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Managing Heat, with Rob Pickels

Coach Trevor Connor and Caley Fretz are joined by Rob Pickels, a physiologist who studies ways to make clothing work better in hot weather. They discuss the mechanisms that cause your performance to drop when your body gets too hot, how to trick these mechanisms, and why you don’t want to.

Photo: Sharon McCutcheon on Unsplash

Is the heat of summer getting you down? Fast Talk is here to help. Coach Trevor Connor and Caley Fretz are joined once again by Rob Pickels, a physiologist who is currently studying ways to make clothing work better in hot weather. The panel discusses the mechanisms that cause your performance to drop when your body gets too hot, how to trick these mechanisms, and why you don’t want to. Finally, Fast Talk digs into the best ways to stay cool and safe when the mercury rises.

Episode Transcript



Welcome to Fast Talk developer news podcast. Everything you need to know to run like a pro.


Trevor Connor  00:14

Fast dock is sponsored by cork maker of kick ass bicycle technology systems. Now with cork prime you can hit the ground running bicycle makers or shipping bikes with a new cork prime power ready crank set. Add the affordable court D zero power meter spider and you’re ready to achieve new personal bests as your bicycle dealer about cork prime. Welcome back listeners to another episode of Fast Talk. I’m Trevor Connor here with my usual partner Kelly fretts. Hey, Trevor, how you doing Kaylee,



I’m doing well.


Trevor Connor  00:45

And today we have a special guest who you might have remembered from an episode. Getting back to I think the fall or this summer for us. We have with us Rob pickles, who I know from back in the days of the boulder center for sports medicine, but is now the head physiologist at Birla zoom and will always be known as the illustrious Mr. Pickles. I have known Rob for a while a long time now long time, we’ve known each other from you when you worked at the cu Sports Center. We’ve known each other from when you were at bcbsm as the the physiologist there. And I was that annoying little cyclist or the sat around and asked a question. So



it’s funny to me that I’ve known you when you were an athlete, I’ve worked with you and that professional sort of capacity. And I’ve also worked with you sort of as a colleague as a researcher in another physiologist. And so it’s been a good few years for us. And I will say in 10 years, that’s possibly the first time I’ve gotten a compliment.


Trevor Connor  01:46

I’m very used to rob test to me and just shaking his head and I go, what does that mean? He goes, No



walks away, it’s better not knowing.


Trevor Connor  01:56

So we’re here to talk about heat management. It’s the summer you’re gonna be doing a lot of races and really hot weather. And that can affect you. And we’re all trying to figure out how to deal with the heat. So let’s talk a little bit about why he does a factor how it affects you. And then we’re going to go into different strategies for managing heat. With that. Let’s make it fast.



So as usual, I will be playing the village idiot around this table today and trying to trying to sort of move things forward. So let’s let’s just get started here. I know from personal experience that when I go and climb, sunshine, which is a climb here in Boulder, in the middle of the afternoon in August, I do not go as fast as when I climb sunshine early in the morning on a nice March day when it’s 55 degrees. I guess let’s start from the with a very, very basic question, which is why is that? Why would I overheat? Do I climb and perform worse on a climb like sunshine.



For most people, it’s probably because they’re overtrained. By the time August rolls around beautiful summer riding weather and people are feeling real good back in March,


Trevor Connor  03:11

not Caleb’s problem after



Yeah, after covering the entire Tour de France, that is not my



people might seem complex. And sometimes we like to think that we are. But for the most part, we’re just fairly simple machines. And as a machine, we take energy. And out of that comes work. The problem is we’re not overly efficient. When you’re out there pedaling, you’re burning a lot of calories. And most of those calories are actually going to heat production, depending on how efficient somebody is probably between 20 and 25% is actually going to putting force to the pedals. And the rest of those calories that you’re burning, they’re being lost as heat, that becomes more or less difficult to manage depending on the environment that you’re in. And when you’re climbing slowly up a canyon on a on a sunny, hot day with very little breeze, that environment makes it very difficult to move all that extra heat that you’re building up. And so it’s 100% expected that on those hot days, you’re definitely gonna be going slower. And we see that both in cycling, we see that in the laboratory, we see that in running. And that’s a very real, measurable effect. And we are going to be talking later today about ways to solve some of the problems some of the ways that you can keep your core temperature down, but we’re gonna, I think we like I said, we’re going to start with with the broad, the broad questions I see the next thing on the board in front of me is core temperature and that it sounds to me like that might be the primary issue here is that core temperature is rising Is that correct? core temperature is very much rising. And you know, the reason for that is all that heat that you’re producing. Out of that equation, we subtract what you can put into the environment either through evaporation or radiant heat loss, conductive heat loss, and whatever we can’t get into environment while our body tissue has to absorb, you know, we’re, we’re full of a lot of water. And so we can absorb a lot of that heat. But when we do that our core temperature starts rising. And the body is very astute and it wants to keep us in a good safe protected place. We’re constantly monitoring things like core temperature, and that temperature is rising too quickly or getting too high, the body will lower its workload, it will slow you down so that you’re doing less work so that you’re producing less heat. And it keeps sort of that temperature gauge out of the red zone in a good safe place for you to continue riding.



So it’s not that there’s some sort of physical change, I guess there would be a physical change, like when you overheat. It’s not that, that that itself makes you less efficient, it’s that your body’s actually shutting itself down,


Trevor Connor  05:46

basically. So I did to make sure I keep up. Try to keep up with Rob today, I did a little research on this coming into this podcast. And I actually went back to possibly the most referenced study on heat, acclamation and dealing with heat. And so this is from 1993 at a Denmark. And one of the really interesting things I found in that study was whether you are acclimated or not, they were they were having these athletes time trial to exhaustion. And the point of exhaustion was always at the same core temperature. It was, you know, with very small variance, it was 39.5 degrees Celsius, they hit that temperature and they shut down. And yes, Kaylee, I know that was Celsius, I’m Canadian hundred and 3.1 degrees Fahrenheit.






I’m very happy.


