Using Deliberate Cold Exposure for Health and Performance
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Welcome to the huberman la podcast, where we discussed science and science space tools for everyday life. I made your huberman and i'm a professor of neurobiology optio logy at stanford school of medicine. Today, we are going to discuss the use of deliberate cold exposure for health and performance.

Temperature is a powerful stimulus on our nervous system and indeed on every organic system of our body. And cold, in particular, can be leverage to improve mental health, physical health and performance, meaning for in dance exercise, for recovering from various forms of exercise, for actually improving strength and power, and for enhancing mental capacity in order to properly leverage deliberate cold exposure. For sake of mental health, physical health and performance, you have to understand how called impacts the brain body. So today we are going to discuss that. We're going to talk about some of the neutral circuits and pathways, some of the hormones involved.

I, to make IT all clear and accessible, regardless of whether not you have a scientific background or not, we are also going to discuss a very specific protocols that you can apply, which leverage variables like temperature, how cold, how to deliver the cold for instinct, whether not use a cold shower, cold emersion, ice bath, circulating water or still water, whether not you're going for walks outside in A T shirt when it's cold, or whether not you're purposefully using things like cro, if you have access to that or not. One thing I can promise you is that by the end of today's episode, you will know a lot about the biology of thermal regulation, that is, how your brain and body regulates its temperature. You will also have a lot of tools in your arsenal that you can use and leverage toward improving mental health, physical health, reducing information in the body, improving athletic performance, improving mental performance.

I promise, ed, to spell out all those protocols in detail as I go along and to summarize them again at the end. I'd like to make a point now that i'm going to make several additional times during today's episode. And that is that temperature is a very poor stimulus for the brain and body.

That also means that IT Carries certain hazards if it's not done correctly. Now everyone shows up to the table, meaning to protocols with a different background of health status. And there simply no way that I can know what your health status is.

So any time you are going to take on a new protocol that means a behavioral protocol or a nutritional protocol or supplementation protocol, you should absolutely consult a board certified physician before initiating that protocol. I don't just say this to protect us. I also say this to protect you.

If you'd like to see our medical disclaimer, you can go to our shows notes as described there, in fact, that I encourage you to please do that. And in general, when embarking on new protocols, in particular, if they involve strong stimuli, changing temperature or placing yourself into unusual temperatures, I would encourage you to progress gradually. I would also encourage you to not look at gradual progression as the kind of weak version of a protocol.

In fact, today i'm going to discuss a really beautiful peer reviewed study that involved having people do deliberate cold exposure. So they were missing themselves into water up to about their neck. And the water was actually not that cold. There was only about sixty degrees far height, which for most people is pretty tolerable. So nowhere near the kinds of extreme temperatures that one could use in other protocols.

And the interesting thing is, despite that fairly modest cold temperature, by simply extending the duration of time that people were in that water, they experience enormous increases in north chemicals that ought to translate to improvements in focus and mood. And indeed, that's what's been observed in subsequent studies. So again, please see our medical disclaimer in our shows notes.

Please proceed with caution always. Please also understand that the most post stimulus isn't always the one that you experience as the most intense in the moment. In fact, I would encourage you to find the minimum threshold of stimulus that will allow you to drive the maximum benefit from each protocol.

And indeed, I will point out what those resus ought to be today. I'll give you some simple formulas, ages or guides that you can use in order to navigate this extremely interesting and tool that we call deliberate cold exposure. Before we talk about deliberate cold exposure and its many powerful applications, i'd like to highlight a study that I find particularly interesting, that I think you will find particularly interesting and useful.

The title of this study is brief. Ero bc c exercise immediately enhances visual attentional control and perceptual speed testing the mediating role of feelings of energy. Now the reason I like this study is, first of all, it's a fairly large size sample group.

They looked at one hundred and one students. These were college students, and they had two groups. One group did fifteen minutes of jogging at moderate intensity, so when they did measure percent heart rates at seta. But this would be a analogous to zone to cardio, which i've discussed on this podcast before.

Zone to cardio is cardio accused exercise that places you at a level where you can hold a conversation with a little bit of strain, meaning that you can get the words out, but everyone's while you have to catch your breath. Whether if you were to push any harder by any mechanism going faster or on a steeper incline, that said, a that you would have a hard time Carrying out a conversation. So zone to cardio is, uh a common form of describing that level of intensity that they call moderate intensity.

So one group did fifteen minutes of dragging at moderate intensity, which i'm translating to roughly zone to cardio. The other group did fifteen minutes of relaxation concentration, that is somewhat, I came to mindfulness meditation. And then they were analyzed for perceptual speed, visual attention, something called working memory, which is your ability to keep certain batches of information online.

Just imagine someone telling you their phone number, and you have to remember that sequence of numbers in your, in your head for some period of time. That working memory and IT depends very heavily on the so called preferences. Cortical networks, which are involved in planning and action, and they also looked at people's feelings of energy, and they measured that subjectively, how energetic people felt.

Now, the major take away from the study that i'd like emphasize are that the fifteen minutes of jogging group experienced elevated levels of energy for some period of time after they ceased the exercise, whereas the group that did mindfulness meditation actually reported feeling more calm and having less overall energy. Now that's very subjective. And indeed they used subjective measures to analyze energy.

But what gets interesting is when they looked at performance on these various cognitive tasks, and the two tasks that they use were called the trail making tests, they have different version of this. Versions a, version B. I don't want to go into too much detail, but versions a essentially involves having a page of numbers that are distributed somewhat randomly.

So one, two, three, four, five, six, seven, eight and so on, but distributed randomly across the page. And people have to use visual search to circle those numbers in sequence. So this involves visual attention and involves some motor skills, involves the number, things that certainly require energy and focus.

The second test was the trail making test part b, as I mentioned earlier. And this involved also circling numbers in sequence. But interests between those numbers were letters.

So rather than just having to circle off numbers in sequence, they actually had to connect one, then the letter a than two than the letter b. It's set. And remember, these are randomly distributed across the page.

The major take away from the study is that the group that did the fifteen minutes of moderate exercise prior to these two tests showed significant decreases in the amount of time required to complete these tests accurately. That is interesting and indeed surprising, at least to me, because there have been many studies looking at the effects of mindfulness meditation on the ability to focus the key variable. The study turned out to be energy.

This feeling, subjectively measured feeling, I should say, of having more energy, and thereby the ability to focus, especially in these high cognitive demand task. Now they take away from this study for all of us, I think, is pretty straight forward if you are going to sit down to do some work that requires focus and working memory and cognition tention and especially if it's some visual spatial control, meaning you have to search for things on a page, you have to organize things on a page. So this will be writing arithmetic, basically, cognition of any kind.

Fifteen minutes of moderate exercise done prior to that workout could be very beneficial for you. This does not mean that mindfulness meditation would not be a benefit to you. I wouldn't want you to conclude that.

But if you had to choose between doing fifteen minutes of mindfulness meditation and doing fifteen minutes of moderate exercise prior to a cognitive workout, I would say the fifteen months of moderate exercise would be more valuable, at least based on the data in this paper. In many previous podcast, i've talked about the powerful effects of doing things like mindfulness meditation and other forms of n sdr. Non sleep deep pressure.

This could be twenty minute nps, or just lying there quietly with your eyes closer. Yoga edra or nsd r scripts are available on youtube in the way as other places, free of cost of any kind. You just go to youtube, put in n sdr on sleep depressed. Those protocols have been shown to be very beneficial for enhancing neural plasticity.

The changes in the brain and body that encode or shift the neural circuits that allow for memory to change, that allow for learning to occur after a learning about what i'm referring to today in this particular study is the use of moderate exercise in order to increase once focus and attention in order to trigger that neutral plasticity. So the simple sequence here is, get energetic and alert, do that prior to the learning about, engage in the cocoa nive work, or learning about, and then mindfulness meditation, N, S, D, R and so forth should follow. And if you would like to access this paper and like to look more, the details in the paper will be sure to put a link in the shown note.

The first author r is the grand. And again, the title of this paper is brief. Aerobic exercise immediately enhances its visual potential control and perceptual speed testing the mediating role of feelings of energy.

And I also just want to emphasize immediately, I think most people out there are interested in tools and protocols that work the first time and that work every time. And indeed, I think this protocol fit that. bill.

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 sponsors of today's podcast.

Our first sponsor is athletic Greens. Athletic Greens is in all in one of vitamin, mineral probiotic drink. I've been taking athletic Greens since two thousand and twelve, so i'm delighted that they're sponsor in the podcast. The reason I started taking athletic Greens and the reason I still take athletic Greens once or twice a day is that IT helps me cover all of my basic nutritional need to make up for any deficiencies that I might have. In addition, IT has probiotics, which are vital for microbial on health.

I've done a couple of episodes now on the so called gut microbiome, and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With related Greens, I get the vitals I need, the minerals I need and the probiotic to support my microbes. If you'd like to try athletic Greens, you can go to athletic Greens dotcom flash huberman and claim a special offer will give you five free travel packs plus a year supply of vitamin d 3k two ton of data now showing that vitamin three is essential for various aspects of our brain and body health， even if we're getting a lot of sunshine, many of us are still deficient in vitamin d three.

And k two is also important because IT regulates things like cardiovascular function, calcium in the body and so on. Again, go to at let Greens dock calm slag huberman in to claim the special offer of the five free travel packs and the year supply of vitamin three k two. Today's episode also brought to us by element.

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They're all delicious. So again, if you want to try element, you can go to element element dot com slash human. Today's episode is also brought to us by waking up, waking up as a meditation APP that includes hundreds of meditation programs, mindfulness trainings, yoga ede, recessions and nsd r non sleep depressed protocols.

I started using the waking up up a few years ago because even though i've been doing regular meditation since my teens, and I started doing yoga eja about a decade ago, my dad mentioned to me that he had found an APP turned out to be the waking up APP, which could teach you meditations of different durations, and that had a lot of different types of meditations to place the bringing body into different states, and that he liked IT very much. So I gave the waking up up a try, and I too found IT to be extremely useful, because sometimes I only have a few minutes to meditate. Other times I have longer to meditate.

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Again, that's waking up dot com slash huberman to access a free thirty day trial. Okay, let's talk about the use of cold for health and performance. I confess I love this topic because IT takes me back to my undergraduate years when I worked in a laboratory studying cold physiology, its effects on the brain and its effects on the body.

And over the years, i've always kept track of the literature in this area. And indeed, they're been some tremendous discoveries, both in animal models, so in road, things like mice and rats, but also in humans. And today, we're going to talk about both categories of studies, and I ll be careful to point out when discoveries were made in animal models and when they were made in humans.

A key point when thinking about the use of cold as a tool. And the key point is that you have a baseline level of temperature that is varying, changing across the twenty four hour cycle. So any use of deliberate cold exposure is going to be superimposed on that rythm, that circadian rythm, meaning that twenty four hour rythm, the basic control of your circadian rythm in temperature is that approximately two hours before the time you wake up is your so called temperature minimum.

So your temperature minimum is a time within the twenty four hour cycle when your body temperature is at its lowest. Kay, so if you Normally wake up around six A M, your temperature minimum is probably about four A M. If you Normally wake up at about seven A M, your temperature minimum is probably about five a.

It's not exactly two hours before you wake up time. It's approximately two hours before you wake up time. Now as you go from your temperature minimum to the time in which you are going to awake, your temperature is rising slightly.

And then at the point where you wake up, your temperature starts to go up more sharply and will continue to go up into the early and sometimes even into the late afternoon, and then sometimes in the late afternoon and evening, your temperature will start to decline. And indeed, as you approach sleep, your body temperature will drop by anywhere from one to three degrees. And in fact, that decrease in core body temperature is important, if not essential, for getting into and staying in deep sleep OK.

So temperate rises with waking that easy to remember, IT tends to continue to rise throughout the day. And in the late afternoon and evening, your temperature will start to go down, and the drop in temperature actually helps you access sleep. That background, or what we call baseline circuiting rythm in core body temperature, is important to remember because IT helps us frame both the effects of deliberate cold exposure and helps us frame when you might want to use deliberate cold exposure in order to access specific states.

