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Heat Mitigation Strategies with Julien Périard, PhD #229
Uncover the secrets to excelling in extreme heat with Julian Perriard, a leading expert in environmental physiology. As the Western States Endurance Run approaches, Julian provides cutting-edge strategies for heat mitigation, including ice baths, slurries, and menthol gels. With rising global temperatures impacting athletic performance, we delve into crucial safety measures for endurance athletes. Learn how to maximize your performance while staying safe, regardless of the weather conditions.
Julian also shares his expertise on heat acclimation strategies tailored for athletes. From exercising in environmental chambers to passive methods like hot baths, we explore how to incorporate heat acclimation into your training without compromising performance. Discover the physiological benefits of thJulien Périard is a Research Professor and Deputy Director of the University of Canberra Research Institute for Sport and Exercise (UCRISE), where he also leads the Environmental Physiology Research Laboratory. His integrative research examines the physiological mechanisms that mediate health and performance during exercise in adverse environments (heat and altitude) and the adaptations that stem from chronic exposure. He has worked with both amateur and professional athletes from various disciplines, along with National (Australian Institute of Sport) and International Federations (FIFA, World Athletics and World Triathlon). His work also examines how regular exercise can build resilience against rising global temperatures. He has authored over 125 research papers and book chapters, including a textbook on Heat Stress in Sport and Exercise and an invited review in Physiol Rev (which we will be discussing today!).
EXERCISE UNDER HEAT STRESS:THERMOREGULATION, HYDRATION,PERFORMANCE IMPLICATIONS, AND MITIGATION STRATEGIES
Heat Acclimatization Strategies Podcast- Koopcast 97
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Trail and ultra runners. What is going on? Welcome to another episode of the coop cast. As always, I am your humble host, coach jason coop, and this episode of the podcast is coming to you at a very special time. It is the mond Monday before the famous, the historic Western States Endurance Run, and I can think of no better topic to discuss than how to race in the heat and what interventions we should actually use when we are racing in the heat. Regardless if you are one of the lucky ones that is towing the line for this year's Western States 100, or if you are training for another hot weather race, you are going to want to listen up, because on the podcast today, back for his second appearance is Julian Perriard, who is a research professor and deputy director of the University of Canberra Research Institute for Sport and Exercise, where he is also the lead of their environmental physiology research laboratory.
Speaker 1:Julian comes back on the podcast today to discuss very specifically how and what interventions do we actually use when there is a hot weather environment in front of us, which ones of these work, which one of these don't work so well, and how do they actually work differently? Julian is one of the foremost experts in this type. On this particular subject, he's worked with the Australian Institute for Sport, international federations such as FIFA, world athletics and world triathlons. He also examines how regular exercise can be built as a resilience tool against rising global temperatures. He's authored over 125 research papers, book chapters, including a textbook on heat stress in sport and exercise, and the paper that we are going to use as a framework for today's discussion is a free, open access paper, the link to which will be in the show notes. The title of it is Exercise Under Heat Stress, thermoregulation, hydration, performance Implications and Mitigation Strategies. It is a great one. It's a dense one, with over 1,000 cited papers in it, but if you are interested in this topic, go and check that out.
Speaker 1:This podcast pairs very well with the first podcast that I did with Julian, which I will also link up in the show notes, the focus of which was more how to use acclimation and acclimatization strategies in order to prepare for the heat. So if you want the whole shebang, check that podcast out as well as this podcast, which is very specifically focused on what to do when it's hot. Should you take an ice bath? Where should you put ice? Do these menthol gel works? Should you use an ice slurry? Should you cut holes in your shirt? What about these silly little headbands that everybody's wearing? We go through it all and I hope that at the end of the day, everybody has a great toolkit for how to actually race and perform in the heat.
Speaker 1:And with that out of the way, I am getting right out of the way. Here's my conversation all about how to race in the heat with the incomparable Julian Perriard. Thanks for coming back on the podcast. By the way, pleasure pleasure. Yeah, I'm always reminded it's your winter but our summer. So I don't know whether this is like a hot quote, unquote hot topic for you, because all the north american countries are kind of going through the summer. The northern hemisphere countries are starting to go through their summer review.
Speaker 2:It's kind of the opposite that's right, it's cool, so it's not necessarily a hot topic. But given it's an olympic year and the olympics are starting very soon, it's definitely a hot topic.
Speaker 1:Obviously, pun intended and the endurance events at the olympics, not to deviate too far from far from what we're going to talk about. It has the potential to actually be kind of warm there. I mean it's July, it's in Paris, it's in the middle of the city. Those are challenging environments for sure.
Speaker 2:Oh, absolutely yeah. Yeah, and, as you probably know as well, Europe kind of typically gets one heat wave per year as well. So those heat waves now are getting more frequent, more severe, more intense, a bit longer. So you know, God forbid that there's a heat wave during the Olympics. But yeah, Paris could be hot. It's always a chance. It's July, middle of summer, so it will be hot. But just how hot it will be is, I guess, the question there?
Speaker 1:Yeah, exactly, and ironically enough, I got a chance to actually run the Paris marathon course when I was out there earlier in the year, and it's hard, it's a hard marathon course. So I think you combine, like the invite, the potential environment with a really hard course and then it creates a really dynamic racing environment yeah, absolutely, especially if it's hard.
Speaker 2:You know the athletes are producing a lot of heat. It's harder they get hot. The environment is less conducive to losing heat.
Speaker 1:Yeah well, yeah, so it'll be interesting we'll see, we'll see there's some time for that to materialize. But so we're gonna talk about, we're gonna talk about ultra, yeah Well, yeah, so it'd be interesting. It's going to be a relatively hot year. It'll be probably in the low 90s. That will continue to shake out between when we record this and when we actually post it, but there aren't going to be a lot of freebies, as there have been in the past, where the temperatures are actually quite a little bit cooler. So we're going to talk about heat mitigation strategies, kind of. In that context, in a prototypical ultramarathon context, what can athletes do during the race itself? What interventions can they undertake to make sure that, first off, they're safe but second off, they can maximize performance? Because in a lot of these ultramarathons you do have to take it from a safety first perspective because the conditions can be so arduous and you're out there for so long. Right, it's not surely performance that we're talking about?
Speaker 2:That's right. Yeah, yes, I mean, you have to survive the course first of all, and if it's hot then it makes it even worse. So, yeah, definitely you have to be prepared, and I think one of the things as well, they come down to the race organizers. So how well prepared the race organizers are to provide the resources to the athletes throughout the course and at what interval, and so forth.
Speaker 1:Interesting. You mentioned that I had this great conversation with the race director, craig Thornley, before the last hot year, which I believe was 2001, not 2000, sorry, 2021. And he had just ordered this was the Thursday or Wednesday before the race another grip of ice. And we did the rough calculations there and it turned out that he was, or that on average he was, ordering over 40 pounds of ice per athlete to disperse throughout all the aid stations. So I mean, they take it seriously and they do. You know, I think that's a really great example where the race directors are trying to take care of the health and safety of the athletes. They're not thinking about it from the necessarily, from the perspective of all we want to make sure that the course record is broken or anything like that. They're literally trying to keep people safe and part of the part of the strategy that they're deploying to try to keep people safe is just to have as much ice out on the course as possible.
Speaker 2:That's right, yeah, and it's an interesting one as well, because I mean logistically just ordering all the ice and you need to produce that ice, you need to move it, you need to, you know, to put it all through the course. So if you parallel that with the olympics, for example, where you have multiple events going on over several days, like can you imagine logistically the amount of ice they need to produce different locations? So yeah, but in terms of yeah, it's what which also demonstrates the importance of ice itself as a medium to kind of cool people down throughout different events even.
Speaker 1:Well, we're going to talk about ice and a lot of different strategies. We're going to talk about ingesting ice. We're going to talk about carrying ice on your body where you should use it and things like that. But I would be remiss to bring you on the podcast and not discuss something that's kind of like more powerful in all of this, and I hate to talk about this so close to, or have this podcast be released so close to the race, but we still have to mention it. Right? We're going to talk about a lot of things that people can do during the race itself in the toolbox, the bigger hammer that you should be using to get prepared for a hot weather race, or acclimatization and acclimation types of strategies, and I want you to paint the picture of the magnitude of how important those are in the whole thing before we start to get to the specific race stuff.
Speaker 2:Yeah, sure, and you're right, I think acclimation and acclimatization are probably the most important things to do. So just a quick definition, I guess. So acclimatization is are probably the most important things to do. So just a quick definition, I guess so. Acclimatization is adapting to the environment, to the outdoor environment. So athletes that train on a regular basis in hot environments or throughout summer. So if you have a cold winter and then get into spring, you acclimatize to summer as you train throughout summer, whereas acclimation is more artificial. So you go into a heat chamber, if you have access to a heat chamber, or you jump into a hot bath after you're running outside in cool conditions. So it's more artificial. But what both of them do is induce adaptations that are a bit more specific, I guess, or I guess they're adaptations that improve physiological function. So if we think of heat acclimation relative to heat mitigation strategies like cooling or hydration, those are more acute. They're in the moment, they're in the race and if it's available for you you can use it, you can cool down or you can drink, whereas heat acclimation kind of helps you adapt to that hot environment. So it helps your stomach regulate better, so you start sweating at an earlier core temperature. Your core temperature is lower to start with, you might sweat more. If you reach your maximum sweat rate, your sweating sensitivity is improved. So for a given core temperature you might sweat a bit more.
