Welcome to the huberman Lab podcast, where we discuss science and science based tools for everyday life. I'm Andrew huberman, and I'm a professor of neurobiology and Ophthalmology at Stanford school of medicine. Today. I have the pleasure of introducing. Dr. Craig Heller as my guest on the huberman Lab podcast. Dr. Heller is a professor of biology and Neuroscience has at Stanford, his laboratory works on a range of topics including thermal regulation down.
From and circadian rhythms. Today, we talk about thermoregulation, how the body Heats and cools itself and maintains what we call homeostasis, which is an equilibrium of processes that keeps our neurons healthy, our organs functioning well, and as dr. Heller, teaches us, thermoregulation can be leveraged in order to greatly increase our performance in athletics, and mental performance as well. Learning to control your core body. Temperature is one of the most, if not the
The most powerful thing that you can do to optimize mental and physical performance regardless of the environment that you're in. He also dispels, many common myths about Heating and Cooling the body, including the idea that putting a cold pack on your head or neck is the optimal way to cool down quickly. And in fact as dr. Heller tells us it actually can be counterproductive and lead to hyperthermia. It's a fascinating conversation from which I learned a tremendous amount of new information and we didn't even get into the other.
Interesting work that dr. Heller, does on down syndrome and circadian, rhythms and sleep. So we hope to have him back in the future to discuss those topics as you'll soon. See, dr. Heller is a wealth of knowledge on all things, human physiology, biology and Human Performance. It's no surprise. Then that he's been chair of the biology department at Stanford for many years, as well as director of the human biology program. So, if you're interested in human biology and how to improve your performance in any context or setting,
Let accor otherwise, I think you'll very much. Enjoy today's conversation before we begin. I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is however, part of my desire and effort to bring zero cost to Consumer information about science and science related tools to the general public in keeping with that theme. I'd like to thank the sponsors of today's podcast. Our first sponsor is rokka rokka, makes sunglasses and Eyeglasses that are of the absolute highest quality. I've spent a lifetime working on the visual system.
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and the year supply of vitamin D3 k 2 and now, for my discussion with dr. Craig Heller. Great to have you here,
it's good to be here.
It's been a long time coming. I know that. I and many people have a lot of questions about the use of cold. So one of the
Things that's happened in recent years, is that for many reasons people have become interested in things like taking cold showers and taking ice baths for many different purposes, you know, sometimes this is introduced as just a general Health tonic, you know, but other times people get specific about how it can improve resilience, or it can improve one's metabolism. Could you just tell me a little bit about
What happens when I get into a cold shower or an ice bath? What are some of the basic responses at the level of metabolism? Obviously? Psychologically, we don't know exactly it will vary from person to person. But what happens when I submerge myself into an ice bath? If I've never done it before?
Well, first of all, you get a tremendous shock. And what that's going to translate into is a bit of a shot of adrenaline. And I think this is really the
So called benefit, but I wouldn't call it a benefit of the cryo Chambers, you go into a cryo chamber and it's a shock, so you get a shot of adrenaline. So sure, you're going to feel different. When you come out, you had a shot of adrenaline, but it doesn't necessarily translate into any benefit in terms of your physiology or performance and so forth. Now if you take a cold bath or a cold shower, a couple things are happening. One is you're going to stimulate vasoconstriction.
So if anything is going to make it a little bit more difficult for your body to get rid of heat because you're shutting off your Avenues of heat loss. If you're in a true cold bath, the overall surface area of your body is so great that it doesn't matter. If you've as a constricted, you're still going to lose
heat. Okay, so so vasoconstriction, the constriction of is it capillaries vessels and arteries all constrict or
Just one or two.
Well, this is an area of controversy in general. When people talk of vasoconstriction. They talk of the overall skin surface and that is not true. The primary sites of heat loss, which we're going to get into our the palms of your hands, the soles of your feet and the upper part of your face. And the reason these are avenues for heat loss. Is there underlain by special blood vessels and these blood
Vessels are able to shunt the blood from the arteries, which coming from the heart directly to the veins, which are returning to the heart and bypassing the capillaries, which are the nutritive vessels, but High Resistance. So you can tell, when you shake someone's hand, what his or her thermal status is the hands hot, or it's cold.
Do you think that's part of the reason why humans evolved this practice of shaking hands and assessing each other's level of anxiety. We all know that a limb.
Jake is pretty indicative of something. In a firm handshake is indicative of something. As is the crushing handshake for that matter. But
yeah, I really don't know what the evolutionary origin of handshaking is other than to get your hand away from your weapon, the perhaps,
right? But couple of questions before we get into these specialized vascular compartments On The Soles The Palms and and the upper face. You mentioned whole body immersion like into an ice bath or very cold water up to the neck.
Versus a cold shower is is there something fundamentally different about those two? Besides the fact that they both provide their release of adrenaline. Is there anything that's that really important to understand about the difference in the physiological response evoked by the by cold shower versus immersion in
cold? Well, there are differences that are more physical than anything else. So if you are in a cold bath and you're still, you develop a boundary layer if you're in a shower, you can't develop a
Relay,
could you explain what a boundary layer
is? Yes, if you it's best to explain it in terms of a hot bath was everybody's experience that you get into a hot bath. And oh my God, it's really hot, almost painful. And then you sit down and eventually it doesn't feel so hot anymore because the Still Water, which is close to your skin is coming into equilibrium with your skin. So it's like having a blanket on you or an insulator on you. And then if you move around
You disturb that still water layer. You feel the hot temperature again.
I see. So, if I were to get into a cold ice bath, or very cold, right? Body of water of some kind and stay still, I'd likely feel warmer. At least
until I start. You're not going to be losing as much heat. I see where. And then what I do is I all around flail around, then you're going to lose more. He got it. Yeah, but I think getting back to your original question about benefits. You have to keep in mind, whether you're talking about.
About aerobic activity or anaerobic activity. If you're referring to Performance and exercise and so forth. So if you're doing aerobic activity, that you can sustain for a long time, your production of heat is rising gradually, and is being distributed throughout your body. So eventually your body temperature is going to come up to a level that's going to impair your performance. So the benefit of a cold bath or a cold shower before, aerobic
Tivity is that you increase the capacity of your body mass to absorb that excess
heat. I see. So could you say that in a in a rough sense that a protocol that one might use if they're going to head out for a long run. Even on a reasonably warm day. Not not super hot. Right? Well, maybe it is super hot would be to take a cool shower before they go run. Would that be
beneficial or it'll take them longer to get to the sweat point and to heat up
and what will that translate to in terms of?
A performance increase your
well could increase your speed or depends on how you use that benefit? Some people are Pacers. They will go at the same pace and then they will go farther or some people are going to say Pacers and regulators. And I know no Pacers or for Source, they will take that advantage and use it up as fast as they can, so they will go faster but not necessarily farther.
I see. As far as I know not many.
Athletes. At least not the ones that I know are getting into cool bodies of water taking cold showers before they head out to train, but it sounds like there could be a real performance benefit there.
It could be a benefit. I know our we're going to talk about our technology for cooling. But at one point our I don't know if they're using it now, but our cross-country team, when they would go to compete in a very hot place, they would do their warm-up exercises. They're stretching, then they would extract heat before the beginning of the race.
So they I like to think of it as you have greater scope
for heat. Absorption interesting about how long would one need to take one of these showers or cold versions before heading out for a run to roughly speaking. We don't have to get into details because everyone's performance level and regimen is going to be different where they live is. Going to be different etcetera,
right? It's not as long as you think it's minutes, couple minutes. Yeah, for because, what's going to happen is as your core temperature goes down. You will eventually shut off your
Loss and that keeps it from going below normal. So it you can if you're if you warmed up and your temperature has risen by half a degree, let's say it doesn't take more than a few minutes to extract that heat if your
vasodilating. Interesting. And what about for the anaerobic athlete? The strength is
right for the anaerobic athlete and let's say they're doing several several. They're doing several sets.
And how many reps whatever they're doing their core temperatures, not going to rise that fast because it's only certain muscles, which are being used, but the temperature of those muscles will go up.
So it's a local effect. It's
a local effect. Right? So
let's say, let's say for sake of today of made for this discussion. Let's if we assume that the basic workout, even though people do variation on this is, you know, five sets of five or ten sets of ten. So for those listening would be five sets.
10 of 5 repetitions or 10 sets of 10. Repetitions ten by ten five by five. Yeah. So if somebody let's say is doing a large body, compound Movement Like barbell squats, where there are a lot of large body movements hip hinging etcetera, but for instance, the biceps are not there involved, but more or less indirectly, right? So the effect is going to be to heat up the quadriceps. Heat up the hamstrings. He
Up the glutes this kind of thing, right? I see
and then during rest that heat will leave the muscle but it's not fast and certainly the heat can't leave the muscle very fast while you're working out because when the muscle contracts, it squeezes, the blood vessels. And the only way heat gets out of a muscle is in the blood and your muscle metabolism. Can go up 50 or 60 fold during anaerobic activity. That means the heat production in the muscle goes up, 50 or 60 fold.
The blood flow to that muscle cannot go up 50 or 60 fold. So you literally have the capacity to cook your
muscles. So this is a probably an appropriate time to just mention briefly what the underlying mechanism of this is. Could you just, we will return to the specifics of what one can do to mitigate this heating up, but could you just explain the relationship between energy production, ATP and pyruvate kinase? And the role of heat there?