IT also points to times within the twenty four hour cycle when you might want to avoid using deliberate cold exposure if your primary goal is to get to sleep. Okay, so that's the circadian rythm in temperature. Now I just briefly want to touch on thermal regulation at the level of the body and the brain. And this will be very surprising to many of you.

Let's do what's .

called the a dunk in experiment, which is a thought experiment. Let's say, I send you out into the desert heat for a jog or run, and it's very hot outside one hundred and two degrees, or one hundred and three degrees, and you start to movie, you start to sweat. And of course, your core body tempera goes up.

Now, then I offer you a cold towel, maybe a really, really cold tower. And this towel is saturated with the water. You could actually squeeze the water out of that and cool your body off.

And our government can experiment is for me to say, okay, where are you going to place the towel? How are you going to cool yourself off? And i'm guessing that most of you would think that the best way to clear yourself off would be to drop that tower over your head, maybe your neck over your torso, that IT would feel really, really good, and they would cool you off.

Well, that's exactly the wrong approach if you want to cool off. And in fact, if you were to use that approach, your body temperature would continue to increase even more, yes, even more than had you not placed that called tell on your head or your torso. And here is why thermal regulation, meaning your brain and body's ability to regulate your internal core temperature is somewhat like a thermostat.

And that thermostat resides in your brain. So if you think about the thermostat in your home or apartment, if it's too warm in your home or apartment, and you were to take a bag of ice and to put IT on that thermal state, what would thermostat do? IT would register the environment as artificially cool, right? IT would think that the environment was actually much colder than is.

And so as a consequence, IT would trigger a mechanism to further increase the temperature in the room. And you have such a thermostat as well. It's called the media preoptic area of the hypotheses.

The hypothalamus is a small region of brain tissue about over the room of your mouth, and a little bit in front of that. So it's basically right behind your nose and over the room of your mouth. And it's a collection of neurons.

Those neurons have a lot of different functions that include things like the control of aggression, the control of sex behavior, the control of temperature regulation and so on. The media preoptic ario has connections with the rest of the brain or areas within the brain, I should say, and with many areas within the body. IT receives input from receptors in our skin and inside our body that registered temperature and IT acts the thermal debt.

So if the surface of your body is made cool, your media preoptic era will send signals by way of hormones and by way of chemicals that will serve to heat your body up. So what this means is that if you, anna, cool down, the last thing you want to do is to bring a cold surface of any kind tower, or splashing water to the majority of your body surface. I might be very, very surprising to you.

You might say, weight, if I want to call down, I should jump up to a cold lake or something that that's a different thing altogether. What i'll tell you, and we'll get into this in more debt later, is that if you really want to cool down quickly, efficiently, you should leverage particular portals, meaning particular sites on your body where heat can leave your body more readily. And where cooling can have a dramatic and fast impact on your core body, tempera can even save your life.

If you're going hypervisor mic, we're going to talk more about the specific protocols to reduce core body temp ure for sake of performance and avoiding hyperthermia later in the episode. Hyper therm, of course, is a very, very dangerous situation, because while your body can drop in court temperature somewhat and still be safe, you can't really increase your body temperature that much before your brain starts to cook in other organ. Start to cook in.

By cook, I mean, the cells actually start to die. So you have to be very, very careful with the use of heat. Heat stroke is no joke. People die from heat stroke all the time. You really want to avoid that.

One way to avoid that is to cool the appropriate services of your body and the appropriate services in this case, or the upper cheeks, or that, I would say, the upper half of the face, the palm ms of your hands in the bottom of your feet. I've talked about this on the podcast before and in the guest episode, doctor crag heller, my colleague in the biology department, stanford. But just very briefly, these services, the upper half of the face, the bombs and the hands, and the bombs and the feet, are what we call glabrous skin surfaces.

G, L, A, B, R, O, U, S. And those surfaces are unique. And that just below them, the vasculature is different than elsewhere in the body.

Normally, the passage of blood goes from arterial capitals devins. But just beneath the glabrous skin on the bombs of heat, the hands in the upper of the face, you have water called arterial Venus estimates. These are portals, les of blood, that go directly from arteries to veins. And in doing so, allow the body to dump heat more readily, more quickly.

So as IT turns out that if you are to cool the palm s of the hands, the bombs, the heat and up or half of the face, you can more efficiently reduce core body temperature for the sake of offsetting hypothetic and for improving athletic performance and maybe even cognitive performance. So we will return to the specific protocols for doing that later in the episode. I'll give you a lot of details about how to do that.

How to do that without the use of any fancy or expensive technology. There are some technologies that are now commercially available, for instance, ince, this so called cool MIT, that will allow you to do that with maximum efficiency. But i'll also give you some at home methods to do this, either in the gym or on runs or psychic cognitive work.

Okay, so the two key themes, again, are understand that baseline cryan rythm in temperature and understand that the best way to cool the body is going to be by making sure that something cold contacts the bombs your feet, the bombs your hands in the upper half of the face. Ideally all three, if you goes to lower core body temperature quickly and again, just cooling off the back, your neck or the top of your head or your torso with the toe is going to be the least efficient way to lower core body temperature and might even increase body temperature under certain conditions. Okay, with those two points in mind, we can start to think about directed, deliberate called exposure protocols.

And there are a number of different reasons to use deliberate cold exposure. And I want to separate those out for you. There are cold protocols that have been tested in the review studies that are designed to improve mental performance.

They are designed to improve things like resilience or your greatness ss, or your ability to move through chAllenge, or to regulate your mind and your internal state under conditions of stress. And we can define stress very specifically as times when a drena, also called epa and or napa fan, also called na genin, are elevated in your body. Forgive me for the north general and north and f an, a general up, an effort naming later.

I didn't make that up. IT turns out that everyone's in a while. Scientists disagree.

Imagine that. And you'll get mutio scientists naming the same molecule, different things. okay? So epiphone and a gentle are the same thing.

I will use them interchange able, nor up in offend. And our journal are the same thing. I will use those terms interchangeably, nor generalin. And a journal are often go released in the brain and body, so they work as kind of a pair to increase our level of agitation, our love of focus and our desire and our ability to move.

They are often go released from different sites in the brain and body with dopamine, a molecule that is commonly misunderstood as the molecule of pleasure, but is actually the molecule of motivation, reward and pursuit. So dopamine napa nor generally tend to be released together under certain conditions. And today you will learn how deliberate old exposure can be used to cause increases in the release of several, if not all, of these, in ways that can improve your levels of attention and your mood.

But the key point is that your mental state is shifted when you are exposed to certain forms of cold. And many people use deliberate cold exposure specifically to shift their body state as a way to train their mental state so that they can Better cope with stress in real life. And by real life, I mean, when life presents stressful events.

And I will give you specific protocols as to how you can do that, in other words, how you can become more resilient through the use of deliberate cold exposure. Now, because of the ways in which deliberate called exposure can increase, this category of chemicals called the category means that includes dopamine or an f, an f, an f IT can also be used to elevate mood for long periods of time. And i'm going to discuss a specific protocol that has been shown to increase these chemicals anywhere from two point five acts or two hundred fifty percent to as high as five hundred percent, five times over baseline.

Now you might be asking whether that is a good thing to raise chemicals like fan and dopamine to such a great degree, whether or not that healthy for us, whether not that can harm us. But IT turns out that these elevations in european ran dupine are very long lasting in ways that people report feeling, vast improvements in mood and vast improvements in levels of cognitive attention and energy. So by my read of the nature, they seem to be healthy increases in our baseline levels of these chemicals in ways that can really support us or give you a protocol for that.

Now those are some of the mental effects of deliberate called exposure. A deliberate code exposure has also been studied in animal models and in humans in the context of increasing metabolism, even in converting certain fat cells that we call White fat cells, which are the ones where energy is stored, the the ones that we typically think of this kind of beloved fat to beige or Brown fat, which is thermogenesis fat, meaning that IT can increase core body temperature and serves as of the furness by we increase our core metabolism. So with a very broad stroke, I can say that White fat is generally the kind of fat that people want less of.

And bay fat and round fat is generally the kind of fat that if you're going to have fat cells and you certainly need fat cells that you want more of their thermosetting, they help you stay lean. They actually serve as a reserve war for heating your body up if you're ever confronted with a cold chAllenge. So we going to talk about how to use code from metabolism as well.

And of course, people are using deliberate cold exposure to reduce inflation tion, post exercise to reduce inflation tion generally. And people are also using cold to enhance performance in the context of strength training, in the context of endless training. And we'll talk about those data as well.

But where i'd like to start is with mental performance. And i'd like to detail what happens when we deliberately expose ourselves to cold. It's key to point out the word deliberate, if I don't say otherwise. Then throughout the episode, if I think cold exposure, I mean deliberate cold exposure.

And the reason I point that out is that as my colleague gave its speed in the department of psychiatry, stanford says it's not just about the state that we are in, it's about the state that we are in and whether not we had anything to do with placing ourselves into that state and whether not we did that on purpose or not. And what he's really means by that statement is that there are important effects of what we call mindset. Mindset was a topic disgust in the guest episode with ali chrome some weeks ago.

If you haven't seen that episode, a highly recommended. And the science of mindset tells us that if we are doing something deliberately and we believe that it's going to be good for us, IT actually can lead to a different set of physiological effects then if something is happening to us against our will or without our control. Now, this is different than placebo effects.

Placeor effects are distinct from mind's set effects. If you want to learn more about the distinction, please see the episode with ali chrome. But again, and when I talk about cold exposure in this episode, i'm talking about deliberate cold exposure, meaning that you are placing yourself into a cold environment on purpose in order to extract a particular set of benefits. When we talk about deliberate cold exposure, almost always, that means getting uncomfortable.

And one of the most common questions I get when discussing the use of cold for sake of mental and physical performance of metabolic ta, is how cold should IT be, how cold should the water be? How cold should the environment be? And I just will tell you now, and i'm going to say this again and again throughout the epsom, because IT will continue to be true throughout the episode and long after the epsom is over, how cold depends on your cold tolerance, your core metabolism and a number of other features that there is simply no way I could know or have access to.

So I would like you to use this rule of thun. If you are using deliberate cold exposure, the environment that you place yourself into should place your mind into a state of, wow, I would really like to get out of this environment, but I can stay in safely. Now, that might seem a little bit, but let's say you were to get into a warm shower and IT would feel really, really nice.

And you were to start turning down the warm and turning up the cold. There would be some threshold at which you would feel uncomfortable to you. And if you were to continue to make a little bit colder than that, you would really want to get out of the shower.

But you were confident that you could stay in without risking your health, right, without risking a heart attack. Now that's very different than jumping into a very, very cold leg. Or you know, i've seen these images of people that will cut holes into.

You know, frozen over lakes and you'll get into that cold water if you are trained to do that and you have the bright conditions and that a that can be done reasonably safely. But that's certainly not what I would start with. And for many people, that will be too cold.

And indeed, some people can go into cold shock and can die as a consequence, again, to that extremely cold water very quickly. Now that's not to scare away from deliberate cold exposure. It's just to say that there is no simple prescriptive of how cold to make the environment in order to extract maximum benefit for mental or physical performance.

So the simple rule of them them is going to be place yourself into an environment that is uncomfortable ly cold, but that you can stay and safely, okay, you'll have to experiment a bit. And that number, meaning that temperature will vary from day to day IT, will vary across the twenty four hour cycle because of that. The ordinary, meaning that internal rythm in temperature that I talked about earlier, low early in the day, rises into the afternoon, drops at night.

You can actually do this experiment if you like. Try getting into a cold shower at eleven o'clock at night if you want, versus try doing IT in middle of the afternoon. It's quite a different experience.

And by quite a different experience, I mean, it's IT requires quite a different degree of resilience. And leaning into the practice, your willows will have to be higher, I suspect, late in the day as IT compared to early in the day. But that will vary, of course, between individuals as well.

So the most common question I get about deliberate cold exposure is how cold should the water be? And we ve answered that with uncomfortable ly called to the point where you want to get out, but you can safely stay in. The second most common question I get about deliberate cold exposure is whether not cold showers are as good, Better or worse than cold water immersion up to the neck.

