 Welcome, welcome. Yeah, so it's nice to be the leadoff speaker here at EHS. So what if I told you that by exposing yourself to cold temperatures on a regular basis, you could maybe shed a few pounds, reduce inflammation, get fewer colds and flus, and improve your mood and your resilience? Would you believe me? Well, so anyway, my name is Todd Becker. I've been taking cold showers every morning since 2009. It's my wake-up routine. And I'm hoping to convince some of you to at least try this by explaining some of the benefits and maybe some easy ways to get into experiencing the cold. So I've given now six previous talks at EHS on a really wide variety of topics, everything from improving your vision, reducing myopia, to overcoming obesity, to improving memory last year was my topic. And this year I'm going to be talking about cold. And the common theme in all these topics, and it's also the theme of my blog, Getting Stronger, is hormesis. What's hormesis? It's the application of low-dose intermittent stress to improve your health. Low-dose intermittent stress to benefit yourself in different ways. A lot of people try to avoid it. But I'll try to convince you that increasing your exposure to cold is probably one of the most actionable, practical ways to experience hormesis in your life. So here's an outline of the talk. There's a connection with evolutionary mismatch. That's why we're here at EHS. Basically, we evolved in an ice age. And we didn't evolve to live in with central heating and air conditioning. So that's a relatively modern innovation. And it has a lot of implications. When our ancestors, our forebears, migrated from Africa into Europe, they developed the ability to adapt to the cold. And we'll go into that a little bit. If you expose yourself to the cold, you're still able to activate those ancestral genes for cold adaptation. It takes practice, but you actually have to expose yourself to cold to turn on those genes. And there are several ways to do this that are practical. And I'll get to that at the end. But I'll start out with more of the benefits. Why would you even think about doing something crazy like this? So animal adaptation of cold. It's ubiquitous, fish, mammals, all animals that have moved into colder climates. They're genes that have evolved. And their metabolism has changed. So let's look at our early evolutionary cousins, the Neanderthals, who were some of the first to move from Africa into Europe and Asia. And also, woolly mammoths moved from Africa into Europe and Asia. And they developed similar adaptations, right? More body fat, body hair. And interestingly, some researchers at Tel Aviv University were able to look at the genetics of the Neanderthals and woolly mammoths. And they found that we have some coevolution. Some of these genes evolved the same types of allele. So there's a gene called LEPR, which codes for the leptin receptor. And that was highly upregulated. And that deals with fat regulation and thermogenesis. And the MC1R gene, which caused evolution of lighter skin and pigmentation, which allowed better absorption of vitamin D. So this was just the effect of the environment on convergent evolution. And this happened over a very long time scale. It was really about 350,000 years ago that the Neanderthals and the Denisovans migrated north. And they had to adapt to these colder climates in Europe and Asia. Our own species, Homo sapiens, left Africa about 60,000 years ago. But there was a lot of interbreeding. So we picked up a lot of the Neanderthal genes. I think some of us may have around 2% if you check here at ancestry.com. Interestingly, some of those cold adaptation genes, like EPSI, are found in modern Tibetans. And there's a couple of other genes that are found in Inuits that, again, help with adaptation to the cold, better utilization of fat. So again, our progenitor, Homo sapiens, has arrived on Earth about 400,000 years ago, but stayed a long time in Africa. During the Ice Age, the Pleistocene, which lasted up until really just about 12,000 years ago with the advent of agriculture, we were living in basically a cold environment. So we had all these cold adaptations. And even when agriculture started and the Earth warmed, we didn't have access to hot water all the time, right? We didn't have access to air conditioning. Central heating is only about 100 years old in terms of most of the population having access to it. We bathed in cold water. That was the way we typically lived our lives. So it's a recent lifestyle. It's a mismatch that we're always living in this warm climate-controlled environment. So we can live indoors. I mean, it's great. It's convenient. So why would you even consider getting cold? I mean, just think about it emotionally. What do you prefer? Warm or cold, right? I mean, heat you think of sitting out on the beach here in Santa Monica, relaxing. Cold, it's uncomfortable. You're shivering, you're miserable. That's the way most of us think of it. So we would just avoid getting into cold water. So why deliberately expose yourself to cold? Well, let's take a look at