Trevor Connor  06:37

So that’s what you’re trying to deal with. And what they say in the study is, there’s a lot of research showing that at that right about that temperature, there are biochemical changes in our body, we rely on enzymes to keep our bodies functioning, those enzymes start breaking down at 39, right around that 39.5 degrees. So our bodies have a way of saying, we don’t want to go above this temperature, you will die. So we’re going to stop you and that you experience as fatigue, you just can’t go hard.



I mean, 103.1, I mean that that’s getting into the range, where if you have a fever, like you’re starting to look at going to the hospital, right? I mean, that’s where we’re getting into a range where you’re potentially doing damage to what do brain damage and things like that, it’s certainly possible heat stroke is typically thought to be brought on at about 41 degrees Celsius, or 105.8 degrees Fahrenheit.



And so that’s why we do want to make sure that we’re keeping these temperatures below those, and a lot of research, there is an upper limit of 40 degrees Celsius, or what 104 degrees Fahrenheit, where researchers aren’t really willing to push subjects past that point anymore, even if they can to make sure that they stay in a nice safe place. So yeah, we’re talking about dangerous situations, for sort of the the conservation of life.



So it’s, yeah, it’s your body protecting itself, and that that the result of that is decreased performance, right? Because the only way that your body can make you produce less heat, and therefore keep your your core temperature underneath that sort of death zone is to prevent you from producing as much work basically.


Trevor Connor  08:20

And the issue you’re dealing with when it’s hot outside is, nature does not like gradient that is possibly one of the greatest rules of science. So if the external environment is very cold, and you’re generating heat, it’s very easy to get that heat out out of your body and have it cross as gradient to the cold environment. When it’s hot outside and you have less of a gradient, it gets much, much harder to get rid of that heat to remove it from your body.



Exactly. You know, initially at the onset of exercise, we do things that are going to help us remove heat, we’re going to increase the blood flow to our skin, which helps us radiate heat away from our body, we start sweating, which helps us evaporate heat. So there’s a lot of different mechanisms that we can go through to remove heat. But if that heat production is so much greater than the removal capacity, like you’re saying the only way to deal with that then is to slow down and stop producing as much heat.


Trevor Connor  09:18

So another important thing to know about when you’re talking about the physiology of managing heat, and a lot of the research they talk about two different physiological responses that they’re trying to manage. One is what we were just talking about that rising core temperature making sure that the core temperature doesn’t get too high. Another one they talk a lot about is cardiovascular strain. When you are not exercising in the heat, vast majority of your blood flow can be just going to those exercising muscles to fuel your muscles. When you are exercising in the heat. You now have an additional strain of getting blood to the skin so that you can sweat so that Takes blood away from the muscles and you have to work harder to keep getting the fuel on the oxygen to the muscles. Then if you are dehydrating you have a further strain that basically your blood volume is dropping. When people talk about cardiac drift, the end result of all this is you will see at a given wattage, your heart rate go up and up and up and up as your heart is working harder and harder to get muscle blood to the working muscles. However, a lot of the research that the least I read showed that it was really more the rising core temperature that ultimately shut you down, that our body is still actually very good at maintaining and managing that cardiovascular strain. So your heart rate will go up. But it’s going to be able to maintain those mechanisms far longer than the core temperature. So it’s the core temperature, not the cardiovascular strain, that’s generally going to shut you down.



You know, when when we’re looking at that the body is really good at it sort of managing, where things are going. And if we take this all the way back to caveman days, we need to run away from the enemy. And in a sense, when we’re exercising, that’s potentially what the body is going back to. And non essential organs are going to be shut down in the pursuit of maintaining our muscles. And so we can end up in a place where we’re even reducing blood flow to the gut to the intestine, you don’t need intestines if you’re about to get eaten to your kidneys. And so we take this to the the truly extreme, and we’re trying to exercise really hard in a dehydrated state on a hot day, then we can end up with a little bit of kidney damage or a little bit of gi issues because of that, because the body wants to send as much to the muscle in the skin as possible. And then that hot variable that’s thrown in there that it means that we need to send blood to the skin, really places that stress that you could have otherwise been sending that blood to your organs. And that need for thermal regulation is pulling it away from there. Yep.



So Rob, when we were off mic earlier, you use the term and participatory regulation. Yeah. I don’t know what that means. Care to explain.



Yeah, essentially, it’s that the body is smart. You know, we’ve been talking about reaching these high core temperatures. But you know, with a theory of anticipatory regulation that really came out of Tim Noakes, his lab, if anybody readers or listeners have heard that, but then also Ross Tucker, who is a very well known researcher in these areas. And essentially, it’s not necessarily crossing that threshold of core temperature, it’s the body sensing that the heat that it’s storing, related to the rising core temperature, if that is increasing too quickly, the body will slow itself down to prevent being in a bad place before you’re ever in the bad place. So the way that they did this was they really, they set up two studies. And in the first one, they held everybody at a constant workload, and you had to pedal offhand, I don’t remember that 200 watts I’ll make up and the core temperature of individuals, it increased over time as we would expect it to. And like Trevor said, you know, once they crossed a certain boundary up fatigue set in, they got too hot, it wasn’t because they had run out of carbohydrate. It wasn’t all the reasons of fatigue can occur, it was because their core temperature was too high. And then they did something different. They They asked the individuals to to ride at a certain rating of perceived exertion. So they asked them how hard it felt. And on a scale that goes to 20. They asked them to ride it a 16. But it was up to them how hard they rode. They measure the workload for the first few minutes of that. And over time, as the person tried to maintain that 16 out of 20 effort level, their workload slowly decreased throughout the trial. Now their core temperature held in a good spot throughout most of that trial. And so what they’re proposing is that by lowering workload over time, they were managing their core temperature. They also did that in hot vers cool environments, and in the hot environment where their core temperature up to have gone up more quickly. What actually happened was their workload decreased more quickly. And so even though they’re maintaining a 16 workload, they were pedaling less and less hard, but it still felt hard, and it’s still maintain their core temperature.