For instance, I also get a lot of questions about whether not crowd chAmbers are Better than all the others at, at, at ta. I'm going to make all of that very simple for you by saying cold water emerge up to the neck with your feet and hands. Submerged also is going to be the most effective.

Second best would be cold shower. Third best would be to go outside with a minimum amount of clothing. But of course, clothing that is culturally appropriate, and that would allow youtube experience cold to the point where you would almost want to shiver or start shivering.

Now there are a number of different important constraints that are going to dictate whether not you use one former code exposure or the other. For instance, some people don't have access to cold water emerge. They don't have access to ice, baz, or cold water tanks, cold ocean or cold lake at sea.

In that case, showers would be the next best solution. I do want to emphasize that there been very few, if any, studies of cold showers. And you can imagine why this would be the case in a laboratory you want to control for as many that variables as possible.

So placing people into a cold water immersion or an ice bath up to the neck and insisting that they keep their hands and feet under is very easy to control. IT means that everyone can do essentially the same thing, where, as with cold showers, people are different size bodies. Some people put head under, some people are going to, are going to learn forward, measuring the amount of cold, the water exposure on the body is very hard to do.

And so there aren't a lot of studies of cold showers. But of course, a lot of people don't have access to cold water immersion, so they have to use cold showers. And if you don't have access to both, of course, then going outside on a cold day can be of benefit.

But I will point out that the heat transfer from your body into water is much higher, four times greater, if not even greater, depending on the temperature of the water, in water as opposed to in air. So it's going to be much more efficient to do cold water immersion than anything else. Cold showers after that and put yourself into a cold environment would be the third best thing.

I'm not going to a get into crown chAmbers because they Carry quite a high degree of cost. And again, there aren't many studies of them. So if you access to crowd chAmbers, i'm sure that the crowd chAmber facility is told you about all these incredibly benefits.

And I don't doubt some of those benefits truly exist, but most people just don't have the resources or the access to those who we're gonna crown chAmbers out of today's discussion. And of course, I realize a fourth category of called exposure out there. People who are wearing ice, of us believe not.

Those exist ice underwear. Yes, those exist. We can look for them on the amazon, if you like.

They are putting cold packs in their armed pitcher and their growing or elsewhere in order to stimulate some of the effects have called on mental and physical performance. I'm not going to address those in too much detail today. They can be efficient in certain ways.

But as you'll learn about later in the episode, cooling the palms, the upper face and the bottom of the feet is going to be far more efficient. And unfortunately, I think most of the people that are using ice packs to increase their core metabolite are not aware of the glass or skin cooling and how IT can be a very, very poor stimulus. So we will return to that later, unless I say otherwise.

I mainly going to be focusing on cold water emerge in cold showers. So let's talk about protocols for enhancing mental health and performance using deliberate cold exposure. What happens when we get into cold is that we experience an increase in north, an american in nan release and in a drennan release.

The fact they called exposure, deliberate or no, increases neumann and epa in our brain, in body, means that IT is a very reliable stimulus for increasing nuphar f. That's of an obvious statement. But that obvious statement can be leveraged to systematically build up what we call resilience. Now, when we experience a dresser in life, whether or not it's something bad happens in our relationship or something bad happens in the world, and we feel stress, that stress is the consequence of increases in napa, ein and appendant in our brain and body, very similar, if not identical, to the kind of increases that come from deliberate called exposure.

So deliberate cold exposure is an opportunity to deliberately stress our body, and yet, because it's deliberate and because we can take certain steps, which all describe in a moment, we can learn to maintain mental clarity, we can learn to maintain calm while our body is in a state of stress. And that can be immensely useful when encountering stresses in other parts of life. And that's what we call resilience or grit, our ability or mental toughness, our ability to lean, to chAllenge or to tolerate chAllenge while keeping our head straight, so to speak.

So one simple protocol for increasing resilience is to pick a temperature that's uncomfortable of shower, or called emersion, and then to get in for a certain duration of time, and then to get out now, it's important, understand that people experience different levels of north penetrant and gentle in release when getting into cold water. Some people, because they dread the cold so much, will actually experience american, american, american, american increases even before they get into the cold water or under the cold shower. You may have experiences.

I've certainly experiences. I'm drawing IT. I don't want to do IT, and I have to force myself to do IT. And indeed, epiphone and nor ean effort and its surges can be thought of a sort of walls that we have to confront and go over.

And i'd like you to conceptualize them that way because IT allows us to build protocols that can be very objective and can allow us to monitor our progress in terms of building resilience. So one option is to simply say, okay, i'm going to force myself to get into the cold shower for one minute. How cold? Again, uncomfortable cold, but you can stay and safely.

Or i'm going to get into the ice bath for one minute. Eyes, baas are very cold, inevitably. And what is also inevitable is that when you get into the cold, you will experience a surge in ein f and nor epa.

That's non negotiable because it's immediate by cold receptors on the surface of your body, in your skin and the way that they trigger the release of north and epa effort, not just from the adrenals, from the general lands above your kidneys, but also from regions of your brain, like the locust rulest, which caused increases in attention and alertness, and from other locations in your body, or epifani or epiphone released. In other words, cold is a non negotiable stimulus for increasing epidemical. And nor, even if you are the toughest person in the world and you love the cold, that increasing up an everyone and nor up an effort is going to happen.

So the way to think about north and ef an in this context of building mental resilience is that you have two options. You can either try to extend the duration of time that you are in the deliberate cold exposure, so are going from one minute to seventy five seconds to two minutes and so on, over a period days. Or one way to approach this in the way that I particularly favor, to take the context of the day in the moment into account, meaning we have different levels of britain, resilience on different days.

And depending on the landscape of our life at the time, even the time of day, that we're doing these protocols and start to be able to sense the release of an effect on, excuse me, and not penetrant in our brain and body and see those as walls that we want to climb over in order to build resilience and to start counting the number of walls that we traverse and the distance between those walls as we do deliberate cold exposure. Let me give you an example of the time protocol, because that one is very straight forward. Although I do not think IT is as powerful for building mental resilience, time protocol would be, monday, I do one minute of deliberate cold exposure at a given temperature.

Wednesday, I extend that by fifty percent. And friday, I do deliberate cold exposure for twice as long as I did on monday. And if I were to continue that every week, monday, tuesday, friday, I will continue to either increase the duration or I would lower the temperature and reduce the duration.

This kind of thing very much like sets reps in the gym. Now that option is very objective, right? You could even log IT in a book.

And as you develop the ability to stay in cold temperatures, even progressively colder and colder temperatures, for longer and longer periods of time, you will become more resilient. What do I mean by that? Well, my Operational definition of resilience is that you are able.

To resist escape from the dresser, the cold, by virtue of your willpower, which is really your prefrontal cortex causing top down control on your reflexes in your olympic ics system, in your hypotheses omas, which are basically telling you to get out of that cold water, get out of that cold environment, and in doing so, you are basically getting Better at controlling your behavior when your brain and body are flooded with, or an f, an and up and F N. That's a very reductionist way to explain resilience or grader mental toughness. But it's a reduction this way of explaining that, that is very closely tied to the biology end of the psychology and IT is a fact that no penetrant een ea release in the brain body are the generic universal code for stressor.

There is no unique chemical signature for different forms of stressors. That is the only one, although of course, there other chemicals involved as well. So you could go for time and you could try to reduce the temperature and increase the time over a period of days or weeks. Now that's an attractive way to approach things.

But the problem is that you don't have an infinite amount of room with which to lower temperature, because eventually you will get into temperatures that are either so cold that they are dangerous, or you have to stay in cold temperatures for such long periods that IT becomes in practical. Because personally, you also have to take care of other aspects of your life. You can just sit all day in the ice bath.

Now, for that reason, I favor a protocol in which you build mental resilience and mental toughness through two different types of protocols. The first one involves counting walls. Now, what do you mean by walls? I mean, the sensation of, no, I don't want to do this.

And the idea, or the sensation in your brain, in body, that you actually want to leave that environment and go warm up. Now, again, for some people, that will be even before getting into the ice bather cold shower. So if you are feeling very resistant to getting into the ice baths cold shower and you manage to do that, that's going over what I would call one wall. okay? Then for some period of time, you might actually feel comfortable in the ice bath, cold water or cold shower, and you feel like you could stay there for some period of time that you could stay there for a minute or two minutes, but inevitably the next wall will arrive.

And I would encourage you to pay attention to when that next wall arrives and actually having an awareness, that so called interaction tive awareness, as we call IT, of when that next surge in a generalin eena phone comes, or whether not IT reaches a certain threshold in your brain body that you feel you want to get out and you are able to stay in for even just ten seconds longer. That means you've traversed yet another wall. And if you continue to stay in that cold environment, you e'll find that the next one will come.

And the next one will come now. Eventually, of course, you will get very, very numb, depending on how cold IT is. And you could also place yourself in the danger. So you have to maintain cognitive control, counting these walls, traversin these walls, but getting out at some point, of course.

So my favourite protocol for building mental toughness, A K great, A K resilience, is to take into account that some days just getting into the ice bath or cold shower represents a wall. Some days IT. Some days you get in and you feel like you could go ten minutes.

Other days you get in and you feel like you could only go a minute and setting a designated number of walls before you start. The protocol is going to be very beneficial here. So you say, as long as I can do IT safely, i'm going to do three walls.

Today, the first wall is getting in. The second wall will arrive when he arrives, and the third wall will arrive when IT arrives. And i'll get over that wall, and i'll get out. The next day you might do five walls. The next day, you might do three walls again, but you might lower the temperature.

This gives you tremendous flexibility and indeed, IT gives you much more attitude to be able to use the same temperatures in different ways or to reduce the temperature only a little bit and still get a lot of stimulus, meaning a lot of results out of a given protocol. Whereas people who are just going for temperature and time eventually become cold adapted. They get very, very good at doing three minutes or six minutes or even ten minutes at a given temperature.

And so then they feel like they have to lower the temperature even more and even more, and eventually, they just bottom out. There's nowhere else to go. There's nowhere to get improvements out of the protocol, at least not in terms of mental resilience.

Of course, there are still the positive effects on information and metabolic sector that will talk about in a little bit, but the key thing here is to design protocols that are going to work for you over time and for you very, very Hardy, very, very tough guys and gals out there that can get right into an ice bath or a very, very cold emersion, and you can just grind IT out for six or ten minutes, or you can even do that by remaining peaceful. Well, more points to, but guess what? That's the equivalent of already having loaded up the barbell with six hundred pounds and done your ten reps.

There is not a whole lot more variable space with which to get benefits from that stimulus. And in the waiting room, people understand that you can adjust, for instance, the speed of the movement til you can start combining that movement with preexisting sinitta, with cold exposure, you don't have as much variable space to play with. So if your goal is to build resilience, either go for time as a function of temperature, or what I suggest is to start recognizing these walls as an experience of resistance in you.

And going over those walls, set a number of walls that you're going to go over on a given day and do that at a given temperature and then to mix IT up. And ideally, you might even throw in one more wall at the end if you're really feeling bold and brave because that's gona build out further resilience. But if you want cold exposure to work for you for sake of building up brazilians and mental toughness over time, you're going to want to vary this parameter space in some sort of way.

And you don't have to be super systematic about IT. That's the beauty of this kind of approach because you're relying on the fact that those walls really represent times in which you are forcing your top down control, your prefrontal cortex to clamp down on your reflex and you're learning behavioral control in the context of your body having elevated levels of these categories, nor eon, e and epiphone. And that translate tes to real life in a much more realistic way, I believe, because in real life you are not really engaging and stressors for a given amount of time that you know how along it's going to last, and you know the context, know most stressors arrive in the form of surprises.

We don't like text messages that deliver bad news, information about the outside world or real world, and online interactions that send our system into a state of increased or epa, n and epa. And if you start to think of those as walls that you can tolerate and climb over west, staying calm and clear of mine, then you can really imagine how the ice bath and other forms of cold, the exposure, are really serving to train you up for real life stressors. okay.