Speaker 2:So obviously sweating is important, especially in hot conditions. Well, primarily in hot conditions, because if the conditions, so if the ambient air, for example, is hotter than our skin temperature, then the only avenue by which we lose heat is by sweating. Because the two main mechanisms are sweating and convection. So if it's, if your skin temperature in celsius is 35 degrees and it's 30 degrees outside, then you have a negative gradient so you can lose heat by convection, with that's the air going through over the body and kind of removing some of the heat. But the opposite is true. You can gain heat by air movement if air temperature is hotter. So at that point, once again, sweating becomes very important. But regardless, sweating is always the primary mechanism.
Speaker 2:So with heat acclimation it improves. That improves your blood volume and your plasma volume, so you're you can sweat more, improves your cardiovascular stability, so you can maintain your heart rate at a lower rate for longer in the heat. Because when we exercise in the heat obviously we send blood to the periphery, to the skin, to lose heat. We also need to keep sending blood, obviously to the muscles, because they need oxygen to kind of keep turning over. So there's that competition, so to speak, for blood flow.
Speaker 2:So with heat acclimation you get those physiological adaptations to be able to maintain, I guess, your cardiovascular stability, heart rate a bit lower by doing that as well. Your perception of effort is a bit lower. If your core and skin temperature are lower, your thermal perception, so your perception of the environment is better. So it's obviously those perceptual adaptations, those physiological adaptations that are induced with heat acclimation. So if you do that and then you go into a hot race, then you're obviously a step ahead of the competition. Then if you can use those other mitigation strategies so maintain proper hydration, obviously, eating well, and then endurance races, obviously very important, but also potentially pre and cooling during If you can combine all those things then you're in an ideal scenario.
Speaker 1:I'm really glad that you just mentioned the all of the above piece because, not to belabor the point too much, on the acclimatization and acclimation strategies, but there is a menu of things that athletes can choose from.
Speaker 1:There's passive strategies, there are active strategies, there are combinations of both the passive and the active strategies, and coaches and athletes and physiologists have always kind of gone back and forth to what is quote, unquote, the best, you know the best way to do it, and there really is no one single best one.
Speaker 1:It's all very situational, depending upon what the athlete is actually going to experience.
Speaker 1:One thing that I always come away with all of this is that I want to kind of like finally finally touch on, before we go to the all the during interventions that we're going to talk about, is that, irrespective of how you are actually trying to acclimate the athlete to a hot environment, it's not your prototypical endurance adaptation where it takes weeks and months and sometimes years to reap a benefit. We have this kind of like locked in our heads as endurance athletes, specifically not team sports athletes, but endurance athletes. It takes months and months and months to create an adaptation from a physiological perspective. Most of the things that are happening when we put athletes in these hot weather environments actually happen on the order of several or maybe a dozen or 20 or so days, and that tends to trip up a lot of athletes when they're actually trying to trying to prepare for this. And I was wondering if you had any kind of like commentary around that that you could throw into the mix here oh, absolutely, and that's a great point.
Speaker 2:And I think there's two things there. The one is the, I guess, the different approaches that you could use to heat acclimate, and then the time frame that you acclimate. Based on what you know, laboratory settings are deemed as being the optimal way. So first of all, there's different ways, and you're absolutely right. So, like it's, the two classical ways are kind of you jump into on a bike or on a treadmill in the lab and you do the constant work rate or constant speed approach. So I say, okay, I do vo2 max test and I find out my VO2 max is whatever and then, at relative speed of that 65% of my VO2 max, let's say 12K an hour I jump on a treadmill and I run at 12K an hour for 60, 90 minutes per day and I do that for 10 to 14 days. So that's the recommendation. So, if you do something, 60, 90 minutes a day, 10 to 14 days in hot conditions Again, I keep referring to Celsius, but roughly 40 degrees and 40% humidity. So just over a hundred degrees, that's hot, 40% humidity.
Speaker 1:Yeah, it's hot, it's really hot.
Speaker 2:Yeah, yeah, yeah. But that's the point, right, you want to induce adaptations, so you want to sweat a lot, you want to increase your skin blood flow and you want to increase your heart rate and your core temperature and your skin temperature. So if you induce kind of those responses, then you will adapt and you want to get to that point and then maintain it. So that's one approach, so exercising at a constant speed. The other one is a self-paced approach. You could do the same thing again, thinking of an environmental chamber, for example. You jump on there and you just do intervals or you just run how you feel. Another one is just passive, right, if you don't have access to an environmental chamber, you can just jump into a hot bath. That's completely passive, so you don't even have to exercise. If you jump into a hot bath again, 40 degrees, 42 degrees, just over 100 degrees Fahrenheit, and you want to I'm not exactly sure of the conversion, but given that our core temperature, again in Celsius, is around at rest, you know, 37 degrees you don't want your bath to be just slightly above that. You don't want 37 or 38 or 39. You want to go 40, 41 if you can tolerate it for a good 40 minutes or so to increase again your core temp, to sweat and so forth. So that's the passive approach. But the other one is if you don't have access to an environmental chamber and it's cool where you are you can just do your run outside. You're still going to sweat, you'll increase your core temperature a little bit, but then when you come home you jump into a hot bath again 20, 30 minutes, same kind of temperature, and that'll induce some adaptations. Another one is by controlling your core temperature, which is a bit more logistically challenging because you need a way of measuring your core temperature and typically it's increasing that to 38.5, again degrees Celsius and then you maintain that for about an hour. And then one that's similar and less logistically challenging is by a heart rate. So if you go into a hot room and you start running, obviously you have to get to the heart rate you want to achieve. But then you just maintain that heart rate and you'll find, let's say, you do 10 days of acclimation at a controlled heart rate. You'll find that you'll have to lower your heart rate in your first session quite a bit. So you'll have to lower your running speed to maintain a given heart rate when you're running in the heat. But then in the last session, you'll find that, for the same heart rate, you'll find that for the same heart rate, you lower your heart, your speed, much later on in the session and much, much less. So that's the adaptation. So you'll get the same heart rate, actually the same core temperature, but you'll be running at a higher speed, which will be associated also with probably a higher sweat rate, so you're losing more heat. So there's all those different adaptations.
Speaker 2:And to come back to what's optimal, well, really what's optimal is what you can do, right, what you have available to you logistically, financially, in terms of where you are, in terms of environment, and that's what we try to do with elite athletes. Because elite athletes, let's say in the lab, again I would say, while 14 days in the lab, 90 minutes a day, cycling or running at 65% of your vo2 max or whatever the intervention is, obviously athletes have quite significant not significant, but quite regimented training programs, right? So if I'm going to tell an athlete, finish your 14 day acclimations, three days out of your or four days out of your race, they're going to be like, well, I don't think so. Yeah, I've got specific training planned. So for the ultra distance athletes, athletes, as well as for Olympic and high level athletes well, again, the training is very regimented.
Speaker 2:So I would recommend and we've published a little bit on this kind of adapting that and doing basically your best to integrate heat into your training program, because one of the things you need to remember as well is like yes, heat acclimation is probably the most important intervention you can do, but if that messes up your training, you don't get the training right, then there's no point of acclimating. I could be the most acclimated person in the world, but if I'm not running well, what's the point? Right, I'm not going to complete 100 miles if I'm running 20K a week, but I'm super acclimated, right. So get the training right and then try to incorporate that as best you can. So you right, and then try to incorporate that as best you can.
Speaker 2:So you can even go out three months before or two months before. You can start doing one or two heat sessions a day and then maybe, in a period where you know you have less of a focus on intensity, you can do a few more sessions in the heat, so you can kind of build it up and not do those 14 days in a row but do two or three a week and then have a set, have a week where you do a few more and do some top-ups. So kind of putting it here and there where it fits and then using the approach that fits your circumstances. I guess is the recommendation I would provide to athletes, especially if they don't have access to the university lab or something like that.
Speaker 1:Yeah, your point about access is actually really well taken, and then also the point about trying not to mess it up right in advance of an event because you are trying to be relatively regimented. I'm going to link up in the show notes a couple of articles that I've written on this in terms of describing how we actually do this very practically with athletes. And it kind of boils down to two phase protocol, where we do one phase, as you were mentioning, a few months or several weeks out from the event, and then we do the final phase a little bit closer and maybe it's a little bit less intense because you're trying to balance all of the recovery and stuff like that. But it brings in all of these practical elements into the kind of what we know about research. So we won't belabor the point there. I'll leave a like I said I'll leave some resources there, okay, so it's going to be hot for Western States.
