[03:40] About Dr. Ronda Patrick
[08:29] How Heat Can Help You Produce the “Runner’s High”
[14:33] 3 Ways Getting into a Sauna Could Actually Grow New Neurons and Make You Smarter
[17:28] How Much Heat Exposure is Enough, and How Much is Too Much
[35:07] Whether it’s Really True that You Can Increase Growth Hormone Inside a Sauna
[41:31] The Amazing Anti-aging Effect of Saunas and How it Works
[50:06] What the Best Type of Heat is, and whether there is a difference between wet heat vs. dry heat vs. sauna suits vs. infrared saunas
[55:47] How to ideally combine heat exposure with cold thermogenesis
Ben: This podcast is brought to you by the Thorne FX AM/PM Complex, the best multivitamin on the face of the planet. You can check it out now at bengreenfieldfitness.com/multi.
Hey folks, it’s Ben Greenfield and I’d like to welcome you to week 3 in which my podcast sidekick, Brock, is still off exploring Europe somewhere, probably in some salt mine off the coast of Portugal or maybe off catching sardines in Norway. I don’t know, but either way, I once again here relegated to having to sit around with yet another amazing special guest. And I’m gonna introduce my guest to you in just a second but before I do, I wanna remind you that something I’ve talked about before on the podcast is the fact that I go to the sauna, and I go to the sauna about once a week. Sometimes in the winter when it’s cold here in the frozen tundra of Spokane, Washington, I’ll go twice a week and I’ll get this huge pile of magazines and journals that I subscribe to like ESPN and Fast Company and Mother Earth News is another one that I read. Sometimes I’ll even grab a book that I don’t mind destroying, and I settle in for a good 30-45 minutes of a sweat session in the sauna, and usually it’s after about 25 minutes that it gets really tough and my heart rate and my core temperature start to go up. And I eventually get so hot that I have to stop reading and start staring at the wall and doing deep meditative breathing to sit things out for as long as I can. Sometimes I’ll pretend I’m in some kind of a Native American sweat lodge or some prisoner of war tossed in a heat torture chamber even though I’m really in the YMCA where there’s a water fountain about 10 feet away.
But anyways, then I get out of the sauna and I generally take a cold shower right afterwards, and then I feel freaking amazing for the rest of the day. And I’ve used this strategy to train for everything from racing Ironman in the Lava Fields of Hawaii to prepping my body for tennis tournaments where I know I’m gonna be in a stifling, indoor, hot, tennis court stadium. But when it comes to heat, there’s some pretty cool physiological adaptations that occur. The biology of heat is pretty cool. It can work to enhance performance, it can build muscle, it can burn fat, it can even make you smarter. There are some really interesting things that heat does, but it’s hard to understand. What the best kind of heat is, saunas or steam rooms or sauna suits, how to use heat, how long to heat for, so this all leads into who I have on the show with me today.
Her name is Dr. Rhonda Patrick, and Dr. Patrick is actually a pretty amazingly smart woman. She has a PhD in Biomedical Science, she’s got a Bachelor’s of Science in Biochemistry/Chemistry. She’s done a bunch of research on things like again, cancer and nutrition. She did graduate research on the link between mitochondrial metabolism and cancer, and she’s also got some videos that she’s published on heat stress. And by the way, I will link to those in the show notes. She’s currently a post-doctoral fellow at the Children’s Hospital in Oakland, where she does clinical trials looking at the effects of micronutrients, like vitamins and minerals, on metabolism, inflammation, DNA and aging. She’s done research on anti-aging at the Institute for Biological Sciences, she’s investigated the role of vitamin D in brain function, just a ton of different areas when it comes to physiology and pretty much all things nutritional geek-dom. She’s actually immersed herself in quite a bit, so like I mentioned, today she’s gonna talk to us about what she knows about heat. So Dr. Patrick, thanks for coming on the call.
Rhonda: Thanks for having me Ben and thanks for that excellent introduction.
Ben: [laughs] Yeah, I feel like I just talked for the first ten minutes of our podcast.
Rhonda: Well I was sitting there totally relating to your sauna experience. I’m like “oh my God, that’s exactly my experience.” [laughs]
Ben: Yeah, it really is interesting because it’s one of those things where I know it’s good for me, I feel all sorts of cool adaptations. Frankly, as dumb as this sounds, I even see my veins get bigger when I start doing my sauna training, so I know there’s some pretty cool cardiovascular adaptations that are occurring too.
Ben: I wanna delve into those, and before we even get into that stuff, how did you come to study heat. It seems like kind of a weird thing to study what sitting around in a sauna does.
Rhonda: Yeah, right. So my interest in the sauna came through experience. When I was in graduate school, I lived across the street from a YMCA for a long time, and I also then moved to another apartment complex which had a sauna in the building. So I was using the sauna just because I had access to it on a pretty regular basis, and what I started to notice I would go into the sauna early in the morning before I would go into the lab to do my research. And one of the really profound effects I started to notice is like you said, I started to feel amazing, like after my sauna session the stress from graduate school, the stress from my experiments going wrong, everything throughout the day was so much easier for me to handle if I went to the sauna before I started my day. And I mean it was very, very noticeable, so that sort of sparked my interest in the sauna. It actually had nothing to do with muscle or endurance or any of that, it was actually brain, the effects on my brain and that, to me, was very noticeable and interesting so I started to read about it [laughs]. Being a scientist, I have access to these scientific journals and I also obviously know how to…
Ben: Did you take your journals into the sauna with you?
Rhonda: Oh man, I totally did. It’s so funny because I start out the first 20 minutes, I’m reading my journals and then my heart rate starts to increase, it’s really pretty much like cardiovascular exercise as I noticed.
Ben: Mmhmm, yeah. I got my heart rate up to about 160 in the sauna before.
Rhonda: Wow, I’ve never actually measured mine but it’s very obvious after about 20 minutes of sitting in there that it starts to kick up, and then after a while I begin to experience so much pain that I can no longer read.
Rhonda: And so I am sitting there just sort of meditating, in a way. It’s very, very interesting, the effects that occur after that pain that I feel.
Ben: You brought it up first, so let’s jump in right there, let’s talk about the brain and what happens to your brain when it’s subjected to heat stress. Coz I know we wanna talk a little about muscle gain, endurance, stuff like that, but why don’t we start right in with the neurological adaptations. What are the effects of hyperthermia or sauna treatment or heat stress on the brain?