The next question that I always get is, what should my mental state be while i'm exposing myself to this uncomfortable yet safe condition of cold? Well, you have two options, and there probably other options as well. One is to try and calm yourself to remain as mentally still as possible.

The other is to lean into that chAllenge and so to grind IT out. And here I have to say that this is a lot like teaching someone to drive on a gravel road. For any of you that have driven on a gravel road, you know that there is no optimal speed for all gravel road that depends on the density, the grave at a.

And so for instance, on some gravel roads, when you start to drive and the dust starts to kick up, your best option is to drive fast and put dust cloud behind you. On other gravel roads, if you try to do that, the dust actually kicked up around the vehicle and makes IT hard to see. And sometimes you have to slow down.

The same thing is true for getting through deliberate cold exposure. Sometimes it's easier to calm yourself. One way to do that is through double inhale through the nose and extended exhale through the mouth, or simply by trying to control your breathing, reduce th Epace o f y our b reathing a nd i ncrease t he v olume o f y our b reathing.

I have to say that everyone experiences are shortening of breath when they get into uncomfortable ly cold water, that is a universal physiological response. Everyone also experiences a thirty to eighty percent decrease in cognitive function, in particular the frontal cortex. The metabolism in frontal cortex goes down. The metabolic meaning, the activity of brainy is associated with stress, and panic goes way up. And so anchoring your mind in cognitive activities as you get into the cold can be very, very helpful for maintaining clarity of mind.

In fact, one thing that I sometimes recommend is that people try and engage in some sort of cognitive exercise while in the cold, not as a form of distraction, but as a way to maintain clarity of thinking and to learn how to do that when the body is flooded with all these chemicals that make us stressed so far. Rens, he could do math problems, and not two plus two equals not, you know, three times three equals nine, but things that require a little bit more focus on attention, working memory and so forth. You could also start to have thoughts that you deliberately impose a full sentence structure on.

That actually quite tough. You could try and recall specific doubts of information that are chAllenging. This is teaching your mind how to they online. Or rather, I should say, this is you teaching your prefrontal cortex how to stay, engage while you have high levels of stress in your body.

Years ago, I had a friend who works in the neurosciences world research news scientists, who was obsessed with this very bizarre sport that I don't necessary recommend at all, which is the combination of boxing and chess. You may have seen this on youtube, where people were boxing around, legitimate boxing around. They are sparring all out often.

And then at the end of the round, instead of resting in the corner, they actually sit down and play chess, and then they go back to boxing and back to chess. Again, not a support that I recommend. But the reason he was obsessed with this is because he studies the impact of stress on cognitive performance.

And what that particular very bizarre sport was doing was toggling back and forth between different states of mind. Now it's used both to increase cognitive clarity for the fighter when they box, because staying calm and clear thinking is very important to winning boxing matches IT not it's not in all outrage. It's a very calculated game of mental chest and physical chest that's quite high stakes, as you can imagine.

It's also used in some circles as a way to teach people how to engage in cognitive performance when their body is simply filled to a stress. So in the boxing chess singapore, the replacement for the cold water is actually the boxing right. It's the thing that supposed to induce the stress is getting hit, the stressful and the risk of getting hit stressed for most people.

So again, if you think about deliberate cold exposure as a way of just systematically and reliably inducing a pen ein or a pen ethon release and delivering stress, well then this idea of maintaining cognitive clarity and actually engaging in cognitive tasks well in the ice bath or cold shower can actually be very beneficial. Even though I might sound a little bit silly, you are really training up your ability to keep your brain working when the reflects is to shut down the parts of your brain that are involved in deliberate planning and thinking. Now, another important aspect of deliberate cold exposure that I rarely, if ever, here discussed, but is vitally important, is whether not you move around or not.

Here's the reason. When you get into cold water and you remain there for some period of time, your body is generating heat. And that heat generates what's called a thermal layer that surrounds your entire body.

So if you stay still, you are actually warmer than if you move around. You can try this the next time you're doing. You're deliberate cold exposure if you're emerge up to the next set there for about ten thirty seconds and be very, very still of body.

In fact, this is the way that most people start to do deliberate cool exposure. They give this very stoic look. They don't blank.

They look very peaceful. Some of them even look tough like that where they make a very even a emotional face. And so that looks like there's they're really tough. But they are so still that, believe or not, they are not providing the most poin stimulus. If they were, you were to move around in that water. What would happen if you break up the thermal layer and that you actually experience that as much colder? So if you really want to push the resilience aspect, or for instance, if you want to use a given temperature that you're comfortable in but that you want to increase the stimulus and you want to get some more benefit for mental resilience training, will then get into the cold water, move your body around continuously, but trying keep your mind still or even do some sort of cognitive ask.

So as you're starting to realize, there are bunch of different variables that you can play with while maintaining the same temperature of water and doing so really keep you in the zone of what should and absolutely has to be safe for you without having to just continually drop the temperature from, say, sixty degrees to fifty five to forty to thirty three, because I eventually, before eventually you're gna bottom out. So if you're one of those people that likes to look tough or really relaxed while you're in the ice bath or cold water, emersion just realized that you're actually cheating yourself out of part of the stimulus. Keep those limbs moving.

And of course, limbs under the water, feet and hands is going to be a more post stimulus than hands and feet out for reasons that should be obvious based on what we talked about in terms of glass or skin cooling. To keep those submerge, move your body peddle, maybe move your knees up and down, pedal your feet. And trust me, it's going to feel a lot caller than where you to remains.

Don't still another very common question is how often to do deliberate cold exposure, it's tough to make a recommendation on that based on any p reviewed study. Although there are a few in humans that point to a threshhold of eleven minutes total per week. So that's total throughout the week divided into two or four sessions of two or three minutes or so.

Now that eleven minute cut off is not a strict threshold and is actually geared more torr's increases in metabolism will get into this little bit later in the episode. But I think the eleven minute threshold, meaning eleven minutes total of deliberate called exposure per week, is a pretty good number to use if you need a number in order to keep you consistent. But as we talked about earlier, some of you are going to be in the ice bath or cold emersion or cold shower for one minute.

Others of you will be in there for ten minutes, depending on how frequent and how high, if you will, those walls of a gentle are coming. So for some of you, getting into a cold shower for three minutes total for the whole week will represent a tremendous achievement in terms of willows and overcoming the resistance to doing that, overcoming those walls. For others of you, three minutes is nothing.

So what do I recommend? I recommend that you get at least seven minutes total per week. But at the point where eleven minutes total per week is very easy for you or is no longer representing a significant mental chAllenge, meaning you're not experiencing many of these all you're excited to get into the cold shower merge, you're going through IT easily, you're cruising basically.

Then I would say either lower the temperature safely, of course, extend the duration safely, of course, or increase the frequency of that. You're doing this perhaps every day or maybe five days a week or three days a week. I personally get tremendous benefit from doing deliberate cold exposure three times a week and using the walls method that I described earlier as my gage for how long to stay in.

And typically that means that i'm staying in for anywhere from two minutes to six minutes per session, and that averages out to about eleven to fifteen minutes total per week. So again, I do not think that you need to be super strict about these guidelines. It's most important when embracing a protocol, a that you do IT safely, but secondarily, that you do IT consistently.

So find what you can do consistently, and then vary the premise that will allow you to continue to do deliberate called exposure consistently, regardless of whether not you have access to a shower called emersion. etta. okay.

So we've been talking about mental effects and the use of deliberate called exposure for sake of building resilience, which I do believe can be tremendously powerful. Look, it's no coincidence that the screening and the training for navy seals involves a lot of exposure to cold water. One could argue that IT is deliberate because they elect to go to budget, but when they get into the cold water at buzz is dictated by the instructors.

And the reason they use cold water exposure as the dresser is that IT does offer considerable ley in terms of duration and temperature, in terms of how you can use IT as a stressor. Whereas things like heat don't offer much variable spaces. As we say, there isn't a lot of room beyond which you start injury or even killing people by using heat.

So there are a lot of forms of stressors out there, but cold is one that we can titre that we can adjust in ways that can allow us to continually build up and or maintain mental toughness. Now deliberate al exposure also has many effects on chemicals other than north and f and the most notably the nurse dulce, or doping, which is involved in elevating our mood, making us feel energized and enhancing our ability to focus. And that has a lot to do with how dopamine engages us in motivated states, tends to narrow our thinking in our behavior into a particular trench of goal directed behavior.

If you want to learn more about depine, you can learn a lot about dopamine in our episode about doping. It's a huberman lab docs. You can find IT.

It's a two and a half hour plus kind of deep dive in to all things, doping, focus, motivation at sea. Deliberate cold exposure has a very powerful effect on the release of dopamine in our brain, in body. And this is one of the main reasons why people continue to do deliberate cold exposure.

Basically, IT makes us feel good and IT continues to make us feel good even after we get out of the cold environment. In fact, some people would say they don't feel good in the cold environment, all stress for them. Afterwards, they feel great.

One of our previous guests, doctor on a lumpkin who's a medical doctor at stanford university school of medicine, she's a close colleague. Vine described the use of dopamine in her book dopamine nation, in incredible book about addiction in dopamine should mention, and the use of dopamine e illicit by cold water exposure by one of her patients. What i'm referring to is the fact that one of her patients helped themselves get and stay sober off drugs by using deliberate cold exposure to increase doping.

So a healthier form of dopamine released, then they were engaged in proud of getting sober. Now the basis for dobin released in response to called exposure is that the category es nor appan, eappen, ean and doping tend to be co released by the same sort of stimuli. But most stresses, and in particular things that evoke stress.

There are feelings of stress internally that we don't like, do not increase dopy. They only increase norphlet f and f and f. But deliberate cold exposure seems to cause a dramatic increase in dupine.

And this has actually been substantiated in a really beautiful study entitled human physiological responses to emerge into water of different temperatures. The first author is strap on, almost certainly pronouncing that poorly, if and if not incorrectly. S R A M E K.

This was publishing the european journal of applied physiology in the year two thousand. Really a beautiful study. I love this study. They took people, and they had them sit in chairs under water, but their head was out, and they were. So they were merged up to the neck in either three different, either of three different temperature.

Excuse me, thirty two degree sales, which is eighty nine degrees very in eight twenty degrees celsius, which is sixty eight degrees very in eight or fourteen degrees sales us, which is fifty seven point two degrees very in height, so not super cold. But then what they did is they measured people's core body temperature throughout. They measured their metabolism, and they looked at serum levels of things like nor appan, ean, ean, ean, dopamine and cordial lt.

Cea, meaning within the blood. So really nice and quite thorough study. There were not a huge number of subjects in the study, but nonetheless was a very thorough study in terms of. The number of variables that they explored. So I just want to briefly highlights some of what they saw or what they observed in the study.

First of all, all the groups were in the water of a given temperature for one hour, which is much longer than most of the deliberate cold exposure protocols that anyone is using at home. I mean, maybe you're taking one hour long cold ours, maybe you're getting into the ice baths for an hour, although I don't recommend that, I think you'd probably get badly hypothermic or maybe you're getting into a cold water emersion for some period of time. But I have a hard time.

Imagine that I would be an hour, and I don't suggest that if it's very cold. So this study on actually somewhat moderately cool temperatures, not what I think most people would consider very, very cold temperatures, but extended the duration for quite a while. So again, thirty two degree ccs, twenty degree celsius, or fourteen degrees sales.

Here's what they observed. The group that was immersed up to the neck and thirty two degrees southeast, that is eighty nine degrees for in height water, did not experience a shift in metabolism, nor a significant increase in dopy, nor up an effort. These other category means the group that was in twenty degree self cius, meaning sixty eight degree far height water for an hour, experience a ninety three percent increase in metabolic rate, which is remarkable given that the water isn't that cold, and yet an hour is a pretty long time to be in there.

And again, IT speaks to the dramatic effect of heat transfer that water has, which I mentioned earlier, as supposed to be out in the air at sixty eight degrees IT would certainly not cause that increase in metaphoric rate. The group that was at fourteen degrees celsius, meaning fifty seven point two degrees for in high water for an hour, experience a three hundred and fifty percent increase in metabolism. So huge increases in metabolism.