Speaker 1:One of the things I initially want to point out here is that we know a lot about about cooling strategies during endurance events. But our primary, the primary reason that we that we know a lot about this goes back to what we're talking about earlier. It's the Olympic cycle. So whenever there's a hot you, a hot Olympics whether it's Rio or the Atlanta Olympics or things like that everybody gets super interested in this and all the teams and the national governing bodies start to pour a lot of resources into it. And research emerges in heat mitigation strategies that are intended for Olympic duration events and heat mitigation strategies that you might use from an ultra distance perspective. These Olympic events are, you know, a couple hours long traditional marathon or maybe even a sprint triathlon or something like that. But then when you get into races that are 15, 16, 18, 20 hours long, or even the bad water ultraathon or something like that, where you're constantly exposed to a hot weather environment, the strategies you use might actually change, and the strategies that you see deployed in a 40 kilometer time trial or something like that actually can have the potential to backfire.
Speaker 1:And the thing that I initially want to start to point out with this is something that you mentioned earlier is there are two types of, there are two types of things that you're basically working on.
Speaker 1:Right, you're working on your perception of the thermal strain. Right, your thermal comfort, and there are strategies that you can use to improve that. And then you are actually working on physiologically controlling your core temperature, that, and then you are actually working on physiologically controlling your core temperature using things to just make sure that your body is, like, literally not overheating. And there are overlaps between strategies that can kind of do both, or maybe they do a little bit more, a little bit one or the other, but there are definitely strategies that only kind of do one or only do another one. And so, before we kind of jump into all of them, I just wanted to get your perspective on that, on this kind of like bifurcation of strategies between things that are intended or mainly work through our perception of the heat and then things that are truly focused on controlling core temperature, and what are the pluses and minuses of both of those?
Speaker 2:Yeah, that's a good point and that's exactly right as well. I mean, you know, if you jump into a cold bath, well, that'll do both. Right, you'll definitely get much cooler and you'll definitely feel a lot cooler, right, and one of the things that we've talked about as well before is menthol. Whereas menthol does not cool you down, it gives you the perception of feeling cool. So there's two very distinct and different things. There are different physiological responses happening. One, there's nothing physiological that's happening other than, obviously, neurons firing in the skin or, if you're swallowing menthol, telling you that you feel cool but you're not cooling down whatsoever. Whereas this, if you use eye slurry ingestion or things like that, or even again, cold water immersion, then you will get that physiological response. So it's probably, as you mentioned, kind of finding a way that, if you have access to several of these things, how you can use them in combination to get the, I guess, the ideal or the optimal benefit from those things at different points in the race.
Speaker 2:And I think you highlight a very good point about an ultra distance race which lasts a lot longer than any event in the Olympics, even the 50K race walk, for example, where actually they're quite good. Actually, the race walkers at using strategies, because oftentimes it's a small loop and they can come back and get a slushie or get something to cool themselves down, but, yes, using it in different points in the race. And another thing we talked about just offline before we started is about those ultra distance races and Western States. You know you start off in the morning, it's a bit cooler, so you know, do you really need a cooling strategy there and then? But yeah, throughout the race, if you get a bit lower altitude afterwards, then maybe you start needing a bit of cooling strategies, which also help, depending on which one you use can help with hydration, which is factor as well.
Speaker 1:Right, well, and I think some of the something that the listeners are probably thinking and I'm thinking this as well is that with some of the strategies like we'll just take menthol as an example not to pick on it, but it's a fairly well studied strategy now and, as you mentioned, what you're doing is you're essentially tricking your body into thinking that it's cooler. Let's just call spade a spade right, it's not actually cooler.
Speaker 1:You're just tricking your body into thinking that it's cooler and that can be really effective in like a 40K time trial right, Because it's a finite amount of time. You can run the engine really hot. You can get to a super high core temperature for a very short period of time, but that is limiting. Some people are thinking. In my question specifically, is there a risk of using those types of strategies in a longer distance event because you are going to potentially override this mechanism that you should have in place of overheating? Is that a real risk that people need to start to think about when they're designing their strategies?
Speaker 2:That's a good point, and I think you see that quite often in the literature. But I then there may be some literature, but I've never seen anything that suggests that if you put menthol on and you feel cooler, that you're going to have a dramatic increase in core temperature. Because one of the things we need to remember as well is that even that menthol doesn't actually do anything physiologically, there are some physiological limits to performance, right? So if you're doing a time trial and you're on the limit and you put menthol on, you might feel cooler and you might increase your work rate a little bit, but if you're on that limit, you're not going to increase it for very long, right? Or else your heart rate is going to start going through the roof and at some point you're going to have to slow down. So there's that. And then the other one is how long those effects last. So if you do have, if you take menthol, either you put on your skin, you have it as a gel or whatever the case may be, and you feel cooler and you do have that little surge in running speed or power output on the bike again, how long does it last? And then do you have to compensate for that afterwards. You know, if you're on the, if you're redlining and you kind of go in a bit I mean, obviously you would be redlining an ultra distance race, but in like a 40k time trial, for the example he provided if you're running, go a bit too fast, then you might have to compensate and go a bit slower, then kind of catch back up, and how long does that effect last? So there's all those things I think that still need to kind of be investigated, and the thing with many or most cooling strategies, as well as the length of the effect.
Speaker 2:Right, and we did a meta-analysis just recently and I can send you a link if you're interested and we looked at there's two types of exercise you can do in the lab, right, like the constant load stuff and the self-paced stuff. So I say, okay, exercise at a constant work rate, so run for 15 at 15k an hour and then we'll see what your react, what your responses are. Or I say, complete a 30k ton trial or a 15k ton trial running. Then we see that there's more of an effect on the constant load trials than the self-paced trials, primarily, well, because of two reasons. One, they're mostly shorter. So the shorter the event, the more the effect, right.
Speaker 2:So if you're cooler, given that you know we're going to run or cycle for 30 minutes, then that effect obviously will be more powerful. But if you're doing 60, 90 minutes, then obviously that effect relative to the distance is not as important. There's also probably the effect of work rate. So if I say, go at a constant speed, well, your work rate is fixed, your heat production is fixed. But if I say, do a time trial, you're probably going to start at a much higher work rate and then you'll decrease. But given that you're producing a lot of heat from the beginning, then that effect of the cooling allows that. But then you also heat up more quickly. So there's all those kind of caveats.
Speaker 2:So if you're doing like a 12-hour race, well, obviously it doesn't really matter if the first 30 minutes you feel a bit cooler because you still have to go quite longer. So that's where I guess the point comes in about using those different strategies throughout the race, if it does get a bit hotter. So in terms of to come back to circle back to your point about health and safety there may be that effect of and it's been highlighted that, yes, if you feel cooler you might push harder and get more hyperthermic, but I've never seen evidence of that. Because I just think that the response is so transient and, if anything, your physiological responses will be like actually, well time, well time out, you're going to do quick here. You can't hold that pace, let's slow down, kind of thing.
Speaker 1:Yeah, it's interesting because I recognize the transient nature of the very quick, you know nature of those types of interventions. I just think about it almost from a performance standpoint where if you have all of these like inputs that are lasting for a short period of time, usually the disruption in that steady state activity that you're having, those small disruptions, end up being a net negative to this constant what. What ends up? Even though it's a self-paced activity, it's a pretty constant workload because you can only go so hard for these long periods of time, and that's what you want as well.
Speaker 2:Right when you're, you want to maintain it steady, yeah.
Speaker 1:Yeah, and so sometimes I think that these very specific, uh, narrowly focused, transient types of interventions end up doing athletes a disservice because they cause this undulation and output. That's an I think statement that we just raised my hand there, but it makes sense to me when I'm trying to piece all of this together from a practical standpoint. Trying to advise athletes on what to do is I'll always default to what creates the more consistent, stable situation. What are the interventions that keep homeostasis in place as much as possible, versus causing, you know, rapid disruptions unless you need the rapid disruption, and we might talk about that almost from an abortive standpoint right, yeah, if you see the finish line and you're not doing well, pop some menthol and you can sprint.
Speaker 2:There you go.
Speaker 1:There you go, different scenario, okay. So let's start out with some of the nutrition ones. So the things that you can ingest right versus put on you. We already talked about menthol ingesting. Either a cold beverage or and or. You can do both.
Speaker 1:It's not none of none of it, it's not, they're not mutually exclusive and an ice slurry beverage, and it's been really interesting to me, and I'm sure more interesting to you, to see how this is actually like played out in the theater of sport, in terms of how, how much these different interventions have actually been used, of how much these different interventions have actually been used.
Speaker 1:And at Western States we'll see the range. We will see people that go to the gas station that's right around the corner from the course and grab a slushy right, grab a high fructose corn syrup Slurpee from the gas station and bring it out to their runners. And then we will see deliberately designed, commercially available sports nutrition products that are intended to be consumed in a type of slushy format. You'll see that whole range of sophistication, for lack of a better word, and so I was wondering. So, out of these cold drinks and then ice slurry types of beverages, let's set the table a little bit on how they can actually work and then which ones might be a better choice for athletes in this type of race.