Rhonda: Right, so there’s actually quite a few different effects on the brain. The effect that I was describing where I felt really great the rest of the day and what you also noticed actually has to do with the manipulation of the opioid system in the brain. And this is actually related to the runner’s high as well. So the brain has different opioid receptors, people are probably most familiar with the endorphin system, right? I think that’s what most people are familiar with endorphins, beta-endorphins and how they make you feel good and how you release them after exercise. Well actually, there’s another part of this opioid system that is the counter to endorphin and that’s called dynorphin, and dynorphin is responsible for that feeling of dysphoria, so obviously when you’re running or you’re doing a very intense exercise or you’re even sitting in heat stress, you start to feel that uncomfortable, dysphoric feeling.
Rhonda: And that’s actually, you’re releasing dynorphin, and dynorphin binds to a receptor in the brain called kappa opioid receptor. And the binding of dynorphin to this kappa opioid receptor actually has interesting feedback mechanisms on the endorphin system. Endorphins bind to something called the mu opioid. Mu opioid receptor is what things like morphine derivatives bind to so it blocks that pain message, it’s involved in the [0:10:01] ______. So bringing it back to the kappa opioids, when you activate that kappa opioid, that painful feeling, you actually upregulate the mu opioid receptors, and you sensitize them to endorphin. So what happens is the more pain you feel, the more discomfort your feel, later on when you release the endorphins, you’re gonna be more sensitive to them and so you’re gonna experience and even better endorphin high.
Rhonda: And so it really physiologically translates to the more pain, the more discomfort you feel during physical exercise, the more intense it is, the more intense the heat stress, the better the runner’s high is gonna be after that endorphin response is going to be.
Ben: Do you know how long these endorphins stick around after you do a sauna session?
Rhonda: So I don’t know exactly how long they stick around, I know that you do also dump a bunch of endorphin as well, but because you’re more sensitive to them, just like other things that cause endorphin release, you’re gonna be more sensitive to that endorphin throughout the day.
Ben: Right, so very similar to the whole idea behind if you have a test or a talk or something that is mentally demanding later on in the day, it can help to go out and spark endorphin release by going on a run in the morning. You could do the same thing by doing a sauna session?
Rhonda: Yeah, absolutely. I’ve actually done that, so if I’m giving a big talk, I’ll do… well I used to, I don’t have this great access to a sauna right now as I did previously, but I would go into the sauna before giving a talk and it was amazing. Amazing response where I felt like dealing with that stress was so much easier for me.
Rhonda: Part of the mechanisms why heat is important for this opioid system is they actually regulate body temperature, so if you inject dynorphin into a rat, it cools the body temperature. So it makes sense that when you’re experiencing extreme heat stress, your body’s gonna have a biological homeostatic mechanism response where it’s gonna try to cool itself, and dynorphin is that mechanism that actually cools the body temperature. And if you notice when you’re anxious or when you’re feeling anxiety before whatever, before giving a talk or whatever’s stressing you out, sometimes your hands will get cold and clammy, that’s the dynorphin.
Rhonda: Yeah, it’s very interesting. So that’s just one of the really cool effects on the brain that I really found interesting because I personally experienced it.
Ben: What else happens to the brain?
Rhonda: So heat stress also activates or causes the release of norepinephrine, which is interesting because norepinephrine is what’s involved in focus and attention.
Rhonda: And actually if we talk a little bit about thermogenesis later, I can kinda come back to that because norepinephrine does a lot of other interesting things as well. But what I find interesting is the effects on improving attention and focus because for me, sometimes I have a problem with becoming very distracted. I get very interested in a lot of things, and so it’s like “oh my goodness”, I’ll read one thing and then I’ll go on to the next instead of kind of diving down deeper, which I’ll do but sometimes it’s hard for me to do that because I find myself distracted by a lot of interesting things.
Rhonda: So the norepinephrine release is cool, and also what’s really cool is that heat stress has been shown to also increase the storage of norepinephrine. What that means is when…
Rhonda: Yeah, you can actually, when you’re storing norepinephrine and it’s available for later release…
Ben: Where do you store it?
Rhonda: In vesicles. I mean, I dunno the exact mechanisms of all that, but I do know that it does increase the storage of it, so…
Ben: Okay. So basically like a synaptic ending or something like that? You just have more epinephrine stored up and ready for release?
Rhonda: Right, ready for release. And it’s not being metabolized and turned over as readily as reuptake so it’s not being… yeah.
Rhonda: So the other really cool thing on the brain is brain drive neurotropic factor, which is something that exercise is also known to increase.
Ben: Yeah, BDNF.
Rhonda: Yeah, exactly. Yeah, BDNF. So heat also increases BDNF which is, I think, part of the reason why exercise can increase it because when you’re exercising, you’re elevating your core body temperature. So a lot of these heat stress mechanisms are very common in exercise because exercise is elevating your core body temperature. So yeah, BDNF is cool because it’s an important growth factor for growing new neurons.
Rhonda: And that’s obviously been shown to be important in learning and memory and also for… well, the cool thing about the learning thing is we’re finding some new mechanisms by which increasing neurogenesis actually helps you forget things that you wanna forget. So it plays a role in forgetting things that make you anxious, yeah.
Ben: Total segue here but we all know that alcohol kills brain cells and sometimes people go into a sauna to detox and feel better after they drink. Do you think that there’s some type of a repair, like a neuronal repair of alcohol-induced brain cell damage that could occur if you were doing a sauna session?
Rhonda: Yeah well it’s important to not do a sauna session while you’re drinking alcohol. [laughs]
Rhonda: That actually can lead to death, so like, seriously… But yes, if you are going into the sauna post alcohol induced neuronal cell death, increasing your brain drive neurotropic factor obviously is gonna help you grow new neurons so… I definitely think that would be a beneficial thing to do.
Ben: But from a pure biohacking standpoint, for the people out there who are using things like modafinil of aniracetam or phosphatidylcholine or any of these smart drugs, they could actually get a pretty good benefit from the dynorphin, from the brain drive neurotropic factor and from the norephinephrine just by doing something like potentially using a sauna instead of supplements or maybe as an adjunct to supplements.
Rhonda: Absolutely. Yeah.
Ben: Interesting. Now how, in these studies that we’re talking about right now, how long are we talking? Coz you and I, we’re talking about how we would do 30 minutes, I’ll usually max that at 45. The longest I’ve ever stayed in a sauna was an hour, it was horrible.