Now.

the most interesting data to me, at least in terms of mental effects of deliberate called exposure, were that the plasma a or syrian levels of north an f, an in the blood, increased five hundred and thirty percent. These are huge increases in north an american. So IT suggests that this is a stressful stimulus at least nor chemically speaking, stressful despite the fact that it's not super, super cold.

The forty seven point two degrees here in high fourteen degrees sales is not, you know, it's not a warm environment, but it's not a ultra tro environment, but an hour is a very long time to be in there. The subjects also experienced a two hundred and fifty percent increase in dopamine concentrations, which, while not five hundred and thirty percent as IT was within panettone, is still a very large increase in baseline levels of doping. And what was interesting is that those increases in dopamine persisted for a very long period of time afterwards, even out to two hours.

okay? And they did. They stopped to study after one hundred and twenty minutes of getting out of the a cold. But none of less. These increases in north penev are huge and long lasting, and these increases in dopamine are very large and long lasting. And I do believe that these documented effects and humans explain much of the enhancement of attention and of feelings of well being in mood that people typically experience after doing deliberate cold exposure.

And the reason I say that is that if you were to go back to the episode that I did on dopamine, or you were to go back to the episode that I did with doctor ona yma chi on addiction and dopamine, what you would find is that increases in dopamine of the sort evoked by deliberate cold exposure are actually very similar to the kinds of increases in dopamine that are illicit by things like nickey or from other behaviors that are known to be addictive and bad for us, because they lead to other effects on the brain and body that we simply don't want. And yet, deliberate call exposure provide is done safely, can create similar, if not greater, increases in dopamine that are not just fleeting, that don't just occur during, say, the consumption of some bilateral ous drug or activity, but that are very long lasting, and that can be leverage toward activities other than deliberate cold exposure. So I want to emphasize this, i'm not suggesting that people do deliberate cold exposure for an hour a day.

And unfortunately, there are not many studies yet expLoring how shorter, colder temperature environment exposure, say, one minutes or three minutes or six minutes at, know, fifty five degrees or at fifty degrees, whether not that leads to similar, greater or reduced levels of dopamine in in the brain and body. And yet almost everybody who does deliberate cold exposure will say, yeah, IT was stressful. I didn't enjoy IT or I eventually grew to like IT, but that I always feel Better afterwards.

And then that feeling last a very long period of time. And I think it's almost certain that those experiences that people report relate to these increases in dopa mine and in concert with the cases in north and ever, and also explain the other effect that's commonly reported, which is an enhancement in mental acuity and the ability to focus. Now here we can extrapolate to the study that I discussed at the early part of the episode where I was talking about the use of short fifteen minute exercise, kind of moderate intensity exercise, and how that was shown to increase levels of energy and mental acuity in these working memory, visual attention task.

And there again, we have to assume somewhat because they weren't doing to our chemical measures, but we can reasonably assume that those improvements and cognitive performance were due, at least in part to the increase in category means known to accompany moderate intensity zone to cardio. So what you're trying to see here is a theme. The theme is that virtually any stimulus that delivers more, nor a eeon, ean and dopamine are system, will sharpen in our mental acuity and elevate our mood, and will do so for some period time.

Deliberate cold exposure, IT, turns out, is a very poor way to increase this category, means the category of chemicals, and thereby to improve mood, mental acuity and levels of alertness. And as well next, see, IT not only has that effect, which can be very beneficial for many people in a bunch of different circumstances, but IT also has the positive effects that many people seek in terms of meta lisp in lowing, inflation, tion in the body and other physiological effects as well. And forgive me, I was almost ready to move on to effects of deliberate cold exposure on metabolic and inflation tion and so forth.

But I neglected to point out one of the other very interesting aspects of the study showing deliberate cold exposure can increase in urban african dupine, which is that they observed no significant increases in the stress hormones. Court is all. And that is both surprising, interesting and important, because what that means is that the quality of stress that deliberate called exposure is creating in the body is likely to be one of what we call you stress.

Hang sila, the great physiologist, one a nobel prize for distinguishing between distress, which is stress in the brain and body that causes the release of things like curtis, all along with the other category, m means, and that we experience as negative happening to us and can lead to negative health outcomes. And he distinguished that from you, stress, which was stress that we now understand associated with increases in things like north and f and dopamine. But no increases or minimal increases in cord is all.

And that can lead to positive health outcomes. So IT appears that deliberate cold exposure can create what we call, or what on solid called you stress. In other words, that can create a condition in the brain body in which we are stressing ourselves.

We are training up brazilians, and yet we are creating a neurochemical menu that actually has many health benefits. Now I D like to shift our attention to the effects of deliberate called exposure on metabolism. And i'd like to start by detAiling a study that was performed on humans and published just at the end of last year.

The title of the study is altered Brown fat thermal regulation and enhanced cold induce thermo genesis in Young, healthy winter swimming men. And I should point out that while the study was only performed on male subjects, there's no reason to think that the effects that they discovered would only pertain to men. I would hope that they would also do a study on women some point in the future.

But the effects that they describe, our very basic core physiological processes, what they did is they looked at deliberate cold exposure in this group of Young men, and they use that eleven minute threshold per week. So in other words, they had them get into cold water for approximately eleven minutes per week. And again, that's eleven minutes total per week.

They divided that into two sessions, although in speaking with the first author of this study, doctor Susana sobering, I learned that IT probably not important that IT be two sessions. IT could be three or even four sessions, as long as IT reaches that eleven minute threshold. What they discovered was that by going into these cold environments, in this case, cold water merge up to the neck for eleven minutes total per week, that these men experienced increases in so called Brown fat thermo genesis.

I'll talk more about what that is in a moment. And increases in core body temperature that translate to increases in core body metabolism. Now, the overall increases in core body metabolic that they experienced were not extremely large. They were statistically significant, but they weren't extremely large. However, the changes in Brown fat stores are perhaps what's most interesting about this study.

And i'll tell you why the meta lic increases of deliberate cold exposure are both acute, meaning happening in the short term when you get into the cold and immediately after one does experience in increase in core metabolic, you burn some calories, in other words. And while those might not be very significant increases, or I should say they can be statistically significant, but they are not enormous. The large numbers of calories burned, the longer lasting effects of deliberate cold exposure on metabolic, seem to take place by changes that occur in the types of fat that we store in our body and the way that, that fat impacts our metabolic at other times throughout the twenty four hour cycle.

This actually has a somewhat anodos basis in, particularly in scannable. A I don't speak swedish, nor I speak danish, nor do I speak norwegian, but I do have danish relatives. And they were able to help me defer a common swedish saying, which essentially translates to the fact that in preparation for the summer, they say one should expose themselves to warm environment.

So that one is comfortable in warm environments in the summer. That's one half of this traditional swedish and also danger saying. The other half of this traditional danger, swedish saying, is that in preparation for winter, in order to not feel too cold in cold environment, one should prepare for those in the fall by not wearing a jacket in exposing oneself to cold environments. Now, of course, this is just anecdotal cultural law, but IT actually has a physiological basis, which is by exposing oneself to cold environment on a repeated basis in anticipation of exposure to more extreme cold environment, one can feel more comfortable in those extreme cold environments. And that's exactly what they observed in this study by suburb at all.

The men felt more comfortable in extreme cold if they had trained through deliberate cold exposure, which might not seem surprising at all, but based on what we talked about earlier, whereby deliberate cold exposure evokes this discomfort in this experience of north, an ever release, at least in the short term, then you would say, well, shouldn't a deliberate called exposure also make them feel uncomfortable, like they really wanna get out? Well, that is true with the beginning of a deliberate cult exposure protocol, meaning in the first week or in the second week of the third week. But what one finds, and what you will find if you do deliberate cold exposure consistently, is that you will then become more comfortable at cold temperatures away from the deliberate cold exposure.

So whereas you might have previously been, the person who has always cold in the room with our conditioning, are always seeking a sweater, always anting to bundle up, you will be more comfortable in those cold environments. And the reason for that is well substantiated from this study and from animal studies, whereby deliberate cold exposure converts one particular kind of fat cell, the White fat cell, which is a very low metal bolic output cell. It's basically a storage site for energy in the body fat cells to a different type of fat cell, which is the beige fat cell called beige, because it's actually beige or slightly Brown under the microscope, or even to Brown fat cells, which are very dark under the microscope and dark because they contain my contra and are very metal balick and thermojetics active.

In other words, White fat doesn't burn many calories. It's basically a storage site, is a bank account for energy is filled with lipids, and those lipid ds can be used if the body needs energy and if IT goes into a chord deficit, bash fat and Brown fat act a sort of a fairness or the sort of fat that we would find in a kindle, a fuel that can increase core body temperature. So bash fat and Brown fat is very good at raising our metabolic and helps burn White fat.

Now of course, IT does that only in the context of a color c deficit, but IT can actually help create that color c deficit having more based fat and Brown fat. Can increase your overall core meta list, in other words, the number of calories that you burn per day, and therefore the number of calories that you need to either maintain or to lose weight. The simple translation of this is that getting into cold water for a total of eleven minutes, perhaps more, but at least five minutes per week, divided into two or four sessions, can increase your core metabolic, in part by increasing your beige and Brown fat stores.

And we know how that works, at least in animal models. And there is no reason to suspect that the exact same mechanisms are occurring in humans. The primary way in which deliberate called exposure converts White fat cells into these more methodology, thermojetics active metabolic increasing beige and Brown fat cells is because nor up an elephant released when we get into the cold, binds to receptors on the surface of White fat cells and activates downstream pathways such as ucp one.

So this is an uncoupling protein, one that acts on the ma control meta lisp of cells and increases the meta control output of those cells and the meta control density of those cells. In other words, IT takes a cell that has a kind of a weak engine or no engine for generating energy, although every cell has some might. Contra IT takes cells that have very few meta country a and increases the engine size and have stokes the furness of those particular cells, and actually can change gene expression in those cells.

So that's what's really interesting. Deliberate cold exposure causes increases in north p an, which bind to receptors on the surfaces of White. That cells, which triggers the release of things like uc.

P one. IT also causes the release of things like P P. Gama and co factor pgc. One, i'm going to refer you to a review if you want to learn more about these.

For those of you that don't want to learn more, all you need to know is that the downstream of all that are increases in meta concrete and metabolic and actual genetic changes in the White fat cells that convert them into beige and Brown fat cells. This is especially important for adults because babies and Young children actually don't have the ability to shiver, or they have a less robust capacity to shiver. Very small babies really can't shiver, so they have a lot of Brown fat.

In order to keep them warm, Young children eventually develop the ability to shiver and maintain these Brown fat stores, mainly around the covers, the heart, the upper spine and in the upper back. And it's no coincidence that kids can often run around with a minimal of clothing and be comfortable in environments that adults would be called in. As life goes on, we tend to lose asian Brown fat, but this mechanism that are referring to points to the plasticity of White fat, meaning the ability for White fat to actually converted identity into this metabolically thermojetics enhancing form of asian Brown fat.

So deliberate cold exposure is a terrific way to increase your corn metabolism. And often times critics will say, well, the incase of metabolic isn't that significant, although I do want to a point out again, the ninety three percent and three hundred and fifty percent increases in metabolic that previous study. But critics then will say, well, that doesn't really translate to that big of a coLoring burn during the deliberate called exposure.

But to that you should say, uh, but that's only limiting your optics to just a portion of the effects of deliberate cold exposure, because deliberate code exposure can also convert White fat to based fat and Brown fat and lead to these more lasting increases in metabolism. So for any of you interested in increasing your metabolic and being comfortable in cold environments and or being comfortable in terms of being able to combat experimentally delivered exposure, I do believe as a powerful tool. And there is simply no reason why you couldn't and shouldn't use the same protocols that I described earlier for building resilience to increase metabolism.

Provided you're hitting that eleven minute per week threshold, you ought to be stimulating both mechanism increases in resilience and increases in corner taboo. Sm, as I mentioned earlier, most of the detailed studies on the conversion of White fat to bed fat and Brown fat through the use of cold have been done in animal models, but the human data are starting to emerge. And if you'd like to do the deep dive into these mechanisms, things like uc, p one, p gamma, set a, there's a beautiful review that was published recently in the journal cell, which is one of the three apex journals, nature science cell.