Speaker 2:Yeah, well, I guess both are from a certain perspective, or both are pretty useful because one they have the potential to to cool you down, I guess, depending on the the temperature of the beverage, or at least cool you down or potentially attenuate the rise or record temperature and maintain it there. So some of them might not cool you down if it's not too cold. And the flip side of that is it provides hydration, right, and it's a medium to stay hydrated and potentially have some electrolytes in there if you have sodium, for example, or even glucose and carbohydrates if you need them. So it's kind of a good bang for buck if it can cool you down, provide you some nutrition at the same time. But there's different, I guess, potential for cooling or different cooling power between, obviously ingesting cold water and ingesting a slurry. So cold water would be something to the effect of 10 degrees to 24 degrees, whereas a slurry is zero degrees, right, so it's cool. So the effect of the slurry is a lot more potent in terms of cooling you down or attenuating your rise in core temperature, because you have to convert, you're not just heating up fluid or water, but you have to convert ice into water and then you're kind of heating that up. So I guess the conversion of ice to water is three times more powerful in terms of cooling than just warming up water. So that's why those slurries are much more effective at kind of cooling you down.
Speaker 2:And there's different ways of using that. You can use it in terms of pre-cooling and then you can use it in terms of per cooling or mid cooling or cooling during a race. So you can use that. And again, we use cooling in terms of a description of it but doesn't necessarily cool you down right. If you're gonna go, if you're doing a race and you take a slurry, you'd have to ingest quite a bit for it to kind of cool you down. But what it might do is it might maintain your core temperature stable or prevent it from rising.
Speaker 2:We've done an intervention before where we used it for pre-cooling. So we used I can't remember how much ice we provided. It was like 8 to 12 grams per kilogram of body mass and you ingested that within half an hour. 12 grams per kilogram of body mass and you ingested that within half an hour. So let's say you're 60, 60 kilos, um, and it's 10. So you'd have to ingest 600 grams of ice in 30 minutes and we were like rotating cold towels on the shoulders and the legs for half an hour and it's not super fun, right, because I mean yeah and then they have that on it and it cooled core temp by 0.2 or 0.3, which is not a ton.
Speaker 2:It's not a big yes, it's not a big decrease. But then if you go out afterwards and you do your warm-up, well then you're back to your normal core temp. You might be a bit lower than you would be normally if you had done a normal warm-up, but it's not a massive reduction in core temperature. But still, if it makes you feel a bit cooler and your event is shorter and you have to produce a lot of heat or produce a lot of speed at the beginning, well then that might be helpful. But there's definitely two ways or two kind of pathways of doing that before, during or together. Really.
Speaker 1:Some people have heard that the ice slurry solution interferes with your sweat mechanism, somehow blunts your sweat response somehow, and I wanted you to enlighten the audience of, first off, the context of that, like the research context of that, because you know, you know that very well but then also bring it into a practical perspective where an athlete is actually competing in a real event, outside a lab. Is that you know where I'm going with this, and is that something that we need a material.
Speaker 1:This is something that we need to materially take into consideration that's right.
Speaker 2:So we have. We have receptors, obviously, in our mouth and in our guts, in our gut, I guess. So if you drink really cold beverages, it's the same thing as those as the, to a certain degree as the menthol, right. So the menthol triggers those cold receptors, as does cold fluid or ice slurry. So when you ingest that, one particular study showed that, yes, it can kind of cool you down or at least attenuate the rise in core temperature. But in hot and dry conditions it kind of lowered sweat rate to a certain degree or sweat output, so attenuated, I guess, evaporative heat loss to a certain degree.
Speaker 2:But I guess what you to come back to your point about practicality what you have to balance then is how transient that reduction or that small reduction in sweat rate might be relative to the benefit of attenuating your rise in core temperature and also consuming fluids again.
Speaker 2:So, to come back to my point before, you're still consuming fluids to a certain degree, but that will hydrate you. So it's kind of balancing that out, because one important side note as well is with dehydration, severe dehydration. So if you lose, you know, in excess of five, six, seven percent of your body mass, that will have a significant impact on your ability to sweat. So you're conserving a bit more fluid, you're sweating less in blood flow is less. So the more you dehydrate, the more you can compound or exacerbate the environmental conditions in terms of increasing your core temperature, because you're sweating less. So again, you kind of have to balance those things out. So if you're consuming a lot of slurries, yeah, it might affect your sweat, your sweating, but it could also, you know, cool you down. So you have to balance those.
Speaker 1:I guess that relationship Well then, the other thing I was thinking about from a practical standpoint and this is very specific to this race, but I don't think it's indifferent from a lot of other endurance activities the sweat that you are actually producing is not the only liquid on your skin that you can use to cool you down. You can also use water from aid stations and water from your hydration pack and things like that. So this potential negative even if we try to take it to the nth degree of how impactful that reduction in sweat rate actually is I kind of come back to the practical aspect of it is does it really actually make a difference because you've got all this other water on your body from other places?
Speaker 2:that's exactly right that's a very good point as well. So, and I guess, just to go back to sweating, like those beads of sweat or those beads of water that are on your skin, they obviously need to evaporate from the skin to cool you down. So they cool the skin and then obviously the blood in your skin kind of goes back to the central circulation and cools you down or at least again attenuates the rise in core temp. But you're right, if it's really dry, if it's very humid, we'll be probably saturated with sweat anyway. So a lot of it will be dripping so we'll get dehydrated.
Speaker 2:But in hot, dry conditions you might find that you might think I'm not sweating. What's going on? That's just because the sweat's evaporated very readily and very well. So you're absolutely right. In those cases you can dump some water on your head, on your skin and so forth. And those beads of water, if they evaporate, that's the same thing as sweat. Essentially they will cool you down. So you're right to put it in the context of that ice slurry situation. If you have a transient reduction in evaporative heat loss capacity because you're sweating less and you're producing less beads, well then if it's dry, just putting water on your skin, then you kind of compensate for it that way dry, just putting water on your skin. Then you kind of compensate for it that way there might be a reduction in skin blood flow, but as long as skin temperature is still elevated, uh, you will evaporate those beads of sweat.
Speaker 1:So menthol ice slurries for everybody. That's what we should be serving at aid stations these out.
Speaker 2:Of it is that.
Speaker 1:What is that what you're saying? Is that what we're going to endorse?
Speaker 2:yeah, well, the other thing too is obviously and I'm sure you know, any listeners know, that you wouldn't try something for?
Speaker 2:the first time, so we're not recommending someone, just pounds the ice, slowies back next weekend and just smashes the menthol because there could be gut issues. Right, I mean because pounding a lot of slurries back might slow down your digestion you might have too much water than running around, obviously, with too much water. I'm sure many people have experienced that. It's not a pleasant experience. Cycling is not too bad because you don't have that kind of bouncing up and down. So it comes back to being well prepared for the race, having mitigation strategies in place that you've trialed, that you know you can tolerate. Menthol is another one. You know you don't want to pound back a bunch of menthol in and have some gi disruption because then the race is over right well, and to bring it back to a more serious point, that that is something that you actually do see in the ice slurry.
Speaker 1:Research is some sort of commentary around the athletes who, for whatever reason, they just don't tolerate it as well. They get a brain freeze, they get a headache, they get disruptions within their digestive tract, whether it's in their esophagus or in their stomach. I guess it's because of the, maybe the absolute temperature, maybe the difference of temperature between the warm air and what they're actually taking in. It's not something unless you just really unless you just absolutely really need it, that you should be specifically deploying on race day. You should have some degree of familiarity with it that's exactly right.
Speaker 2:Yeah, yeah, just trying it on a long run beforehand. I mean, the ideal scenario obviously is that you try these things in kind of a similar condition for a good length. Obviously not maybe a hundred, a hundred miles, but you know something similar. So, because you know the way that your gut responds six, seven, eight hours into a race might be different than the first two, three hours. So if ideally you can experience that something as well that people might want to try, Okay.
Speaker 1:So we went through the ice slurry thing, the ice slurry gate, ice slurry debate. We went through menthol a little bit. Let's talk about things that people can put on their body Ice water, ice packs. There's all different types of commercial like delivery systems and before we get into them, like specifically, just an overview of what they're trying to accomplish. I mean, it seems like, yeah, it's trying to make you cooler. Right, we're trying to improve, like either evaporative cooling or we're bringing something cold onto the surface of the skin to, to, to give a bigger temperature gradient to work with. But can you just describe generally what all of these things are trying to do to keep people cool?