Trevor Connor  14:38

So let’s take a quick step back here. You would think it’s a really simple answer to the question what causes fatigue, but it’s actually really heavily researched right now and there are a whole variety of factors that can contribute to fatigue. One of the biggest ones being that core temperature, you hit it, you hit that certain temperature you shut down but and Robert, I think there’s a lot of the research you’re talking about, there’s been some really interesting recent research where they say actually, ultimately, the cause of fatigue is mental is a big part of it, meaning our minds want to prevent us from doing permanent damage to our body. So it has all these different ways of gauging, okay, your glycogen is depleting, and that’s a bad thing, because then your brain is gonna shut down or your core temperature is getting too high. And ultimately, your brain is going to shut you down before you hit that point of doing damage. So that’s why you are seeing a lot of these perceptual effects on power production on core temperature, your brain trying to keep you within a limit, that’s not going to do damage.



Well, I’m assuming we’re talking kind of Deep Brain Stuff here. And this is clearly not frontal lobe.


Trevor Connor  15:51

Yeah, this is not looking in the mirror, you can do this



harder. And that’s, that’s one of the biggest things that I’ve had to deal with over time, right, as we start talking about these perception trials, and people say, oh, I’ll just will myself to go harder. And that’s not necessarily the case. I think one of the most interesting studies that’s out there, and I think that this really changed how I felt about thermal regulation, and made me interested in this science, is a study that was done by a guy named Paul castle, where they use deception to deceive people as to what was actually going on. And in short, it was a study where there was three different trials, one of those trials was a cool condition, and they had people do a cycling time trial. And they did great. There was another condition where it was hot. And they were shown an accurate core temperature, they were told that it was hot. Lo and behold, they didn’t do nearly as well as they had in the cool condition. Then Then the third condition, the third trial, they were deceived, and it was another hot condition. But they were lied to, they were told it was cooler than it was. And they were shown that their core temperature was actually lower than it was. And lo and behold, they didn’t perform like the hot condition before they perform like the cool condition before. And so this goes back to that brain sort of integrating everything that it has all the knowledge that it has around itself, trying to maintain a good, you know, place a good safe place. And if we’re lied to, and again, it’s not that you can lie to ourselves. But if we have inaccurate sort of information, then the body will respond to that inaccurate information and alter our performance similar to the concept of placebo. Right.



So exactly very much similar to the concept of placebo. And there’s been a lot of interesting discussion of placebo effect and things like that recently, I see on the board in front of us, which is our little list of things to talk about mouthwash, and pouring water over your head, which I think are related to this, this concept of potentially deceiving your own brain, right? Someone explained mouthwash to me.


Trevor Connor  17:59

Yeah. So testing this, this concept of perception, there’s been a few studies where they tried cooling the mouth of the individuals to see if it affected perform one study, use basically an ice slushy, that they would swirl around in their mouth, and then they would spit it out so they wouldn’t ingest it. Another one. They didn’t have any brands, but they basically use mouthwash. So it was a menthol containing mouthwash that would cool their mouth. And then they would spit it out. And they certainly saw just just like Rob was saying it reduce discomfort from the heat. So they were doing these time trials are doing these tests in hot conditions, it would reduce their discomfort, and would also lower their their rate of perceived exertion. Yeah, and the case of the ice slushy, you actually saw some improvement in their time trial performance.



Yeah, I think that stuff stemmed from, you know, some of the original pre cooling research that’s out there. When everything is going into the gut, right, it does it through the mouth. And when we talk about swirling carbohydrate in your mouth can help improve performance. Well, we have cold sensors in our mouth as well. And so if we’re swirling a cool liquid in there, we’re activating those cold sensors in the body assumes that we’re going to be getting a cold, liquid or ice or something into our gut, which is going to help lower our core temperature. And right away, it can start sort of increasing the workload because of the assumption that it’s making. Now, if we spit that water out, we’re not actually getting the cooling sensation or the actual physical cooling. And therefore, in a sense, we’re overriding and that’s where we need to be really careful with things



because you’re tricking your body into potentially going into dangerous zone



Exactly, and that’s where menthol comes in to where menthol actually stimulates the cold receptors. xylitol is a sugar that does this as well and they’re ingredients in gums. It’s why we get that cooling sensation when we have our winter mint gum, it’s an actual stimulation of those cold sensors, it works in the mouth. And it also works on the body, you can topically apply menthol, and you don’t actually get cooler. But because your body perceived your cooler because you stimulated those neurons, the body will increase workload a little bit, heat storage will increase, but there’s really no physiological cooling that’s going on. So we very much see changes within the body, based on all I mean, you could call it a placebo, but you really are stimulating nerves.


Trevor Connor  20:34

And I’ll say one of the interesting things about some of this research on this perception and deception is at least a couple that I read, they actually bring up the ethical question of, is this a good thing to do? Because our brains have these mechanisms to shut us down to prevent damage? So if we override them, yeah, do you get yourself in trouble. And I had that experience to the healer 2012, I got really sick the night before the first stage, I was in and out of the bathroom all night. So I started the stage severely dehydrated, was stupid enough to race in the heat for four hours. And when I got to the finish line, I don’t know how I got to the finish line. Apparently, I was standing by the Gatorade table trying to open a gate array, this woman saw me grab me, walked me over to the medical tent, my blood pressure was 70 over nothing. And I had to get three IV bags and almost took me to the hospital. Yeah. And that’s you shouldn’t be doing that stuff to yourself.



Yeah, I mean, as Kelly said, we have these safeguard mechanisms in place. And when we start sort of altering our perception or, or doing things to alter where those safeguards kick in, then we’re just bringing ourselves that much closer to the danger zone. And, you know, I definitely cannot recommend that people do things to alter these because we want to ultimately, what’s more than performance is, is being healthy and being in a good safe place. And really, no performance is worth heatstroke or other negative consequences that can come with a thermal regulation, this is somewhat dangerous things that we’re talking about.