Rhonda: Right. [laughs]
Rhonda: It’s really hard.
Ben: I had to play videos inside my head of me riding my bicycle down the Lava Fields in Ironman to just motivate me to make it that long. But in these studies, are we talking about 10 minutes, 20 minutes, what are they looking at?
Rhonda: Right. So the effects of the sauna, of heat stress on the brain and also on other mechanisms that improve muscle growth and such do depend on the time and temperature spent in the sauna. So they’ve shown that if you’re in a sauna, most saunas, dry saunas at least, I think they range between 140-180 degrees Farenheit.
Rhonda: Maybe some of them reach up to 200, as well. So having two 20 minute sauna sessions back-to-back, so you can do a 2 minute session, get out for like 5-10 minutes, and then go back in. And you can have some of these effects from heat stress occur.
Ben: Do you think that heat-cold contrast, like hot-cold contrast in a situation like that would make it even more beneficial, like going sauna into cold shower?
Rhonda: Yeah, actually.
Ben: Does it cause a nitric oxide release or anything like that?
Rhonda: It does cause a nitric oxide release, and it also, I’ve seen a study where they did a sauna and then cold shower and it caused an even more robust release of norepinephrine from the locus coeruleus. So that I found very, very interesting because I’m interested in norepinephrine for one, so there are… I think people like the Russians, don’t they do this heat stress and then jump into a cold ocean or something like that after, or maybe the Fins do it as well?
Ben: Yeah, they do.
Ben: A lot of those crazy countries with amazing warriors who are super tough, like Vladimir Putin.
Rhonda: [laughs] Right. But honestly to get back to your question in terms of the time spent in the sauna, it really does, when you’re in the sauna, you’ll feel your heart rate elevate, you’ll feel that dynorphin that you’re expressing where it’s uncomfortable and that’s really the key. Getting to that point where it’s just uncomfortable enough for you to wanna get out. They’ve shown in studies that when they put people in the sauna and they let them stay in to that point where it’s physiologically and psychologically hard for them to stay in, that’s the point where they start to have all these mechanisms kick in where their hypothalamus-related mechanisms kick in.
Ben: That makes sense because you don’t get a runner’s high if you’re out on an easy jog. You only get a runner’s high after you go through discomfort.
Ben: Actually I interviewed Steven Kotler who wrote “The Rise of Superman”, and he talks about this, how the theta brainwave release necessary for you to tap into the runner’s high and get into what he calls “the zone” that you actually have to have physical discomfort present.
Rhonda: You do, you absolutely do, and that’s part of the dynorphin-endorphin system that I discussed earlier. But I think that people will know, when you’re in there and if it’s easy for you to stay in there, you have to kinda get to that point where you and I talked about where you can’t, it’s no longer comfortable and it’s really hard to stay in.
Rhonda: That’s the point where all these mechanisms start to kick in. And you don’t wanna push it too much, obviously heat stroke is a very serious thing, so staying in there an hour, I’ve done it as well and sometimes I’ll take a big mason glass jar of water in there with me to help.
Ben: Yeah, you have to push it. Honestly, I hear what you’re saying, we don’t want to recommend that people go do this and have… well I’m just saying that for selfish reasons. I don’t wanna lose podcast listeners to heat stroke.
Ben: Coz that’ll affect my podcast download numbers, but basically I feel the best when I get myself to the point where I am just a little bit dizzy, just slightly, slightly scared that maybe I stayed in for too long, that’s when I feel the best when I actually get out. So I think you do have to tap into some amount of discomfort, but yeah, like you said, obviously gotta be smart too. And what were you saying about taking the mason jars?
Rhonda: Oh yeah, so I take a big mason jar of water in there and it helps me stay in longer.
Rhonda: Because I have some water to drink and you know…
Ben: Did you ever dump the water on the sauna rocks?
Rhonda: Yeah, yeah, I have. And then it gets really hot. [laughs]
Ben: I did that the other day and a guy who was sitting there started to get angry with me because he said that the chlorine in the water was getting vaporized and would wind up in your lungs.
Rhonda: Interesting. [laughs]
Ben: Yeah, I thought that was an interesting take. I actually didn’t care coz I had filtered water from my home and there wasn’t chlorine in it anyways and I explained that to him, but I thought that was interesting that maybe if you are dumping water on the coils in a dry sauna that maybe you wanna be careful about where the water came from.
Anyways though, I want to talk a little bit here, kinda flip around from the brain and talk a little bit about endurance, coz we got a lot of listeners who are athletes, who are doing everything from marathons to triathlons. Can you talk a little bit about the actual biological mechanism that would occur via which heat could theoretically actually help with endurance?
Rhonda: Yeah, yeah. So I mean obviously this is your expertise being an endurance athlete, but so heat stress from a sauna, what it does is it causes vasodilation and you get increased plasma volume and increased blood flow to a variety of different tissues in your body including your heart, your skeletal muscles, and also your skin. And what ends up happening is that this biological mechanisms kick in where you train your body to be able to deal with this heat stress. So for example we’re talking about increased plasma and blood volume to the heart, what happens is you’re now reducing the cardiovascular strain on the heart so that it’s easier for your heart to move blood to various tissues, right?
Rhonda: So it lowers cardiovascular strain which is one of the biological mechanisms by which heat stress can improve endurance. It also increases the blood flow to your skeletal muscles, so that’s obviously carrying things like esterified fatty acids and glucose as well as oxygen, to your muscles. And what’s been shown is that if you’re increasing the amount of esterified fatty acids and glucose going to your muscles, then at that point where endurance athletes usually have to rely on their local glycogen stores…
Rhonda: When they’ve basically exhausted, like when you’re running a marathon or something like that, your body will rely on local glycogen stores as a source of energy for your muscles. What they’ve shown is that endurance athletes that train in heat, they’ll actually rely on glycogen stores less because of the increased blood flow to the skeletal muscles.
Ben: So what are they using instead of glycogen?
Rhonda: Well, they’re using the glucose and stuff still, because of their increased blood flow to the skeletal muscles.
Ben: Okay, so you basically got more glucose and theoretically I guess if you were eating a decent diet like more glucose, more fatty acids.
Rhonda: Right, obviously you have to.
Ben: Less glycogen breakdown.
Rhonda: Right. I mean the point is that at some point you might end up relying on the glycogen stores no matter what, but if you are having that increased blood flow to them, then it’s just getting more of it there quicker, basically. So it is interesting.