Speaker 2:Yeah, well, that's exactly right. I mean, it's just, the idealistic is to keep people cool other than mental, which again is the sensation. But the idea there is, depending on the cooling power of the medium that you're using, you want to either lower core temperature, lower skin temperature. You don't really want to lower muscle temperature, which is, I guess, the caveat with ice baths. If you stay in there too much, then you lower muscle temperature and it might not be at the ideal temperature for performance. I guess from an ultra distance perspective it doesn't matter too much because you're not going to start off sprinting. So that's, I guess, the caveat with that. But that's the idea. So either you cool internally or you cool externally. So if you put something on your skin, what you're trying to do there, I think it's cool, cool the skin. And by cooling the skin you're going to bring that cooler blood back to the central circulation, which again might lower your core temperature or prevent it from increasing too quickly. But I guess the important thing with a lot of these is the surface area that you're actually cooling. So you want a large surface area, you want a cooling power that's strong and you want to apply it for a certain amount of time.
Speaker 2:You know a lot of the things that you can apply other than water, that you can apply on your skin. You want them on there for a good 20 minutes and, as you mentioned, you could have ice vests. You could have face change material. So if you could have something that kind of goes on your skin like a vest, that kind of wicks sweat even more or, based on it, if you put it in cold air and cold in a cooler, for example, you put it on, like the time it changes its phases, kind of keeps you cool, that's probably a bit more quicker and less potent. An ice vest, which obviously, if you put directly on your skin then might last longer as well.
Speaker 2:With those things as well, you have to be careful with balancing how long you put it on your skin and then at which point it no longer provides a benefit and becomes a barrier for evaporative heat loss, and how heavy it is. Like. If it's something with cold, with ice that melts and then rips down, well, yes, you might be wet, but then you might be less heavy. But if it's just an extra five pounds of ice that cools you initially and then eventually coal turns into water, then you're running around with five extra pounds of water that you're just running around with. That's providing nothing and, with the best, preventing you from cooling down. So it's kind of finding those happy mediums with all of these cooling strategies and again coming back to the surface area cooling power and length that it's applied, I guess, to to the skin, to the body, I guess I want to go into each one of those, but I'm going to start with the cooling power piece, kind of the one in the middle.
Speaker 1:A lot of people are going to think about this in terms of I'm going to, I'm going to rephrase it a little bit and then let you clarify, being the expert here in terms of the temperature gradient, so the temperature difference between the surface of the skin and the thing that you are putting on it, whether it's ice or water or cooling pack or whatever. But what do you mean by cooling power? Is it that plus something else, or is it something more sophisticated?
Speaker 2:well, it's that and the time right. So you might have something that has a big gradient, because obviously the bigger the gradient, the more heat you'll lose to that medium. So this works via conduction, right? So we talked initially about the evaporation of sweat and convection, which is airflow going across your body, but this is conduction, which is the when you things are in contact and heat is transferred across. So if you put something in contact to your skin and your skin is hotter, then you'll lose heat to that medium that you're in contact with. So the greater your skin is hotter, then you'll lose heat to that medium that you're in contact with. So the greater that the gradient between that, the greater potential is for losing heat.
Speaker 2:So I guess the power is both that the difference in temperature, but also the length, right? Because you could have something that has a gradient of five degrees and something that has a gradient of 20 degrees. But if something stays at that five degree gradient and you put it on that skin for 20 minutes, obviously it's going to have more cooling power than something that has a greater gradient, but for two minutes, for example, right? So it's a combination of those two things. So how much of a difference is there between the skin and the medium that you're using and how long you put it on your skin, and not that I want to come back to the other one, but also how much surface area. Surface area you have right. So if I'm cooling down this much area, or my entire back, obviously the back, the entire back's going to provide more cooling power.
Speaker 1:So it's kind of all of them together really okay, so we can talk about surface area now too as well, and and that to most people is, are good. It's going to be fairly self-explanatory the more skin that you can cover, the more heat that you're going to be able to dissipate. But is there, are there targeted areas within our skin that have the potential to dissipate or to transfer more heat, either due to the proximity of blood vessels, or they're just hotter in general? Can you kind of like paint that picture as well, because we do see selectively certain areas of the body that people just preferentially like to cool? You know, I was going over this with one of my athletes earlier today.
Speaker 1:If we're going to remove it from a sport context, just to make it really simple, when you're, when you've got covid and you've got a fever, you put a cold pack on your forehead because it feels really good. Right, it just, it just feels good. The very hot area of your body, it feels really good. But you're not putting it on like you know, your forearm or your bicep or anything like that. You put it on your. You put it on your forehead for a reason and so in you, so, using that as a little bit of logic, are there, within this whole proposition of trying to cover or trying to get as much surface area as possible, are there strategic areas that athletes can kind of look at?
Speaker 2:to apply more of this cooling power to that would result in a bigger advantage well, we can maybe kind of parallel this with people that have exertional heat stroke, right? So you want to cool them down very quickly. So the idea there just a bit of a side note is you know, we want to cool them down very quickly and then transport them to the hospital and ideally you put them in a hot sorry hot bath, not a hot bath, a cold bath and cool them down. If not, if you have ice packs and things like that you're right in what you mentioned initially you might want to put it in areas that are closer, in proximity to arteries and things like that, or highly vascularized areas, so you might put that, you know, under an armpit or in the legs, just in the groin area and things like that, which obviously when you're racing, those areas are not really easy to access, and try and cool down. So people do the back of the neck or the forehead, as you said, but if you think of how much surface area relative to your whole body this provides, or the back of your neck provides, it's not much right. So in terms of cooling power it's little to nothing right. You'll feel better, but it's not going to cool you down and not really going to attenuate your rise in core temperature. And again, I have to be careful when I say this, because cooling you down you need a lot of cooling power and attending the right attenuating the rise in core temperature. That's more so when you start exercising, cycling or running if you have a lot of cooling power. That attenuating the rise in core temperature, that's more so when you start exercising, cycling or running. If you have a lot of cooling power, then you might not increase as much. But if you're doing a long race, your core temperature is probably going to go up and then stabilize. So if anything, that might not change or might change a little bit, but it just might reduce your heart rate a little bit. So if you put something on your skin, you might reduce skin temperature and then that might reduce skin blood flow and then you're allowing to have a bit more blood in central circulation. So your heart rate might go down a little bit but you might not notice that your core temperatures go down. It's going down. But if you were to measure skin temperature, maybe your skin temperature is going down, but that's a bit harder to to measure, especially in a race. Yeah, so there is that balance.
Speaker 2:And again, if you go back to those more targeted interventions or more targeted areas, they don't provide a ton of cooling power. One of the things you didn't mention, though, is like forearms and hands, so maybe that's one thing, that it's a lot larger surface area. It's well vascularized. So in the military and I think in firefighting as well, they do do that, so they have, like, these tubs of water and ice, and if you get to like, for example, in running, if you get to an, a station, there is that you could plunge, you know, your, your forearms into that, for you know five minutes or something like that, and that would help with cooling um, a little bit more so than something in your forehead and your back of your neck, for sure the hands as well.
Speaker 1:I mean, this is a trick I'm using trick and air quotes here that only the youtube people can kind of see. But a lot of ultra marathoners even before we had a lot of really good heat research would like you use this strategy, because they would just carry ice in their hands out of an aid station and once again, they're using their experience of this. Feels good, it cools me down to have ice in my hands in a really hot day. They're not consuming it. The hands aren't that big of a surface area, right, even for people with really big hands, let's be honest, like that's not that big of a surface area, of course, but people would do that. But what you're saying is there might be something that, just because of the vascularization in those areas specifically, yeah that.
Speaker 2:And if you dump the forearms obviously you get more than the ham. Right you get the forearm and above the the elbow and because, depending on how much obviously body fat you have you can, it's an area you can cool down relatively quickly and then once you start running again pumping the arms, that kind of cooler blood goes back to the central circulation and might cool that, cool you down slightly or again kind of make you feel cooler, at least cool the skin so that your your heart rate might be lower to improve your cardiac output.
Speaker 1:Yeah, whenever all these different strategies like start to emerge, I always go back to I'm the environments where we're trying to cool athletes down that you can control the most, and the prototypical example that everybody's going to see in the Olympics and everybody's going to see in the next Olympics it's really hot or however it actually works out are the cooling vests, where all of the cold is right up against your torso, right up against your stomach, and sure, the vest is clunky and it's not practical to kind of use out in the field, but what that's telling you is you're taking advantage of one, the big thermal difference between the ice packs or the ice that's in the vest and your skin, and also, simultaneously, the large area of your torso and your stomach and your back, to where you can get a really reasonable thermal power or cooling power with that type of intervention that's's exactly right and I think, well, even in a few weeks, the Tour de France will start.
Speaker 2:Then, when they do time trials, what they do is they go in the shade, they put a fan in front of the riders because they're warming up on a trainer and they put their vests on which, again, if you parallel to running, it's a lot easier to do that in cycling because we're not moving, but with running, what you might find is that you might find that athletes are warming up as they do normally, but then after the warm-up, in the waiting area, they put that ice vest and, as you said, because the ice that, depending on where the ice packs are positioned in the ice vest and in the back, then yeah, you can have a lot of cooling power.