So you can trick your body with mouthwash with with swirling cold water in your mouth. What about just like pouring water over your head? I mean, when you watch the Tour de France every summer in July, it’s hot. In the Alps, we see a lot of guys just pouring bottle after bottle after bottle of water over their heads. Does that actually do anything? Is that is that I think is probably some evaporative cooling is, is working there. Right? Is it useful in any other way?



I think that at this point, we’re at a really interesting intersection between what’s perception, and physiologically, what’s actually cooling you down. I’ve done a lot of research in this area. And one of them involved a head cooling study. And this proprietary head cooling device was created. We use multiple conditions, we use one where the cooling device worked the entire time. And it just provided cooling and cooling and cooling. We were doing this on cyclists doing time trials. But then I could also alter the head cooling device so that it only cooled for say 10 seconds and then took a 32nd break. And believe it or not with performance, the condition that showed the best improvement in performance was one where there was intermittent cooling. So even though we weren’t cooling the entire time, even though we were actually removing less heat than the hundred percent condition, the body perceived that there was more cooling going on. Now we’ve all experienced this, you jump into a cold pool or into the ocean and it is frigid. Initially, you give it 30 seconds or a minute or two and it doesn’t feel so cold anymore. Our cold sensitivity sort of changes once we’re in that new environment. And if you applied 100% cooling to the head, eventually the body kind of forgot any cooling was going on. And the subjects didn’t feel any cooler. And then the performance showed that. But when it was a pulse on for 10 seconds, and then a pulse off for 30 seconds, it gave time for those sensors to reset. And every time boom 10 more seconds of cooling you felt this wave come over you and that helped individuals ride






Hmm. But I mean it is cooling you as well, right? I mean, that’s that that’s that’s the difference between that and just swirling some water in your mouth.



The evaporation of water can actually remove more heat than drinking can if we look at sort of kilojoules of heat from the evaporation of water it is significantly higher. And so in a sense cailli we’re better pouring that water over our head if we want to cool ourselves down. Now, we talked about environment in the beginning here in Colorado. That technique works really, really well. It is very dry here and we evaporate really well. If we’re riding in the northeast or some other human location, and we’re already soaking wet. Well, we’re wet because that’s not being evaporated. It’s not that you sweat more when you’re in Georgia versus Colorado, it’s just that because of the humidity in the air, there’s not the gradient that allows that evaporation. So if you’re out running, riding, doing whatever you do, and your shirt is relatively dry, but you’re feeling hot, sure, grab that water from the aid station, pour it over your head, it’s going to help you cool down. If you are dripping on the ground with sweat, you’re obviously not evaporating very effectively, you’re better off in that situation, drinking that water, because it’s going to be a lot more useful than dropping on the ground. So the


Trevor Connor  25:37

pouring water over your head, and that’s a huge one with cyclists. And if you watch pros, one of the things they really like to do is get what are called ice stockings. Where you get women’s knee high nylons, you put a bunch of ice in them, and then you put them down the back of your jersey and the ice very slowly melts and just gets this nice cooling effect going down your back for a long time. And a lot of cyclists swear by it. I still remember with the with the team, we were at a race in Arkansas. And I went to the supermarket. It wasn’t even thinking about this, I bought a whole bunch of nylons. I bought fingernail polish to touch up the paint job on our frames. I go to the checkout, this woman looks at what I’m buying. Looks at my shave legs. Just kind of gives me a look and like I’m Thank you not he explained this one.



But don’t mind me just having some fun. I’m having a great weekend. What do you want.


Trevor Connor  26:38

I remember my environmental extremes class at CSU, our professor said do not pour water over your body, it actually has a detrimental effect. This is a 2012 study in the Scandinavian Journal of Medicine and Science and sports, it’s actually a pretty respected one, where they brought up one of the criticisms and pouring water over your body, which is it causes vasto constriction. So basically, your body feels it’s cooler says now I don’t want blood flowing to the surface, which means you stop sweating. So you get a little less of that evaporative effect. And more importantly, all that heat in your core that you’re trying to get out to the surface and let go is no longer getting out to your skin,



right? Because that is building up, right? Because that’s one of the ways that your body naturally cools you is essentially just putting as much blood out near your skin as possible. Right?


Trevor Connor  27:36

Okay, so this study actually tested it in performance. It was with runners, they had them do 90 minutes at a fairly easy steady state and then do a five k run. During the five k run there was zero difference whether they did external cooling or not in all the different metrics. So they basically said it didn’t help. There was during the steady state a perceptual advantage. They didn’t see any effect and core temperature core temperature was the same whether use the external cooling or not. So their ultimate conclusion was at a steady state, not super hard effort for a long period of time. In the heat. Yeah, pouring water over your body will help.



Yeah. And that’s the difficult part with research is that you need to first determine what is the study actually investigating. And you can find research that support really any side of an argument, right? When we look at stuff like this news, fake news, when we look at stuff like this, and we use a five k as a model, you know, perhaps in that situation, core temperature wasn’t the limiting factor for these individuals. And so you can do anything you want. If we feed people in this condition, it probably doesn’t have too much of an effect on their performance because glycogen depletion isn’t isn’t a factor there. And so for me, I’m always looking at stuff like this with a critical eye. But the concept that you’re talking about is is very well known, and it’s especially well known to athletic trainers who deal with heat stress and athletes all the time. And so in my opinion, I think it’s a very good way to remove heat again, assuming that the environmental conditions are appropriate for that.


Trevor Connor  29:16

As always, we will put both Rob’s studies and the studies that I mentioned, we’ll put those references on the website.



Fast dock is sponsored by quirk the brand that connects bisons most talented innovators with the sports early adopters, power meters, CT collector shockwaves and the Calvin app are just a few of their innovations. Core continues to refine its fast track pipeline for new products and innovations. So be sure to follow them on Facebook, Twitter and Instagram for all the latest and actually just use the Calvin this morning to try to calibrate my power meter and when I did my 20 minute time trial it was still sad I


Trevor Connor  29:55

guess it only goes



on calibrate your parameter.


Trevor Connor  30:00

Yeah, you could, which is what I really should have done? Because I did that whole time trial going. And that’s my real numbers because I just fully calibrated so I’ve got nothing to hide.



