and now we were so we have condition one we have condition two condition one is going to incur lots of damage and condition two we're hoping that doesn't incur that much damage hence the repeated bot effect and then this was the design of the study and then we had some variables of interest to look for and so can you

summarize generally what happened between week one and when you brought them back in the lab and once again this is such a weird thing because you just had them go they did i forget what you said 30 minutes 30 minutes running downhill 20 slope that's going to be hard but no other training at all in between 0.1 and 0.2 which were three when you're evaluating these people which were three weeks apart can you encapsulate what the differences were that you found between those two points in times in terms of the damage that was occurring the biomechanics the biomechanics that were going on uh while they were running and things like that so yeah in this study it was quite a comprehensive study in terms of uh both physiology and biomechanics in the physiology term we looked at the muscle damage and we found close to threefold increase in a specific marker of muscle damage we call it creating kinase um and that was uh after the first sound they run that indicates that the muscles were quite damaged uh and that variable was almost non-existent the increase uh in the second downhill run so that was the first thing that was very interesting so ck went up three x after the first one it didn't go up at all after the second one and after the second one significantly no it didn't go up at all like almost non-existent um and the second thing was that the

we also looked at the neuromuscular function and what we call it neuromuscular fatigue we look at the neural aspect of fatigue and we look at the skeletal aspect of fatigue and in most cases what we found that before and after we can measure how much force that they their quads can produce and we did it before and after the first run and before after the second run and again there was a huge reduction in the uh force production capacity or in better term we say a lot of neuromuscular fatigue while in the second one there was almost nothing almost nothing so that that's quite interesting to uh to see in the course of three weeks so across these two parameters right you have you have the muscular damage and the and and the neuromuscular component of it both of them were impaired significantly after the first one but hardly impaired at all after the second after the after the three week period in between the two trials yes and yeah that that's quite uh we that's what we were expecting to see and it was just to show that this exists and it is it is of course very interesting for runners uh hopefully that there was no other

intervention in between these three weeks they just ran one downhill and three weeks later they did the second downhill and that was the large effect so every time i see these things i'm always impressed by the stark nature of the before and after footprint of the physiology and the biomechanics and what i mean by that is is normally when we look at training intervention studies in the endurance world if we get like half a percent you do an altitude intervention right you do an interval training intervention you do anything like that you would do a backflip over six weeks of doing a bunch of intervals and you see half a percent of vo2 max increase half a percent at pace at lactate threshold increase you'd absolutely you'd go bananas over that you think you're the smartest person in the world for coming up with whatever intervention that you came up with and that's with an intervention that lasts six or eight weeks they're doing a bunch of intervals it's very it's very time consuming it's hard there's you know it's it's arduous on the part of the athlete and here we have an intervention that all it takes is one and there's nothing they don't they literally don't do anything for three weeks and they come back in the lab and there's such marked improvements in these uh in these parameters and i mean it's almost i hate to use the word magic right because we're trying to drill down on the science of it but almost does seem like magic when you start to look at that and you compare it to

everything else that we know about athletic and in particular endurance physiology yes it's it's very interesting to just like i've been an athlete before and i've uh i try to keep that um running as a part of a hobby for myself as well just thinking about it like if i like i'm just thinking about like uh in terms of squat if i go today to the gym squat 100 pounds and then i come back i don't know three weeks later and squat like 150 pounds that would be that would be a huge huge increase and i think as an athlete i i think any any athlete who gets to know this effect should make use of it okay as much as they can so that that's where we need to drill into and i i always i'm always a little bit remiss asking people in the scientific community these types of questions because you're it kind of takes you out of your wheelhouse and you're trying to extrapolate beyond the you know beyond the the study or the series of studies that have been done in in the area but you'll have to entertain you'll have to entertain the questions for a little bit we want to try to make this practical for athletes and we've danced around some of the um uh some of the ways this can appear in more of an intervention or some sort of way that athletes can actually train but if you're consulting with athletes that are doing

you know uphill downhill types of races and knowing what you know about this repeated bad effect and about the work that you've done what are some really pragmatic um what are some really uh uh pragmatic pieces of advice that you could give athletes about their training to harness what you know about the repeated bad effect and how to deal with this eccentric component of the sport that we're doing so i i try to think of in terms of an athlete trying to either win a race or have a good race so in terms of winning a race one of the things that we know about downhill running specifically and we know it from 1990 i hope i'm not mistaken 1992 or uh i think it's 1992 we know that uh uh there is the oxygen consumption or what we call it at a cost of running some sort of cost of running is not exactly cost of running uh but it's very it is very related to cost of running we know that in downhill running after like for half an hour downhill run it increases quite a lot and we know that this increase does not occur in level running in level running if you run for half an hour for one hour there will be a small increase in oxygen consumption due to some physiological factors