Sure, we don't get something for nothing. So like a steam engine, most of the energy in our food is lost as heat. So we are roughly about 20 percent efficient. So of the energy that we take in our food about 20% of that, can go into doing work and the rest of it is lost as heat. Now. We're mammals. We use that heat to keep our body temperature, considerably above the environment, but
But if you raise body temperature, a few degrees higher you're in trouble. That's hyperthermia. So individual muscles can reach hyperthermic limits before you might experience it in the whole body. So to keep you from damaging, your muscle by hyperthermia, we have failsafe mechanisms. And one of those failsafe mechanisms is an enzyme which is critical for getting fuel.
Other words, the results of metabolism of glucose getting that fuel into the mitochondria, which is making our major coinage of energy exchange ATP. So, that particular enzyme is temperature sensitive. So when the muscle temperature gets above 39, or 38, Vibe, it shuts off and that essentially shuts off the fuel supply to the mitochondria. That's when you cannot do one more
rep, so you may only
Could we say that muscle wanted one component of muscular failure? Is overheating of the must locally, right? Probably other things too.
Well, if you, yeah, if you lack oxygen, but our oxygen delivery is pretty good to the to, to the muscle. If you run out of glucose. Yeah, that's going to impair you but the most immediate most immediate impairment of muscle activity muscle fatigue. In other words is the rise in temperature of the muscle,
interesting.
I want to talk about how that muscle fails locally, but I have this Burning question in my mind that I cannot seem to answer for myself. I'm hoping you can answer it for me. So let's say I'm doing five sets of five with squats. Mmm. I hit fit, muscular failure at a given weight. And according to what, I now know, it's my quadriceps and the muscles Associated mainly with the squat that have failed because of this heat triggering this mechanism triggered by
Either shuts off the muscle, but my biceps are nice and cool. Every time me, they're not there. They're not doing too much work. It's only indirect work. So why is it that I can't set the bar down in the squat rack walk over and do barbell curls with the same intensity that I could. If I were to do those barbell curls, fresh had not having done anything
prior. Well, you will still have a fatigue curve with your upper body. Okay, and that will be
once by any rise in temperature that has been generated by your lower body
exercise. So temperature in both cases is the limiting factor.
It's when one limiting factor, it's one limiting. I
find that amazing. I find that amazing because I always thought naively, that the reason muscles fail is because we quote don't have the strength to do another repetition that word. It's the you like glycogen or some ability to access that glycogen, but of course
We still have glycogen. Oh, it's naive for me to think that because if I wait three minutes and go back, I can do those repetitions again. So the glycogen wasn't restored in that three minutes, right? Obviously, it was their right. So I realized there might be other mechanisms involved sounds like heat is if not, the dominant mechanism that prevents more work.
It's one of them. It's one of them and it's of quick one. It's a fast one so it can happen with let's say you are a really
Reinstate weightlifter. Okay, you may be doing very, very high weights with sets of five or
six. Got to be clear for the audience. I'm not doing very high weights for this itself is not particularly strong. I'd not super weak, but I'm not particularly strong but Craig's are referring in the general sense to with to you. So it why, why is it that if I finish a set of squats? I can't simply cool off my quadriceps by throwing a nice. Cool.
On my quadriceps. Why would why is that? Not the best way to go about
it? Because your body surface is a very good insulator. Okay. We think we don't have fur and therefore we're not insulated but the skin the faccia the muscles underneath underneath that they're all very good insulators. And that's why I said earlier that the way the heat gets out of the muscle is in the blood.
So I want to step through a couple other portals by
by which one might think that heating and cooling would be ideal and then get back to these. Sure. Specialized services on the hands, the feet in the face. So, if throwing a cold towel or ice even ice cold towel, on my quadriceps isn't going to work or standing in front of the fan because I'm insulated from that cool. I can't cool off my blood fast enough. What about drinking 16 ounces of ice,
water. Sure. You can do that, but you can calculate how much heat that can absorb and you can't continue drinking.
Leaders of ice water. You're going to dilute your your blood and have other problems but yes, it will help, sure it will help but it is not doesn't have the full capacity. You will need
what about an ice pack to the back of my neck or to my head, or squeezing the cold sponge over the head. I'm deliberately moving through these options because these are the ones that we see most often. We were actually just watching the Olympic track and field trials last night up in Oregon. I'm a huge track and field fan and there were a lot of
Of there were a lot of sponges on the backs of necks before and between and after events and how good is that or how poor is that as a strategy. Since now we know that he being overheated locally and systemically throughout the body is is a serious limiting factor on performance. Well, you have
to understand something about our Thermo regulatory system. We have a thermostat just like you have a thermostat in your house and that thermostat is in the brain, okay.
Do we know the specific site? Yes.
Yes. It's called the preoptic anterior hypothalamus. It does many things in terms of physiological regulation, but it serves as a thermostat. Now, that thermostat has to have information. It has to have input. Where does that input come from? It comes from our overall body surface where we sense temperature. So, one of the things that can happen when you're overheated is that you can send in a cold stimulus to your thermostat.
At and that's sort of like wanting to cool your house by putting a wet washcloth over your thermostat. Now. It's it's doing the wrong thing. So we've actually had experiences where we've had people exercising, getting overheated and then cooling the body surface and they say it feels great. This is fantastic and their core temperatures going up.
I think this is such an important point for. So I was I was weaned in a laboratory where there were always battles over the temperature in the lab.
So people were always putting ice packs on thermostats for putting fans towards thermostats and trying to play this game. Good to know. We were all being foolish. Even though we were neurobiologist.
Putting a cold towel over my torso or putting ice on the back of my upper back. You're saying could actually heat up my core. It
least decrease your heat loss your rate of heat loss as we're, you're going to raise the issue a little later. I know and that is our natural portals for heat loss. So you can think of the natural Porter's portals for heat. Losses are air conditioners. Okay, thermostats in the brain and the information,
From the thermos to the thermostat is coming from the overall body surface. So what can happen if you, let's say cool, the Torso with a nice vest, you can actually cause vasoconstriction of your portals, your heat loss portals. So that's what impairs the rate at which you're losing heat. Feels good. Now, back to the head, that's really interesting. The major blood flow to the brain, comes up for arteries through the neck. There is a class.
Carotid arteries and there's the vertebral arteries. So, when you put a cold towel around the neck, you're going to be putting a cold stimulus into the brain. Well, that's great for protecting the brain. You want to protect the brain, but it's also going to make you feel cooler than you are. So you will think you're ready to go again quickly when you've just essentially cooled the thermostat.
This is an important Point. There's a lot of
Interest nowadays in people doing marathons and there are even some people do these Ultras ultrarunning which I guess is everything longer than a marathon and go, and go last man standing, that's man. Last woman standing, kind of things. So you're saying that if somebody's hyperthermic, they could trick themselves into subjectively thinking that they are cooling off, but I can go cartel and that they can go further, but their brain could cook.
Well, if they stop the cooling then that hot blood from the body core is going to go to the brain.
Interesting.
Well, many, it's a bit of a tangent. But many people report after long bouts of exercise or even just very intense bouts of exercise feeling a kind of brain fog or mental fatigue. I assumed that was due to lowered brain, oxygenation post exercise, but is it possible that there are some post exercise effects on Heating and Cooling of the brain that might impact cognition or I should say negatively impact cognition
it sir.
Only possible because we know that Rising temperature decreases cognitive capacity mean. You can experience that yourself, you can get on a treadmill and follow your temperature and then just do a simple activity, like, adding and subtracting, you get to about 39 degrees. You can't do that anymore. You can't just calculate how much how long you've been on the
treadmill so that the phrase cool calm and collected is a comment that that's the goal in all
Pursuit.
It's that's right.
So I want to talk about these portals. Yeah, because you've mentioned them a few times before I asked about what the portals are, exactly and how they work and how they can be leveraged for performance. I just there's a question that my neurobiologist self can't resist, but ask
We have this thermostat in the preoptic area of the hypothalamus, which is interesting to me that pre-op. The medial preoptic area is also one that's known to be sexually dimorphic depending on testosterone exposure early in life. Very Etc. Although people should just note that it's not actually testosterone that creates these sexual dimorphism. These difference is actually testosterone converted into estrogen. It's actually estrogen is the effector which is fascinating. Nonetheless. We've got this area that acts as a thermal.
Lestat, and you said it's collecting information from the whole body. Does that mean that there are Pathways as the neuro scientists like, you and I refer to them as these these afferent or input Pathways from the body to the preoptic area. Is there a map of our body in the preoptic area? Because that, yeah, I have to imagine that, you can't have the information just coming from the left shoulder just from the right toe. It sounds like you need a pretty probably a pretty crude map.
Map, but that you need a complete map of the body surface there.
Well, you don't need a complete map in the hypothalamus mean that thermal afferent information that you mention. It also goes to the somatosensory cortex. So, you know, if an ice cube has touched you on the back, but that doesn't necessarily translate into a change in. Let's say you're shivering or or sweating. So the information that's going to the hypothalamus is more integrated.
Rated representation of body temperature.
So, it's sort of an average of what's an acid wash. So if I were to listen, I get hot on a hot day and popsicles when we were in summer camp and went to a sports, camp near here actually and we'd run around like crazy and then we get into the shade if we could. But we were you know popsicles brain freeze or the kids were putting ice cubes down each other's. Yeah, you know Sheriff's or something, but that's an average because other parts of the body aren't exposed. The mouth is exposed to the ice in the
Popsicle case, or the cold cubes, or in the hands, as you said, it feels really good. It feels good, but it sounds like it, it's feels deceptively good because in reality could still be quite warm internally.