Well, yeah,


Trevor Connor  30:14

still a big fan.



What about the classic ice vest that’s become very popular in time trials these days. I mean is that is that potentially too much cooling?



Ice feser typically used while people are warming up and when they’re not at rest, and so we have a much better balance of heat production versus heat removal. But I agree, if you were sitting around watching TV with an ice vest on, you’d be shivering, you wouldn’t be doing anything. Even if you were sitting in a fairly hot environment, there’s too much of an imbalance there. But there’s a lot of pre cooling strategies like that Megan Ross, we can put this research up that she was one of the pioneers, if I remember right in drinking the slushy and cooling from the inside out, as opposed to just doing external, what they found was that I believe it was ice towels across your shoulders. And drinking a slushie was sort of the best way to pre cool the body. If we cover too much surface area, we end up in this too cold of a place, and we have bad thermal regulation. But they found that even prior to warming up if they did this technique of drinking a slushy and putting ice towels across your shoulders, that you would actually maintain a lower core temperature, even even after you did your warm up and got to the start line of the race, you’re still in a better place. And that was interesting to me. I had figured that that exercise during the warm up would would obliterate any sort of core temperature and you’d end up right at the exact same place. And that’s just not true.



Interesting. So if you drink cold water, it just acts as like a heat sink in your belly. Is that essentially how that’s working it? Yeah,



exactly. Um, you know, Trevor, if you want to speak to sort of calories, I know this is right up your alley and what a calorie actually means.


Trevor Connor  32:00

Oh, we have we covered this one. Yeah,



we have we have covered calories? Yes, we have. We’ve covered calories, because you tested me one time. And I and I did not remember the answer. But I remember it right now. What is it? It’s the amount of energy it takes to raise the temperature of a


Trevor Connor  32:17

certain amount of water, a certain amount of temperature. liter of water one degree



a liter of water one degree Celsius. This is way back to my AP Biology days. Sorry, Miss Allard, you did not



take we’re talking about the kilocalories Yes. And actual little sea calorie is a cubic centimeter of water one degree Celsius, but they’re ultimately the same. It’s just how big of a unit you’re talking.



So I’ve failed again, I’m sorry. So yeah,



when when you drink that water, it takes energy to increase the temperature. And so if you drink water, that’s 33 degrees Fahrenheit, and you want to bring that all the way up to your normal core temperature of about 98 degrees, maybe a little bit higher, when you’re exercising, then that’s a lot of calories that that water is going to absorb as it raises its temperature up. So yeah, it’s very much a heat sink.


Trevor Connor  33:08

So that study I was talking about before where they put the slushy and in the athletes mouth and have them swirl it around and spit it out. They also had them drink it. And that helped performance even more. And it helped maintain core temperature even more. But they they studied a variety different factors to figure out where it was having its effect, they looked at heart rate, they looked at peripheral blood flow, they looked at core temperature, the only place that they found a big difference was temperature within the gut. So it was it was doing actually exactly what you’re saying. And that was the term they used in the study. So KLM and press is they said that the this ice slushy was creating a heat sink in the gut.



You know, I know that term, disc brakes. My tech background comes back and is handy sometimes so. So we’ve established that tricking your body into thinking it’s cooler than it actually is is potentially dangerous. There are definitely ways to keep yourself cool. We’ve we’ve discussed a couple of those just now obviously drinking water pouring over your head. What else can people do? You have a hot race you’re racing in August, it’s it’s guaranteed to be hot. What can people do to prepare for somebody that?


Trevor Connor  34:28

Well, so the first and obvious thing people are going to go to is hydration. Hydration is a really complex subject and it’s actually quite controversial on the pros and cons of hydrate and hydration and how to hydrate. We’re not going to go into that in this podcast. I might be a future podcast, but we’re not right now going to talk that much about how to effectively hydrate yourself. The one thing I am going to bring up that I thought was really interesting is in that study Where they talked about the ice slushie, creating a heat sink, they brought up the point that and when you’re you’re exercising in the heat, that rising core temperature is going to shut you down before diet dehydration does, that athletes actually have a pretty good ability to manage a fairly large range of dehydration. So they said, it’s actually they felt it was more important to be consuming for maintaining core temperature than hydration status. And we’re not going to say a ton about the the pros and cons of that right now. But the point that they did make that I really liked is, too many athletes are drinking liquids that are air temperature. And so they’re too focused on the hydration and not the cooling factor. And I do agree with what the study said is, you should be drinking cold liquids, or even those ice slushies and really hot temperatures to create that heat sink to help maintain the core temperature. Rob, how do you feel?



Yeah, you know, I feel I feel similarly, where the body can definitely tolerate a large range of dehydration. Now, we do know that, at some, some level of dehydration, we are going to be reducing our power output that it is going to have an effect on performance. Where exactly that occurs in people is somewhat nebulous, and it’s fairly individual. What is important when we’re reading research on this is to look at exactly how the research is being conducted. And a lot of the research that has shown hydration is important for thermal regulation did so in an environment that was not necessarily representative of riding your bike outside, which is what we all like to do. So if we’re setting somebody up in a room on a trainer, and we just have a fan blowing in their head, and that fans only going five miles an hour, we’re not getting the same environmental conditions as we are outside. And in studies that are set up like that, then there is a huge tie of hydration to thermal regulation. But when we set up studies that maybe they’re in more of a wind tunnel situation, and we’re getting a much more representative outside riding experience, then suddenly, we don’t necessarily tie thermal regulation to hydration anymore, because the body has all of the other mechanisms available to it through evaporative cooling or conductive convective cooling. And suddenly, being hydrated. 100% isn’t as important for thermal regulation anymore. And that might be what we’re experiencing when we’re outside. But I think that there needs to be more research specifically in that area before we can say definitively what’s going