And the title of that paper is at opposed tissue plasticity in health and disease. I love this review. IT has beautiful diagrams detAiling all of the pathways from cold and or an f in through uc p one downstream of things like cyclic amp.

If none of those names meaning thing to you, don't worry about IT. You certainly don't need to know these mechanisms to benefit from deliberate called exposure protocols. If those names do mean something to you or you are interested in expLoring the downstream m effects of deliberate cold exposure, and something else that's really nice that's covered in this paper is how deliberate cold exposure interacts with fasted states, fed states.

I think you'll also find this review very interesting. I don't want to go to deeply into fastest states and fed states right now surface to say that when we are fasted, meaning when we haven't eaten for some period of time, are baseline levels of north and F, N and evenement are already elevated. And so cold exposure at those times ought to have an even greater effect on metabolic and resilience and so on.

So for you festers or your intimate and festers out there, if you really want to get fancy, you can do your deliberate cold exposure when you are fasted. I certainly won't recommend doing IT with a very full stomach in any case. And as I mentioned before on this podcast, intervention, fasting is but one way.

And certainly there are other ways to limit total clerk intake for sake of maintaining or or losing weight, if that's your goal. I know many people are using a benefit from internet fasting, however, and so IT certainly can be combined with deliberate cold exposures in order to get even greater increases in nan and up. And if so, for those of you that are primarily interested in using deliberate holt exposure to increase dopa levels in your brain and body, you can also do a combined protocol whereby you, in just caffeine, sixty to one hundred and twenty minutes before the deliberate cold exposure.

This is based on a study that i've talked about before, entitled caffeine increases straight dopamine E D two d three receptor availability in the human brain. And as the title suggests, this study was done on humans looking at the density and or efficacy y of the dopa receptors in the area of the brain called the striatum, which is involved in planning and action, and also suppressing planning in action. It's involved a very closely with whether not we can engage in behavior and withhold behavior.

The so called go and no go pathways in the brain dopa mean plays a critical role in that and many other things as well, as you now know. So why would you want to adjust caffeine and sixty, two hundred and twenty minutes before deliberate cold exposure? Well, I talked about earlier, dopamine can increase quite substantially in response to deliberate cold exposure.

But dopa mean, on its own, doesn't do anything that has to bind to receptors. And this paper shows quite definitively that ingesting caffeine, in this case IT, was three hundred milligram dose of caffeine, which is about the dose of caffeine in two or three cups of coffee. That depends on the strength of the coffee, of course, but it's not now rage's amount of caffeine that .

increases .

the density and or effect acy of these receptors, which you would allow that dopamine to have it's greatest effect. And for those of you that want to get really, really fancy, I suppose you could do this fasted. So you get the further increase in european f and you get the dopamine increase from the cold exposure, the by in the dopamine. Although I do want to a point out that at some point you start layering together enough protocols that you would be spending your entire day trying to get this dopamine e polls. And I would hope that you had would have other activities that you would engage in.

But if you're getting up in the morning and you're fasted because you have a eat all night and you have a cup of coffee and then sixty minutes later, you'd take your cold shower or two hours later, you do your cold emersion or your cold shower, you would be layer and together, these different mechanisms of dopamine receptors, up and f and so forth, in a way that, at least to me, doesn't seem incompatible with having some other life, like going to school and having relationships at sea. And this increase in dopamine, particularly in this striae m, is not a trivial one. I do want to point out, as the authors do, that preclinical studies have shown that increases in straight al dopamine induced by things like modano, which is used to treat A D, H, D and h treat narcolepsy, is necessary for the wake promoting actions.

What this really says is that just having elevated levels of dopamine from a drug or from an ice bath, or what have you, is not sufficient to get the effects of doping. You really need the receptors to be available, and you need those receptors to be available in the appropriate density. And you need those receptors to be available the appropriate density in the stride om, in particular.

So I think there are a number of reasons why, if it's compatible with the other aspects of your health, because, of course, always you have to consider the sound of background of cardiovascular health and blood that a that ingesting a couple two of coffee an hour before your eyes bath, maybe fasted as well, could be quite beneficial for increasing topmen over quite extended periods of time. A couple of key points that you want to pay attention to. And thinking about deliberate cold exposure and metabolic in the sober study, they also explored the use of sona and how to use sona, meaning deliver heat in conjunction with cold.

We are going to do an entire episode about the use of heat for health and performance. So that is not the focus. Now however, IT does raise an important point that we do need to address at this moment, which is if you are using sona or if you are taking warm showers or if you are simply using deliberate cold exposure of any kind, should you get into the heat afterward or before or not at all? And this is where we can point to the so called solid principle.

I call IT, the sobering principal. The sobering principal named after first author of this study I referred to earlier doctor Susana soberly in science, IT is appropriate to take a key piece of data and call IT a principle, if in fact, IT translates to something larger, which I believe IT does. IT is. Generally not appropriate for people to name a principle after themselves, although there are a few scientists that have done that. So I have named at the suburb principle, but I did that to give IT appropriate credit to dis.

And a sobering who discovered that and pointed out, quite appropriately, that to achieve the greatest increases in metabolic through deliberate cold exposure, you want to force yourself to reheat on your own after the deliberate cold exposure, meaning you wouldn't want to go from the cold shower to a hot shower or from the cold shower to a sona. Rather, if you were going to start with a hot shower, or you are going to start with a sauna, that you would end with the cold and then you would reheat naturally. Now, I personally take a cold shower a few times a week, or do cold version.

And because i'm not specifically focused on increasing metabolism, although I probably should be, that's not what i'm using IT for. Now I will take a hot shower afterwards. And in doing so, i'm short circuit some of the further metabolite increases that I would achieve where I would just end with the cold.

So the sober principle is if you want to increase your metabolic and with cold, and we can take this a step further and say, if you want to use deliberate cold exposure to increase metabolic, that you should make sure that you get to the point where you shiver. And the reason for this is that there are a series of studies, but in particularly one study, publishing the journal nature, excEllent journal in the year two thousand eighteen, showing that deliberate cold exposure that evokes shivering from the muscles causes the release of a molecule called second eight from the muscles. And that second eight plays a key role in activating Brown fat thermo genesis, which you now have heard about and understand as critical to the increases in metabolic caused by deliberate cold exposure.

So what this means is, if you want to increase your metabolic and on cold, that's a sober principal. And as best you can try and get to the point where you are shivering, either when you are in the cold exposure or immediately afterwards. Now one efficient way to do this is to, for instance, you could get into the cold shower for a minute or two minutes or three minutes, uncomfortable ly cold, but safe to stay in.

Remember that our general relief thum then turn off the water and stand there, make sure that your not holding yourself close to your body, you're not hug yourself to try and keep yourself warm, but rather your limbs or extended at your side. And then if that fails to induce driver, then to turn on the cold water again and then turn IT off again. So alternating perhaps a minute to three minutes of cold exposure, followed by a minute to three minutes of drawing out in air and going back into the cold exposure at sea.

I can tell you this from experience. This is a pretty brutal protocol. If you have never tried getting into an ice bath or cold water emersion or cold shower for one minute, and then getting out and trying to stand there with your arms extended in cool or cold air for one minute, and then getting back the cold shower or water emersion, you are in for an experience.

Because even for those of you that are pretty shiver resistance, you will find that IT is much, much harder to get out of that cold water and stand their arms extended and drawn off by evaporation, which further draws heat from the body. Then IT is to rap yourself in a get in a warm shower, a sona. So there's certainly no requirement to end on cold.

There's certainly no requirement to endure shiver. But if your primary goal is to induce increases in metabolism, both in the short term and in the long term, following the cold exposure, will, then you want to end on cold and you want to find a way to shiver, provided that the level of code that you're exposing yourself to is still safe for you overall. So up until now, i've been talking about deliberate called exposure as a post stimulus for the release of north and afraid, the brain and body.

And indeed, IT is. But the way of been describing IT has been in the context of circulating plasma levels of north pan effort, meaning circulating within the blood. What I haven't mentioned, but is absolutely true, is that the fat sells themselves, actually receive input from neurons.

So there are neurons that released north, and even in response to cold, directly into the fat. So I want to give you this picture of how the architecture of all this works, because I think I can help you navigate and indeed build Better deliberate cold exposure protocols. Your dream al gLance released, or epiphone and epinephrine, your brain has sights within IT, like the locust sauce that released no up and up and happen, happen. But there are also neurons within your skin, that sense, cold and other neurons that can directly release north and everyone into the fat stores and cause those White fat cells to convert to beijing Brown fat.

And I think this particular aspect of our physiology often overlooked in studies, and when people say, oh, well, the cases in metabolic rents that great, the circulating levels of north, an ephron, those are very large, but they're very transient and so on, that fails to understand that neurons that actually sense cold are in a position to communicate via other neurons directly to the fat cells and released or up an effort into those fat cells, which, as I pointed out earlier, set off a huge set of a media and long term cascades of even gene expression changes. So the picture that i'd like you to have in your mind is that when you get into the cold, yes, of course, you experience that as a experience of, I don't want to do this, i'm going to overcome this. I'm going to climb over these mental walls that represent a journal and released in my brain and body, but also that your fat cells are receiving signals, nor up an effort, signals that are changing those fat cells in the way that they metabolite energy.

Now i'd like to shift our attention to the use of deliberate cold exposure for sake of physical perform. And there are a lot of opinions out there about the use of deliberate cold, whether not IT should be done, for instance, before or after exercise, whether not if done immediately after strength training or hypocrisy training, meaning training, design to grow muscles or make them stronger, whether not IT can inhibit that process, and so on and so forth. I think today in looking over the literature and trying to bring forward the simplest and most straight forward and yet scientifically grounded protocols, we can set up some general guidelines that will allow most, if not all, of you to still extract the benefits of deliberate cold exposure on physical performance without getting too neurotic about the exact timing.

But for sake of discussion and because it's a prominent theme in many online communities, let's just start with the big one out there. Meaning the question of whether not doing an ice bath or doing deliberate cold exposure or taking a cold shower after strength slash hyperdrive py training, meaning training designed to increase strength or and or, I should say, the size of muscles will somehow short circuit or diminish that process, whether not IT will reduce or eliminate those strength gains and hypothesi gains. And the short answer that I was able to arrive at on the basis of a review article that i'll talk about in a moment and some other studies as well, is that if your main goal is hyper phy and strength, IT is probably best to avoid cold water immersion and ice bath emersion in the four hours immediately following that strength and or hyperdrive phy training.

Again, if your main goal is to achieve hyperdrive phy or strength or some combination of those, probably best to avoid cold water immersion up to the neck or ice bath emersion up to the neck immediately after strength and hybrid phy training and extending out to about four hours after that training. If you're really neurotic about this, then perhaps you'd want to move the cold water exposure to a different day entirely. But IT all depends on how noodles ally attached you are to getting every last bit of strength and hypothesis.

And if that's your goal, terrific. Well, then probably moving the cold exposure four hours or more away from that training is going to be necessary for you. Now you'll notice I did not talk about cold showers. And the reason I did not talk about cold showers is that there simply are not very many studies of deliberate cold exposure through cold showers for the reasons I talked about at the beginning of the episode. It's hard for me to imagine that taking a brief cold shower after a strength or hyperdrive phy training session would completely reverse or short circuit the effects of that strength and hypertrophy training but again, if you're noodle ally attach to getting every last bit of strength and hypertension y out of your training sessions, then by all means air on the side of caution and wait four hours or more to do your cold shower, just as would wait for hours or more to do your cold water emotion.