what it does. And I think it's important when you talk about adaptation to distinguish three levels of adaptation. First, there's the primary response that happens when you first get into a cold shower or jump into a lake. You're uncomfortable. Your skin vasodilates. All of the warm blood rushes into the core to maintain body temperature. You start shivering. Your sympathetic nervous system kicks in. You have noradrenaline. That's your sympathetic system. That's your fight or flight nervous system. It makes you anxious and anyway, it starts to produce more energy. Now, after a while, if you hang out in the cold shower or the lake, after a few minutes, that shivering will warm you up. That's called shivering thermogenesis. Your body's actually generating heat by the contractions of the muscles. And you might start to feel a little bit more comfortable. You also start to turn on some anti-inflammatory cytokines which helps sort of calm you. And if you try this, you'll start to experience a slight elevation in mood. And when you step out of that cold shower or get out of the lake, you actually feel pretty good and it can last for a while and we'll get into that. The third phase is the adaptation. This is when you've done it many times, over days, over weeks. And this happens to a lot of types of hormetic adaptation. If you repeat it, your body adapts. And this is what I mean by adaptation. It's not the initial exposure. You're actually now starting to activate brown fat, grow more brown fat, grow mitochondria. And you get some benefits from this and I'll go into some of these benefits. First of all, the brown fat will allow you to warm up without all the shivering. You get some immune benefits and you get the sustained mood and resilience benefit and we'll go into some of these attributes. So let's start with thermogenesis. That's your body producing its own heat. How does that work? Well, when you step out into the cold or get into cold water, you have these cold thermoreceptors in your hand on your skin all over. And that's through these afferent fibers, it sends a signal to your hypothalamus. Your hypothalamus is your body's, your brain's thermostat. And it's maintaining that 98.6 degrees at all costs or 37 degrees C for those of you from Europe. If it drops too low, you're gonna get hypothermic. So when you're exposed to the cold, that process happening. Now what happens then? Your hypothalamus sends a signal to your, your skeletal muscles. It's time to start shivering. It turns on noradrenaline, which causes that shivering, right? And that's what's called shivering thermogenesis. That's what all of us experience on the first pass. But what happens if you do this again and again, the adaptive response? Well, there's an interesting hormone called irisin. Really exciting hormone that's produced in the skeletal muscles. And that turns on your brown fat. It activates your brown fat. It gets those mitochondria revved up. It grows for mitochondria. And then your brown fat, brown adipose tissue, it's sometimes called BAT, B-A-T. It also has a couple other proteins called thermogenin, which is also called uncoupling protein one and FGF 21. Now thermogenin is, or uncoupling protein is very interesting because what it does is it bypasses the TCA cycle, which is what you use to convert sugar, sugars and fatty acids into energy, you use ATP to move your muscles, to digest, to do everything. It just short circuits that. It's called a feudal cycle. And it just says we need heat and it just starts dumping heat and you get warm fast when you're turning on this thermogenin. And that's called non-shivering thermogenesis. You only get that when you become adapted, okay? So that's absolutely key here. Now what is brown fat? Babies are born with a lot of brown fat. Animals have it, babies don't shiver as well, so they need that brown fat to stay warm, but you lose a lot of brown fat as you age. You get less and less. If you look at this picture here, the person on the left is a healthy fit young person with a lot of brown fat. Where is it? It's around your neck, your shoulders, a little bit down your spine. I was surprised when I saw that, really? That's where that is. So when you do cold exposure, try to get the cold water around your neck and your shoulders because that's gonna stimulate the brown fat. The person on the right is an older person who's lost most of their brown fat. And I would venture to say there's a lot of people in the world who look like that person on the right. Now if you look at it on a cellular level at the bottom here, you'll see white fat, WAT, white outer post tissue on the left. Brown fat looks very different. It's this dense, reddish, brownish fat that's got a lot of mitochondria, a lot of iron in it. And it is primed to generate heat. It's very anti-inflammatory. And what's interesting, and this has only been known for the last decade, you can convert white fat to brown fat. That's called Beijing by exposure. And you see in the middle, the white fat has got the little brown fat growing within it. And that's what you do