Ben: Do you know if they’ve actually looked at that from a muscle biopsy level? I mean I know there are many studies that should be done that haven’t been done yet, but have they looked at heat-treated versus non heat-treated athletes and actually checked out to see if during exercise they’re maintaining higher levels of muscle glycogen?
Rhonda: During exercise? I think there might be a study that did do that. I’d have to look back at my references coz I can’t remember off the top of my head. If there is, I’ll link you to it. I’ll send it to you.
Ben: Okay, that’d be interesting.
Rhonda: Right, that would be a really good way to directly show that.
Ben: Yeah, I’m actually looking at a reference here from the 80’s, Journal of Applied Physiology, late 80’s, substrate utilization in leg muscle of men after heat acclimation.
Ben: I wonder if they actually did a muscle biopsy to look at whether or not you had higher glycogen levels after heat acclimation.
Rhonda: Right. I think they might have, actually.
Ben: That’s pretty cool. I had no idea they actually study stuff like that, that’s very cool.
Rhonda: it is cool.
Ben: So we’ve got better maintenance of muscle glycogen, we obviously got increased amount of plasma and so we got higher blood volume which is obviously a great cardiovascular improvement. What else?
Rhonda: Right, and thermoregulatory mechanisms so when you’re training your body through heat stress, the heat-sensing neurons in your hypothalamus get activated and what ends up happening is the more you condition your body to that, they get activated at a lower core body temperature. So you actually begin to dissipate some of that heat earlier to lower core body temperature and also you can maintain it for a longer period, and so you end up cooling your core body temperature. And I don’t know if you’ve noticed this but I know that I sweat, coz I’m pretty athletic as well, I end up sweating easier. I think a lot of athletes might notice that.
Ben: Oh yeah.
Rhonda: Yeah, because when you’re exercising you’re obviously also elevating your core body temperature and the same heat-sensing neurons are getting activated and such, so it’s another mechanism by which you’re able to maintain this thermoregulatory, homeostatic mechanism that helps you deal with this elevated core body temperature. I mean that’s part of the reason when you’re going for a long run, when you’re getting super, super hot, you just wanna stop. There’s something going on at that level of the brain that you’re just like “I can’t take this.”
Ben: Yeah, it’s the central governor, it begins to shut your brain down. Two of the things that the central governor senses, two of the biggest things are core temperature, and then interestingly also your blood levels of amino acids, that’s another one. Your brain will tend to shut things down pretty quickly once your blood levels of amino acids drop. Actually, this is kinda interesting. They’ve done studies on muscle glycogen and found that the infamous bonk that we’ve all thought was just due to pure carbohydrate depletion…
Ben: You still have carbohydrates stored when you bonk, but if that’s in the presence of very, very low blood levels of amino acids, you’ll still bonk.
Rhonda: Oh wow, that is interesting.
Ben: Total segue but…
Rhonda: Yeah, yeah.
Ben: Now I have to ask this question because I’m sure some people are wondering it. This is all great that it increased plasma and maybe staves off some depletion of muscle glycogen and improves thermoregulatory control, but does it make you faster? Have they actually looked and found out, are the folks who are doing heat acclimation actually faster?
Rhonda: Yeah, so faster I’m not sure but one of the studies, they looked at male runners that did a 30 minute sauna session two times a week for three weeks after their workout, what they found is that when they had those runners run to exhaustion, that they could run longer.
Ben: So increased time to exhaustion?
Rhonda: Right, yeah, which would make sense based on the mechanisms that I just described. They also noticed that these runners had an increase in obviously their plasma volume, but they also had an increase in their red blood cell count which they think was common. If you’re increasing your plasma volume, there’s a compensatory mechanism. Your body obviously wants to maintain homeostasis so it increases red blood cell count also to keep that hematocrit normal.
Ben: Right, so if your plasma volume is going up, it doesn’t do you any good if your plasma volume goes up if you don’t have more red blood cells?
Rhonda: Right, exactly. Yeah, and they theorized that the increase in RBC count is due to increase in EPO, but they haven’t actually proven that yet. But the faster, I did some experimenting with it back in graduate school, I was really, really doing a lot of sauna training with my running as well. And I noticed an increase in my personal running time, and it’s totally anecdotal.
Ben: Yeah, myself as well just from an n=1 standpoint.
Ben: We noticed that it makes a big, big difference especially when you are actually exercising in the heat. That’s where I’ve seen a huge difference, I did the whole minimalist training for Ironman Hawaii last year where I tried to train 8 hours a week to be able to complete Ironman in less than 10 hours. And I actually, this was kind of a cheat, I didn’t include the time that I spent sitting around in the sauna reading my magazines, like as part of that 8 hours. But I still think that that played a huge role in my ability to be able to tolerate the heat stress without excessive amounts of exercise.
Ben: But that’s just totally anecdotal. Now what about people who are maybe not so interested in endurance but are wanting to go after this from a muscle gain type of standpoint or a hypertrophy standpoint?
Rhonda: Yeah, really one of the cool things about the sauna or what I’m calling hyperthermic conditioning where you’re conditioning your body to heat stress in order to be able to deal with heat stress later on better, I think that this is a sort of hormetic response. It’s really actually a classical example of hormesis where you’re giving your body an amount of eustress/good stress. Exercise is a good example of that, heat can also be a eustress as long as you’re not overdoing it [laughs]. You’re actually going to activate some genes that help you deal with heat stress or help you deal with stress in general, and one of the really cool genes that gets activated in response to heat is called heat shock factor 1. And it’s a transcription factor that activates a variety of different downstring genes that encode for heat shock protein. So these are called HSP, heat shock proteins are really, really cool. They play a role in making sure the proteins in your cells are in the right structure, meaning they’re properly folding and doing what they’re supposed to do.
Rhonda: They also have antioxidant activity so they can scavenge radicals and alleviate a lot of that oxidative stress that occurs from normal metabolism, that occurs during exercise. So having a high expression of these heat shock proteins is a good thing, so that was one of the things that I found really cool about heat stress is that it very robustly activates these heat shock proteins.
Rhonda: And the heat shock proteins have been shown to play a role in preventing the degradation of protein, specifically in muscle tissue. So if you think about it…
Ben: Could you have too many heat shock proteins? Could you overdo it?
Ben: I mean if it is a hormetic effect, this just makes me think about this just because this whole hormetic effect thing is based on damage, right? So I’m just wondering if you could get a sauna session, get so much heat shock protein produced that it would potentially cause some kinda of an immune system bounce back or something like that.