Now there are nice data pointing to the fact that doing cold water emersion after a hard run, so in dance training, or even sprint in interview training or after a weight workout, where your main focus is on performance of those movements, or after a skill training workout or your main focus on performance of those, that there's no reason to think that, that cold water immersion or ice bath or cold shower would inhibit the progress or the stimulus that would lead to progress that occur r during the training session. In other words, I don't see any reason based on the literature to avoid deliberate cold exposure immediately after training again, unless your goal is hypocrisy and straight th, in fact, there's a very nice review that was recently published on deliberate cold exposure and how IT can impact physical performance, whether not it's done before or after types of training and so forth. The paper is entitled impact of cold water emersion compared with passive recovery following a single boult of strenuous exercise on athletic performance in physically active participants, a systematic review with meta analysis and meta regression.

So this is a meet da analysis of fifty two studies that looked at a tremendous number of variables and context, as you would expect, in a mental analysis of fifty two studies. I'm going to read you the conclusions of the study, and I will provide a link. We certainly don't have the time to go through all the details of the study.

I will highlight a few specific outcomes that I found particularly interesting. But here I am perrache their conclusions that cold water immersion want to emphasize immersion, not cold showers, but cold water immersion, they say, was an effective recovery tool. After high intensity exercise, they observe positive outcomes, meaning improvements in certain variables for muscular power, muscular sourness meaning reduce muscular sourness, increased muscular power, perceived recovery after twenty four hours of exercise.

However, there were certain forms of exercise that were not benefit by cold water immersion, such as a centric exercise, exercise focusing only on the lowering component or the so called events. C component of resistance exercise. They saw some very interesting those response relationships for things like in dance training, meaning the longer the cold exposure post international training, the more improvement in insurance performance, reductions in circulating, creating kinneys ses and things that relate to muscle damage under certain conditions.

Some point in the future, by the way, we'll do an entire episode on creating and creating kinney ses, which are important not just for muscular function, but also have a brain function. But the basic takeaway was that cold water emersion performed after high intensity exercise was beneficial from a number of different standpoints and indicated that shorter duration, cold exposure and lower temperatures can improve the efficacy of cold water exposure if used after high intensity exercise OK there are directly pulling from their conclusions. So what this says is that it's not just those longer duration, thirty, forty five minute and sixty minute protocols of cold water emersion that we discuss earlier, but also shorter duration, one minute, three minute, five minute exposures to lower temperatures, temperatures that would make you psychologists want to get out as soon as you possibly can.

But again, that you can safely stay in done after training really have been shown to improve outcomes in terms of reducing sourness and improving training efficacy, meaning your ability to get back into training more quickly and thereby deliver more training stimuli, a given muscle, or in your enduring training protocol. Translate in english. What this means is that taking a cold shower or getting into an ice bath or some other form of cold water emersion within the immediate minutes, or even the the immediate hours following your training has been shown to be beneficial.

I'm sure in a number of you have questions, for instance, how long should you be in that cold exposure? Is IT the same as the eleven minute thrash l described earlier? To be honest with you, there are not enough studies to really point to the critical threshold .

for eliminating .

or reducing delayed onset muscle sourness or for getting maximum results from power and enduring training. But this study does make a couple of key points. And here I will just paraphrase, for instance, that cold water emersion is more likely to positively influence muscular power performance, to reduce muscle sourness, to reduce syrian creasy and kinds, and to improve perceived recovery after high intensity exercise as compared with recovery. This can be translated to cold water exposure after training is beneficial and probably Better than passive recovery from a number of standpoints. In addition, they say that those response relationships, meaning the amount and the degree of cold that people were exposed to and how often they did that, in particular in lower temperature, cold emergent.

So this would be the sort of cold emergent protocols that are one minute or two minutes, three minutes, maybe five minutes, but that one couldn't stay in their longer because IT feels stressful, and one wants to get out maybe more effective after high intensity exercise for removal of syria, creatine kindness as well, that these shorter duration cold water emersion approaches may be more effective after high intensity endurance performance as well. So all this can be translated to say that unless your main goal is hydrophone and strength, that cold exposure, ideally called immersion in cold water ice bath, but if you don't have access to that, then cold showers is likely going to be beneficial if done immediately after or in the minutes or hours after your training, especially high intensity training. One particularly nice thing about this metal analysis is that in included some studies that involve the use of cooling packs.

So again, this that can hold essentially ice packs and indeed even cal therapy chAmbers and so on. There's a nice table in the study if you want to get really detailed and go and look specifically at those studies, I invite you to do that will put a link to this study in the caption for this episode. But all in all, what this study shows is that deliberate called exposure can be very useful for recovery, likely through reductions in inflation, tion in muscle and connective tissue.

And while this study did not look specifically at the mechanisms of reduced inflation tion caused by deliberate cold exposure, those mechanisms are somewhat known. There are a number of studies that have pointed the fact that deliberate cold and cold generally can reduce inflammatory sidelines, such as I sex interview and sex IT can increase anti inflammatory ory ca, such as influence in ten and so on. Without getting in all those details, I think it's sufficient to say that if you are somebody who experiences a lot of delayed onset muscle sourness taking a cold shower after your training or getting into a cold emersion after your training, even if it's a few hours later, ought to help.

And if you are doing particularly intense training, then you probably want to batch IT up the number of called exposure sessions that you're doing, even if those have to be done on separate days from your training, because a lot of the inflammatory effects of training endurance and syn thinc are actually occurring some hours away from the training stimulus. So it's not just that inflation tion goes up radially during training, which is often can, but that IT can occur even in the days and even weeks afterwards, depending on how intense and how long duration that training is. So delivery, called exposure, is very powerful as an anti inflammatory tool. Now i'd like to emphasize the topic that we touched on at the beginning of the episode, which are those glorious skin surfaces, the hands, the upper face in the bombs and the feet through .

which heat .

is especially good at leaving the body. And another way of putting that is that one can cool the body much more efficiently through the global skin services. Now if you want to understand all of the science behind this and all of the various applications, I invite you to please listen to the episode that I did with dr.

Crag heller, again in the biology department at stanford. For sake of this episode, i'm just gona detail a couple of findings from his laboratory. The first one dealing with exercises induce hyperthermia because I think this is a very interesting and IT can even save lives if you understand the way this works.

There's a particularly paper that .

focuses on this um and we will put a link to this as well. The title newspaper is novel application of chemical cold packs for treatment of exercise induce hyperthermia a random zed control trial. This is a pretty brutal study, brutal for the subjects.

That is what the study involved was having. Subjects walk on a trade mm at a pretty significant incline, anywhere from nine to seventeen percent, wearing a substantial amount of clothing that was not well ventilated. And the room was kept to forty degrees south ist, which is one hundred and four degrees farenheit.

This is definitely not something to do at home. This study was designed to induce hypothermia, which, as I mention earlier, can be quite dangerous. And they compared two types of cooling in the first form of cooling that they call traditional cooling.

They had ice packs on their neck, in their armed pits and in their growing and in the other group there was the so called glabrous skin cooling, so the palms, the souls of the feet, which actually so they were cooling inside the boots um or inside of gloves and on the upper portion of the face. And the basic takeaway of the study is that by cooling the glorious skin, the subjects were able to sustain this, walking on these inclined trade mills for much longer than were the people who received traditional cooling. And also, the return to baseline temperature was much faster in the glabrous skin cooling group.

So how this translates to the real world is that if ever you are hyper YSL c or someone else hythe's c one way to cool them down quickly is to cool these palmer glabrous souls of the feet glabrous and upper portion in the face glabrous portion of the body, using cool rags, using ice packs, or using any number of different cold objects or temperatures. One key thing if you're going to use glorious skin cooling is that whatever you use to cool those services cannot be so cold that IT causes visual construction. Because, as I mentioned earlier, the arterial vanus estimates these portals les of arteries directly deviance that exists only in these glass or skin surfaces the way that they're able to cool the body and essentially pass cool into the body.

Although that's not really what they're doing, they're actually extracting heat from the body to be technical. They're tracking heat from the body. The only way they can do that is if those veins don't collapse and veins will collapse if they are made very, very cold.

So if you want to use glabrous skin cooling to offset hyperthermia or for the other forms of performance, which we will talk about in a moment, you need to use a cool objective or surface that is not so cold that causes visual constriction. And this can be a little bit tough to dial in, meaning IT can be tough to identify such an object. And for that reason, doctor heller and some of his colleagues have developed a commercial product called the cool met.

You can actually go to their website, cool IT dcom. I don't have any financial or other relationship to them. I know they're been developing this technology for some period of time.

IT involves a glove that you put your hand into its circulates water of a given temperature, and IT does so and does so at a temperature that is sure to not cause visual construction of the palm. And you may be asking, how can you just put your hand into one glove and have this work? Well, that's how powerful these glabrous skin surfaces are.

Even just by cooling one palm, the core body temperatures drops radically. Now that's their commercial technology. I know that some people out there have started to experiment with a home version of this, which you would be taking a package, for instance, of frozen blueberry or some other cold drink or cold metal object and actually bring you into the gym or out on a run.

The even people who are now developing cool cyc bicycle handles for long rides. Ah this might seem a little cookie or crazy to you, but as you'll soon here in the study am about to describe the increases in endurance and in the volume of strength training that people can conduct if they appropriately cool their body through these these glabrous skin portals is actually quite significant. So again, as IT relates to hyper therm, if someone is overheating, by all means trying get them out of that heat, get them to stop exercising.

You can die from hydrothermal, trying cool the bottom of the feet, the palm s of their hands and the upper portion of their face. That does not mean that IT would be a bad idea to put cold water on the top of their head. That probably would also help him perhaps on their neck.

What is probably not going to be a good idea is to do the more standard thing of dreaming someone in cotton on the surface of their body. Because, as I mentioned, the beginning of the episode, that thermostat in the hypothalamus, the media preoptic area, will to be react to that by increasing core body temperature further, the effects of glass, our skin cooling on physical performance are truly remarkable, provided the global skin cooling is done correctly. And I want to point out that the main degree of effect is on volume or the ability to do more work.

And I want to point this out because I think that many people, certainly in the exercise science community, but even in the general public, when they hear about some of these effects that are measured in the laboratory, they sort of look, as at deals, affects a bit of scans. Anything, well, that's not possible, right? Effects, for instance, that have been documented showing doubling or tripling of the number of depth that one can do in a relatively short amount of time, or doubling of the number of pull pse one can do, or fourteen percent increases in strength, or even comparable degrees in increase wait training output to people who are on performance enhancing drugs.

At that part of the confusion is that the effects of proper palmer cooling, because they almost always is done by palmer cooling, and less often in these experiments, by cooling on the bombs in the feet, the upper portion in the face. But those effects tend to be the ability to do more work over time. And just to illustrate, ate some of the major effects that the hello lab is seen, and they are documented in this manuscript that i'll share with you in a moment.

The typical protocol is to have people come in and do some in dance training, are running on a trade mm, and to have a condition where one group is actually doing palmer cooling while they're on a biker on a trade mill. And inevitably, the outcome is that they can do more work, they can pedal further at a given speed, or they can run longer at a given speed than people who are not doing palmer cooling or who are receiving cooling by way of called compress to the back of the neck or ice back, uh, to the ARM pits at setting up. So the effects of palmer cruelly are very clear and very robust, and in the context of entering exercise, almost always allow people to do more work to go longer with less perceived effort into quit later, so to speak.

In terms of strange training, they've looked at the capacity to perform sets of dips. So one of the more famous examples of this, that dr. 点 heller shares in the episode that we did earlier， and that you can find a huberman lab out com involves someone coming in and doing sets of depth, maybe forty dips.

This person actually could do forty dips on their first set, then resting for a period of two to three minutes, and then doing thirty five, and then arresting for a period two or three minutes, and then doing progressively fewer and fewer and fewer to the point where over a period of time, they add up the total number of dips that they can do. And then they have them come back after a period recovery. So not immediately after, but take a couple of days, come back and do effectively the same protocol.

But during the rest periods, they're during two minutes of palmer cooling, which accept essentially allows heat to out of the body, lowering core body temperature, in other words. And what they find is that they see enormous increases in the total number of depth that people can do. But that doesn't mean that the person goes from being able to do forty depth to being able to do fifty dips or sixty dips on that first set.

What that means that they are able to do forty on the first set than forty on the second than thirty eight on the third and so on and so forth, so that the total duration of the workout is extended. And yet they're doing much more work even though IT takes more time. So that's an important point.