when you expose yourself to the cold. So if you zoom out here a little bit, it actually, this is part of a much bigger story, which I could talk about a whole lecture on this one slide. But you see down in the bottom here, the conversion of white fat to brown fat produced by the iris and coming from the exposure of your system to cold. But if you back up here a little bit, there's a master metabolic regulator called PGC-1-alpha. And this responds to all manner of different stresses, not just cold, but hypoxia, high altitude, low oxygen, exercise, calorie restriction. It turns on the PGC-1-alpha. And that, of course, stimulates the iris in and the conversion of brown fat to white fat. But it also inhibits mTOR. It also turns on BDNF in your brain. It also suppresses appetite, gives you the urge to exercise. It improves insulin sensitivity, autophagy. It's system-wide. So again, cold is particularly effective at activating the brown fat, but it has all of these other benefits in terms of anti-inflammatory, mood and ability to lose weight. So speaking of cold exposure, does anybody here recognize this gentleman? He's one of my heroes. He's, Wim Hof is this wild Dutchman who's probably done more than anyone to popularize the idea of cold exposure. And he has a whole following. He's big following on the web. He leads nature expeditions, takes people out into the snow, gets them comfortable with that. He has records for running marathons in the arctic and swimming 50 meters under the ice. And, but he can even adapt himself to the heat. He's hiked, he's run marathons through the desert. So anyway, he also, he's big on cold, but he has developed a breathing technique based on this two-mo breathing cycles of hyperventilation and breath-holding. And so he puts these two together. Now, he is controversial. He's made this claim that he can voluntarily control his immune system. And he went into a Dutch hospital and had himself hooked up, had himself injected with bacterial endotoxin with lipopolysaccharides. And in fact, they monitored him and his vitals were pretty steady. His inflammatory cytokines didn't boost. But, but you know what? Maybe he's a freak of nature. So anyway, Wim said, I think anybody can do this, right? So he, he, he set up a study with, I think it was 48 healthy males. And he had the, one group of them practiced the breathing technique when due cold exposure and cold exposure, he actually had them take ice baths and cold showers and run around in the snow. The breathing technique, he had them all practice this for four days. So they got, they had it down. And then there was a control group and they were injected with tune in diagrams per kilogram body weight of this lipopolysaccharide and monitored for symptoms over two and a half hours. And so, and so what did they find? It's a pretty interesting result. The cyclic breathing alone, 30% drop in pro-inflammatory cytokines, like interleukin-6, not really much effect on an anti-inflammatory cytokine, interleukin-10. The cold exposure actually didn't have any significant event effect by itself. But when you combine the two, this had the best effect. You had a similar reduction in the inflammatory cytokines, but a huge boost in IL-10, which is the anti-inflammatory one. And there's statistical significance around this. You can read the study by SWAG. So I think that's interesting. Of course, a lot, you know, the questions, that was a short-term study. What about long-term effects? Can you get immune enhancement by repeated exposures? And yeah, there is actually an interesting study by Buija et al. in 2018 where they took over 3,000 people. This was very large statistical study. Ages 18 to 25, who had no prior experience with cold exposure. And for 90 days, they did cold showering. All right, 90 days. And all kinds of measures on them. But the one that was, I think, the most significant was they looked at days of absence from work, sick days, basically. And interestingly enough, almost 30% of the group that did the cold showering had, there's a 30% reduction in sick days among that group and not in the control group. And that had a very high statistical significance there, too. So I think that's a pretty interesting. Now, my own anecdotal experience, I've been cold showering since 2009. And I don't get colds and flus. I haven't missed a day of work. Now, that could be a coincidence, right? I do a lot of other things, too. But I think studies like this help to sort of provide a little bit of scientific backing. So another benefit of cold exposure is it's an anti-inflammatory, right? All trainers know that what you do when you get a muscle injury or you need to recover is soak in ice, you know? And yes, there is that short-term benefit in terms of the cytokines. What I think is interesting, though, is there's also a long-term anti-inflammatory effect through the PGC1-alpha cascade, through the conversion of white fat to brown fat. So I think if you do this repeatedly, you get this anti-inflammatory effect. Okay, this next benefit is one I'm really excited about and people don't believe