Speaker 2:There's obviously different ice vests and different I guess grades of how well they provide that cooling power, depending on what the I guess the the garment is made of and how close and how cool that ice pack, depending on what the I guess the the garment is made of and how close and how cool that ice pack can actually cool the skin. Because if you have a super thick garment, that obviously the cooling power is not going to be very strong. But if you go right against the skin or at least a thin jersey because they don't take off their jerseys and cycling and even running, you probably keep a singlet on. But yeah, if you can cool a lot of the torso and in the back, as you said, it's a bigger surface area and does provide that cooling power I'm glad.
Speaker 1:So I'm glad that you mentioned textiles. This wasn't on our outline, but we're going to talk about it anyway. There's any number of opinions on the right fabric to. I'm going to set out the prototype here, just so that we're not going to like mix metaphors or anything like that. You're going to get wet at an aid station and you're going to set out the prototype here, just so that we're not going to like mix metaphors or anything like that. You're going to get wet at an aid station and you're going to run out of that aid station dripping wet and then that water is going to be kind of what cools you down.
Speaker 1:So there's any different number of opinions on what the fabric should be or what fabric you should wear. Should you wear something that is highly wicking, like super, you know, like super technology? We're going to put the most wicking fabric in the world there, even something with holes. People will cut holes out of their shirt, you know, to get like more airflow and things like that. And then, honestly, you will see the exact opposite side of that camp, like the exact opposite of it, of where you want a garment that retains the moisture as much as possible cotton, right, you want it to retain the moisture as much as possible. Cotton, right. You want it to retain the moisture as much as possible in order to keep the athlete wet. And it's always and it kind of is just to let you in on the inside of some of this ultra marathon nonsense that you know we get to see every every june in olympic valley. It is a very polarizing debate, like to the point where people get mad at each other for like one opinion, one opinion or the other.
Speaker 1:And so here we go. We can opine on this garment, technology doesn't even matter. And then what are the? Certainly, we can notice the differences, but what would be the situational differences? On what one, when one garment would outperform another one in terms of its cooling power?
Speaker 2:Well, I need to preface this by saying that I am not a garment expert by any means.
Speaker 2:So this is just a little bit of my knowledge and opinion kind of together. But we did do a study a few years ago and this was some colleagues in Greece and we looked at different kind of garments like one was like a cooling garment, a wicking one and a cotton, and there wasn't much difference in that study. And I think what's important as well is using the garment in the proper context. So those wicking garments are very good, but at some point if you're running for a hot, for a long time in a hot environment, then the garment becomes saturated with sweat anyways. So I guess it's wicking properties. At that point Do they even matter? You know, cause it's all wet and sticking to you and so forth.
Speaker 2:So I think a cotton shirt will be, this would be the same thing. So I think at some point it probably doesn't matter all that much, to be honest, right, because the properties of the garments and how they may be helpful are kind of nullified just by the fact that they're completely wet and sticking to you. I think a garment that's wet at some point will become the same temperature depending on the environment of your skin. So there's not going to be much of a gradient. And then if you keep putting water on it. I don't know if it'll help much with evaporation of sweat anyways, because it's going to be fully saturated.
Speaker 1:So I think at some point when those garments are fully saturated with water, I don't know how much more helpful it becomes, but again, that's water your sweat, a combination of everything, a sports drink that you accidentally poured over your head like because that's what creates the temperature gradient is the evaporation of those water droplets interface with you and the environment, not your skin.
Speaker 2:So there is that to consider. But yes, you want it to be to evaporate, unless you have very cold water and you have the opportunity to kind of put cold water on yourself and on your garment periodically that it stays cooler than your skin and you can provide that cooling power. But I can't imagine that would be the case in an ultra endurance rate. You would have, you know, eight stations every kilometer or something yeah we will.
Speaker 1:I don't think we're gonna. I don't think we're gonna solve this here, but, needless to say, there are people that are going to be listening that are like, ah, they have the perfect solution. Like the holes in the garment should be exactly here and exactly there and it should be this, you know, perfect fabric and things like that, and I kind of I'm of the opinion of it probably doesn't matter all that much yeah, well.
Speaker 2:Well, I mean, if they're interested in having the funding, then just let me know. We can definitely test it in a lot All right, there we go.
Speaker 1:We'll strive for that, okay, so. So, speaking of speaking of technology, there's there've been a number of products that have kind of come out on the marketplace, and the triathletes have made this famous. Now, they're always first adopters, they're first at the table If anything new. That's why we love them. The one that that that people are going to be the most familiar with are these funky looking headbands that have these squares on them, and there's a few different manufacturers that actually make them now, and the claim of these manufacturers is that it increases the effective surface area of the forehead. What's going on here with these different devices? Because, first off, they're not cheap. They're a couple hundred bucks for a headband, right, a sweatband. I'm always thinking of the old school basketball players that had you know the head, the sweatbands and things like that, god bless.
Speaker 1:Bill Walton, who just passed away, was really famous for rocking those. But what's going on here with these $200 headbands? Is there something here that athletes need to pay attention to?
Speaker 2:And's the right context for it well, I want to say there's probably not much going on because, again, if you come back to what we were saying before about cooling power, surface area and so forth, the forehead is not a massive area, I should say.
Speaker 2:I mean, if it, if you buy one, you wear it, makes you feel cool and you feel you perform better, well then that's fine if you perform, perform better.
Speaker 2:I haven't had a chance to do a deep dive into this, but I guess the first thing I would do is that I would look on the website to see if there's actual research that's been done around that. I'm not sure if you've had a chance to do that, but oftentimes you see a lot of products with big claims Some of them actually have a research link and say, hey, no, we commissioned some research and they found this, which is the products that I would probably trust the most. I would read the research carefully beforehand to see. But if there's no research behind it and it's just claims and they haven't objectively been looked at in the lab, then I would be a bit careful about some of the claims and how accurate those claims are. And again, I haven't looked at this product so I can't comment, but just from a purely cooling perspective and again, as we talked about before, the cooling power of that surface area, how cold it is, how long it stays cold, it's unlikely to kind of cool you down per se.
Speaker 1:But still it could potentially have an impact on your sensation, your thermal sensation, right, or it could improve your thermal sensation as opposed to just dumping water on your head, because there's something to do with the device itself or the garment itself.
Speaker 2:Exactly and it comes back to what we were saying before and you summarized about. You know there's a physiological and then there's a perceptual right. So physiologically, maybe not much is going on, but perceptually, if it improves your thermal comfort, your thermal sensation, lowers your rating of perceived exertion despite your heart rate not changing, well then maybe you can perform a little bit better. Will that catch up to you, as we were talking about before, if you accelerated it too much? Potentially, but it is a perceptual thing, potentially a bit more than a cooling thing. Menthol I would suggest but again, I haven't done a deep dive into this product, but it would have to. I mean, it would have to cool you down a lot and in that area, yeah, that might be very uncomfortable, it would cool you down quite a lot. Okay, so we're going to. Are you aware on the website if there's any research?
Speaker 1:they do have some. Certain manufacturers do have some research on there and I have gone into it and it kind of just points out what you were just saying is that the the area isn't the area from a functional perspective isn't really increased all that much to be a big thermal sink. But it could be.
Speaker 1:There could be some perceptual changes that if that's what you need for a race once again. This is why the context matters. Right, exactly if you are looking to improve your sensation of temperature somehow, to use that ergogenically fair, fair game like absolutely if you need to, actually, if you need to reduce your core temperature probably not fair game that's right.
Speaker 2:Yeah, yeah, and again in. In an ultra distance race, as we were talking about before, the race profile changes quite a lot, so maybe it's just using it strategically. Yeah, maybe not necessarily to speed up, but even just to maintain the particular pace, just because you want to feel cooler. Well then maybe. Yeah, by all means, if you want to help, then yeah, go for it, I'll take it.
Speaker 1:I'll take it. Just a quick break here before we go on to the last topic, since we are bringing up Western states in advance of the race. There actually is a really great weather profile that I believe the race actually produces it and puts it out of, where they will give the temperature estimations per in like time blocks for each of the aid stations and once the temperature starts to materialize which this is going to come out on the Monday before the race, and usually that's Tuesday or Wednesday and once the those temperature profiles start to actually be real and not just, you know, wild guesses, which is where we're at right now Once they become real, I absolutely advise athletes to look at that and to look at them individually, because the temperature differences are so big. You're going to use a whole host of different interventions, different hydration strategies, different amounts of fluid that you need to take in, depending upon those wild temperature fluctuations. And one of the things that trips athletes up the most in Western states is the fact that they have to just simply change their hydration requirements from the beginning of the race to the middle of the race, to the end of the race, so wildly. It's not a constant 500 milliliters per hour. Sometimes it's three or four X from where you actually from where he actually started with. So, for all you athletes out there that are training in hot weather races, look at the race section by section, because you're probably going to want to do something, in some cases drastically differently on certain sections of the courses compared to others. Okay, so we talked about small surface areas.