  1. I mean, you know, I think in general, it’s probably a good idea to be hydrated in general,



good idea to be hydrated, every everyone would agree with that. You know, the


Trevor Connor  37:52

one sort of interesting bit about this is when we are adapting to heat, one thing that occurs is that our plasma volume are the amount of water essentially in our blood increases. That’s one of the ways that we adapt to that hot environment. And so we do know that that hydration, it you know, it is important to help maintain the plasma volume. And there are products on the market, sort of the preload hydration of the hyper hydration products that can help mimic this by increasing the sodium and the bicarbonate content in your blood, you can hold on to additional water. So you brought up heat acclamation. And ultimately, that is one of your best methods of handling the heat is to spend time dealing with the heat learning to deal with the heat. So if you’re going to go do a race in a very hot environment, don’t be like me, the Canadian, come in from somewhere nice and cold and jump into a hot environment that you’re going to perform at your best you need that time at that temperature or at the hot temperatures acclimate. And Rob pointed out some of the really important things that you see, with heat acclamation. One of them is that you see about a 13% rise in plasma volume. You see improvements in stroke volume, that’s how much blood your heart can pump per beat. And another big one is sweat response. Once you’ve acclimated to the heat, you are actually I always thought it would be you’d be less responsive to sweat, but you’re actually more responsive. You’re going to sweat sooner and you’re going to sweat a little bit more.



Yeah, exactly. And these as you know, Trevor said, we’ve all felt this before, right, that first hot day in Colorado, we’re kind of getting into our warm days. Right now. We’re recording this a little earlier than you’re listening to it. And 70 degrees feels like 120 degrees the first day that you’re out in it and I know as soon enough in the middle of summer 70 is going to feel really nice and cool. And so this is a very transients situation because our cardiac output increases as Trevor said, Our stroke volume goes up, then we physiologically are benefiting from this. But depending on where you live, as he said, you know, maybe you’re doing a race in a warm environment, there are some ways that we can, I don’t want to say get an artificial, but there are some ways that we can alter our environment, so that we can induce these adaptations. And you know, a lot of people will will use a sauna, and they’ll do long, hot, or at least long dehydrating training, and then go sit in a sauna for approximately 40 minutes. And you do that for a week or two prior to an event. And you’ll induce these adaptations as if you were living in a warm environment.



So you don’t actually have to do the, the exercise in the sauna. If anything, it’s



probably better to not do it in the sauna. Because if you’re doing if you’re doing this exercise in the hot environment, and you’re not adapted, and even if you are adapted, you’re going to be decreasing your workload. So your training is going to be of lower quality. Now, I personally don’t have a sauna, and I don’t have a gym membership that gets me a sauna. And so there are other ways of doing it. You know, you’ll hear about people talking about writing in their bathroom with the shower on and being in that hot, humid environment. I don’t necessarily do need to ride for that, you know, do what I just mentioned. But taking a warm bath does the exact same thing. Fill that bathtub up with some nice hot water, you know, I believe 100 to 105 degrees Fahrenheit, you know, is plenty, and lay in that hot water after and expose your body to that warm environment. And you’ll start inducing these adaptive changes.


Trevor Connor  41:35

Going back to the sauna, though, I will say be careful. I had a teammate who did that went out for a long ride got in the sauna. was in there for about 40 minutes. And then he stood up and passed out. Yeah, fell over and cracked his head. Yeah.



Yeah, I mean, at that point, he’s dehydrated, right, his blood volume is a little bit lower. So his blood pressure is low because of that. You’re in the sauna. And so your everything is vezo dilated, your blood vessels trying to move that hot blood around. And you can definitely end up in that place where your blood pressure is just too low and you stand up and you faint. Pat pad those benches. Make sure you have a friend in there with you to make sure everything’s on the up and up,



huh. Yeah, I remember hearing about riders doing similar things before the world championships in Qatar last year, because they were it was gonna be so hot. And actually same thing for the Rio Olympic Games, because it was SPECT expected to be so hot and humid. That Yeah, essentially riders were actually heard about them doing like interval sets in a sauna. It sounds totally miserable. But it seemed to work for him. So



for those specific things, you know, when we’re talking about a 1% improvement in performance, right, we’re and this isn’t just for your masters race on Saturday. But when we’re talking about World Championships and Olympics, then training in that hot environment, it might give you a little bit of an edge, because you can tough it out a little bit more because you’re used to that because you’re not suffering quite as bad.


Trevor Connor  43:03

You just have to keep it in balance. So I remember back in 2008, I was involved in some of the studies up in Canada, unfortunately, as a subject, if you want to toss up a really good picture of me with sweat bags on my arm and a heat tent,



being a subject is always the wrong side of


Trevor Connor  43:20

the stick. Oh, especially when they handed me that core temperature thermometer and told me what I had to do with it. Oh, God. So they wanted to do a training camp inside a heated trailer with these poor cyclists training four or five hours a day on trainers in a heated room. Yeah. And some of the cycles I think Swain tough and they’re unwilling and a few others just went No, sorry. Yeah. See you later. And? Well, yes, it probably adapted people a little bit to heat it. So burnt them out. And it was so hard to do that training, it wasn’t worth the game. So you have to keep it in balance.



Don’t be an idiot. Hard,


Trevor Connor  44:03

much more concise.



In general, that’s, that’s my general training advice. Yeah, don’t go crazy with any of this stuff. Let’s talk a little bit about sodium loading. And I know that you too, are maybe maybe not totally and have the same mind on sodium floating. Am I getting that sense?



You know, I think that Trevor and I always have some some point of agreement. and if we talk long enough, we eventually agree at the end, we probably agree in the beginning, we argue in the middle and we agree again, you know, I had touched upon sodium loading with hyperhydration previously, and having the additional sodium content can help increase your blood plasma volume and hydration that way. But an important point to remember is that when we have extra water in our body, we’re going to be heavier. And if you’re starting out a stage, maybe with a lot of climbing and it’s not overly hot, we’re carrying around extra weight that we don’t necessarily need to you know, this is only going to be worthwhile of dehydration is going to be an important factor in what we’re doing. For me, sodium loading, if you want my personal, you know, use an opinion. If I’m in, say, a cyclocross race, and it’s early in the year, you know, we start racing in September, it’s still pretty hot here in Colorado, and I can’t really drink over the course of that hour, then I at least feel more comfortable with sodium loading My mouth is a little bit less cottony. And perception wise, at the very least, it works out well, for me, I don’t feel the need to drink where otherwise, I’m in the middle of the race, and I’m dying for a drink. And that makes you ride slow. But if we’re talking about, you know, big climbing stages, and the, you know, tour California, then I don’t think sodium loading is necessarily helpful to your performance.



