How Cold Exposure Affects Norepinephrine and Training Adaptation
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In this clip from Dr. Rhonda Patrick's appearance on Modern Wisdom, she explains how cold-water exposure activates the sympathetic nervous system and raises norepinephrine. In a small controlled study, one hour of head-out immersion in 14°C water increased circulating norepinephrine about fourfold. This acute response helps explain why cold can feel intensely alerting. [1]
Timing matters when cold exposure follows resistance training. In a 12-week study of 21 men, ten minutes of cold-water immersion immediately after each session attenuated gains in strength and muscle mass and reduced selected anabolic signals. This supports separating regular cold immersion from lifting sessions when hypertrophy is the main goal. [2]
Dr. Patrick treats cold exposure as an optional tool rather than the foundation of metabolic health. A tolerable dose may be useful for an acute alerting experience or heat relief, while exercise supplies a much stronger and better-established stimulus for cardiovascular and mitochondrial adaptation. Matching timing and dose to the intended goal keeps cold from competing with resistance-training recovery.
This clip is excerpted, with permission, from Dr. Rhonda Patrick's appearance on Modern Wisdom. Thank you to Modern Wisdom for allowing us to share it.
- ^ Janský, L.; Šrámek, P.; Šavlíková, J.; Uličný, B.; Janáková, H.; Horký, K. (1996). Change In Sympathetic Activity, Cardiovascular Functions And Plasma Hormone Concentrations Due To Cold Water Immersion In Men Graefe's Archive For Clinical And Experimental Ophthalmology 74, 1-2.
- ^ Roberts LA; Raastad T; Markworth JF; Figueiredo VC; Egner IM; Shield A, et al. (2015). Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. J Physiol 593, 18.
Chris Williamson: Talk to me about cold. We've got hot, cold exposure.
Dr. Rhonda Patrick: Yeah, so deliberate cold exposure is another type of hormetic stress, and there's some overlap, but there's different, like, you can increase heat shock proteins from cold exposure. Heat shock, these stress response pathways, there's a lot of overlap where you can, like, because it's just, it's an adaptation, right? We were meant to move, we were meant to be hot, we were meant to be cold, we were meant to get plant phytochemicals. Our bodies respond, and we activate all these really beneficial genetic pathways. So, they all kind of overlap. Some do it better than others. Like, heat shock proteins are more robustly activated by heat, but cold also activates them. Just an interesting thing to think about.
Dr. Rhonda Patrick: So, cold exposure, one of the most robust physiological responses to cold exposure would be norepinephrine release. And, we were talking earlier about mood and neurotransmitter optimization, things to do behaviors you can engage in, and timing of those behaviors around things that are perhaps going to require a better mood, or more motivation, or something like that, right? So, norepinephrine does play a role in motivation, and mood, and those things, and I got in the cold shower before I came here, and I usually do that before a talk, or something like that, as well. But, so, norepinephrine release is one of the most consistent physiological responses.
Dr. Rhonda Patrick: You can get that from 20 seconds at like 40-degree Fahrenheit water, or 2 minutes, excuse me, 2 minutes at 49 or 50-degree Fahrenheit water will release norepinephrine twofold over baseline. Or you can be crazy and stay in like 50-degree water for an hour.
Chris Williamson: Who does that? And you'll get a fivefold increase.
Chris Williamson: So why would you want norepinephrine?
Dr. Rhonda Patrick: Well, it is a neurotransmitter. It does play a role in focus, attention. It regulates mood. It helps with anxiety, all those things are important. So, it's kind of, I personally like to time it around things like cold exposure. Also, sort of benefits with respect to mitochondrial biogenesis, you can get in cold plunge and stay in there for 15 minutes and increase mitochondrial biogenesis markers in muscle tissue.
Dr. Rhonda Patrick: So, that's the growth of new mitochondria in your muscle tissue, that's great. Mitochondria are producing more energy, so it's associated with less muscle atrophy, but you can get that from a high-intensity workout too. So you do not have to necessarily do the cold.
Chris Williamson: When should you do the cold?
Dr. Rhonda Patrick: So, I can tell you when not to do it. When not to do it would be after sort of a strength training or resistance training workout.
Chris Williamson: How long is the window?
Dr. Rhonda Patrick: So, that's the good question. So, I've come up with my own sort of window on this, and I can tell you the rationale behind that. But, so here's the thing, there's been a couple of studies, and it's actually not all consistent. The first study that came out that was like the big made the big deal.
Dr. Rhonda Patrick: It was like, I don't know, 2015 or so when it came out or something like that. And, the study did, it was a cold ice bath, and it was 5 minutes after a strength training workout, where people, like, the men went in and, like, put their leg or something like that in the ice bath for 15 minutes. And, this was right after the workout, okay? Or, they did passive recovery where they were actually on a stationary bike. So, the control group wasn't just sitting around, they were actually, in my opinion, increasing hypertrophy by movement. Okay, that's clear. I think that's a flaw in the study. And so, the people that did the ice bath right after their resistance training workout still had hypertrophy, but they had less than the control group. And so, that was like, oh, it's blunting gains.