Rhonda: Uhm, heat stress actually can depress the immune system because it is a very strong stress. The heat shock protein response is actually the good thing that you want to counter some of them, because heat stress can induce apoptosis. It can induce damage, and the heat shock protein response is what counters that. And actually, they’ve shown that people that have polymorphisms in their genes that encode for heat shock proteins that make them more functionally active, have increase longevity. I think having more of the heat shock proteins itself would be a good thing, but I do think that doing something like the sauna everyday would be such a strong stress that even having those heat shock proteins won’t be able to counter that at a certain point.
Ben: Okay cool, so if you’re listening in, don’t go download 4 hours worth of podcast and subscribe to 18 magazines and go visit the sauna for 2 hours a day. It’s not definitely that more is better type of thing.
Rhonda: Yeah, that’s a little bit extreme. [laughs]
Ben: So in addition to heat shock proteins, what else can happen?
Rhonda: So also there’s been a really robust induction of growth hormone, and this is part of the stress response as well. They’ve shown that if you’re in the sauna for 30 minutes, for example, you can increase your growth hormone two-fold over baseline.
Rhonda: In some cases they can activate it 16-fold but that’s pushing it to an extreme case where you probably don’t want to do that. You don’t wanna do that. But obviously, heat shock proteins are important because they’ve been shown, in mice to prevent the oxidative stress that increases protein turnover or protein degradation in skeletal muscle. And so if you’re exercising and you’re having an increase in oxidative stress, the heat shock proteins can sort of sequester that and prevent them from breaking down muscle.
Ben: So what if you’re already injured? Do you think that the production of heat shock proteins could assist with more rapid healing of injury? Your sauna’s like an injury healing protocol?
Rhonda: Yeah, so they’ve shown that. They’ve shown that in mice, when they immobilize a mouse, they’ll put a little cast on its little hind limb, and keep it immobilized.
Ben: Keep it immobilized.
Rhonda: Yeah, keep it immobilized for like a week. And so what they’ve shown is that if you take these mice and you either heat shock a group or you don’t, and heat shocking being like 30 minute hyperthermic treatment so it’s sort of like a little mini-sauna for the mouse. What happens is that after immobilization, when they sacrifice the mice and they look at the soleus muscle, they find that the ones that were heat treated basically lost less of their muscle. And also what they’ve shown is that after immobilization, when they allowed the mice to run around again to regrow their muscle, those mice that were heat treated can grow more muscle. In fact, like 30% more muscle after the immobilization. So they’ve definitely shown that heat shock proteins play a role in that. I’ve noticed myself when I’ve been injured and I’ve been sitting in the sauna as a sort of surrogate way of getting some sort of cardio exercise, sitting in there and get my heart rate up, I’ve noticed that I lost less muscle when I’m using the sauna as opposed to when I don’t when I’m injured and I just can’t do anything.
Rhonda: And that’s totally anecdotal like I said, but…
Ben: I think this whole heat shock protein thing is interesting though because you talked about how it increases endorphins and there’s this physician, and I’ve had him on the podcast before, his name is Dr. Mark Sircus and he lives in Brazil now. And he’s actually written books on hyperthermia for cancer.
Ben: And he’s talked before on the podcast about heat shock proteins and activation of T-cells and lymphocytes and how it can have this anti-cancer effect to use hyperthermia treatments. He uses infrared saunas and infrared mats.
Ben: He has his patients lie on the, actually I have one on my bed, it’s called a Biomat. He uses infrared for cancer and immune system activation, and he says it’s because of the heat shock protein.
Rhonda: Yeah, that’s interesting. What I know about heat shock and cancer cells, so cancer cells are primed to die. They’re expressing a lot of what’s called apoptotic proteins that are priming them to cell death. However, they have countered that by expressing a lot of anti-apoptotic proteins and that’s how they sort of keep going because the balance between these pro-death and anti-death proteins that they’re expressing. So because they have a high amount of these pro-death proteins, any sort of stress that can push them over that edge can induce cell death, and because heat stress is a very severe type of stress, it can actually induce apoptosis in cancer cells. And I know they use that in conjunction with chemotherapy as well because it does kill cancer cells much, much better when you have stress plus stress equals death.
Rhonda: Eustress, a little bit of stress, you get hormesis but too much stress, you’re gonna get cell death.
Rhonda: But in terms of heat shock proteins and the immune system, that’s an interesting angle that I wasn’t aware of.
Ben: Yeah. I actually bought one, maybe I’ll ask you more about the type of sauna that works well, but I bought one of these infrared mats and I sleep on them in the afternoon, and I wake up feeling like a millions bucks. I dunno if it’s because of the dynorphins and endorphins or the heat shock proteins or what, but I think even that is giving me a little bit of a heat effect.
Rhonda: Yeah, heat shock proteins are awesome. [laughs]
Ben: Yeah, yeah. I wish we could just bottle them up and drink them.
Ben: Okay, so what else, when it comes to muscle gain or endurance or cool physiological effects occur with exposure to heat?
Rhonda: Yeah, so I mentioned the growth hormone which is another really cool, obviously… they’ve shown that growth hormone can prevent the breakdown of proteins in the muscle, so if you’re looking at balance between muscle breakdown and muscle synthesis or protein synthesis, I guess would be more accurate than… anything that can prevent the breakdown will have a net increase in protein synthesis. And also, IGF-1 which is downstream mediator of growth hormone activates mTOR which is really important to make proteins, so you’re talking about being able to increase protein synthesis at the level of actually making proteins through mTOR. So that’s another interesting effect of heat stress but it does depend on the amount of heat stress, so you really have to push it to that degree where you’re uncomfortable.
Ben: So does that mean that there could be some kind of an anti-aging or longevity effect?
Rhonda: There absolutely is an anti-aging… by the way, when I’m talking about the effects on muscle growth, you obviously need to be applying a force to your muscle tissue, so obviously in combination with working out, lifting weights. I mean you can’t just sit in the sauna and expect to grow muscle. That’s not how it works.
Ben: [laughs] You can’t just go to Whole Foods everyday and do yoga every morning and then visit the sauna and turn into a beast?
Rhonda: Yeah, I mean you obviously need to be applying a workforce to your muscles to make them grow, but I’m saying in combination with that.
Ben: Right, yeah.