Speaker 1:Let's go to the biggest surface areas, kind of like the final topic here, and this is full ice water immersion. And I'll give a little bit of a kind of an anecdotal story to lead this off the incomparable Scott Jurek, who won Western States seven times and he also won Badwater, I believe, twice. He was very famous during the Badwater ultra marathon for having one cooler in his crew vehicle that was specifically dedicated to an ice dunk. It was a gigantic cooler. I think it was like 120 liters or something like that.
Speaker 1:He's a big guy, six foot four tall guy, so it's a big long torso, right, not a standard cooler. He's going to fit his whole body in and he used to get in the thing like a coffin. He would cross his arms and he would get his whole upper body immersed, all the way down to his shorts in this ice water slurry and he'd stay in there for kind of as long as tolerable and then get out and then go down the bad water course again. And there's all kinds of good research on this whole water immersion piece of it and there's also practical elements of it. So, this being kind of like the biggest intervention that you can throw out during, let's kind of discuss like how powerful can this actually be, and then also how transient it actually might be during the race, since you might be deploying it at one specific point or another.
Speaker 2:Yeah, no, that's interesting, it's. It's, as you said, the most powerful cooling intervention. I'd be interested to know. Do you know roughly how long he stayed in there? I'm just out of curiosity.
Speaker 1:So I remember it was. I mean, it was not more than a couple of minutes, but he would get in, he'd hold his breath, he'd hold his nose for air, so only so basically his from his shoulders or his neckline to his waist was submerged, or maybe like mid thigh. And then I remember him staying in there scout, I'm sorry if you're listening to this, I'm totally butchering it but I remember him staying in there for for a couple of minutes, essentially on, yeah, whenever he would deploy it, which would be several times during the race yeah, well, that's.
Speaker 2:that's interesting because I mean, you know I talked about initially, about cold water immersion and being careful not to cool muscle temperature too much, but again, in this context it doesn't matter too much because you're not again sprinting, you don't need to have that higher muscle temperature, because higher muscle temperatures you need to produce more power, more speed, but no one's coming out of the gate sprinting in an ultra distance race. So, and the fact that he didn't put his legs in there as well, probably not a bad idea, right, because you cool the torso and so forth and you cool down, but yeah, it does provide a tremendous amount of cooling power. Just a bit of an anecdote as well uh, during my master's, 25 years ago now, we were looking at cooling power of water and I would run I think it was four trials we did and I would run in an environmental chamber until, um, my rectal temperature got to 40 degrees. I had an esophageal probe in, but I'll probe in probe in my ear for companion temperature and, as you may know, rectal temperature responds more slowly than esophageal temperature. So, anyways, when I got to 40 degrees, I jumped into baths of different temperatures and, if I remember correctly because it was a while ago, I think it was like 18, 12, maybe 8 and 4, and I remember in four degrees there was ice blocks floating around and from 40 and I think it was 38, 5 we needed to get down to. It took about five, seven minutes. So, oh wow, that's just how, how quickly, I remember correctly, but that's how we, how quickly it occurs.
Speaker 2:So there's obviously the cold of the water, the more the cooling power, so you definitely can get very cold. So in something like a race like this it's probably not a bad idea to jump in. You probably don't have to have four degree water, but anything under 15 degrees or something like Celsius will cool you down. Again, if you want to put your legs in there or not is something that you might want to try, because I guess if the water temperature is a bit higher, it doesn't matter too much if your legs are in there. But if not just kind of sit back, as an example you were providing up to the torso, I don't think you need to put your head in there, but up to the I guess you know shoulder height and cover up to your thighs that that will provide some cooling power. Then you come out of there, you start running again, you'll feel cooler and if you can do that periodically, yeah, that might be helpful, especially if you're down in the valley and it gets a lot hotter, for example, different races.
Speaker 1:But part of the reason it's so powerful is because it's a big mass of. It's just a big mass of water that you're submerging yourself in, which has the capacity to take to transfer a lot of the heat. Am I understanding?
Speaker 2:that correctly Like that's one of the big to absorb the heat right.
Speaker 2:Yeah, that's right. So because it's well. Again, going back to power, to cooling power, it's a large surface area. I mean you're cooling from basically down to your thigh and then water obviously conducts heat very well, so you absorb a lot of the heat. So you're not gaining cool, you're losing heat to the water. And the best thing to do as well if they kind of circulate or move the water a little bit, because if the water stays still then you might have kind of a thin layer of warmer water around your skin, that then you lose heat a bit less. If you're moving the water, it's kind of that convective flow, same thing with air and water. So if you move that then you'll lose even even a bit more heat. So yeah, it's the temperature gradient, the surface area and the cooling power of moving that cold water.
Speaker 1:So a lot of people are thinking about the magnitude of the event, of the intervention, versus the amount of benefit that they actually get from it, and I think there's two performance contexts that we can think about here. Yes, the first. The first one is like abortive. So you are trying to get an athlete from being in a hyperthermic state back to a normal temperature so just they can function and get down the trail, right, that's where you're just throwing everything. Every solution that we just talked about, especially the ones that create big temperature gradients, have big cooling power. We're going to throw it at it.
Speaker 1:But on the performance side, this is actually where it gets kind of kind of interesting, because there's the math, is all is really fuzzy. Right, we can do everything. We can do things in a lab and say, okay, so for every you know, one 10th of one degree Celsius core body temperature increase, it affects performance by this much. But then when you overlay the intervention and then what the intervention costs, you're sitting in an ice coffin for three minutes, right, like it kind of becomes a. It just becomes really cloudy in terms of what you're actually getting out of it. So I would turn that over to you from a practical standpoint in terms of like, whether the best interventions bang for buck, that both will improve performance as well as don't cost a lot of time, energy and effort into the whole thing like? What do you have to say about that if you're actually advising athletes out on the course to to get the most out of it?
Speaker 2:oh, that's a tough one. That's why we're ending with it.
Speaker 1:I'm ending with the tough one here julian, because I think you'd have.
Speaker 2:You'd have to put the context of what the environment like, the ambient condition, the prevailing conditions the athlete is in and what their physiological strain. So how hot are they? What's their heart rate? Because that kind of provides, I guess, the reserve or the understanding of how much faster they can run or how can they maintain their pace, right. So let's put this in the worst case scenario it's very hot, the athlete is struggling to maintain their pace.
Speaker 2:Then, yes, it's probably worth jumping in three or five minutes in a cold bath, as we were saying, to kind of lower your core temperature to make you feel better. Maybe get some nutrition in. That's easier to get when you're not necessarily on the run. That might provide some benefit in that. For how long afterwards? Again, that's a bit debatable. The pick is dependent on how hard they start running afterwards, how hot the environment is. But then that trade-off becomes okay.
Speaker 2:Well, at what point, as you were saying before, what point do I stop and do this and lose three, five minutes relative to if I slow down slightly but I'm still running, because three, four minutes, three or five minutes could be a kilometer, not three, but three or five minutes could be a kilometer. So you're a kilometer down the road but you're going slower. So how long, how much time does it take you? But for an ultra distance race maybe you can catch up, but by the time you catch up the effect of the cooling might have worn off anyway. So it's kind of a it is a very good question.
Speaker 2:So I think it's weighing up all those situational factors and that reminds me of kind of quantifying the thermal environment which an individual is, so that thermal environment is basically the ambient conditions and that's provided by ambient temperature, globe temperature, so the effect of radiative heat and sun, airflow from wind and relative humidity. And when you look at temperature so you talked a bit about the Western states providing an indication of weather conditions coming up. So one thing to think about is when you look at ambient temperature, that's always measured in the shade. So if you look at ambient temperature, let's say it's going to be again in Celsius 35 degrees, which is hot, that's hot, but it's measured in the shade. And when you measure globe temperature, that's like a temperature measured inside a globe which takes into account radiative heat, and oftentimes in Celsius again, I apologize for that it could always easily be 10, 12, maybe even 15 degrees hotter Big difference, big difference.
Speaker 2:Exactly. So there's that perspective, but then the other perspective is the metabolic heat production that the individual is producing. So the faster you run, the more heat you produce. And then the other factor, so the other personal factor, other than the four environmental ones, the two personal ones, so the heat you're producing and the clothing that you're wearing. So all of those things, together with the, you know, will hopefully help you make a decision about whether you should slow down and run slower or jump into a hot bath and all those things, or help you decide anyways, because I think it's yeah, it's a difficult one it's tricky because I mean, here's what I'm going to just verbalize this as I'm thinking about it, and you can provide commentary on the top of it.
Speaker 1:So, obviously, the the hotter the environment, whether we're measuring it in ambient temperature or globe temperature the hotter the environment, the the more you're going to want to use interventions that potentially cost you time, because it's worth it. Where those lines of demarcation are, that's it. That's why coaches you know kind of make their money, because we make these educated guesses based on kind of what we know and what the research is actually telling us.
Speaker 2:But then the second part yeah, and maybe a side note to that. So just a side note to that as well is pacing?
Speaker 1:Yes, that's exactly what I was going to say, because pacing is obviously yeah, okay, well, you can go ahead. No, no, go ahead, because we're thinking the same thing there.