it until they've tried it. Cold really helps the mood. It's a natural antidepressant. And this was known all the way back in Greek and Roman times, the orator and stoic philosopher Seneca. He was a great lover of cold baths. And in the Roman baths, they had warm baths, but they also had the frigidarium where people would hang out in the cold. So this was very common. This is, this cultural practice is, you know, practiced by native peoples, by the Finns. You know, cold is not something new. So to me, the key thing here is it isn't just mood, it's resilience. When I started exposing myself to cold, I found that, you know, the hassles, the arguments, the emotional turmoil that you can run into just by day-to-day exposure, they tended to dissipate. But I found this feeling of resistance that I could basically just not be as bothered. And this is something that I think goes back to the Stoics and to Seneca. Now, the question is, is this just an observation or is there actually an explanation for it? And I think the best explanation for this is the work that Richard Solomon and J.D. Corbett did, and it's summarized in a paper, a 1980 paper, on the opponent process theory of emotion. And here's kind of how it works. So Solomon, he was trying to explain this weird effect that skydivers, you know, that's a pretty frightening thing jumping out of a plane. They would be very frightened on their first exposure. And when they landed on the ground, they would actually have this feeling of euphoria for a while. Well, the more they did it, the fright went down and the period of elation and euphoria was extended. So how can this be? And this is shown in the graph here. If you look at the graph on the left, he said, okay, our brain wants homeostasis, it wants everything to be nice and neutral. So that middle line says neutral. So any intense event is a deviation from that and that's summarized as state A, an intense experience. It could be skydiving, it could be getting into a cold shower, it's frightening, the noradrenaline gets going and it tends to with time plateau. But then when you stop that frightening experience, when the skydiver lands or you get out of the cold shower, you actually get an opposite effect, an opponent process that's trying to inhibit that state. Basically, the brain wants to bring you back to the same state so it overcompensates through counter-regulatory hormones. But that state B, that inhibitory response at first is sort of weak and shallow. It maybe lasts an hour or so. Now here's what Solomon found and this I think really rings true. The more you do it with repeated stimulations and that's the graph on the right, you can see that state A is diminished. Your body's kind of prepped for this. It knows how to, you know this is coming, you're gonna jump or you're gonna get in the cold shower so it's already providing the counter-regulatory hormones and when you stop that intense stimulus, it's a prolonged, more profound, deeper, longer effect. So that's the opponent process theory. This also has some other physiological correlates and this has to do with, again, your autonomic nervous system. You know, as I mentioned, you've got the sympathetic fight or flight, half of your system that gets you energized when you're exposed to a stress and you've got the parasympathetic system, rest and digest that's calming you down. Well, there's actually bio-hackers use a technique called heart rate variability to follow this and what is heart rate variability? If you look at the figure on the right, you can see some heart beats. These are not evenly spaced, as you can see. Some are longer, some are shorter. If you have low heart rate variability, which would be not this figure, but metronomic every second, beep, beep, beep. Your heart is basically locked into a situation where it can't easily move faster or slower. You can't gear yourself up or calm down. So you have, it's called sympathetic dominant system, right? And that means you're not very fit, you're not ready for action. A high heart rate variability, something like this figure where you have a lot of variation is healthy. It indicates you're ready for action and I think the physiological reason for this is you can vary the heart rate if it needs to go faster or slower depending on the demand. So this has been shown in a study, shown here by Mechanan on the bottom left, that cold exposure indeed does cause this short-term rise in sympathetic activity, but if you repeat it, you get a shift upward in parasympathetic activity and HRV. And I found this personally. I've done HRV hacking and I'll tell you what the single biggest negative effect was and the single biggest positive effect. Single biggest negative effect on my HRV was having more than one alcoholic drink. So I know one, I'm fine, two, three. My HRV is going down to the toilet. The thing that gave me the biggest boost in HRV, cold showers and then I'll tell you later something was even more than cold showers. That's coming up. Well, so cold showers. I take a cold shower every morning. I know you think that's crazy. People