Absolutely. Yeah. Interesting. Yeah, you can feel great and have a dangerously, hyperthermic temperature, but I should say that when you get into the danger zone, things get bad fast.
What are some of the symptoms that people could be on the lookout?
For for hyperthermia, essentially,
it's almost ironic that if individuals are transfer transition into heat stroke, they actually vasoconstrictive and they stop sweating and that's a pathological situation. I couldn't begin to explain it. But essentially you are just feeling exhausted, you're feeling miserable.
The heart rate is very high. Your heart rate goes up as your core temperature. Goes up called cardiac drift. So you're just feel rotten, but that's why. Since since it's not a it's not a danger signal that you can translate immediately into do I'm going into heat stroke. That's why people can overcome their bad feeling with motivation to continue going to work.
Or so, there have been a number of high-profile athletic deaths due to heat stroke that were during practice. Not in competition, when people, you know, are really trying to do it, but in practice which shows they were just motivated to push.
So, let's talk about these magnificent portals. That not just humans, but other animals mammals are equipped with. So if putting cold on the neck, or on the
Head or on the Torso is not optimal. What is optimal? And maybe walk us through a theory as to why we would have these portals located where they are and then we can talk about how one might leverage them for performance.
Okay, where are the portals are are in the glabrous skin? Big word? Okay. Glabrous just means no hair. So it's the hairless skin. You say. Well, I'm you know, most of my body is
Hair know your most your body has hair follicles. We are mammals mammals have fur, we've lost the fur, but we still have those that hairy skin phenotype all over our body except except for those skin surfaces where our mammal relatives didn't have fur. So the pads of the feet and for the primates upper part of the face for rabbits, no portions of the ears.
Is the inner surface near our forebears, and at the tongue that bears have big tongues, huge tongues. I
didn't know that either. I've been that close to a Marriott
looking match with a
bear. Not yet.
So, anyway, our mat male mammalian, relatives can't lose heat over their overall body surface. So probably very early on in mammalian Evolution. They evolve these special blood
In The Limited surface areas that don't have fur. And as I said, what these blood vessels are, our shunts between the arteries and the veins arteries and veins are both low resistance vessels. So you can have high flow rate, capillaries, which normally are between arteries and veins are high resistance because they're very tiny.
Okay, is it? Is it fair to say that what I was taught is that blood flows flows from arteries then to capillaries and then too,
Veins and back to the heart. So it's sort of like from the heart through arteries, then through these little capillaries, which are like little less to Aries and streams and then to the veins back to the heart. Is that is that generally
true? Except? Okay.
So what I learned in basic physiology is still, it's still I wouldn't I wouldn't get an F in your class. I know maybe a deer her see but not enough.
So it's excellent.
Okay, and so you're saying that in this glabrous or beneath the glabrous
skin. There are these
shunts and those go directly from
Arteries to vein. So you skip the capillaries? Yeah, and is it actually it as long as I as I say that in the skin, you know, when I feel the pads of my hands, how deep to the surface do these? Do these vessels
reside there below. The obviously the sure that the the epidermis. So if you are warm and you look at your palms of your hands, they are fairly read.
The backs of your hands, aren't you? Don't have these vessels in the backs of your hands. Now, if you take a glass, like a water Tumblr, right? And you grab it, you can see if you squeeze a little bit, the hand goes white. That's because you've shut off that blood flow.
So interesting. I'm going to do that little home exterior. If you're
bicycling on a hot day. You don't want to be grabbing your handlebars all the time. You want to periodically?
Well, this is important. I know you.
You're privy to some really amazing results that we're going to talk about. But I actually heard you say this during this lecture recently, that Stamper held about human performance that we were both part of and you mention this that if you're cycling and you're working hard and you want to be able to do more work. It, we now know why you want to remain cool in order to continue to do work. And if you get too warm, that's bad. That gripping the handle bars too tightly will actually limit your performance, right? And that's probably also,
So true in the Peloton or any other kind of device or the skier or anything, right that? Right. So loosen the grip or if you safely can you want to actually expose your hands right to the world. Now, what about four people wearing gloves? What about the to me? That just seems crazy based on everything you're telling
me, well gloves, definitely impede, heat loss from the hands just as socks impede heat loss from the feet. Okay. So if you want to maximize your heat loss you want to have as thin a protectors as
Bubble on your hands, and course, the feeder more problematical because they have to be using them in certain ways. Some people run Barefoot. Yeah. Well,
yeah, that's it. That's become somewhat popular. It seems like it kind of came in went. They had those toe shoes things, but they looked so ridiculous that I think most people just were willing to take the performance hindrance of regular
shoes. Actually. We had a track coach here at Stanford who for a while was famous for introducing training without shoes running just and he thought it was
Because it changed the posture of the runner. And I think it was just due to the fact that he was increasing the capacity of his Runners to lose heat.
Interesting. Yeah, so heating up at the level of the hands obviously is going to hinder performance. So if I can, how about with running I noticed I ran across the country briefly in high school and not particularly. Well at that but that we were told to run as if we were holding, you know, crackers in our in our fingers or something like very lightly and to keep hands kind of loose. So running like this.
Actually be more beneficial performance than then
for gripping a
phone. Yeah, which is probably what most people are doing now is right. Right? Interesting. And
once I'll tell you experience, I had once I was in Alaska in the winter, and I went out running and I absent-mindedly forgot gloves. And I realized this, after a short period running, because the backs of my hands were aching from the cold, the palms of my hands were sweating and we're
hot amazing.
Amazing. So these compartments are a real thing and you mentioned the upper half of the famous
first. That's where our primate ancestors, don't have fur
and the bottoms of our feet. So let's just take a moment to talk about some of the more amazing results that have been associated with proper cooling of these glabrous skin surfaces.
Let me introduce one more thing. Sure. Hose. You asked earlier about the pouring of water on the head, one of the things which
Not appreciated fully is that the blood which is perfusing, these special blood vessels in the face above the beard line. That's the non-hairy skin
that blood
then returns in the venous supply to the heart, but it actually does it in a very strange way. It actually goes through, what are called blocking on the name. Now take your time. These are blood vessels that go through the
Skull. Okay. And that's why the scalp bleeds a lot. If you cut got the Scout and these blood vessels, which are called. I want to say emergent, but it's not emergent. It's a word that means leaving these blood. Vessels, were primarily thought to be ways that blood is leaving the brain, but when you're overheated the direction of flow and those blood vessels reverses, so the cool blood that's coming from your face.
Region goes into that circulation, and actually is a cooling source for the brain. So you can cool the brain. You can have a cooling effect on the brain by pouring water on on your head.
Interesting. So that practice, which we at least for me. I most commonly associate with Combat Sports where someone the fighter goes to their Corner, they usually sit down on a, on a stool unless they're trying to do some mental Warfare from the corner and
in case they don't even take the seat and their Corner crew will squeeze a glove. Excuse me, a sponge full of cold water over them or that you're saying is somewhat effective in cooling the
brain. Yeah. It's one of the natural mechanisms for cooling the
brain. I want to return to this at some point as well. But is there any known benefit to cooling the brain? In terms of offsetting physical damage, you know, offsetting the negative effects of
And because one of the reasons why Fighters will often get a cult on the back, you know, cold item on the back of the neck or on the head is not just a cool them down. But the theory is that it might offset some of the damage of neurons.
I just can't comment on that. I'm aware of those ideas, but they're controversial. One of the things that you want to do for injury to the brain, is to decrease swelling.
And one of the ways that you decrease swelling in many parts of the body is too cool. It decreases inflammation. It decreases. The blood flow. So, you know, I think it's a really interesting topic and it's something that should be investigated. It's kind of hard to
investigate. Yeah, interesting. Okay, so
I hear these stories and I've seen the data. So I believe the stories maybe tell us a story about an observation that your group has made with respect to anaerobic exercise and and this prop and proper cooling of the these glaber surfaces and we can talk about the technology. Maybe give us the dips example. First, of course, you know, I think most people are familiar with dips. You're supposed to, I guess, get raise and lower your be a raise.
Lower your body raise and lower your body, mass. Usually with your legs dangling down. Sometimes people. Strong enough to attach a weight there and they'll do it's essentially a compound upper body exercise, right? One dip would not be particularly impressive for most people. A hundred would be very impressive. 20 would be impressive for some etcetera. What happens when a skilled athlete comes in and does dips for multiple sets? And then what happens when they cool properly using the
Blabbers skin surfaces.
This was a story that occurred early on in our investigations. When we first made the discoveries that cooling has a benefit to increase your work, volume Your Capacity to do more reps. Okay. So the word got over, I think to the 49ers camp and one of their players. Greg Clark, it was a tight end at the time. He had been tight end at Stanford. He
It or I don't know if he was asked or what to come over and check it out. So, Greg came over and we said Greg. What are you good at? What activity do you like to do? He said, dips, I can do a lot of dips. I can do 40 dips in a first set, and I can probably do 5 sets. That's a usual workout for me. And we said, okay, so he came over to the gym one day and that's exactly what he did. He did 40 dips first set and then maybe
25 and 15 and you know, down down
for. Do you recall roughly what kind of rest periods? He was taking
between us. We and we standardize the rest period, to three minutes because that's what we had set on for cooling as the internet's. A good
long rest period. Yeah,
it is a lot of dips. I got it. Yeah, it's actually a longer rest period than many people would prefer during workouts. They want to make them
about me. I prefer to take as much time as I possibly get.