but in downhill running we see a large large increase increase well over 10 percent and one of the ways to uh deal with it and i think um the thinking about the how the bio how you can change the biomechanics of uh the movement uh and for that specific reason i looked at the biomechanics of this downhill running uh uh at the minute one and at minute 30 of this downhill run and what i found during the first downhill run the biomechanics of running was completely shattered like it was completely different compared to the beginning of it uh and uh to just compare how different what is uh it was uh we can think of like a like a contact time like i'm pretty sure runners know exactly what the contact time is the time that your leg is on the ground when you do when you take steps the contact time increase increasing contact time during a one hour level run is around like one or two percent while in the 30 minute downhill run we saw eight to nine percent increase in this uh contact time and in this contact time is quite related to uh the cost of running or the uh energy aspect of running so that was the downhill running one and during downhill running two we did not see that much of an increase there was an increase but it

wasn't as much it was close to four percent so that is one of the things in terms of energetics of that run or how much energy you consume to run that specific distance in this specific race just previous exposure to downhill running helps by that much and that four or five percent difference between the two belts is a very huge difference and it would make a lot of difference in terms of uh one race so that's uh uh that's kind of one aspect of looking at how you like the importance of the previous exposure let me try to contextualize this a little bit because we we were both uh in a series of uh uh webinars uh hosted by your colleague gi um and in the up there was a split in between an uphill seminar and downhill seminar and i gave some perspective on the uphill and you obviously gave some perspective on the get downhill but one of the presenters on the uphill was a professor roger crom who did a lot of the uh biomechanics research around the nike vaporfly several years ago if everybody can like teleport back a few years and all the controversy swirling around those shoes which they found made about a four percent running economy difference and it blew

like it completely blew up everything that we knew about the rules and performance and we're going to have to rewrite this and rewrite that what you're saying is is the running economy different or we we're using a cost of quote-unquote cost of running difference just with one bout is over four percent so i want to like contextualize the difference between those two and one being like so astronomical with a carbon fiber foot plate and another one being a simple one downhill intervention kind of causing not the same but a similar type of running economy improvement in air quotes so just to clarify the contact time is quite related to cost of running and the oxygen consumption but it's not exactly the same so the four to five percent increase in less increase in contact time would kind of have some effect on the cost of running that might be one or two percent three percent i think that could be a good next study for someone who's uh interested in to see looking at both variables and see how they are related but there there is there is definitely a uh big aspect of uh big improvement of uh performance between the two bouts and i i just don't know how how many percentage it would be but it's it's interesting even if it's like one or two

percent at the end of the day we're looking at just one mouth of downhill running compared to how many uh years of research has gone into making uh the paper fly there you go yeah so we've got this one component where the biomechanic where the you're i'm gonna try i'm gonna try to coin this term a little bit but you're more you're more biomechanically resilient after this one bout of downhill running meaning your mechanics just aren't changing enough and you're you know from a from a performance standpoint whether you want to talk about it in terms of the cost of running or you're smoother downhill or there's less damage it's kind of everything all rolled into one that's one component of what the what what athletes can kind of take home and what the practical implications are but what are some of the other ones that you've found throughout this research where an athlete who's preparing for an event can look at this and go okay i'm going to practically apply this into my training over the course of the next few weeks i think one of the important thing is that we we now know that uh in many levels we know from physiology from by mechanics that this effect exists and we know how long it lasts or we have a good idea of how long it could last and we know what happens in the first week after you do the first bout so what would i what i would

suggest don't do a downhill run a week before your race don't do it two weeks before your race try to do it like three weeks before your race that we're quite uh sure that by that time you're completely recovered from that previous damage and now you're stronger and so having one or two bouts of uh eccentric exercise and specifically if you're if you're a runner then the downhill running that that could uh do a huge favor on the race state well and one of the things you're referring to is what i just call the legacy effect of these types of workouts and um you're probably not aware but we've had a lot of coaching roundtables on this podcast where we've talked about how to design training camps for athletes who are competing in mountainous events that live on in florida right florida and texas they don't have access to this which is a really common situation for most most kind of normal people and based on this research and the research that has that has come before this we've we've come up with this generalized consensus that if we want to bring an athlete into a mountainous environment to do a training camp and in advance of a mountainous type of event we want to time that training camp to be anywhere between three and five maybe six weeks at the very most in advance of in advance of that race and a lot of that timing comes from this legacy