Dr. Rhonda Patrick: And so, back then, I was trying to dive into understanding—
Chris Williamson: Is it leg or legs?
Dr. Rhonda Patrick: I don't remember.
Chris Williamson: Right, I was just wondering because it would be interesting if they compared the leg— The other leg, yeah.
Dr. Rhonda Patrick: I don't remember. It's been so long since I've read that study, But, so, when you are— when you're doing exercise, when you're doing resistance training, you're obviously causing an inflammatory response, right? That's part of the stress, and there's a counter to that. There's a very potent anti-inflammatory response, and with the resistance training, you're actually damaging muscle, right? You're damaging the muscle. It's like a mechanical force activating all sorts of pathways.
Dr. Rhonda Patrick: Well, turns out that immune cells have to get to that muscle, and that plays a role in the hypertrophy, but, like, this whole response, if you look at, like, some of the science, and IGF-1 that's involved in signaling and all that, it happens like, it peaks like an hour after resistance training. And then, after that, it kind of goes back down. And so, the question is, when you're getting in the cold, you're causing vasoconstriction. So, norepinephrine, I mentioned, is a neurotransmitter. It's also a hormone. It's made in the periphery as well. And, it's involved in vasoconstriction, which is the opposite of what heat does, vasodilation. So, when you're vasoconstricting, you're cutting off the roads to get to your muscle, right?
Dr. Rhonda Patrick: Like, the growth factors, the immune cells, all those things can't get there, right? You're stopping that. I think this is what's happening. And so, you know, it's like, well, what if I just wait like an hour or 2? Would I be safe? Possibly, or maybe just, you know, do it at a few hours, like 5 hours.
Chris Williamson: What's the rule you use, 5?
Dr. Rhonda Patrick: So, I personally don't do as much cold exposure as I should do because I talk about it. I do it a lot more in the summer when it's hot. And, but when I do do it, most of the time it's before something. I know it's like, it's ridiculous, but it's the truth. Or I'll do it in the morning. Like, so I personally don't like to time it right after my heat exposure, mostly because blood pressure changes for me that are just freaky that I don't like. It's wild.
Chris Williamson: Doing contrast therapy is Very, very weird.
Dr. Rhonda Patrick: It is.
Chris Williamson: Yeah, I mean, some people like that, right? I enjoy it, but it's like a dizzy feeling.
Dr. Rhonda Patrick: It's a dizzy, and I've had like even more extreme where it was like vertigo, and I had like— I've had to sit on the side and just—
Chris Williamson: Yeah, exactly. Stare at the floor and hope that it goes away.
Dr. Rhonda Patrick: Yeah. So I'm not too like fond of that feeling. So I like to separate them, you know, a little bit. Although I think if I wait like 5 to 10 minutes after I get out of the sauna, like, and just kind of at room temperature, just chill out for a minute, let my heart rate come down, down, then I get in the cold, I don't have that response. So, like, waiting a little bit.
Dr. Rhonda Patrick: So, I think the rule of thumb for cold exposure is, I think, that neurotransmitter optimization, like, when do you want to use it to get that norepinephrine hit? Because it does help with focus and attention, it helps with mood, anxiety. And so, like, you know, if you want to, like, if you wake up in the morning first thing and do it, that's a great way to start the day. I like to wake up and get on my Peloton or do my workout, but also just timing it around things. Like I said, I did a cold shower before I came here. Yep. If I'm at home, I'll get into the cold plunge before something that, you know, is going to cause me more anxiety or just I need more focus and attention.
Chris Williamson: So you mentioned 20 seconds at 40 degrees is enough for the norepinephrine, but what about if we're looking for the full cascade? We're going to capture as much as we can, most that is realistic for people to do. How long, how frequently, how cold per week?
Dr. Rhonda Patrick: So, we talked about norepinephrine, and we talked a little bit about mitochondrial biogenesis, the growth of new mitochondria in skeletal muscle, and that was 15 minutes at 50 degrees, which, if you can get to the 3-minute, 3.5-minute mark at 50 degrees, you can get to 15. The rest of it's fine.
Dr. Rhonda Patrick: Yeah, but there's another benefit we didn't talk about, which is actually making more mitochondria in your adipose tissue, and that's an adaptation that is a response to cold exposure, because when you have more mitochondria in your fat, You're basically making, it's basically, you're making more energy, you burn more energy, but you also release heat as a byproduct. And so, it's an adaptation. The more you use the cold, it's called browning of fat. And the reason for that is because when you look at a fat droplet under a microscope and there's more mitochondria in it, it looks brown compared to white. So, that's also something that happens. And most of the studies looking at browning of fat in humans have not been done in getting into cold water. They've been done in like—
Chris Williamson: Oh, okay.