Rhonda: But anyways to your longevity thing, yeah it’s really interesting. I did some research, some of my early research was on aging and one of my first publications that I was a part of was published in Science and actually had to do with heat shock proteins and the role heat shock proteins played in preventing the aggregation of amyloid beta protein which is known to be one of the toxic proteins involved in Alzheimer’s disease, where it aggregates in the brain. And what we found is that when we were using this worm model for Alzheimer’s, it’s kinda funny because worms don’t really have brains, we would actually transgenically make them express amyloid beta proteins in their muscle tissue. And what would happen is as these worm age, they express this amyloid beta, it would start to aggregate in their muscle tissue and they’d become paralyzed. They couldn’t move anymore because this protein was just toxic and aggregating in the muscle tissue. And what we found is that when we genetically engineered them to express high level of heat shock proteins, this ameliorated that effect where it delayed the onset of the paralysis because the heat shock proteins were able to help the amyloid beta protein properly fold and help it not aggregate. These worms were actually, it delayed the onset of that.
Ben: With amyloid beta proteins and I think it was, do you know who Nora Gedgaudas is? Have you heard of her before?
Rhonda: I do not.
Ben: Okay, she wrote this book called “Primal Body, Primal Mind”, she talks about brain inflammation and one of the things that she talks about with aging is formation of amyloid plaques in neural tissue. Is that related to these amyloid beta proteins?
Rhonda: That’s exactly what it is, yeah.
Rhonda: We were using the same protein and making worms express a high level of it.
Ben: So theoretically, you could stave off the accumulation of plaques in the brain that can lead to accelerated brain aging if you were to do something like make sauna a practice?
Rhonda: Yeah, and also exercise because exercise also induces heat shock proteins because you’re also elevating your core body temperature. And I think that’s part of the mechanisms by which exercise can protect against brain aging, so heat shock proteins, they’ve shown in worms and they’ve also shown in mice when you genetically engineer them to express more of them, it extends their lifespan. And then in people, if you look at people I think I mentioned this earlier in the podcast, people that have polymorphisms in the gene set in code for their heat shock proteins such that it makes them express more of them, they’re more functionally active. It’s associated with longevity and living to be in your hundreds, so heat shock proteins play a very interesting role in aging. We, as we age, express less so the gene expression goes down. So anything that you can do to increase their gene expression, in my mind, is really good, and they’ve shown that there’s an epigenetic mechanism by which heat actually increases the expression of it. So people, for those listeners out there that are like “what is epigenetics?”, you can actually change the expression of your genes through different environmental signals, things like exercise, heat, sleep, what you eat. You can change how much of your gene is expressed and this happens mostly through methylation of regions of your gene that are important for activation or also acetylation. Methylation’s often associated with decreasing the expression of the gene.
Rhonda: And acetylation’s often associated with increasing expression. What they’ve shown is that heat stress will, they’ve shown this in chickens actually and also in mice, what ends up happening is when you heat stress, the promoter region, which is that regions that is important for activation of a gene, gets acetylated in heat shock protein. Genes that encode for heat shock proteins, and so you end up getting more activation. Not only like when you’re heat stressed but also just under normal physiological level. So under normal conditions, when you’re conditioning yourself to heat stress, you will then express higher levels of heat shock proteins.
Rhonda: And this is really cool. They’ve shown it in chickens and also in rats, they did a really cool experiment where they took baby chicks that were 3 days old and they expose them to heat, and then they expose them to heat again at 1 week, and what they found is that they have higher levels of heat shock proteins in general. And also, when they were adults, when they exposed them to a really, really severe heat stroke-like stress, like the bad “sitting in the sauna for 2 hours” kind of thing.
Rhonda: It protected them from mortality, heat stroke induced mortality, compared to the chickens that were not conditioned to heat early on. So there’s really a cool epigenetic mechanism in play that conditioning your body to heat stress, you can express more of these heat shock proteins.
Ben: I’m gonna start driving around everywhere in my car with my heater turned on.
Ben: And if any of my passengers ask why, I’m gonna tell them “coz I wanna live to be a hundred.”
Rhonda: Yeah. It’s also cool, heat shock proteins does protect against some of the toxins, so your question about the alcohol and killing brain cells. The thing is if you express more heat shock proteins, it’s been shown that the heat shock response can actually protect from the neuronal cell death that’s induced by things like alcohol and even heavy metals and other xenobiotics. Obviously, the heat shock response is part of the hormetic response, so when you are taking things like EGCGs, things that are little toxic to the body that induces hormetic response, heat shock proteins are a part of that and they do protect against some of those toxic effects.
Really, I think I wanna just draw the parallel again between exercise and sauna because the point is that exercise also induces the same physiological effects that heat stress does because when you’re exercising, you’re heating your body. That’s part of the cool thing about exercise, and I really think that some of these benefits of exercise come down, at the molecular level, to heat shock protein.
Ben: Yeah. The interesting thing is, I think I already mentioned when I was talking about the central governor, Timothy Noakes, this South African exercise physiologist, he’s done studies on core temperature and specifically he started doing the studies to disprove the idea that staying hydrated during exercise would somehow keep your core temperature regulated.
Ben: And the fact is he was kinda right, we have to drink way less than what we’ve been led to believe to keep our core temperature low during exercise. But what he also found was that you gotta be exercising pretty freakin’ hard to get your core temperature up.
Ben: So, I don’t wanna turn this into the “go into suffer-fest mode” in a sauna and then destroy yourself in the wait room around the treadmill” type of podcast, but I think it does point out the whole idea here that discomfort is a good thing. In many cases, mild amounts of discomfort are a good thing, and it sounds like in the case of whether it’s a sauna or exercise, part of it is not just breathing hard or moving of blood flow, but it’s the actual increase of temperature causing these heat shock proteins to be produced.
Rhonda: Absolutely, and I think that the sauna…
Ben: Make it hurt, people, make it hurt.
Rhonda: [laughs] Exactly. In combination with exercise, I think the sauna can have really, really good benefits like ones we’ve already discussed. So it’s something to keep in mind.
Ben: Yeah, there’s this guy, he’s the 70+ year old Ironman world champion, he has this rule. He says “go anaerobic every day.” I love that, it’s a good way to get the heat up. So, I’m curious, when we’re talking about heat, you and I have talked about saunas a lot, like just there basic dry saunas that you’re gonna find in the YMCA or health club or whatever, but have they ever looked at the effects of different kinds of heat? Coz we have steam rooms, we’ve got saunas, we’ve got those dorky sauna suits. There are now, of course, in health circles like I already mentioned. I sleep on an infrared mat and there are people installing infrared saunas in their homes, I’ve even seen these nerdy-looking pop-up infrared saunas that you just put in your living room and stick your head out of and just kinda sit there for a little while. Have you ever looked at all these different kinds of heat and specifically has research ever looked at this stuff and found any one type to be most beneficial?