Yeah, so several days later, he came back and his first said he did, I think maybe 42 a little bit better, but now people were standing around watching. So there was a little impetus, their gem show off. So then it's second set was, I don't remember the numbers, but very much above the second set on the control day. This was after we cooled
his. Okay, so he does all, and when is he doing the cooling? He's, he's
sitting down and putting his hands in the device.
Has that we had built which were cooling. The palms of his
hands for. How long does that Googling take? Can he do it inside of a 3-minute
recipe? Yeah. That's what we were doing. We standardize the the interval for resting or cooling to three minutes. Okay, but the point is he got to his fifth set and he and all of the sets were above what he had done on the previous day. And he said, you know, I'm not tired, I can do another set and then I can do another set, I can do another set.
Do another set. So from one day to two or three days later with cooling. He doubled. The total work volume. He doubled the total number of
dips by adding more sets and more repetitions to
each set. Right? So then he kept coming back for four, more weeks, twice a week and by the end of that month. He was doing 300 dips.
Well, so what percent he tripled? He
traveled tripled.
And as a, here's a, here's a professional athlete at Peak Physical conditioning and he triples amazing, what he can do amazing.
And, in terms of his ability to recover did, was that explored or discussed at all? Because my understanding is that if we caused enough stress to a muscle during anaerobic training, we provide the stimulus for compensatory regrowth Etc. Right, but if we do more work, we essentially
Up the amount of recovery that's needed, or the recovery time. I'm very curious about whether or not he needed a longer to recover between these super performing. Work
out. That's very interesting. That was a major discovery, which we didn't realize we were making at the time. There is this phenomenon. You're referring to as delayed onset muscle soreness Dom's and this is due to those little micro tears and so forth that are happening as we extend our work out.
Capacity volume. Okay. So we've had this experience so many times, that an athlete or anyone will come in to the lab and they will exceed what their previous goals, where their previous expectations and I can always see the words coming out of their mouth. I'm going to be so sore. Tomorrow. They never are interesting and we've actually demonstrated that with a naive group. We had a class physical.
In class and we had half of them. The first days of the class we had to establish their true capacity what they could do. So this is were pretty heavy workouts, for these new recruits and we gave half of them, the benefit of cooling and the other half, not. And then we had them record their subjective levels of delayed onset muscle soreness, and they those that were cooled didn't have significant muscle, soreness,
amazing, and I know.
There are also published results and we will provide links to some of these papers for people seeing similar effects. I should say, similar performance, enhancing effects using bench presses, bench press, or push-ups or other other sorts of things. Maybe you could give us an example from the realm of endurance work or or aerobic work running cycling. Things of that sort.
Well, one of the problems with, for us, is that our equipment now,
It's not really portable mean. It's portable in the sense. You can carry it to the gym, or to the football field, but you're not going to run with your other run with it, like work wiggle bicycle
with it. Although winner. The cooling handles on bicycles coming. Yeah,
it would be that way. Be good. But one, one itinerant activity is golfing, people have put it on their golf carts and
their animal really heat up that much in golf. They do not to be disparaging of the golfers, but the way I conceptualize golf. It's like a swing and then a walk and then
An A, and then a cart ride and then a meal. I probably just offended all the golfers out there.
Well, we what, one time we had we were doing work for the, for the Department of Defense and they wanted to check it out. Whether or not what we were doing was really worthwhile. So they sent out a team of special special ops soldiers to be our subjects and test it out. They were here for a week. So that was a fun wish.
Yeah, there are
Some work with those guys. They're, they're hard-driving, guys. They also know how to have fun. But are they? Yeah, they definitely have if they have an off or as quits, which it's buried deep within their nervous system. They don't like to hit that quit switch.
So the guy who wrote the final report, he gave an addendum to the report. He said, well, I'll tell you this after I've gotten home, it's added that technology. They took the technology with them. They wanted to
tell ya.
That sounds about, right? I said,
yeah. And and using it is added 20 yards to every Club in my bag and that's no effing small
home. Wonderful. So it's allowing people to hit it further hit the golf ball further, right? Interesting. You all right. So for the for the golf players out there in the it then that's the that's a reward. You get back from Craig for all my, my little knocks on golf. I actually, I don't have any knock on golf. I just don't think.
Out as a sport where heating up, is a limiting factor. So, well, since they're getting more out of their Drive. What's what do you think's going on there?
Well, they can be heating up and there were special right there. Wearing like one hot day and so forth. But let me just tell you one more serious story about golfers and that is individuals with multiple sclerosis are exceedingly, temperature-sensitive. I didn't know, so they may still be mobile, but they have to stay in cool locations.
Has and not increase their exercise, to any great extent. But we've had subjects that have with multiple sclerosis who just essentially put the device on their golf cart and they're back out playing golf in the middle of the
summer. Oh, that's great. That's great. Hey does anything that allows people to have normal levels right of you know livelihood and and Recreation is great. We always think about performance as the at these kind of like pecan Elite levels and pushing harder but anything
It allows people to be to be mobile and functional is great. So what's your favorite example of endurance? And feel free to give us the extreme one and then we'll talk about averages to be, you know, make sure we're thorough about averages versus exceptions,
right? We haven't done a lot in field. I mean Outdoors, most of our endurance has been in hot room with treadmill work and so forth. So the very first experiment we had I think.
Maybe 18 subjects just off the street. Maybe we just recruited people in the hallways come on in and do this. And what we found is we could for this group with one trial with and without cooling. We could double their endurance work going on, the treadmill walking uphill on the treadmill in the heat, like maybe 40 degrees ambient temperature,
40 degrees Centigrade. So what does that experiment look like? You're having people walk on an incline. It's really warm. Some people are just going to hit the quit button and say I've had
Enough and get off the treadmill, right? With proper cooling. When are they doing the cooling?
There? They're doing it continuously. I see because in the laboratory we can suspend devices from the ceiling. For example. Now we do have prototype wearable devices. We did them in response to emails from Ebola workers number of years ago. In Sierra Leone. They said we've read about your work with athletes. Can't you do something for us? We're in the person.
Protective gear and we can't be in The Hot Zone for more than 15 or 20 minutes. So that was started us on the challenge of developing, wearable systems, that could go under the PPE. We published that work now, that's
great. They're not missing the military special operators that are out in the desert. And other locations are probably excited about this
technology. Well, once they get once they
get it, it's coming. It's coming. Yeah, you know, I think some people might wonder, you know, if they're all these studies.
Are these incredible results over the years? Why haven't we heard more about it? And I will ask your opinion on that as well. But I'll just editorialize a little bit that the, the best laboratory work and it's practical applications often times requires many studies and oftentimes, there isn't a portal so to speak to get that information out into the technology sector. So there is a company that's developing this technology for people.
People to use right to purchase in use we might as well just tell us now. What is the name of that company and do they have a website? People are going to want to know where can they get this magical technology? Right? And, and is there a poor man's version of it as
well? Well, the company's arteria Arte, riaa, and the website is www.qcnet.com. So cool. MIT is just c000l, MIT Dem it dot.
It's a great website. When I went there. It says that right. Now, the technology is only available to professional sports teams in military. Is that true?
Well, where we stand now, is the new version of the technology is sort of in beta test versions. We got it into the hands of people who had use the technology before. So there's NFL teams that are using, there's college teams. There's Olympics. There's the Navy, Seals Major League Baseball, the
Ba the national tennis Association, they have locations where now they are trying this out and Reporting back. How's it working? How could you change it? How could you improve it? Right? And so forth. So that's that's where we are. But on the website, you can actually sign up for being one who will be able to get one when they are finally manufactured. They're now being made in fairly small Lots because you want to change things to realize how it can be improved.
Yeah, this is Stanford. After all you want to get the technology, right? I like to joke that one of the reasons I like being at Stanford so much is that not only are my colleagues amazing and they're so forward-thinking, but they're all perfectionist. And so that the perfectionist mindset is that it has to be perfect before it can go go live. So to speak. Well, I think there will be a lot of interest. Let's talk about the technology in a little more detail for a moment and then let's talk about whether or not cruder forms of that technology exist, either.
For sake of safety and or performance. So what is the the cool met as I understand? Is it Sam? It's a glove, you put your hand into you, you hold onto a surface and that surface cools, you cools your hand and thereby through this specialized portal cools, your core body, temperature and all the muscles of the body. Subjectively. If I were to do this right now, what I think that it was ice cold, or would I think it was
Just cool. Just cool. I say
ice cold is too cold. So people always ask, why can't you just stick your hand in a bucket of ice water? It's to hold. What that does is that causes reflex vasoconstriction of the very portals that you're trying to maximize the heat loss from. So you stick your hand in cold water when it comes out. It's cold.
You just sealed up all the
heat. Yeah, right. So what I sort of recommend it to someone
One at one point, they said, well, when I'm running, can I just carry a frozen juice can and it will gradually melt. And I said, well, no because that's going to decrease the heat loss from that hand. But if every couple minutes, you switched hands so
it might work. Well, I have a feeling that there are people now doing that as well as trying trying this. So how long in the cool met at the proper temperature? How long are people putting their hands into the mitt
what we once again?