Yeah, we were talking about this again, off, Mike. But, you know, we’ve heard about Team Sky doing things like functional dehydration, where they actually let their riders essentially get dehydrated, just so that they’re lighter for the last climb. That’s not necessarily the kind of thing that we want to recommend that your average amateur cyclist is messing with, but paying attention to how much or how hydrated you are, it is going to be relevant to how heavy you are. And then therefore how well you’re going to, you’re going to climb.


Trevor Connor  46:10

So this winter, I had a bit of a surprise visit from you. I’m living up in Toronto, and I get an email from Rob saying, Hey, I’m coming up. which point I was like, Why are you coming to Toronto in February? It turns out, there is a giant wind tunnel at a car plant just outside of Toronto, and in Oshawa. And you’re doing some pretty cool studies there on heat regulation, if I remember correctly.



Yeah. You know, the University of Ontario, teamed up with General Motors, and essentially created environmental chambers for automobiles. And one of them, as you said, is, is a wind tunnel. These were originally constructed so that General Motors could test their cars to see if the gaskets on the window is leaked in extreme temperatures. But we were able to use it to essentially recreate outside riding in a very controlled condition. And so I got a bunch of subjects together, we put them in the wind tunnel. And for this one, we kind of froze them a little bit. I was interested in testing outerwear. In cool or cold environmental conditions were about 39 degrees Fahrenheit. So we had workload set at an appropriate metabolic heat production. All of this was calculated and it was done per body meter squared of body surface area. So that heat leaving the body would be equal for people of different sizes. And I was able to look at the microclimate that existed between the skin and the membranes of the jackets that we were testing, looking at skin temperature, looking at humidity, looking at how cold people felt, as we said, perception is an important part of this. And it’s information that we gather like this through research that can really help improve products that cyclists get to wear. And it was important that we did it in this environment, right with this, essentially, wind flow, and temperatures and radiant heat exchange that was going to be similar to if you were pedaling down the road through your favorite cycling location.


Trevor Connor  48:20

So the one thing that’s important to understand here is that Rob was testing Canadians at 39 degrees. So this was actually a heat study. But I do want to take a quick moment to do a call out that I’ve been wanting to do for a while to the morning glory cycling club, because that’s the team I coach and they all participate in the study and just want to say hi guys, I love working with you. And



I love putting you in wind tunnels and freezing you.



I will say that I’m on the second day, we had a lot less participants than we did on the first day. I think people realize it wasn’t nearly as fun as they thought it was good chili.



Clearly, clothing has a pretty dramatic impact on your ability to to stay cool. I mean, I think that anybody who has accidentally thought it was going to be a bit cooler that day, threw on the heavier base layer and went out and and then sweated their bum off for a couple hours knows that. So what what can we do from a clothing perspective to keep core temperature down? And what are clothing manufacturers doing these days to try to keep core temperature down? I mean, is it is it as simple as just putting mesh everywhere. That seems to be what everyone’s doing.



I wish I wish that it was so simple. And prior to really being in the apparel industry. I thought that it was that simple. You know mesh makes sense, doesn’t it? But if you think people that live in truly hot environments in the Middle East, they don’t walk around naked all the time. Right, they’re covered up with clothing from head to toe. Now it’s clothing of light colors and it has a lot of layers and attracts heat in that situation. The environment is so hot, it’s so much hotter than the body that we need to insulate the body from the outside environment. And in a sense, that kind of carries over to cycling mesh is great for evaporative cooling, but it allows the sun’s rays and energy to boom, shine right on your skin. And you might get a lot of radiant heating because of that. And so when we talk about thermal regulation and clothing, it’s really not a simple answer. And it’s one that we’re in the midst of changing and challenging right now, it is important that we pay attention to things like color, but at the same time, the other research is saying that dark colors might be better at absorbing the heat and not letting it pass through to the skin. At this point in time, kind of what we know is that lighter color is going to help reflect some of that personal research has said that a thin white garment doesn’t do any different than a thin black garment, in terms of preventing your body from getting hot. Okay, so base layers, I just referenced base layers in terms of like, I definitely worn to think of base layer on a day what I thought was gonna be a lot cooler, and it was very uncomfortable.



It is kind of a running debate, I guess, whether you wear a base layer when it’s hot. And I’ve heard both sides of this, some people say okay, yes, it helps pull the, the sweat away from my body or whatever. And some people say just wear as little as possible, I actually tend to like baselayers up until it gets pretty darn warm. Because I don’t feel like it does handle the sweat a little bit better. Have you come across anything that is more definitive than than that?