Speaker 2:Yeah, because I mean that's the important bit, right? Because, well, another important aspect, just about learning to pace and being patient in races so if it is hot, well, maybe you slow down, and then, when it gets to a point where you can, okay, pick up the pace because it's cooling down or whatever the case may be, uh then that's quite important because, again, part of that whole similar environment is pacing, which is associated with metabolic heat, heat production. So if you slow down, you're producing less heat, you might not necessarily have to cool down as much. So combining all of those things, obviously with nutrition being an important one for all the distance races, I think the combination of all those things is quite important.
Speaker 1:So Rob Krier he's won the Western States 100 twice.
Speaker 1:He was very famous for having a pacing strategy and maybe this is a little bit too granular, but he won the race.
Speaker 1:So how are you going to criticize him where he would speed up when it was shaded and slow down when he was in the sun, which sometimes can happen on, like you know, every 10 or 20 meters or something like that.
Speaker 1:You go through 10 meters of shade and then 10 meters of sun and then 10 meters shade, and he would micro, micro, he would micro pace his effort out so that it was just a little bit harder during the shade part, a little bit easier during the sun, during the sunny part. But to your point, you can actually take an advantage. You can take advantage of that. This dovetails into my other thought is that the elite athletes who are running the race in a shorter duration right, the lead athletes will finish in 15 hours and the cutoff is 30 hours right, so they can do it at a higher intensity than much higher intensity, because they are better and that the duration of the event is is shorter as well. They are actually better candidates, or maybe even earlier stage candidates, for like the advanced stage interventions, because they are producing more heat, because they have the opportunity to run harder, yet they are the ones that are going to also want to take the most risk because they don't want the downtime.
Speaker 2:So it's this interesting like conundrum that they're in terms of what to actually take on board and what to just like roll the dice with that's's a very good point, cause I was reading something recently and, uh, if you kind of compare marathons and ultra marathons, you know the hotter it gets in a marathon, the more that affects the slower runners because they're out in those conditions for longer. But in contrast, the hotter it is in an ultra marathon, the more it affects the elite athletes because they're spending more time in the heat, whereas the slower runners might spend more time in the evening and so forth and overnight. So they said to your point, yeah, it's an interesting one, because they're more affected by the heat. So, you know, do they gamble and not do any cooling or do they gamble and do some cooling to slow down, to potentially benefit? Um, and again, it just depends on that whole situation of how hot is it, how hard am I going?
Speaker 2:I mean, the heart rate's always a good indicator. You know heart rate and rpe. So you know, if you're finding that, oh man, it's fine because they probably have a pace that they know they can hold or they may go by heart rate. But you know, if you're going to compare, okay, my pace relative to heart rates, well, I'm going to a proper heart rate but my pace is slower, or I'm going the proper pace and my heart rate's higher, maybe I need to cool down, maybe I need to slow down. So it's kind of in the context in the race, kind of making those decisions on the fly. And maybe you know before you were highlighting about having different things at different hydration points within the race. Well, maybe you have different strategies for the same hydration um place in the race or the same kind of a hydration place but the um, the aid station in the race, depending on how you're going and how the environment is.
Speaker 1:Yeah, I mean a hundred percent. I think you can tune at that and I do think the elite field is getting sophisticated enough to where they are finally tuning that based on all of those different parameters and I was going over this with one of my athletes just this morning who's in the elite field it even influences the equipment choices. So do I want to take a pack that is potentially going to insulate me more but I have more fluid carrying capacity? Or do I want to use hand bottles, because it kind of frees up everything and I can dump stuff over my head? It's just a really interesting kind of decision decision matrix here. All right, we're going to let you go, man, If we ended up on the hard question there.
Speaker 1:I always like to do that with guests, just throw the grenade in right at the end. I can't tell you. I can't tell you how much. Just for me to you. I really appreciate your work. I've referenced it countless times. The review paper that we used is a little bit of an outline I'm going to make it's freely available. I'm going to put a link to it in the show notes. I do encourage everybody to check it out. It's a heavy one. It's not a light one. There's a lot of references are in this thing. I'm just going to find that that's always a good choice or a good oh my.
Speaker 1:God, a thousand 67 references. Holy cow, we'll just call it an even thousand, even thousand, julia. But to just to kind of just to bring my point up again, man, I just really appreciate how thorough you are in these areas and also how we can distill it down to something that people who are racing literally racing this weekend I hope they got something, but not something to where they're going to drastically change their plans. It's kind of a love book, kind of a love, hate, love hate.
Speaker 2:Be careful with that one. I mean as always. I mean, this is our second time having a chat. It's always a pleasure, so thank you for inviting me and I hope, yeah, people get some benefit from our discussion. It's always a pleasure and good luck to everyone racing as well.
Speaker 1:Of course, where can people find more about you and your work? And then what's coming up? If they want to volunteer for some of the studies that we teased out a little bit on garments or whatever. Where can people find you, man?
Speaker 2:We're in Australia, so if you want to be a participant, you're free to come down and be a participant. So I'm at the University of Canberra, I'm at the Research Institute for Sport and Exercise, so feel free to jump that, jump on the website, jump online, I should say, and have a look. I run the Environmental Physiology Lab, so we have a climate chamber where we do a lot of our work, and some of the stuff that will come out very soon is stuff on heat acclimation. So, looking at the difference between dry and human heat acclimation, is it specific, does it? Or, you know, if you acclimate, is it fine? And we're finding that there's not many major differences, which is probably not a surprise given that we can't put people in there for super long periods for acclimation.
Speaker 2:We're doing some work as well now with the Australian Sport Institute, which comes back to, I guess, the discussion we had initially about acclimation and acclimatization and modifying the, I guess, traditional optimal recommendations for elite athletes and how do they put that in their regimented training program. So we're doing that uh for uh, women for men, for paralympic athletes, uh, as well. I'm interested to find out how that works. And we're also looking at a bit of a comparison between sexes as well, because that's an area of contention at the moment between men and women about how they acclimatize, or acclimate is it as quick for men as it is for women, and so forth. So we're doing quite a big study. They're looking at neuromuscular function, cardiac function and so forth. So, yeah, lots of stuff to look at down the line. So, yeah, if you're interested, fire off an email as well the email's in the paper. So I'm happy to chat about stuff like this, obviously with people.
Speaker 1:Awesome, man. Well, we'll have to bring you or one of your colleagues back on as these things start to dribble out, because already I'm like oh yeah, I kind of want to know if this intervention versus that intervention works better or worse, or is it different for men or women? And the practical piece of it that you guys are working on with AIS is what, as a coach, we are always the most supremely interested in is how do we take all this stuff and actually do it with an athlete who's actually training and got all these other things going on? In a quote unquote, I'll use optimal in air quotes, quote unquote optimal setting.
Speaker 1:Those are the zillion dollar questions that we always kind of want answers to.
Speaker 2:Well, you might hear from us, because one of the things we want to do is a survey as well and end up to the coaches that are working with athletes to see how they implement those things. So, yeah, stay tuned. You might get an email. All right, I'm happy.
Speaker 1:I'm happy to distribute that man. Once again, man, thank you for your work, man, it's really impactful Pleasure. I hope the people over at Western States and Badwater folks and Wasatch and all these other hot weather ultra marathon they'd take note to this and reference the earlier podcast that we did together as a couple of years ago now on acclimation and acclimatization methods. That's a. These two things kind of combined really give you a really great resource on how to navigate these land, this landscape.
Speaker 2:Yeah, yeah Again. Thank you, it's been a pleasure and good luck to everyone All right, folks, there you have it, there you go.
Speaker 1:Much thanks to Julian for coming back on the podcast as a repeat offender and, more importantly, thanks to him for all the work that he has done in the area. If you want almost everything you need to know about heat acclimation and heat acclimatization I'm having a really hard time with that word today check out the links that I have dropped in the show notes. It will take you a few hours to move through them all, but you will certainly be armored up for the heat, regardless of if you have time to prepare for it, or you're just racing this weekend or next weekend, or you're going into a race next year where you have plenty of time to prepare. I view this as one of the performance showstoppers where, if you do it right, you have everything in your corner, and if you don't do it right, you can screw it up royally. So take some time, get some knowledge in your corner, make sure you've got these methods and techniques and interventions correct and you know which ones to use, and have confidence in the ones that you can use as well. Appreciate the heck out of all the listeners out there If you are running in this year's edition of the Western States 100,.
Speaker 1:Good luck, have fun out there. Use all the ice that all the volunteers have out there for you. It does look like it's going to be a relatively warm year, or a year that's on the warmer side, but have fun out there, it's going to be a good one. Come by and say hi. We will be there with a battery of coaches supporting our 21 athletes that are running in the race, from the front of the pack to the middle of the pack and the back of the pack and everywhere in between. We're going to be out at nearly all of the aid stations with our tents. So come by and say hi, good luck to everybody out there and if you happen to be racing another hot weather race in the summer, good luck to you as well. I hope you gain some knowledge from this podcast. All right, folks. That is it for today and, as always, we will see you out on the trails.