Standardized on three minutes. And part of the reason for that is that the heat low the rate of heat loss is an exponentially declining curve. Okay, and three minutes sort of gets the best part of the curve so you can go longer and get more benefit. But the biggest bang for the buck is in the first two, three minutes,
you mentioned a number of impressive organization, sports teams and Military that are using this. This is not something that I typically see on the
Sidelines of games. Although, to be honest, I haven't looked very carefully. I'm guessing that they are probably keeping the technology somewhat Under Wraps where and how are they doing this? Are they running back to the locker room? I mean that the military special operators are doing their thing, but in terms of the athletes, is it possible? Hypothetically, the athletes are doing this somewhat Incognito,
it's possible, but I really don't know people have mentioned here at Stanford.
Don't see the football team using it. Well, the football team here at Stanford is mostly playing in cold weather. Cool weather night games are cool. Even date games are not very hot frequently here. But when they go to a hot place, like Arizona or Utah, at least our coach Shaw says that they take it with them and that's when they find the benefit, that's when they use it.
Interesting. So, is there a poor persons?
Poor man, or woman's version of this, you mentioned the juice can passing back and forth. You mentioned cooling, the hands. A number of people said to me after learning a little bit about this science and technology that they've experienced some big effects positive effects of cooling by. And I confess, I've done this taking a package of frozen blueberries and just kind of passing back and forth between my hands. Now talking to you, I realized I probably didn't do it long enough. I probably was I was
We doing maybe 30 seconds, passing it back and forth between my hands and then going back into sets. I did see a performance enhancing effect. Absolutely, but I realized I probably wasn't optimizing the protocol. If you were going to give a crude protocol for, let's just say for the gym because with running it's a little bit tricky. But what would that look like if people want to just play with this in some sort of fashion?
Well that if you know,
it's would be experimental sure. And I,
yeah, none of that is converting
controlled. Your idea of frozen peas is a good idea. And I think since there's been no actual study of that. You would have to be you working out. What is the best for you? But one way to figure it out is that if after you hold the cold peas in one hand and you switch it to the other hand, if someone then comes in, feels your hand, is it warm or cold?
If it's cold, it means you've as a constricted if it's warm, it means the hot blood is still going there. Okay, so we do that in the lab
and the key is for it to not vasoconstrict, right? Okay. So so there's a test out there. Folks. If you're going to try this and kind of crude fashion, at least until the cool MIT is available more broadly to the general public. You could assess you want to assess whether or not the your palms actually feel cool to the touch by
He else to us. And if it does, that means you've essentially shut down the port of your ceiling in more heat, which is bad. What about putting this cold pack of some sort on the face or or the feet more the feet? I work out at home. I don't often work out barefooted but I suppose I could like they did in the 70s, you know, when those guys were walking around without shoes and squatting without you without any shoes or socks on, could I put my feet on them, you
could
You has simply had a waterproof used pad and you were circulating cool water through it. You could just put your feet on it. Okay?
Part of the problem is that you don't want. If let's say you have just a cold pack of something. The problem is back to boundary layers again. If you don't have a convective stream of the cooling medium, the heat sink is not as effective because they'll be a boundary layer developed between the heatsink material and your skin now, so that decreases its efficacy. I see
maybe she just for a moment.
About convection radiation and convection and just make that clear. Like, if I put my hands, let's say it's a cold night and I'm at a campfire and I take my hands and I put them out to the fire.
I'm getting radiation.
You're getting radiation, right? Okay, right. And and then if it's a windy warm night, no, I got enough. That's the best example. Give us a good example, of convection
convection. Sure. Is in a cool breeze, you know, the wind chill factor. That's due to convection. Okay, but in terms of heat transfer,
Over between two objects. If you have convection of the medium, whether it's blood on the inside and water on the outside, you increase the heat exchange, if you have convection on
both side, right? So, this is why just planting my fee. On two packages of fruit. My bare feet on two packages of frozen peas. There's really no opportunity for circulation of and therefore, heat transfer, so it's not really optimal, which is a
And
once again, it depends on the surface area to get any benefit at all. We have a study that we published which was investigating the standard treatment for hyperthermia in the field and the standard treatment. The, the it's recommended by medical organizations. Is you take cold packs and you put them in the axilla, the groin, the
axle are, the are the are the
armpit, the armpits, you have the groin.
Which is
thin skin, lots of
vasculature, right? And the, and the neck. So, what we did is we did studies in which we made people hyperthermic, and then we measure the rate at which we could cool them by putting those positions in the, those heat exchange bags in the recommended location, versus on the glabrous skin versus Palms. Souls and face. The, the cooling rate was double. Wow, it. So we put
The same ice packs. The same cold packs on the heat portals rather than the axle of the grind in the face. Wow,
the neck. Wow, so face hands and bottoms of feet will cool. You twice as fast the as we're putting cold packs into your armpits. Your groin, or back of neck.
So, I like to give the analogy of if your car is overheating. Okay, and you have a
Owes, a garden hose. Where should you spray your cooling system? Should you spray the radiator or should you spray the tubes going in and out of the radiator? Well, the rationale would putting these cold packs in the axle of the groin. And the neck is that you're getting close to the major arteries. Sure that's going to be effective, but it's much more effective. If you actually increase the heat loss capacity of the radiating surface, the radiators,
so you cool the Hot Stuff heading toward.
The core.
That's essentially what the standard operating procedure is the that you hit the arteries, amazing and the veins arteries and
veins. I'm going to just tell a brief story that illustrates how almost everybody gets this stuff wrong. And I'm going to use that as an opportunity to ask you about heating. Deliberate heating as opposed to deliberate cooling. So about four months ago, a friend of mine, incidentally guy.
Guy. Who did nine years in the SEAL Teams? Really skilled, cold water swimmer. We went out for a swim in the morning. I'm not nearly even close to the being in the same universe of his output potential. We do these swims. I'm familiar with them. I got enough blubber on me that I'm stay warm enough in the cold Pacific. No wet suits. We do the morning cold swim for about a mile or so. And we brought with us a young kid that I know real. Well that hangs out with us sometimes in trains with us. Who's got very little body.
He's just exceptionally lean despite eating everything in sight, right? Teenager. Great athlete, great kid, great swimmer. So we're out there swimming and at some point we're talking to him and it's clear that he's gone hypothermic. He's slurring his words. He's not doing well. So we get him onto the beach. His teeth are turning yellow. He's quaking, he's not he's got his saliva is taking on that consistency. That's clear. Like he's hypothermic.
And we go to the lifeguard station lifeguard says, okay. Let's get his vitals. Let's do all this. Meanwhile, trying stand next to him, you know, and heat him up by heating up his torso. So there we are like pressing against this guy, our friend trying to heat him up. They get a blanket on him. He's I'm realizing he was barefoot. His face was exposed. Although we did cover his head with the blanket and he eventually came back. We got some warm liquids into him and he he was okay. He was fine.
I know one of those mothers ever going to let him swim with us again. If I ever disappear go missing. It's because of that incident. Anyway, he did great. He recovered his back in the water and doing well, but I realized that pretty much everything from the point where we got back on the beach until he was back. To normal, was we did incorrectly, we heeded, his torso. We left his extremities exposed and
and we assumed we were doing the right thing and the Lifeguard is a skilled lifeguard at a major public beach. So I guess the simple question is did we get everything wrong? Did we get anything? Right and what would have been the better option to heat up a hypothermic person in that or similar situation?
Well, it's interesting. You ask that because that is the way we got into this area of Investigation. I worked on how the hypothalamus.
Alamos, regulates body, temperature neurophysiology. And one day we were having a discussion with a colleague in the department of anesthesia. And he jokingly said to my colleagues said, yeah, you guys think, you know, so much about temperature. I bet you couldn't solve a problem. We have in the recovery room. What's that? Well, the patients come out of surgery. They're hypothermic and it takes us hours to get them to stop shivering. What do they do in there?
Recovery Room exactly what you suggested they pulled in warm blankets, they put on heat lamps and it takes them an hour or two hours to get these patients to stop shivering to bring them back up to. So we say, oh it's a trivial problem. No, it's a hard problem. It's a hard problem because when you're under anesthesia your vasodilate it when you come out of anesthesia, your hypothermic and you vasoconstrictive that makes it very difficult to get heat into the body.
So we got the idea that well, if we could just take one appendage, like an arm and we put it in a environment wrapped in a heating pad and a negative pressure suction that would pull more blood into that. Limb that blood would get heated and it would warm the body up faster. So my colleague built a prototype device. If you couldn't get such a device into the hospital. These days, we were
We're with our anesthesiologist friend. We took it into the recovery room. And, and first thing the patient said, no way you're not gonna put that on my patient, but he prevailed first patient in didn't shiver at all. First, patient was back to normal temperature core temperature in, I think it was eight minutes. Amazing. Nine minutes. Is
this now standard practice. And no, no. No. So this is another example where I don't get upset about the, although. It's
In to know that it's not, but I think that it's yet another case where a fundamental problem exists. There's a science-based solution that makes sense at the level of physiology, engineering, and practice. And yet, it's not being done. Right? And I mean, we could tweet, that's a whole other discussion as to what the limitations are. Well, perhaps in a 900 number of our listeners are in the healthcare and medical profession, as well as military athletes. And just also
Standard other types of jobs, civilians of doing other types of work. It would be wonderful if people understood this. So once again, is there a is there a homegrown technology that people could use if somebody's hypothermic, what is going to be the best way for them to warm up? Is it gonna be holding a nice warm mug of cocoa or something like that, but not not too hot. I guess as they again, the
idea. Yeah. Well, actually, you can go hotter on the
On the glabrous skin, the
hell because they don't dilate
because it takes the heat away faster. Okay, but back to the anesthesia, what you can do is you can use warm pads. They have them in all hospitals. They have circulating water, perfused pad hot water
bottle times the feet. So the typically they'll slide them under your lower back or something like
that. Put them onput them on the feet. Okay sure. That that will do it but turns out that
we discovered through this work that it had nothing to do with the whole arm. It was only the hand and that's when we came to the realization of these special blood vessels. We didn't discover the blood vessels. They're described in Grey's Anatomy, but nobody knew what they were for
our and you mentioned Bears earlier in other Harry animals. Do they have these Aviation? Yeah, as well. And I suppose we haven't defined aviators. We've been pretty good about the no acronyms relay. Va's
is arteriovenous, anastomoses.