Rhonda: Right, so I haven’t seen studies directly comparing infrared sauna compared to a normal dry sauna in terms of the heat shock protein response or the effects of norepinephrine or growth hormone or BDNF. I haven’t seen studies directly comparing those two types of heat stress, but I will say that the whole point is heat stress and getting to the point where it’s physiologically uncomfortable. And so if you think about something like a steam room, I do think that these types of heat stress responses can be achieved from various types of saunas or even a steam room in general, I think can do that. However, I’ve sat in a steam room before and I can’t get to that point of discomfort that I can get to in a sauna. I think because for one, the steam room is wet and so your skin starts to burn. You can’t stay in as long because you don’t want your skin burning because of the water.
Ben: Yeah, no. I agree, you get a much greater amount of topical discomfort and I agree. It seems like you can’t get your core temp down before your skin gets too hot or your lungs get all annoyed by the excessive humidity.
Rhonda: Right. So I do think you can, it’s not like a steam room won’t have any of these benefits, but I don’t think they’ll be as robust. And this is pure speculation because I hadn’t seen studies directly comparing them.
Ben: Well in exercise research, they have looked at wet heat versus dry heat for physiological adaptations, for performance.
Ben: I know that in exercise, they’ve always found dry heat to be better.
Rhonda: Interesting. Yeah, I’ll have to look at those studies.
Ben: If you look at professional Ironman athletes like Chris McCormack or Craig Alexander and these guys training for Kona, they’ll set up their bike or treadmill in a dry heat setting.
Rhonda: Interesting, yeah. So in terms of the infrared sauna, I know there’s a lot of marketing hype out there, a lot of it has to do with them talking about detoxification. And there are some things that you do sweat out with a sauna, whether or not the infrared sauna does it better, I really can’t say that I’ve seen convincing evidence of that, honestly.
Rhonda: Scientific evidence that I find compelling.
Ben: I don’t sweat at all when I sleep on that Biomat or when I’ve used infrared saunas, I don’t sweat but what they say with those is that the far infrared rays basically penetrate deeper into the tissue so you get this hyperthermic effect quicker without sweat. But I don’t know, I just feel like there’s more of a performance enhancing effect from a dry sauna, and maybe there’s more of a therapeutic effect from using something like infrared. But I can tell you, infrared is definitely not as uncomfortable, and I never feel that same type of distinct performance enhancing effect from something like infrared.
Rhonda: Yea, it kinda makes sense to me. My in-laws have an infrared sauna in their garage and I’ve used it, and compared to the dry sauna which I use more frequently, I don’t notice as much discomfort as well. And I think that part of that discomfort, and I know part of that discomfort, is what’s important to activate that hormetic response.
Rhonda: It’s what’s important to activate that HSP response, it’s important to activate a lot of these dynorphin mechanisms we’re talking about. So I don’t know, I’m not saying there aren’t benefits from using the infrared sauna, I just don’t know if it’s better.
Ben: Yeah, I definitely think there’s benefits. I personally think that the combination of both is really good, that’s what I do. I go to the sauna once or twice a week and then I use infrared, almost everyday I use infrared.
We’ve been going for almost an hour, but I wanna touch also on the total opposite of what we just got done talking about and that’s cold, coz I’ve had Wim Hof, the iceman, on the show who takes folks up into the mountains to do these yoga cold sessions where they’re sitting in the snow, doing power breathing.
Ben: And Ray Cronise who, he’s been in Wired Magazine for his big cold lab for enhancing fat loss through cold exposure. Have you ever run into any of that or studied any cold exposure or cold thermogenesis for biological enhancement?
Rhonda: Yeah, I mean I know a little bit about it just because I’ve looked into some of the uncoupling proteins and they’re effects on thermogenesis. I know that when you’re cold stressing your body, I’m gonna bring this back to the norepinephrine, which is released. It’s released by heat stress but also by cold shock, and I think there may even be a more robust release when you combined the heat stress first and then do the cold shock, at least in one of the studies that I saw, there was.
Ben: Is that coz of the back and forth blood flow?
Rhonda: Yeah, I think so. The norepinephrine causes an upregulation of UCP-1, uncoupling protein 1, and this is really important because the uncoupling protein is expressed in mitochondria. And your mitochondria are, as they’re generating ATP, they’re inducing what’s called a mitochondrial membrane potential. So they’re taking these electrons from NADH and FADH2 which are made from the TCA cycle when we eat carbohydrates and convert everything to pyruvate, blah, blah, blah. We get into that whole cycle and we generate these electron reducing equivalents. The mitochondria takes these electrons and passes it along this chain of proteins, ultimately reducing molecular oxygen to water and using that as a source to make ATP. What happens is it pumps protons outside from the inside of the mitochondria to the outside, and it generates this electrochemical gradient which is negatively charged on the inside and positively charged on the outside. And that gradient is really important because the mitochondria senses when that gradient isn’t happening properly, your mitochondria ramp up and start producing more ATP. So UCP-1 uncouples that mitochondrial membrane potential and all these protons start to flow back into the mitochondria, and so the mitochondria’s like “oh my God”, it’s sensing that it’s not making enough ATP so it ramps up its metabolism.
Rhonda: And this is part of the thermogenic effect, so when you have this uncoupling protein, now the mitochondria starts ramping up its metabolism and you start to have that thermogenic effect where your metabolism’s shooting up. And UCP-1 also is involved in lipolysis, so anything that’s gonna increase norepinephrine and then UCP-1 will then affect thermogenesis, mitochondrial metabolism, and also you’ll start to increase lipolysis.
Ben: So you get a lipolytic, fat-burning effect?
Rhonda: Exactly, and I think that makes sense why these people are seeing effects on fat-burning when they’re sitting on ice or a cold shower, whatever it is they’re doing. The other really interesting thing is that they’ve shown that the more repeated norepinephrine release, the more you’re training your body to do this, you can actually express more of this UCP-1. So UCP-1 is in mitochondria but it’s mostly found in the brown adipose tissue.
Ben: Right, the BAT tissue.