tell me they could never do it. My wife still won't take a cold shower. Some people say, oh, you mean, you just turn it down a little bit at the end? I go, no, no, no, no, no. You jump into the cold shower, cold turkey. So let me take you through, because I actually wrote about this. It was one of my first posts on my blog in 2010. And I love, because this is my experience here. I jump into the cold shower. I find myself smiling or even laughing. I brace myself, I grit my teeth. I'm stiffening my muscles. I'm trying to put my head in. It isn't working. Finally, after a few minutes, I start to feel warm. But I force myself to put the most sensitive parts in. My shoulder, my head and my hands. When I get out, my mood is great. I'm feeling wonderful. My stress tolerance is up. Arguments at work don't bother me. After a couple weeks, the period of time that's uncomfortable is shorter and shorter and down to a couple of minutes. Now it's about 10 seconds, all right? So this is again the opponent process theory at work. So I'm gonna give you some tips on how to do this when you try it the first time. There's two ways to do it. You can take the cold ending, which is the way for the wimps to do it, all right? But if you have to start somewhere, start warm and turn it down and at least end cold. What I recommend is the cold turkey approach. Take your watch timer in. Try to last full five minutes, but here's the key. Write down the time where you start to feel the warmth, where you start to feel the comfort. Note that. Is it after two minutes, three minutes? And then the next day you do it, do it again and see if it gets shorter and that's a sign of progress. Cold baths, okay? This is a little bit more uncomfortable. It's more effective because you're covering all of your skin with cold water and here I am reading this great book, Chill, which I really recommend. We'll talk about that a little bit. Try to get into your neck. Get that brown fat activated. I stand for 20 minutes and I notice the first time I did it, it took 10 minutes to feel before I was even comfortable. Now about a minute. When you get out though, there's some interesting effects. At first, the vasodilation, your skin is turning white. Now the blood's rushing back in, you get this kind of lobster hand effect and it takes a while, it's nothing unusual. You're just, the blood is coming back to your skin. You also can feel what's called the cold drop, which is after about 20 minutes, you might feel a surge of the cold blood in your circulation shifting and you feel cold on the extremities again. So what I recommend is if you do this, go for a walk right afterward. Stay active and that kind of gets the blood mixing. Now another effect is since I've been doing this, I'm warm all the time and this is a picture at the San Francisco Exploratorium. My wife on the left, look at her hands. By the way, white means warm, black means cold in infrared. It's a cool exhibit, you can go in there and you can see her fingers are pretty dark there and look at my fingers, they're bright white and so she tells me I'm a natural heat generator. Ice baths, very popular on the blogosphere. A lot of athletes do it. If you wanna go out and do it, try it. It's a lot colder. My view, it's not worth it. You gotta buy the ice, it takes time. It's less convenient and I think there's other ways to do it but there's a lot of believers out there so I'd like to talk to you if that's the way to do it. Tim Ferriss recommended another approach which is ice packs. You can buy these and just wear them on your neck while you're watching TV or working at the internet for half an hour and you're localizing it in the right space, in the right spot by your shoulders and your neck where your brown fat is. Open water swimming. I love doing this. I live about half an hour from Half Moon Bay. Love to go dipping in the water. There's this great book called Chill, The Cold Water Swim Cure by Mark Harper. He is an anesthesiologist who looked at the usefulness of cold to prepare people for operations and he found that it made recovery better and he teamed up with a guy named Mike Tipton and he started these swim clubs. All throughout the UK he's got 20 swim clubs. He finds the social benefits combined with the cold water exposure have a great effect in treating mood disorders like depression, PTSD and the book's got a lot of great information there. Whole body cryotherapy. I had to try this. I had stayed away for it but I said I'm giving this talk. So a month ago I started and I was scared out. Minus 200 degrees or colder. Minus 200 degrees Fahrenheit for three minutes. Liquid nitrogen. So it's invented in Japan. It's very effective. It's actually not that bad because it chills your skin but it's got very low, the vapor has a very low thermal conductivity and so it doesn't penetrate into the core so it chills the skin and you can see the skin temperature in blue, it drops from 30 to 15 degrees centigrade until you get out. Core temperature barely changes but it has a number of benefits. This has been studied. Not a lot of measured