So a connection between the arteries and the veins. Yeah,
I actually use this technology. I have a Bulldog, Bulldog Master. He has a very high propensity for overheating because they they're terrible. Dumping heat and Bulldogs are great at pushing themselves to the point of exhaustion or death. It happens. And so now we do what we call Palmer cooling. Sorry. I couldn't help myself where I'll take Costello and lower him into a cool body of water. Just
Just the bottoms of his paws. Although I think animals, instinctually know, to do this and we'll go and stand and bodies of water. They don't often lie down all the way some do. Yeah, but they seem to know that's a great way to cool themselves
off. Yeah. Oh, absolutely. Yeah.
And they get the advantage that their pop, that their palms and their feet are essentially the same thing. So,
we actually built devices for dogs. Did you really? And try them on Iditarod sled, dogs and work beautifully. They had a little
Packs with the equipment and pads on all their feet and, and it worked beautifully amazing. He's
a along the lines of heating, deliberate heating, wearing a knit. Cap is something that you see more of that on the East Coast, you know, people run around Boston and New England. Yeah, with a, with a knit cap. I've always done that that the start of my runs to try and warm up more quickly and then I take it off. I shed layers as I go.
Is that a rational practice the way I just described it? Yeah, because warming up is important to you, you know, there's a certain amount of quote-unquote warming up that's required to lubricate joints, or at least to get the sense that joints are lubricated and to be able to move more easily. Yeah, do you still recommend that people warm up?
Yeah, but I think we're misled by the term warm up. As if the major purpose is to raise temperature. I don't I'm not aware of any.
Eat up on this but I do think that the major contribution is increasing flexibility. So you're going to avoid having damage of joints and tendons and ligaments and so forth, but also the ability of the mitochondria to produce energy can be impaired at lower temperatures and you have to keep in mind that we say our body temperature 37 degrees, but
That's not
true varies across the day.
It's well, it varies in parts of your body. I mean, my hands and arms are not at 37 degrees right now. They're much lower.
So that raises an interesting question. What is the best way to measure core body temperature?
Well, the best core temperature is that what we use is esophageal. So we put a thermocouple up, the nose about two feet down the esophagus. So that is about the level of your heart, not
Jim Moore.
Although I know, I don't know some of those covid swab test, go pretty far. Can't even imagine to go any further. I felt like my brain was getting tickled, but it's Julianne has,
tympanic is a pretty good. So theyíre, dear. It's not foolproof because you have to actually have it aimed properly at the tympanum and frequently. What you're getting is, you're getting sort of a mixture of, Don't Panic plus ear, canal temperature,
and the and for those listening, and for those watching, the tympanic is
Not going to be the pinna that this part of the ear. The outer part of the other tympanic is going to be near the tall heading towards the tympanic membrane. And yes, I'm sticking my finger in my ear because that's where the laser would actually have to go to measure your temperature. So when we're walking into restaurants and other places nowadays in their shining, the laser at our forehead, that's probably giving a pretty crude read out of temperature.
It is. But there's much less insulation between your brain and your forehead skin than there is between your biceps and your arm Skin. So if you're going to
To measure a surface temperature, that's where you would do it. And we do temperatures in the infrared. We take infrared videos of athletes and, and our subjects, and of course, the face lights
up. Okay. So if we're knock, I imagine there's going to be a technology coming soon where you can point your Smartwatch or your smartphone or yourself, and you're going to get a heat mat. Right? Right. That's gotta if somebody out there, hasn't already invented this before. The typical folks outside military, somebody, please.
Event that because I think there is growing interest in temperature based on the work that you're doing. And also for sake of something I do want to touch on which is sleep and Metabolism, although we don't want to open up those portals all the way because we need several days to cover it. Okay. So putting on the, the cap, what about some of the helmets and gloves that are used in typical sports. Do you think that those can be improved in order to improve performance in terms of their?
Ability or keeping Palmer surfaces, open for
instance. Well, you mentioned about the knit cap in cold weather especially and that is significant because you do lose a lot of heat from your head, but it's a constant heat loss. It's not variable like your glabrous skin. So if you decrease that heat loss, you're going to be warmer. So sure that that that has an impact.
Act. Now, in terms of helmets, they should be ventilated. I mean, they should have enough space in them and holes in them. So that air can circulate you don't want to insulate thermally. Insulated your scalp that's going to decrease heat loss. Quite consider book, you know just for a resting individual, brain is about 20% of your metabolism. So that's that's a lot of heat
production. Yeah. Absolutely. I realized it was
Russian that I failed asked earlier. That is it burning in my mind now? And I think is likely burning the minds of some of the listeners, which is so you do this Cooling in between sets in the gym. You got this performance enhancing effect. You don't get the delayed onset muscle soreness, which is great. So presumably the body is adapting getting better as a consequence of being able to do more work per unit time or to go harder in some way.
Of course you get that adaptation. Does that mean that you see a performance enhancing effect, even when you don't cool if you've previously done the cooling workouts. So for instance, let's say I can do ten sets of ten dips, which I like to think I can. Maybe I need to go try. I don't know. If I've done that recently. I do the cooling. I cool for three minutes between sets and let's say, I get to the point where I can do, you know, 2410 sets, 10 sets of 20 repetitions.
And then I don't cool. Will I be able to match or approximate my new better
performance? You keep your games. It's a true conditioning effect. You respond to the increased work volume, by all of those Mech mechanisms. You mentioned May. So you increase the number of contractile elements in your muscles and muscles, get bigger amazing. We had an experiment that involves some of our female students, not athletes, but
Just regular, they were freshmen actually and the experiment was 10 sets of push-ups to muscle failure with or without
cooling. Same regimen, three minutes of cooling in between sets of
push-ups, right? Some of those young ladies reached over eight hundred push-ups.
Now, the total duration of the workout could be getting much longer as a cocktail of doing more
work. No, it doesn't take you longer. Well, minor, I mean, push up is pretty fast. Yes. Yeah.
So you do ten sets the maximum 45 minutes total.
The most lot. That's a lot of push-ups.
That's a lot of push-ups. Yeah, and so the interesting thing is they came in one day and they said dr. Heller. You cost us a lot of money. Why we had a formal dance this weekend. We all had to buy new sleeveless dresses. Nice.
It's a good problem to have, good problems out. Let's talk about steroids. Anabolic steroids. We're heading into an Olympics ever.
Time the Olympics rolls around here, about these cases of people getting popped as they call it, or caught for anabolic steroids. There are some accusations out there. Now there will be a more, they'll this will get, you know, handled in the press and then the various organizations clearly athletes and non-athletes, use anabolic steroids and typically anabolic steroids are of the testosterone. Variety. There are, derivatives Etc. And those derivatives. Do different things and anabolic.
Is androgenic ETC, but typically the idea is, as least as I understand it in talking to some of these individuals is that they allow people to train more because they recover faster. They are able to synthesize more protein because they're basically getting a second puberty because as we all know during puberty, there's a lot of growth of the body. And, of course, there are a lot of negative effects of abuse of these things, and they are banned from,
From various Sports organizations, especially I should mention in Combat Sports. It's this is especially concerning because in Combat Sports, a performance enhancement means that you can harm somebody more than you would be able to otherwise as opposed to in other sorts of sports, just to conceptualize it in and I'm not taking a moral stance on the any of this. I just want to ask you when you compare Palmer cooling to anabolic steroids in terms of,
Gym performance. What do you see?
Well, we do not do research on steroids. But there is a lot of research in the literature. A lot of that research in the strength conditioning magazines is not very scientific. No, okay,
but where it might not even be scientific at.
All. Right, right, but we did do an analysis of reputable papers and we did find.
I think it was probably eight or nine ten studies on bench, press increase in bench, press performance on steroids or not. Okay, the
water males or
females. Well, this were all males, but I'll get back to the females. Okay. The bottom line is that in all of these independent studies. Their rate of improvement was approximately 1% per
week. Okay?
Okay. Now I've just told you about studies in which we've had three hundred percent increase in a month. And so
it's an enormous. Yeah, enormous difference
though. So why would you endanger your health as well as your legal ability to compete with such an ineffective
tool? Yeah. No, I think it's the notion of performance enhancement is a really interesting.