effect that you you know that you mentioned where we can see a lot of these a lot of these a lot of these protective effects last up to three and up to three weeks and even longer but shorter than that there is a lot of damage induced so it's this fine you know it's this fine balance between allowing enough time for all of the negative repercussions to work themselves out and enough time to let the positive ones kind of kind of shine through so i'm wondering if you could kind of enlighten us about enlighten us about anything else having to do with that timing or that that legacy effect in terms of what what you know about all this everything going on with the repeated bout effect and eccentric exercise yeah what what i think it would be uh interesting for the athletes that uh there there there's been many research there's been uh uh specifically research in downhill running but what one interesting research was from 1985 and that was like over 30 35 years ago um and in that specific research they showed that the good amount of time would be three weeks to have that repeated bout effect and it would be it would last until six feet as you as you mentioned and after that it it might lose its uh its effect so okay here we get to some really practical pieces right because we know in a research design you're

trying to isolate as many variables as you can and you just mentioned this this totally and you're going to have to forgive me for sounding a little bit contrite here you have this totally over contrived situation where you have these these recreational runners which is the population you were studying do one bout of exercise they don't do anything as to not confound the research and then they do another bout that's not the real world right and the real world athletes will kind of continue to train and things like that so what can we say or what can we what can we theorize a little bit about how this legacy parameter of of three weeks plus or minus gets affected by the the normalcy of the training process athletes are going into an intervention like this or an intervention that like like what we're proposing with some degree of training and they're going to train to to a certain degree after that uh after whatever intervention that they're using what can we say about that how that legacy this proposed three-week legacy process actually gets affected by any of the training that happens before and afterwards it's one one of the things to make sure not to do after the first bout would be to make sure that they're not doing much of a training specifically two or three days after that that that uh that could definitely could incur more and more damage depending on um we're thinking

about a structure that is already damaged and then you're trying to like three days later you want to you want to do another one uh maybe if it is five or six days later that would you would see some effect as well because there's has there has been studies um and i i totally agree that these studies that we do specifically are very very much control to make sure that we don't have any other effects and at least we know but now we know that this is the this is the effect and then the compounding factors can come in um in terms of uh the the specific few days after that i i don't think that would be a good idea to do the first downhill run and then two or three days after do the second one or if you think about like even level running level running is also uh has a lot of not as much as downhill running but it has a lot of eccentric component as well because you you basically uh break and then propels yourself uh for the next step as well so for that specific period i i think the at least for the first week after the very first one probably would be better not to do that but if you want to if you want to incur more and more damage um control damage so that you get stronger and stronger i'd say if you uh feel a few bows divided in uh one or two week or three weeks would be would be a useful thing to do

to kind of get the most out of this effect but i'm pretty sure at some point there is a ceiling or there's a uh there's a uh limit to how much you can get out of this well so you mentioned the word control damage right i love i love i love that term i'm going to steal it from you um athletes are they're they're very familiar they're very familiar with the concept of progressive overload right and and and although that's a that's some training terminology that gets a little bit too far in the weeds athletes will realize that hey one week i can run 20 miles a week and the next week i can run 30 miles a week and the next week i run 40 miles a week and eventually there's going to be some sort of loading effect that produces an adaptation the the adaptation in this situation is is markedly different so does there need to be a progressive overload in terms of any of these parameters the total amount of vertical descent the speed or the force i guess if you want to put it that way that the uh that the athlete is having to withstand uh from an eccentric uh uh perspective what do we know about those loading parameters and do we need to think about progressive overload in in in the eccentric uh form of exercise in the same way that we do in concentric where we just need to keep adding stress in order to impose a specific or further adaptation i i think that

progressively overloading the tissue could be a good thing to a certain point and then after that certain point first of all there will be a point like you you can think about like i i try to think about it in terms of mechanics um think about a i don't know like some sort of a tissue that you're trying to uh put tension on and then you can you can and then the tissue becomes less and less uh resilient to that tension and then you it gets stronger and then you come back and then now you need to increase the tension and so on and on but there's a specific point that that uh tissue wouldn't be able to withstand more than that hence the overuse injury um so to a certain point i think it's it's good to uh get the most out of this uh effect that we could but uh i i i don't think that it could go forever because at some point the tissue like even if the muscles are not so the muscles are getting stronger let's say at the same time the bones are getting you know bashed every in every step so uh at some point one of them has to give up so and yeah you don't want that to happen yeah yeah you don't want that to happen but here here's kind of what i'm getting at right and i think