Dr. Rhonda Patrick: humans walking around at 50 degrees Fahrenheit or putting on a cold suit that's 50 degrees Fahrenheit. I know it's like one of those things you like walk around with the air. Yeah. And so, again, for those, I mean, it's anywhere between 15 minutes to an hour, you start to get that. So, 15 minutes, I think, is a good marker for—
Chris Williamson: For a session.
Dr. Rhonda Patrick: For a session, for the whole shebang, right? Like, not just the norepinephrine, but the mitochondrial benefits, if you're also looking for browning of the fat, and the muscle—
Chris Williamson: At what temperature?
Dr. Rhonda Patrick: And so, that would be like 50 degrees, 49 degrees Fahrenheit, if you can, and which is, I mean, that's cold.
Chris Williamson: Frequency, 15 minutes, 50 degrees, how often?
Dr. Rhonda Patrick: I don't know that there's an established frequency like there is with the sauna, right?
Dr. Rhonda Patrick: This isn't, like, there's not large observational studies looking at people that are cold plunging, but I will tell you, so I talked to Dr. Laakunen about this. I said, what percentage of people in Finland, because these saunas are, The sauna studies are coming out.
Chris Williamson: Finland's ground zero.
Dr. Rhonda Patrick: Yeah, like, are doing, 'cause a lot of people will just, they'll do that. They have like these public saunas, as it's called, and the community will get in there, and then they go in like in the wintertime, they just go into the Baltic and jump in, and it's cold. And I've been there, I've experienced it, I've seen it. So he was saying about 10% of people, I actually thought it was going to be more than that, but it's not. About 10% of people are doing contrast therapy, so they're going from hot to cold.
Dr. Rhonda Patrick: So then you go, oh, well, 'Cause I wanted to know, I was like, are some of these benefits from the contrast? And there's not a lot of research on it. So, the question is, I don't think that you can give a frequency with absolute confidence.
Chris Williamson: 4 to 7 times per week, or what?
Dr. Rhonda Patrick: Exactly, yeah. So, it's more of a, okay, well, are you looking for these browning of fat? Because it'll go away when you stop doing it, so you have to keep it up. And the more you do it, it is kind of dose-dependent.
Chris Williamson: What do you try and do?
Dr. Rhonda Patrick: I told you that I don't do enough cold exposure unless it's the summer. What would you try and do? Yeah. I mean, so I look, I feel great. I felt great this morning when I was doing my cold shower. Right. Like I like to use it for that like mood booster.
Chris Williamson: Acute.
Dr. Rhonda Patrick: So it's a performance—
Chris Williamson: So it's an acute performance enhancer, that neurotransmitter optimization thing. That's why, that's why I like to use it.
Dr. Rhonda Patrick: And every time I do it, I'm like, why don't I do this more? I know why, because I'm doing the HIIT and the muscles and then I'm the mom and I like have the podcast and that, you know, so it's like, that's, It's almost like, I think it's almost easier to just, at least if it's winter, to just get into the cold shower because it's like less of like something about the cold plunge.
Chris Williamson: You gotta like lift the lid, lift the lid.
Dr. Rhonda Patrick: You gotta lift the lid. You gotta think about, you're like, oh, it's the cold plunge and I gotta get past that, that 3, 3 and a half minute mark where, you know, you're burning and then you're not burning.
Dr. Rhonda Patrick: So, um, I think, I think that I just would like to start using it on a more of a daily basis for the way it makes me feel. And that's why I like it mostly.
Chris Williamson: It seems to me, based on what you're saying here, that although there is definitely a place for cold exposure, and deliberate cold exposure has some effect that you don't capture with the sauna, if you were to make a pie chart of what's happening with heat and cold, a lot of it is coming from heat, and only a little bit of it is coming from cold.
Dr. Rhonda Patrick: Yeah, when we're talking about a lot of these health outcomes with respect to cardiovascular disease, and dementia, and all-cause mortality, all it is, it's all, but, you know, again, the hot is mimicking moderate-intensity exercise.
Chris Williamson: So, Yeah, that makes sense.
Dr. Rhonda Patrick: The cold, I really just, it all comes back again to that, it makes you feel so good. You're getting that norepinephrine. Yeah. It does brown your fat, and like, look, browning of fat is a therapeutic target for many researchers that have been researching this now, and for, you know, over a decade, where it's being looked at to help as a treatment for type 2 diabetes, because you do improve metabolic health, like, from browning of fat, but compare that to like, Exercise, diet, what you're eating. I don't know that it matters. I don't know that the cold even compares.
Dr. Rhonda Patrick: Like, don't— I don't even know that we should even be talking about the metabolic benefits of it when you're— when there's like so much more bang for your buck from—
Chris Williamson: That's sprinkling on the top of the icing on the top of the cake.
Dr. Rhonda Patrick: Yeah, exactly. And it's like, okay, I'm making more mitochondria in my muscles, but I want to be doing HIIT and vigorous exercise for all the other benefits. And guess what? I get mitochondrial biogenesis from that, like, pretty robustly.
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