One because people clearly pay attention nutrition. Sleep is now something that I think everybody but especially athletes are paying attention to, right? And I predict that temperature will be one of the more powerful parameters that people are going to be focusing on. Yeah, it because it because of the magnitude of the effects that you're describing and and also because so much of the variability around performance as you mentioned has to do with when you go to a new
Environment, you know, everyone has their home environment, worked out pretty well sleep. Well in your own bed at home, you when you can control everything. Your performance is always great. This is why I think military special operators are particularly interesting group because their whole world is centered around Elite and high performance at with very high risk. High consequence under variable conditions. The essence of their work is variable unpredictable conditions. So you mentioned female athletes
Steroids, I'm curious about this.
Yeah, because everybody has always said to us. Well, you only use male subjects and obviously they have this testosterone background, you know, they have higher levels of testosterone. That's why you get these results. So we did a comparative study on females. We get the same
results, impressive and these are our Stanford athletes or
also know these were not stand for out. They were Stanford students but not athletes will be. We have done of course work on some athletes but in
General we don't do research on our teams are varsity teams. They have their own protocols. They have their own training program. They don't like us together and they they do not work with
some of these folks in the coaches and they're very skeptical with good reason also. And the reason I ask is that when you see these pac-10 or division, one college athletes, and then you see their peers of it. There's there's clearly a difference, right? I mean, they, they are pedigreed at throughout.
Right and more typical folks also have different goals. They may not want to get infinitely stronger or perform more endurance work. So I want to ask you a couple of things about shivering and Metabolism because I think they're very interesting and sufficiently related. So my understanding is that shiver is an adaptation that's designed to heat us up if that we
Brown fat that's in compartments around our body that are activated by shiver or Co activated by shiver. And that shivering is useful for increasing metabolism. Is that true and does it require that cold be the stimulus? So, two scenarios, I'll give you an experiment. I put someone into cold water or some sort and then I make them get out or I have them stand near and then they start shivering. My understanding is that there their metabolism will increase. What if I take some
And I just have them shiver but they're not exposed by cool. It's kind of a deliberate shivering will that also create a substantial increase in metabolism?
Sure. So deliberate shivering without cold, is essentially what happens when you get a fever.
Your set point goes up and your hypothalamus. And you actually, even though your normal body temperature. Your thermostat is telling you, you're too cold, increase your metabolism. So shiver. So sure shivering is is a good way of increasing metabolism, but it only can take metabolism up. Maybe three or four times resting.
Okay, where is exercise
can take you up? Yo, 10
times, got it. All right. I'm gonna ask a couple of more random questions and
Seemingly random do bears actually. Hibernate. Oh, yeah,
the true hibernation. Well depends on how you define true? A bear. Actually. We've done a lot of work on Bears. We do. You
also put the nose thermocouple down in the esophagus. So we implant them surgically. Okay, they're anesthetized when you implant. Yes. What kind of bears are these
black bears? Okay, and did this with colleagues at University of Alaska? And we're analyzing the data now, but what we've done is, we've
We've had now a total of 18 bears and we implant them with EEG EKG, temperature sensors. And sometimes we actually measure their oxygen consumption. These are bears in the wild. These are bears in the wire, but they're brought in to University of Alaska where we keep them in an outdoor enclosure. So they're hibernating in a nest box in an enclosure and we're recording this electrophysiological data continuously for 6 months. Amazing.
How do I get on this protocol? Like, Craig and I are doing some
Together going forward. And then you can slide me onto this
protocol to write something amazing right now. It's a matter of just analyzing the gigabytes terabytes of data that have been collected. So, but anyway, you asked about hibernation. So Bears only go down to about 3334 degrees centigrade and core temperature. And that's been argued that. Well, they can't go lower because they have so much insulation. They're so big. They're surface volume ratio and so forth and that's not true.
They shiver. So if, if we have a day like, minus 40, which you get up in in Alaska, they will go through periods of shivering and maintain a core temperature on 33. 34 now the ground squirrels and the marmots which are small smaller animals. They will drop down to a body. Temperature may be within a degree of the environment so they can go down to one or two degrees, Centigrade just above freezing.
During bouts of hibernation. So they'll stay in hibernation for seven or eight days and they'll come back up to normal body temperature for a day. Then they go back down. And what are,
these are John that day when they're warming up again. Do they do? They
rearrange their nests eat? If they've stored food, some species store, lots of food. Others just depend on their
fat, a former Mentor, my Master's Degree mentor, and a colleague and friend of yours Irving, Zucker at UC. Berkeley. Told me a story once told me a lot of stories.
He's tells great stories. As you know, he told me that when an animal comes out of hibernation periodically that it's a very dramatic thing to observe that. It's not like they wake up and Ian and look around but it's like a little like a complete epileptic seizure. Right? What what's going on sugar? It's just a really dramatic shiver.
So at the low temperatures they cannot shiver because the effect of temperature on the conduction of the month of the nerves in the muscle fiber, so they're shutting down basically.
Down. So there they use Brown fat. So activate Brown fat and then when they get up to a temperature of maybe 15, 16 degrees Centigrade, then the Shivering starts and it gets very, very violent, but they're still
asleep.
Do we shiver in our sleep?
I would imagine we do but it probably wakes us up.
Interesting. So, the brown fat is kind of like kindling.
The brown fat is at issue which has lots of stored energy because it's fat, but unlike our weight fat, our regular fat. It also has lots of these little powerhouses mitochondria and lots of blood supply. So essentially it is a tissue just to produce heat.
That's what it's there for. Now, in these hibernators. There are big patches of brown fat at certain locations that are critical like around the heart. For example, for us. The brown fat is sort of distributed. So for many, many years, it was thought humans, don't have brown fat, but indeed we do. It's just not localized into discrete fat pads. Like it is in ground squirrels marmots.
I don't know why. The the phrase fat pads is so satisfying to say,
Yeah, but it is fat pads. Speaking of fat pads. I was taught that we have by the internet. I should say. I was taught by the internet that we have brown fat between our scapulae in. Our upper neck. Is that truly a source of brown enrichment for brown fat, if you're a ground squirrel, so it's complete. This is all the drawings out there. Okay. So what I'm what I'm hearing you say is that brown fat is actually distributed in past humans. Yes,
distributed.
Along with other fat tissue. It's not as discreet.
So the reason I'm kind of shocked and amused and troubled by this is because there is a somewhat standard protocol in the performance Wellness, whatever World, whatever you want to call it of, putting ice packs on the upper back as a way to stimulate Brown fat thermogenesis. I'm hearing some some
Inhales of concern from from the physiologist. So, tell me why it sounds like that's probably not the best way to stimulate Brown fat activation.
Well, let's put it this
way. You're not attacking anyone. Yes, exactly. Because the whole world believes this, so, it
doesn't. But it may not be totally for seizure false think of what that's doing. If you put ice right there, where your spinal cord is close to the surface. That's where you're going to hit the vertebral arteries. So you're essentially
Putting a cold Source into the brain to the hypothalamus hypothalamus says, you're too cold. So it is going to turn on shivering and round fat. So
would there be a better site?
For sake of activating Brown fat.
Palmer cooling, you know, I I can't say because the activation of brown fat is sympathetic nervous system response. So any lowering of core temperature that will let the thermostat say you're too. Cold is going to turn on sympathetic. Now, people will have perhaps different amounts of brown fat. So in newborn have more Brown fat, and adults and
Newborns can't shiver, correct? I don't know. Okay, that's it. That's what I read. I don't know if strange. I read, I read that in what I believe to be credible sources, but
yeah, it could be, I just don't know. It depends on if it's really newborn. I can agree because you don't have all of the motor pathways connected up yet. That's something that occurs in early days of life and is probably one of the functions of REM sleep, which infants have a lot of
Right, okay, but how to activate Brown fat if you are consistently exposed to cold. So if you live in the Arctic and you go out jogging in the winter, maybe that will increase the amount of brown fat. You have, if you live in the tropics, maybe you have less brown. I don't know. I don't know of any studies which have looked into that.
Okay? Ice headache. Sometimes I'll drink a cold beverage or all eat ice cream in my head will
Brain for letting the brain.
Freeze. And speaking of Special Forces. I talking to, you know, we all see the images of the seals SEAL training, /, screening in Coronado, where they're going in and out of the Pacific, which is very cold, but I know, they also spend some time in the very cold Waters of Kodiak. Alaska, you mentioned Alaska, brain freeze, so-called ice headache is a common occurrence there in those situations, but we all have
Since this we eat ice cream, you get that brain freeze. I can feel it right now. A little bit subjectively. I can induce it what's going on there? And I would always just rub my tongue on the roof of my mouth. Is there something that I'm doing that's functional there just to try and alleviate
it. Good question. The thing is that the roof of your mouth is very close to your hypothalamus. So if indeed it's a popsicle that's giving you the brain freeze. It may be a direct cooling effect from the roof of your mouth.
Put your tongue there. Your insulating the roof of your mouth. I don't know. And I'm
guessing. But what's it? But the sort, what's the source of the brain? Freeze? Is it at vasoconstriction?
It's a, it's a vasomotor change, whether it's constriction. I think it's more likely have a. So an increase in blood pressure, which will essentially caused an expansion of the arteries and activate pain receptors. We don't have pain receptors in the neural tissue in the brain. We have them in the meninges and predominantly associated with the the blood
Vessels the walls of the blood vessels. So if you have something which will dramatically increase your blood, pressure going to the brain, you're likely to get a. We've had some preliminary data even hate to mention this because we have not been able to pursue it systematically, but we've had some experience with people with migraine. That's a. If they use one of our devoy devices to
Eat that the migraine goes away and don't know, you know the item Aryans a lot of people suffer
from migraine. I know there are a lot of different types of migraine right. Been reading a lot about this lately because I get so many questions about migraine, but I hate to say anything. Sure and we'll just underscore this as preliminary and people are have been great about understanding that. When we say preliminary, we mean it has not passed through the the required filters to call it.