this this gets really practical is you can you can choose to overload in a lot of different ways and with downhill running the two fundamental ways that you have is either you can do more descending right so that's just more repetition or you can do the same amount descending faster so that increases the force given those two in what you know what what would you theorize would produce a superior adaptation at the end of the day if you just if you just took your same study and said listen we're just going to have you run faster 30 minutes we're going to have you do more ascending or we're going to have you do an hour at the same speed because once again athletes going out there this is this is how this is how this kind of gets reflected in from a from a practical perspective in people's trainings they either want to run the downhills harder to induce that effect right i'm just going to go as fast as i can or they're going to do more vertical or sometimes both which might be the worst of both worlds as you were mentioning earlier but since we have a limited number of tools to pick from every day what do you think would produce the superior adaptation in this case that's a very difficult question i love stopping you guys by the way it's fun yeah for in terms of thinking how much adaptation it would produce we should think about how much damage that specific bout would would induce in the first place we can think of an equivalent if we're just

thinking about that the reason it's very difficult to answer because i'm also thinking about something else that i'll explain later but if we're just thinking about the adaptation itself and if we're considering the damage being the start of that adaptation we can think about two different equivalent bouts that would produce the same amount of damage we can think about like a say i don't know like it's a thousand meter elevation loss at in 30 minutes that would be one way to look at it or we can think about the same like smaller elevation loss like 500 meter but this time instead of going for 30 minutes this uh this uh this 500 meter you want to go with in 15 minutes almost impossible but uh in terms of speed or if we're thinking about like a pipe here on um but let's just go with the extreme and it then it would be close to that one or another thing another study from 2000 or 2001 uh from dr roger stone if i'm not mistaken um that they looked at the how they can change the stride length so when you're changing the stride lanes you're basically incurring more force into the muscle and you're incurring more damage

so you can think about the same thing or like a little bit less or more changing one variable like stride lines and then you will have uh the same amount of damage but at the at the end of the day i think we should always think about another aspect of tissues in general and the fact that they fatigue and they if you're trying to be away from injury i guess i'd say they get they get fatigued and there's always an exponential component to it like it it looks like this function so you want to you want to say that in low load possibly even if the repetitions are too too high so the safer way i and that's just a guess and don't don't quote me on that but that's a guess i would say that the um safer way to do would be to uh have a longer or or more elevation at slower speed i think that's a that's a reasonable way to come about that answer because once again you don't know you don't know what's going to produce the superior adaptation and we do when you don't know you have to move down the decision making tree and go to what's what's likely to be the least problematic and what's likely to be the least problematic as you mentioned is the low force you know the low force low torque option of the two

which is more descending at a slower speed simply because you you run less of a risk of getting injured in that situation and injury would trump any other intervention right that you could kind of throw at it you miss training time that's gonna that's gonna affect things more than any any contrived uh intervention that we can that we can kind of come up with but i think that's a reasonable that's a very reasonable look at it yes and on the other hand if you think about uh specifically downhill running i said you were in that downhill running seminar as well with the webinar um and marlene talked about this another aspect of downhill running and the fact that they can speed up some people can speed up and some people can't and i think it also has some sort of uh training effect on on it but that is so like running with faster speed in downhill a training in faster speed might be beneficial in that case but again the question would be do you want to risk the injury yeah whenever i've looked at preparing athletes specifically for downhill i've always created two very distinct components the physiology as you were kind of going over and that we have to completely shift our paradigm on thinking about how to train for this um as as compared to normal endurance

events which is a very chronic type of adaptation it's the best way to put it we have to completely shift that around when we're talking about specifically for for downhill that's the first part is the physiology and the second part of is just the skill it becomes a very skillful sport especially in very technical types of terrain but even in non-technical terrain because of the speed component and the visual eye foot coordination that's needed to to cover those distances at those at those speeds i do think that those are both those are both very distinctly trainable parameters that we have to look at this condition of trail running very specifically at because it's not your prototypical the best vo2 max and the best you know power at lactate threshold types of wind scenario there's more things at play yes they're there in terms of trail running it would be much more there are many confounding factors that we we didn't consider in our uh in our study we tried to uh just to isolate a specific effect but yeah that as like you can have a someone who has a very good vo2 max and have them run up hills they would be okay yeah but at the same time if you ask them to run downhill they it depends on on many many other factors and very interesting in my study specifically looking at athletes individually