Rhonda: Yeah, exactly, the BAT tissue. And what they found is, for a long time they didn’t think that we as adults had brown adipose tissue, that we just had it as infants but now we know we do have brown adipose tissue. But what’s really interesting is that you can actually cause your white adipose tissue to express more UCP-1, the more epinephrine that you’re releasing, the more white adipose tissue begins to express it and become brown-like, so to speak.
Rhonda: And that’s been shown in rats and mice and I think that’s a really cool adaptation.
Ben: Yeah, it’s very cool.
Ben: I need to get you one of these CoolFatBurner vests that I wear. I’ll work on my computer and it’s this vest that you pack with ice and it just puts the ice on specific areas where you have more brown adipose tissue like your collarbone and your upper back.
Ben: And you can just wear it while you’re typing so you can get that lipolytic effect.
Rhonda: Oh that’s cool. Yeah, I’ve done the cold shock, the cold shower, after the sauna. I don’t do it routinely but like you mentioned doing it, I’ve also done that a few times and yeah it’s very interesting. The effects on the brain also, what I’m interested in because not only does norepinephrine increase UCP-1 but focus and attention. And I’ve definitely noticed it help me with focus and attention.
Ben: Yeah, the thing that Ray Cronise does is he does five minutes in the morning and five minutes in the evening, and he does cold for 20 seconds and hot for 10 seconds. So it’s called a hot-cold contrast shower, and he’ll have some days where that’s all he does. And I’ve used this before when I’m at conferences and I know I’m not gonna get a chance to exercise, I’ll sneak up into my hotel room and just take off all my clothes, jump in the shower, do hot 10 seconds, cold 20 seconds and just stay in there for 5 minutes then jump out, get dressed and go back downstairs. You feel like a million bucks for the next couple of hours, and I dunno if it’s coz you get a little bit of that dynorphin or the BDNF effect or what, but it actually does seem to work.
Rhonda: Oh, interesting. Yeah, that’s cool.
Ben: Yeah. Women can’t do that as easily as guys can, unfortunately. Just strip down, jump in the shower and run back down, but yeah.
Ben: It’s an interesting strategy. So over at foundmyfitness.com, you have a really cool video, and I’ll link to it in the show notes for this episode where you talk about heat stress, and you’ve got a ton of other cool things over there as well. Do you put out a vide everyday or how do you do it?
Rhonda: No, I’m doing research full time so I really work on these videos on weekends or evening. So I’ve got this goal, I guess, that I’m trying to do two videos a month or four videos a month and I guess people are kind of helping. They can Patron pledge me like 25 cents a month to help me do that or like a dollar a month. And I’ve got these milestones that I’m trying to reach to help me to do that more frequently, and you find that on foundmyfitness.com.
Ben: 25 cents a month, that’s really breaking people’s banks.
Rhonda: Right? It’s pretty cheap so I appreciate anything that people can help with, but yeah. I’ve also got a newsletter people can sign up for and the videos that I put out I also put out as podcasts as well.
Ben: Awesome. Well, I’ll link to all that in the show notes, and by the way I’ve been taking a few notes as Rhonda and I have been talking, and what I’ll do for anybody listening in, if you wanna go check out Rhonda’s video or her website or any other stuff that we’ve discussed, the URL to go to is bengreenfieldfitness.com/hot. If you go over there you can access the show notes for this episode, we’ll have it transcribed and everything over there. So Rhonda, thank you so much for coming on the call today. This is super fascinating stuff.
Rhonda: Yeah, my pleasure. I had a really interesting conversation, Ben.
Ben: Alright folks, if you have comments or questions or thoughts or feedback or anything like that or you have your own special sauna strategy sessions that you use, go over to the comments at bengreenfieldfitness.com/hot. I’d love to hear what you have to say and until next time, this is Ben Greenfield and Dr. Rhonda Patrick signing out from bengreenfieldfitness.com.
I go to the sauna once a week, and often twice a week in the winter.
I get a huge pile of the magazines or journals I subscribe to, like ESPN, Fast Company, or Mother Earth News (and sometimes even grab a book I don’t mind destroying) then settle in for a good 30-45 minute sweat session.
After about 25 minutes, it get pretty tough as my heart rate and core temperature rapidly rise, and I eventually get so hot that I have to quit reading – and then I simply switch to staring at the wall and doing deep, meditative breathing to sit things out for as long as I can. I pretend I’m some kind of ancient warrior sitting in an Indian sweat lodge, or a prisoner of war tossed into one of those heat torture chambers.
Then I take a cold shower and I feel amazing.
I’ve used this strategy to train for everything from racing Ironman in the lava fields of Hawaii to preparing for a tennis tournament in a stifling indoor tennis courts stadium.
But why does heat work so well to enhance performance?
Can you use heat to build muscle or burn fat?
What’s the best kind of heat? Saunas? Steam rooms? Those dorky sauna suits?
You’re about to find out the answers to these burning questions (ha!), and so much more.
My guest in today’s podcast, Dr. Rhonda Patrick (pictured right) has a Ph.D. in biomedical science, a Bachelor’s of Science degree in biochemistry/chemistry, has done extensive research on aging, cancer, and nutrition, she did her graduate research on the link between mitochondrial metabolism, apoptosis, and cancer…
…and she knows a thing or two about heat exposure too, as you can see from her video here on heat stress.
Dr. Patrick is currently a postdoctoral fellow at Children’s Hospital Oakland Research Institute, where she conducts clinical trials looking at the effects of micronutrients (e.g. vitamins and minerals) on metabolism, inflammation, DNA damage, and aging. In addition, she is investigating the role of vitamin D in brain function and other physiological functions. She has also done research on anti-aging techniques at the Salk Institute for Biological Sciences.
During our podcast, you’ll learn everything you need to know about how to use heat exposure to enhance performance, burn fat, and gain muscle.
-3 ways getting into a sauna could actually grow new neurons and make you smarter…
-The best to use heat to build endurance, build muscle and heal injuries…
-How much heat exposure is enough, and how much is too much…
-Whether it’s really true that you can increase growth hormone inside a sauna…
-How heat can help you produce the “runner’s high”…
-The amazing anti-aging effect of saunas and how it works…
-What the best type of heat is, and whether there is a difference between wet heat vs. dry heat vs. sauna suits vs. infrared saunas and mats…
-How to ideally combine heat exposure with cold thermogenesis…
Resources discussed in this podcast:
Do you have questions about how to use heat to enhance performance, or any other thoughts about this episode with Rhonda Patrick? Leave your comments below!