Hard
fact, yeah, but you don't, we don't even have a decent data set, right? It's just these
are anecdotal report and of data as and like to do, but I don't even like to call it that because then if you don't want to give it more weight than it deserves, but that's interesting. The ice headache and the increase in blood pressures. Interesting. Because the only thing that I've heard is similar to, it is something that comes from, you know, they have these competitions where people eat these very Hot Chili Peppers, you know, it's kind of fun. Yeah. An ego thing I guess.
Um, for reasons that that escape me that eating really hot peppers and every once in a while some will eat one of these and get what's called Thunderclap headache where a headache comes on extremely quickly and so quickly that it's caused. That is so severe rather that it's been known to cause stroke and brain damage. So these very very, very hot peppers if you're not acclimated to them and maybe even if you are have been shown to cause actually cause brain damage. Yeah, some good evidence for this, I do.
You want to talk about something that we have not touched on yet, which is meet non exercise-induced, thermogenesis. Right? The so non activity Associated thermogenesis and the fidgets errs, right? So the classic work of like Rothwell and stock, and the idea that some people who overeat are burning off that energy by way of shaking their knee or moving around a lot. These are the kind of nerd.
Quote, you know, quote unquote nervous types, but they quoted in those studies huge degree of caloric burn, you know, 800, 2500 calories per day, burned above those who sit rather still does that seem far-fetched? Those are older data, but any any comment on meat or non exercise-induced
thermogenesis, well, I do think it's a pretty straightforward that if you increase muscle activity of any kind, you're increasing your energy consumption.
And your heat production and know, the really extreme example is hyper and hypo thyroidism people that are hyperthyroid or fidgety. And, you know, they have very metabolic rate and they're hot and people that are hypothermia.
Going to heat. So it may not exert much energy to tap your foot, but four times, the amount of energy that is going into the movement is being lost as heat.
That's very interesting, a couple more quick questions. There's a lot of excitement these days or at least usage, these days of so-called energy drinks or pre-workout drinks. Many of these contain thermogenic compound. So caffeine things there.
As a culture now of taking Arginine, nothing's that support Arginine. So, you know, beet juice and l-citrulline things to dilate, the blood vessels. Sometimes this is for sake of increasing blood flow to the muscles during resistance exercise. But a lot of these are thermogenic is to increase body temperature and are some. Is it possible that some of these energy drinks are actually or similar, you know, six espresso or whatever. It is are acting to prevent?
And Optimal Performance or reduced
performance. I don't think that the temperature rise is that I truly don't know, but what it does is it makes you more jittery and you're going to increase that neat that you were talking about viewer has another thing. And that is that when you are exercising, your muscle and it becomes slightly. Hypoxic mean, it's oxygen supply is is
Not enough, the muscle releases adenosine and what adenosine does in the muscle is cause the blood vessels to open up to dilate. So, it's a way of increasing the blood flow to the muscle in there, for the oxygen supply to the muscle.
So happy and is in an essentially, an adenosine
antagonist and
antagonist. So it's, so if the under the strict logic, ingesting caffeine will reduce adenosine release. And we will reduce oxygen.
Utilization of the muscle, right? So that would lead me to believe that motivational support aside, that caffeine will hinder muscular
performance. I would think so, but I can't give you an authoritative answer on that. Okay. We're
just we're just going through the yeah the logic and the gymnastics around that. I think it's a fascinating area that deserves attention because the question of what one can
Ingest in order to perform better to say nothing of, you know hormone augmentation but has often leads back to stimulants. Yeah, and if those stimulants most of which include caffeine of some sort are inhibiting the adenosine system. And the adenosine system is supporting the oxygenation of muscle, then, I would imagine that avoiding the might be the better
option. Yeah. I just I'm not aware of date.
That would. So this is a general phenomenon of adenosine and blood flow. It has of course a different effect in the brain adenosine causes sleep. So caffeine keeps you awake. And if you stay awake, you're going to have a higher metabolic rate than if you go to sleep. So in the thing, as you say, energy drinks, the question is, you know, what really is is in them? But
usually, a cocktail of things I don't take these, I don't like
I'm at all but they're usually a combination of vasodilators. Stimulants caffeine some sort of stand a
source of glucose your
sometimes a source of glucose. And sometimes not, and often times. There are, there are vasodilators and there are compounds that are thought to be so-called nootropics smart drugs, that basically increase acetylcholine or norepinephrine trip transmission, you know, in the in the 80s and 90s the bait.
Three. Agonist like clenbuterol were very popular, but they were all banned. So those are all banned from from low people, use them recreationally, which I do not recommend. There are actually a number of deaths due to dehydration overheating and as well as cardiac effects before we wrap up. I know you've done a ton of work on sleep. I think we're going to have to do another episode about your work on sleep, because the amount of data that you produce there is vast actually. So I first got to know you and your work.
Work late to sleep in temperature. We all here nowadays that it's good to keep the room that you sleep in cool. Keep it dark. I've talked a number of times on podcast episodes about the role of light and shifting a circadian rhythms. I have two questions related to sleep one is, are there any things that may or may not relate to temperature, but that you think are very useful for getting better sleep.
That you don't hear that much about that. People might want to consider or try realizing that there are a lot of reasons why people don't sleep great. But what are some things that you don't hear that much about these days that you wish people knew.
Well, the sleep medicine Community now, puts a lot more emphasis on cognitive behavioral therapy than on pharmacology. So what cognitive behavioral therapy?
Does is it essentially increases your sleep hygiene? So there are certain just general rules. So have a regular bedtime and a regular arousal time. Don't be skipping back and forth all the time
arousal. You mean wake up time. Wake up time. Yeah. Spoken like a true physiology.
Another thing is don't use screens within a couple hours of bedtime because screens are predominantly.
In blue light. And what that does is you mentioned the Circadian system that affects your circadian system that pushes off your circadian stimulus for sleep. Okay. Another thing is, of course, relax being don't work right up till the time. You're going to bed. Take some time to do something relaxing. And then temperature you've mentioned that and for many people a warm bath, you know, is, is really conducive to
To to good sleep. And people are now swearing by a cooler environment for sleep. And that makes sense in terms of the Circadian effect on body temperature. So our circadian clock is affecting our thermostat. So at the time, we go to bed our thermostat is on its way down to a lower set point. So what happens you go to bed and you're feeling a little bit cool, so you pile on lots of
Blankets, and then what happens is you wake up a little bit later in your hot so you throw them off. It's because your thermostat has sent down word. Now, why is it better to have a cool environment? It's better to have a cool environment because it's easier to thermoregulate. So you can go to Europe in the summer time and the hotel room still have these big comforters these down comforters. So, how do you deal with that? You stick out your hands in your legs. Okay,
I've always
Because I have one leg that just gonna hang it. Hangs out of the. Yeah, but
that's their your heat loss surfaces. Right? So if you're in a cool environment, you can take advantage of that. You can take advantage by passively regulating your body temperature. You don't have to arrive get up and wake up and say, oh my God, I got to change the covers or blankets or what have you if you're in a warm environment. What can you do
need to sleep with one hand in the comb it, right? And right now, that's not available yet.
He is not available.
I've never I've never heard about it that way. I've always heard you want to sleep in a cool room or get the room cold? Yeah, but I never realized why that's useful, which is, as you're you're saying that, then you can move your, these glaber surfaces house in and out. You could even also have your wake up under the blanket
completely. Very, very interesting
that finally a rational science grounded explanation for why we need to sleep in a cool room because I always thought well, if your temperature is going down anyway,
Way, why do you have to sleep in a cool room? What about wearing socks, while you sleep? That was big a few years ago where they said, you know, you should put socks on now, I would think that's probably the wrong advice. You
probably. Well. I don't know if it's wrong advice. There is an old old study that was supported by. I think Eddie Bauer the the Sleeping Bag company. And what this study showed, what the study was asking is where what are the most temperature sensitive spots in the body? Where do you feel cold?
And what that showed was, it was the toes.
So exact. So when you sample water with your toe, you see that
it's oh, so the the socks are essentially are promoting thermal Comfort by insulating that area, that's quite sensitive. Now, of course, if it's too warm, you're not going to put socks
on right? Well Craig, thank you so much. You gave so much information. That's actionable and interesting. I know a lot of people are going to be really interested in the
Palmer, cooling technology from cool. MIT. We will be sure to provide resources to the website so that people can register interest. I do encourage people to play around with so to speak the the Palmer cooling technology that we all have, which are, you know, these glaber surfaces and also, just want to thank you for taking time out of your busy schedule, to share this information.
It was fun. It was lots of
fun. I certainly learned a lot and I know a lot of people are going
Learn a lot that's useful to them these questions. Well, fabulous answers. Thank you. Thank you. Thank you for joining for my discussion with dr. Craig Heller. If you're enjoying this podcast and learning from it, please subscribe to our YouTube channel as well. You can give us feedback in the comments section on YouTube. As two topics. You would like us to cover. Future guests and so on. Also, please subscribe to the podcast on Apple and on Spotify, and on Apple, you have the opportunity to leave us up to a five star review and you can leave us.
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