benefits in terms of anti-inflammatory cytokines but this study at the bottom by Rimsakowski was looking at it as a depression treatment and added to the normal course of medication statistically significant improvements in 11 out of 14 anxiety symptoms and 12 out of 16 depression symptoms. For me, amazing mood boost and this is for a guy who takes cold showers every day. I stepped out of there and I'm like wow, the rest of the day, that was like the best day. I was just really energetic and so I've gone back. Now I've done four sessions. My HRV, it hit the highest it's ever hit too. My heartbeat was just having a lot of fun. Contrast baths, a lot of people ask about this. The fins do this, right? They hang out in the warm sauna and then they go jump in the ice and it's back and forth and that has an effect where it acts sort of like a pump, right? Your blood vessels are dilating and you can remove toxins and cellular debris, athletes like it. I actually kind of against this because I think you're cutting short the benefit of the cold, which is that opponent process. You're not letting it play out. So if you're gonna do saunas, do it at a different time. But going back and forth, I think you're kind of short circuiting some of these mood benefits. Cool sleeping. A very interesting effect. Did you know that not only do we have a circadian cycle that responds to light and dark, but that when you go to sleep, your body temperature decreases by about two to three degrees Fahrenheit. I didn't know that. And if you have poor sleep, consider sleeping cooler and paradoxically, you can improve the rate at which your body cools by first making sure your extremities are warm. So you can take a warm bath, there was a study showing that by warming the feet and hand before sleep, the rate of insomnia in the second half of the night dropped from 58% to 4%. Just by that pre-warming. And then sleep cool, keep your room at 65 or lower, open the window. So what's the best method people ask me? It really depends. It depends what you're looking for. If you live near the ocean, open water swimming, but we don't wanna live by the ocean. So I've rated these by the metabolic benefits, psychological benefits and just simple convenience. And my vote goes for the ones on the two ends, daily cold showers and cool sleeping because you can do it anywhere. I still think you should try whole body cryotherapy and cold baths and open water swimming. It's just that they're less convenient. So to kind of summarize, there's a lot of benefits to cold adaptation. The one above, the obvious one is just you're gonna be more tolerant to the cold. That's the tip of the iceberg, but you've got all these deeper benefits, more energy, more resilience, better mood, enhanced immunity, fewer colds and flus. It can help you with losing weight because that brown fat is just burning the energy. It can improve sleep quality. There are some risks. If you have renal syndrome or your hands turn these weird colors, you might wanna be careful. Although I cite here in the references a couple of people who had renal syndrome who cured it by gradual progressive cold exposure. Hypothermia, Mike Tipton and Mark Harper's book on the chill talks about the risks here. Get in slowly, don't get in all at once and same with heart attack. Don't jump in, head first if you have any risk. Get in slowly and there's some good tips on how to do this here. So to kind of put it all together, we evolved, right? Our ancestors evolved in the cold. We have those adaptations. We just have to turn them on by frequently exposing ourselves. We can reduce inflammation, enhance our immunity, improve our mood by getting in cold water, try open water swimming in cryotherapy, try cool sleeping, but I do wanna give you a homework assignment and I'm gonna ask you guys about this tomorrow morning, try a cold shower, time how long it is before you start to feel comfortable. That's Friday and you get one more chance on Saturday and I'd like to see if this works and then go with it, try it for the whole week. Keep it up for the whole week. So I've got here some references. When we do the videos, you can pause it here and I've got another set of references here and so I wanna just return to that picture I showed. Hopefully I've changed your view of the hot and the cold. Heat, great, but it can make you sort of sleepy and dull. Cold, it's uncomfortable, but it's exhilarating. It kind of makes life worth living. So I'll leave it with that and see if there's any questions. Use this mic to come up and ask a question. Thank you for your talk. Cold showers is something I've been resisting for a long time and now I'm kind of motivated to try it. I am curious, is there any data, you spoke to improving circadian rhythms and sleep cycles. Is there any data around improving hormone balance, specifically female bio rhythms with cold exposure? That's a really good question. I didn't research that. Women's physiology is different than men's. It should be studied separately. One of the studies in there by Meccanin was just looking at