And I think a point that perhaps wasn't as clear or is clearly made by me in the previous episodes that discuss this topic. For those of you that are interested in expLoring palmer cooling, first of all, I recommend taking a brief gLance or even a dive into this study, which is entitled work volume and strain training responses to resistive exercise improve with period heat extraction from the palm. In this study, they described big increases in anoroc c, meaning string training output.

Things like improvement in dips, improvement in bench press, improvement in pull ups, etta in human subjects. And its a really nice study and points to some of the protocols that you might be able to adapt in your own set up. For instance, over six weeks of pull up training, palm cooling in between sets improved volume by one hundred and forty four percent.

And this was an experience subjects so that's interesting because a lot of studies of strength training and improvements in hypocrisy and strength are done in inexperienced, untrained athletes which changes the picture somewhat compared to um experienced to athletes. They found that strength mean the one repetition maximum increased twenty two percent over ten weeks in bedroom ss training. And they point to the particularly strong effects of using palmer cooling when people reach platos in endurance and strain training.

And there, I think it's an important point. I think that if you're going to explore palmer cooling, it's probably not the sort of thing that you're going to do in every run or in every bout of cycling or in every strength training session. But that IT might be used to vastly increase your volume and or vastly increase your in a given session or set of sessions in order to push through platos.

A particularly interesting point in light of that is doctor heller has observed again and again that palmer cooling reduces delayed onset muscle sourness or can eliminate IT entirely. And that's very interesting because IT also points to the fact that reducing core body temperature may somehow be involved in short circuit, the Normal mechanisms of light delayed onset muscle sourness. And you might say, well, how would temperature be involved in delayed onset muscle sourness? Well, I want to refer you back to the meta anal system we talked about earlier, where the short duration, very cold temperature exposure after training did indeed reduced delayed onset muscle sources in part through reduction excuse me, in kindness.

So it's not um inconceivable that temperature and delayed onset muscle sonus are related. And that raises perhaps the most important point, which is the way that palmer cooling can improve performance by way of reducing core body temperature is known. And that is because when one engages in exercise or muscular output of any kind strength or enduring exercise, the range of temperatures under which a muscle can perform is actually very narrow.

There's an enzyme called by uvc kindness, which is critical to muscle contractions. And parodi kinds can only function in a very narrower range of temperatures if that temperature gets too hot, meaning if the muscle heats up locally, whether not by running or cycling or swimming or weight lifting, the ability for that muscle to continue to contract is reduced and eventually as short circuit completely. And I think this is a much Better explorer, at least a much undiscussed aspect of so called muscular failure, or the failure of one to continue to endure in running.

So for instance, when you run as compared to a bench press or something, you don't stop running because you can't actually contract the muscles further. But somehow signals about the heating up of muscular tissue are conveyed to the brain. There's a cross talk.

There is probably by directional. And people stop, they quit, right? This is the quitting reflects in strength training. One can no longer perform a repetition or set of repetitions, in part because of heating up of the muscle locally. There other mechanisms as well of ce, and I realized that.

But what's very clear from the palmer cooling work is that by simply holding onto a cool object, remember not an object so cold that IT constricts the vessels of the palms or constricts the vessels on the bottom of the feet, but by holding on to a relatively cool object in wonder, both hands in between sets for two minutes or so, you can very efficiently reduce your core body temperature. And in doing so, reduce the temperature of the muscles that are doing the work, increase the capacity for pirogue kinds to continue to allow your muscles to contract, and thereby allow you to do more volume of endurance and strength training. So a simple protocol that doctor heller passed to me is find a relatively cool objects.

You could, for instance, fill two bottles with cold water, maybe put a few ice cubes in there, right? This is not exact because we're not talking about the commerce cool MIT product here. We're talking about an at home version or use a pack of frozen blueberry ries or broccoli pack of those as what he described.

And then in between sets to put your hands, and ideally you'd put the bombs your feet. But that's not always feasible in most games where they want to let you take off your shoes. And so for but to put your the palm of your hands on that cool surface for a minute or two minutes between seats and then returning to your sets of work.

Now if you are heading up through mechanisms like you're wearing a stocking cap, you're in a very warm environment. This might not have as poor effect as if you were to do this cooling in a more modern environment, wearing lighter clothing at sea. So by all means, warm up to do your exercise, lubricate your joins and get into a place where you're not going to injure yourself doing whatever form of exercise you do.

But then if you'd like to explore palmer cooling, I know a number of people who have written to me saying they they heard about palmer cooling on the episode without her heller. They've tried this and see quite excEllent result. IT does take some discipline, right? It's one thing to just kind of hang out in the gym and play on your phone in between sets at another to do deliberate cooling with your palm s or the bottom, your fear the upper portion of your face might get some weird looks.

But of course, you'll be the one doing significantly more volume, not experiencing delayed onset muscle sourness and achieving Better insurance and straight gains. Were you to do this properly? Now, as a final topic related to the use of deliberate cold exposure for improving health and performance, i'd like to touch on this theme that exists online, on social media, youtube and in various fitness communities of using deliberate cold exposure to the growing, in particular to the testicle s in order to try and increase testosterone.

And while this might sound really cookie indeed, this practice exists indeed, if you were to go on the amazon, there are actually um. Ice pack underwear that have uh that are being marketed for sake of increasing test host room. Now I am not aware of any specific while controlled studies that shows that this indeed works.

I can imagine based on what I know about the nervous system, testosterone and cold at sea, that there are a couple of mechanisms by which one might experience increases in test astern as a consequence of deliberate cold exposure. First off, let me say there is no reason why you would have to apply these ice packs in the way that I just described. One could of course take a cold shower.

One could of course you use called immersion of various kinds and you're still gone to get that exposure um of the growing and the testicles to cold. Now I should point out that people do report at least an idol ally increases in testosterone as a consequence of this practice. And I have to imagine that they are measuring their serum to stop stone, that they're not just guessing that their test aston one went up.

If you know a study expLoring this directly, please let me know, put in the comments section on youtube or even just email me ah we have we the email that you can find IT human lab up com. Please email me the reference. I wasn't able to find a reference, but I can imagine two reasonably plausible mechanisms by which deliberate, called exposure to the growing and produce that the testicles would increase testosterone.

The first is somewhat direct, which is that any time you cool a body surface, that if it's cold enough, you're going to get visual construction and then subsequently, you're gone to get a rebound increase in visual dilation, meaning you're going to constrict the blood vessels in that area. And then after the cold is removed, there's going to be more blood flow to that area. And of course, blood flow relates to organ health and tissue health, generally a perfusion of that region.

And those are in the go adds to be specific with additional blood. You could imagine in some ways, increasing testosterone that's reasonably plausible. The other probably more likely mechanism relates to the dopamine increases caused by cold exposure that we talked about earlier. Again, any time you have a somewhat stressful stimulus, but in particular with cold exposure, IT seems that category means north and f an, f an, f an doping all increase. And doping is known to be in the pathway that can stimulate to stop one.

And so while there isn't a direct relationship between dopamine stimulating to tosta one, there is an interesting pathway whereby dopamine increases can trigger increases, and things like luti zing hormone, which can trigger increases in testosterone as well as air gen for that matter. So I know that there are a lot of people out there that are interested in the use of cold exposure for increasing testosterone. And some of those people in communities are indeed using cold exposure directly on the go ads on the tests in order to do this.

I'm not certain that, that direct contact is necessary and in some cases, IT might actually be dangerous or you at least should be careful in terms of a tissues there and a aaib ding damage. But none there's I think that a depine impact on testosterone is very likely given the two hundred and fifty percent increases in dopa that have been observed cold water emersion and all of that pots of the fact that cold water immersion very likely increases testosterone, but as a downstream consequence of the cold water version, effects on dopamine and uti zing hormones. And again, there's no reason to think that the increases in uti zing hormones also increased estrogen, probably not to a dangerous or levels that one would want to avoid.

But I don't think that there's anything particularly specific about cold for inducing testosterone and not other hormones. I think it's very likely to increases a number of different hormones. I do hope that there will be a systematic study on this in the nature distant future.

I also hope to not be a subject in the cooling of the goads experiment. Now I promise you the last topic was the last topic, but there's one really important point that I think everyone should be aware of if you're going to use deliberate cold exposure. And that brings us back to the very first thing that we discuss today along the lives of deliberate cold exposure, which is that your baseline temperature is going to be lowest about two hours before you wake up.

It's going to increase in the morning. And as you wake up and increase throughout the day in afternoon and then start to drop in the evening and come down at night as you had to sleep. I also want you to remember that if you are to cool the external portion of your body, in particular your torso, the net effect of that is going to be an increase in body temperature.

So for many people, not all, but for many people, if you are going to do deliberate cold exposure, you are going to increase your core body temperature. And that makes sense if you think about how deliberate cold exposure can increase tablet sm by increasing thermo genesis is. What that all means is that if you are doing your deliberate cold exposure early in the day, you are going to get yet a further increase in core body temperature that would be associated with wakefulness, your ability to be alert that morning or throughout the day and so on.

IT also means that if you do your deliberate cold exposure very late in the evening or at night, so six P M, seven P M, nine P, M, and so on, you are going to increase your core body temperature in IT, if you will call a decrease in core body temperature of one to three degrees is not just beneficial, but is necessary in order to get into deep sleep and remain in deep sleep. So the takeaway from this is deliberate cold exposure done properly will increase your core body temperature and make you feel more alert. So if you're doing IT early in the day, that's probably terrific, given that most of us want to be alert during the day.

However, if you do that too late in the day, evening or night, IT can disrupt left by way of disrupting your core body temperature. Now, the caveat to that is I myself tend to do my deliberate cold exposure early in the day, maybe not first thing in the morning, but mid morning, maybe as latest three or four in the afternoon. In some cases, in the longer days of summer, I might do IT even later, five or six P, M, and have no trouble sleeping.

I have done deliberate cold exposure very late at night, ten P M, eleven P M, and so on, as part of a thirty day chAllenge of doing deliberate cold exposure every day for thirty days. And I got sloppy with my timing, and then in order to not miss the day, I would do at at eleven o'clock at night, and I must say, I found that I could still fall asleep very easily, even doing deliberate called exposure very late at night. However, on those particular days, I was particularly busy, and so I was particularly exhausted when I arrived at the deliberate cold exposure.

And I had no trouble falling asleep after doing deliberate cold exposure and then taking a nice warm shower and then going to sleep. But I could imagine that because of the increases in core body temperature caused by deliberate cold exposure, that we're going to do that too late in the day, evening or night, that IT could indeed disrupt your sleep. So my recommendation would be, for most people, only do deliberate called exposure if you are prepared to be fairly alert for the next one to four, or maybe have been six hours following that deliberate cold exposure.

So for today's episode, as is the case with most episode of the huberman podcast, I covered a lot of material we talk to about mechanisms of categories and stress and pothole, release of epinephrine, tabi, sm, mental effects, performance, glabrous, skin cooling and on and on and on. And while the goal, of course, is to make sure that everyone arrives that specific, very clear, mechanistic and actionable protocols, I do realized that IT is an immense amount of information. And for that reason, i've created a list of deliberate cold exposure protocols aimed at improving mental toughness and resilience, mood performance, meta lisp, reducing implementation and so on and so forth.

All of those have been condensed ed into cnc form and can be found at the huberman lab in neural network newsletter. This is a monthly or semi monthly newsletter that we release that includes take away from the podcast and protocols. You can access those protocols zero cost by simply going to huberman lab dot com, signing up for the neural network newsletter.

It's very easy to do. You just supply your email and you will receive the news letter. We do not share your email with anybody else. In fact, we have our privacy policy laid out on the human lab 点 com website， but you can find that there.

And the protocols that i've designed to make IT very straightforward for you to create a set of protocols that you could use with cold showers, with cold emergent, with or without ice, in combination with exercise, specifically for one goal or another or to accomplish multiple goals simultaneously. If you're learning from and or enjoying this podcast, please described our youtube channel. That's a terrific zero cost way to support us.

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