Yeah, I like that we’re narrowing this down to baselayers in the heat, right? Because with everything, the answer is really well, it depends, you know, depends on those environmental conditions. In the heat. If you’re working moderately hard, and you’re sweating a moderate amount, then a base layer might be helpful. And the reason for that is we sweat first in certain locations before other locations decide that they want to get wet and join the party. And with a base layer, what happens is we can move moisture from those specific locations, and we can spread that out so that it evaporates better. So if you think you typically start sweating on your forehead first, all right, and if we’re dripping off of our forehead, that dripped water isn’t doing anything to cool us down. Well, it’s the same thing, we tend to start sweating sort of between our shoulder blades at the top of our back first. And if that’s puddling sweat, they’re not doing anything to help us out. But with that base layer on, and I say base layer, because they’re typically made of materials that are going to move sweat better than some jerseys, well, then we can spread that moisture across our back and we can evaporate it from a larger surface area, which means that we can get more cooling because we’re actually evaporating everything. Now the downside with base layers is that they’re moving that evaporation off the skin. And so we talked about how drinking water can help cool you because it takes energy to heat that water up. Well, it takes a lot more energy to evaporate water. But if we do that off the surface of the skin, then that cooling that comes from that is actually less, because we’ve sort of broken that thermal bridge, so to say, and we’ve moved that phase transfer away from the skin into the outer layer of that base layer. Now, in a lot of environments, it’s okay that we lost a few percent of cooling efficiency there because we were actually able to evaporate that water. Now we end up Kaley, you’re, you’re spot on. And this is where sort of intuition or folk wisdom can come in. If we move to an environment where it’s really really hot, and you’re sweating everywhere, the base layer is not helping you anymore, there’s no need to move the sweat because everything’s wet at this point. At that point, we might as well just increase our cooling efficiency by having it evaporate off of your skin. Now there is some technology out there that supposedly helps the evaporation based on the shape of the fibers. And we won’t go into that some really solid research still needs to be done in that area. And so there is potential that base layers can improve evaporation in the future. But for all intents and purposes at this point in time, if you’re struggling up your sunshine Canyon climb and you’re dripping with sweat everywhere, there’s no need for a base layer on zip that jersey and let that cool layer evaporated off of your skin. But if you’re out and you’re riding say on the flats, moderately hard and you’re only sweating from certain areas, a base layer might be able to spread that sweat and help you cool off better.



Well. I’m glad to hear I got one thing right today, which is my use of base layers. I’m a professional bass player where apparently let’s let’s leave everybody with a couple take homes. Rob, why don’t you go first. We’ve talked about a lot of different things today. Let’s try to sum up as quickly as we can, what people can be can be thinking about and doing as they head into the heat.



Yeah, it’s extremely important to remember that he is a byproduct of the work that we do. And it is inevitable that we’re going to produce heat. It is also extremely important to remember that it we need to deal with that heat. And if we don’t, we can end up in a bad place at least a place that might affect our performance and worst a place that might put us into a danger zone. There are methods to deal with that pre cooling, drinking slushies, things of that nature can be very worthwhile for both safety and performance improvements. pouring water over ourselves, if we’re in a dry sort of environment, and our clothes aren’t completely soaked with sweat already can be a very effective manner. And if we are wet, then we ought to just drink that water because it’s not going to be effective if we pour it on ourselves. And the last thing is that when it comes to performance, perception, what we perceive the environment to be and things that affect that are almost if not as important as actual physiological cooling, and that the deception trials that have gone on really help our understanding of thermoregulation within the body.



But again, don’t fool yourself into the danger zone. That would be bad, too






That was inevitable.



That was Trevor.



Trevor, what can you add for us?


Trevor Connor  56:31

So I think Rob did a great job of covering it from the physiological standpoint. So I’m going to cover it a little bit from the racer who has suffered heat stroke more times than he should have, approach and tell you some of the things I’ve learned in racing. First one being acclimate. If you are going and doing a race in extreme temperature, don’t show up the night before and try to race you’re gonna have a really miserable day, if at all possible. If you’re traveling to that race, get there a few days beforehand, or figure out a way to get that acclamation started. Second thing I’m going to say is don’t sit around or over warm up for a race. So I’ve done races where it’s 100 degrees, hundred percent humidity, and you see people sitting there on trainers warming up, all they’re doing is raising that core temperature and getting themselves closer to the point where they’re going to crack or they get to the start line an hour before the race and they sit there in the heat and bake at the tour Tobago, which is 100 degrees and 100% every day, I’ve got it time so that we can leave our nice air conditioned hotel and get to the start line every day, two minutes before the race starts. And we always have an advantage over the people that are there an hour beforehand. Finally, this is probably not when you’re expecting to hear in a podcast, bag, bag and grab and get anything you can this is unfortunately experience I’ve learned. I mean, have people in the feed zones for you with ice water, make sure you’re getting enough bottles, but often you’re gonna find yourself in a race in the heat, where you’re not going to have either broad enough yourself or you’re not gonna have the person in the feed zone. Ask people it especially if they have feeders before the race can one of your feeders hold a bottle for me just make sure you have a lot of avenues to make to get cold fluids to either drink or dump over your head as much as you can. I learned that the hard way back at Rice called tour tuna is 104 mile stage in the heat. The first feeds on my feeder handed me a bottle of water that was one of the other races bottle it had nothing but sodium in it to the point that it was undrinkable. So I couldn’t drink that got to the second feed zone. I was dying. Our feeder had gotten lost. And I didn’t get a bottle. And I was absolutely dying in that race and thinking of all the times I heard one of the bros in the race saying hey, anybody want to finish this? Or anybody need a bottle and thinking why did I not take that?



I have very little to add on surprisingly, because this is a you guys are both experts in the physiology behind staying cool. And I am sort of not. Nonetheless, I will say that from personal experience. The ISOC thing as always has always worked well for me, the ladies pantyhose full ice thing. I’ve definitely used that to great success before and again from personal experience climatized to heat is absolutely vital for me in particular, I’m not a big sweater. And so when I just show up in somewhere hot and have not been somewhere hot, I just I just like I’m just parched, and it’s awful. So yeah, I have very, very little to add other than I think that we’ve had, we’ve given you half a dozen different things that you can do heading into your next hot bicycle racer bicycle ride and hopefully the A little bit more comfortable and ride a little bit better. So that was another episode of Fast Talk. As always, we’d love your feedback. You can email us at webinars at competitor group comm subscribe to Fast Talk on iTunes, Stitcher, SoundCloud and Google Play. Be sure to leave us a rating and a comment. And while you’re there, check out our sister podcast developers podcast, which covers news about news from the weekend cycling. I’m also on that podcast. We generally chat about whatever’s happened in the past week. Shoot the shit and makes jokes. It’s a good time. You can kill a fat fan Fast Talk on slash velonews and on slash melodies. Bass talk is a joint production of velonews and Trevor Connor coaching. The thoughts and opinions expressed on Fast Talk are those of the individual for Rob pickles. Trevor Connor. I’m Kelly Fred’s. Thanks for listening