females' athletes. And I think she did look at hormones like ACTH, cortisol, but I don't know about other hormones. So you might look at that paper by Meccanin. Cool, thanks. Great, great, great, great talking topic. Thank you, Todd, you did a great job with this. I'm a big fan of this and have renode syndrome. So I'm really proud of you for putting that in there. I wanna see if you can expand a little bit on that because I find I have a grocery store three minutes from my house. So if I turn on the tub, I get my 50 pounds of ice and the tub is still not full when I get back home again. So it's not inconvenient to do that, but I've usually lift some weights before I get into the cold bath, but I still have days as a renode's person where my response is I'm freezing all day and I'm in socks and slippers the whole day in the summer. Usually not, but I haven't had a. Warm showers are yucky and you can't even get cold enough water to go five minutes because it's too hot. Like the tap water is too hot. But if you could just expand if you know what's going on, what's the technique problem? I think it's something you just have to try gradually until you get more exposure to it. The two references. No, I've been doing, I haven't had a hot shower in three and a half years and I do cryotherapy, but they all closed down with COVID. Okay, so you're doing it. When I run and get ice, whenever I'm in pain, the best answer to inflammation, arthritis and pain go to Kroger and get some ice, right? But there's still that, there's more, obviously we're early days understanding this, but I wondered if you had thoughts about why sometimes I can never warm up again. Even if I'm going out in the sun. It's a good question. Yeah, okay. I don't have an answer. Yeah, thanks. Go ahead. So I spent, you wanna come to the microphone? Sure, yeah, just to ask about it. I was with Wim Hof maybe seven or eight years ago. I was one of the first certified instructors in the US. And one of the things he said, because there was a lot of competition in our group with like who could stay in the longest. And he always said, never leave with the cold in your bones. So for him it was like, if you're cold but you can't warm up, you overdid it. And he would recommend warming up before you go. Yeah, that's a really good point. In fact, I think his breathing technique does help promote the thermogenesis. So it pre-warms you so you can tolerate the cold better. So that's a great answer. Maybe combining the breathing technique and the cold for somebody who needs to work on the tolerance. Yeah, part of his technique can warm you up to go in. I was just wondering if you found a minimum dose. Because like when I was with Wim and when we practice, like you can do five minutes, you can do 10 minutes, but sometimes you only need like 30 seconds. Have you found that to be? You know, I did find that when I get in colder water, it doesn't take, I don't need as long to get the same benefit. I did a cold shower when I was on business trip in Finland, that's cold. I was like energized, the cryotherapy, that's intense, very short, three minutes. And oh my gosh, that had a big effect. So I do think there is a sort of coldness and time and dose response effect and you just have to investigate it for yourself. Cool, thank you. Oh, all right, well, I guess I better make this good. Hi, my name is Adae. So I was very interested in this talk and I wanted to know, you talked about how Homo sapiens, modern Homo sapiens, developed these adaptations to cold after leaving the equator in Africa. So what about for people who never left, who live in warm environments? Are there no adaptations? Is this worth doing for black people, for people who are from the equator? Really good question, well, a couple things. Even in Africa, the nights can be cold, right? So I think I showed some of the groups, hunter-gatherers, but sleep and huts. So cold doesn't have to be snow, right? It can be 50 degrees Fahrenheit. That's enough to activate it. So that's one thing. Another is even African-Americans, typically there's some, none of us are genetically pure anything, right? So we have some of those genes that have crossed from the Neanderthals, the Denisovans. So there's genetic variability within any population. The other thing is even in Africa at altitude, the certain populations that have gone to high altitude and some of those same high altitude genes cross over into cold protective genes. So it's not all as simple as hot and cold, right? Well, how cold does it have to be to develop these adaptations? Yeah, from what I've read, it varies, but for cold water and cold water swimming, you wanna be below 65 degrees. And if you can be below 60 degrees Fahrenheit, you really turn on a lot of the adaptations. Certainly you can do an ice bath, but you don't need to be on ice, right? Just take a shower here at the hotel or in the dorms. It's not that cold, but it will still activate some of that same response. So you don't have to be freezing. Thank you very much, Todd. I'm looking forward to reviewing that when it's on YouTube again.