i had an athlete with estimated vo2 max of close to 70 milliliter quite very good yeah very good athlete yeah quite good athlete and that athlete never ran downhill and that the speed in my study was 2.8 meters per cent 10 kilometers per hour not very fast basically yeah basically like for someone like with 70 milliliter oxygen vo2 max that would be absolutely nothing to run that uh that speed but interestingly he was the one with the highest muscle damage between my athletes i had athletes who could barely run 10 kilometers per hour so we we wanted untrained people right so could barely run that speed level but downhill would be uh simpler and he didn't get much of a much much of a damage so there are other and many important factors in terms of downhill running that needs to be uh focused on yep specificity the more and more i look at this it's just we can divide trail running into several different sports uphill running uphill walking downhill running downhill walking level walking like all those things and use a biomechanistic thing can really appreciate how different those are how different they are in terms of how you're actually locomoting and coordinating all the limbs and what that looks like what that looks like systematically the more and more i come back to it it's they they they're just separate sports that we have to

train for that are all linked by the cardiopulmonary system yes so what do you want to know now we just went through all this you had a really cool study design you've done some follow-up work with it like what is tickling your curiosity that you want to figure out next that the audience might be interested in well the next thing that we were interested and we're hoping to get it published soon specifically for this downhill running was that so we ran for half an hour and this athlete got quite damaged right and good athlete you're good 70 mils of vo2 max athlete got really damaged yeah they got they got really uh damaged after this run and then now we know that the biomechanics completely changed and as a biomechanics for me it's a specifically i was interested to know is this change gonna affect what is called like we call it stress fracture risk is this gonna affect the fracture risk or not and is it something important to even look for or look at it and that that's the next question that we are trying to answer right now interesting and it is quite has to do with uh calculating the muscles of the forces and uh how they are interact in the body and how the um bone looks like the shape of the

bone and so on and then calculate how much uh how much the bone is going to be deformed basically right because they're stressing their bone in a way that it's not used to because the muscles can't or the the musculature can't handle it kind of yes so that would be the next uh question to tackle and i hope that that also has some uh practical applications uh thinking that trail runners might also be interested in knowing the risk of their injury well i look forward to seeing that come out because quite frankly we're pretty terrible at preventing injury as a whole and i put myself as a coach in that you know in that terrible category the athletes the physical therapists everybody who's working in this that you know has skin in the game if they're being honest with themselves we're we're not very good at preventing injury so any research that we can bring to the surface and bring to the forefront that could potentially enlighten us on how those injuries can come about and how we can prevent them as all is always quite valuable yes uh 40 years 50 years of research in trying to work on the injury prevention as has led us to some point but i i guess we still need to know way more and at the same time you uh like the athletes are usually uh kind of take their

themselves themselves to the limit that's true and that that always is challenging and going back to like we talked about an average scenario and now we're talking about the limits and so on so it's i think the argument the uh conversation is going to be back and forth and uh getting better training and then uh at the same time trying to prevent injuries of course i really appreciate you coming on the podcast this is really enlightening for me i look forward to seeing what other future research uh kind of comes out but i can't thank you enough for the research that you've done because it helps me as a coach out and it helps all the athletes that i was conversing with at the hard rock 100 this pack this past weekend it helps them out because at least we have some context to wrap the training around of what we're going to do otherwise we're just guessing so to at least have some context is quite appreciated and um where can the listeners find out a little bit more about the research that you are doing or any of the work that you have in the pipeline these are the research are usually on google scholar so uh i can i can give you a link of the google scholar like specifically for my account and uh yeah that and also uh it's on my uh twitter as well anytime any new research comes i i put it on twitter perfect

i will have links to that in the show notes thank you for coming on the podcast today arash i really appreciate it thank you so much for inviting me it was very fun all right folks there you have it there you go much thanks to arash for coming on the podcast today and explaining a little bit of his research as well as entertaining me in how we can actually extrapolate that research to inform training and best practices for athletes it is always a tricky thing and over the course of my coaching career i have seen any number of ways to try to combat this that have been deployed by athletes and coaches alike and i think one of the things that we can learn from that myriad of different solutions to this is that we don't quite know how to ready athletes for this particular demand quite yet however whenever that is the case i always feel like we can go back to fundamental early stage research in these particular areas and look at the physiology that is elicited for these types of activities and then come up with very practical solutions to try to uh to try to ready athletes for those particular demands it is not as simple as overloading the athlete as much as possible and hoping that that demand or hoping that that load is the right load to impose the particular demand and i think arash's research on the repeat about effect illustrates that quite readily appreciate

the heck out of all you listeners out there if you enjoyed this podcast please feel free to pass it along to your friends your running partners your family your colleagues anybody who might be interested in that means a lot to me personally and helps out the podcast a lot that is it for today folks and as always we will see you out on the trails