Are Cold Plunges Actually Good For You?

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman. Later in the hour, how can we be certain that what we believe is true? And there are a lot of claims about breast milk on social media. But what does the science say? But first, people online submerging themselves in tiny tubs filled with ice cubes.

SPEAKER 1: Morning, guys. It is day 87 of taking an ice bath every single day. The water temperature is 1 degree Celsius.

SPEAKER 2: Let’s cold plunge together.

SPEAKER 3: I’m sure you’re wondering why would someone inflict this much pain on themselves? It’s those who know that it’s worth it.

SPEAKER 4: I’m about to do an ice bath for the first time. Here we go. Oh, boy. My goodness. Wow. That’s incredible. Phew, I can’t move. I don’t know if that was smart, but I just did 20 minutes.

FLORA LICHTMAN: If social media and certain influential podcast hosts are to be believed, cold plunges can do everything from boosting your immune system to reducing inflammation to acting as an antidote for depression. But what does the science say about all this? Here to throw at least a few drops of cold water on the science of plunging is Dr. Francois Haman, who studies human performance and cold exposure at the University of Ottawa. Francois, welcome to Science Friday.

FRANCOIS HAMAN: Thank you so much for having me.

FLORA LICHTMAN: All right, let’s dive in. Should I be plunging? That’s my burning question.

FRANCOIS HAMAN: And it is a burning question, which is interesting because you’ll be cold. You’re not going to be burning. But when I started studying cold probably 25 years ago, I was not expecting the trends that were going to be happening now. So if you would have asked me back then, is it a good idea to jump in ice water, my answer would have been no. The dangers of it can be tremendous.

FLORA LICHTMAN: Really? Tell me about them.

FRANCOIS HAMAN: So the dangers are more related to the fact that ice water is a tremendously strong stress, which means that the body’s going to be responding very strongly. And the first response you’re going to get is cold shock. And even within cold shock, you could end up in cardiac arrest. You can have big changes in blood pressure. And this happens within the first 30 seconds. If you stay in there, you’re stuck in there, and you become hypothermic, then there’s all the issues related to hypothermia.

And if you do it on a regular basis, you can actually develop what we call nonfreezing cold injuries. And these nonfreezing cold injuries have been amazingly well-studied, especially in the military context. I’ve done some work within NATO, and we’ve been looking at making sure soldiers know about these because it’s going to create neuropathies, and it will create permanent damage. So cold plunging is something you need to understand, and you need to really see the science behind it and what you’re actually trying to achieve. And so there are dangers, but there are also benefits.

FLORA LICHTMAN: What do we know about the benefits?

FRANCOIS HAMAN: So the first benefit, which is the obvious one, is the fact that when I go into ice water, it’s a stimulant. It’s going to wake you up. It’s going to give you energy. Dopamine will be released. That’s clear. Endorphins will be released. Oxytocin I’m not as sure, but oxytocin is potentially another hormone that would be released. So there is a feel-good sensation when you get into a cold water.

And most people you ask, why do you do it? I was doing some work in Switzerland, and I was asking the soldiers, why do you do this? And they go because it feels good. And that was their main answer, which is a good answer because it actually feels good. So these are some of the benefits we definitely know.

The ones we’re not sure about that are all over social media is the whole idea of the effects on inflammation. Very good paper written by Dr. Michael Tipton from Portsmouth University showed that there might be a potential for a whole body exposure to ice water to actually reduce inflammation, but it’s not clear at all. And it’s not clear-cut. And it’s mainly because the research is not well-standardized.

On the immune system side, there’s no proof at all that coal will improve the immune system. And again, this is something that is found all over social media.

The benefits that I see most of the time are more psychological. People that might be suffering, maybe, from depression, that are staying inside, are making a decision, maybe, to go cold bathing and to be hanging out with people, doing it as a group. And that’s definitely something that has tremendous benefits. So on the social side, achieving goals, pushing the limits are also some of the benefits that are very, very clear when it comes to ice water dipping.

FLORA LICHTMAN: What about brown fat? What is it, do I need to care about it, and how is it related to this conversation?

FRANCOIS HAMAN: So the idea of brown fat is basically a furnace. So when you look at the mammalian world, it’s a furnace that will be burning fats. And instead of going towards energy production, it goes into just producing heat. So the advantage– and that’s what people are looking for– is that it can actually do it with you making no efforts. So the idea that’s really attracting people is I could just be sitting there spending more calories without really doing anything.

But the problem you have also is the branch that needs to be activated by cold, so you would need to expose yourself to the cold. Even when you’re exposed to the cold, the amount of calories being burned are below 5 calories per hour and even less, which means that it doesn’t. It doesn’t burn a lot of calories. And if you don’t control your diet, you’re never going to be able to modify your body weight. So the general idea is basically, can I lose weight using brown fat? It will not do that. So is it worth thinking about brown fat? Not really.

FLORA LICHTMAN: OK. You mentioned working with militaries in different countries. Tell me about this work and why they’re interested in cold plunging.

FRANCOIS HAMAN: Well, there’s a few reasons. I mean, the main reason is how do you operate in cold temperatures? Are you able to do your job? And are you able to function to the maximum of your performance? So cold, if you look at it as a stressor, high altitude would probably be the top stressor, the lack of oxygen.

Cold would be the second one. Operating in the cold requires a lot of planning. You need to bring the right foods and you need the right behaviors to be able to survive. When most of the wars were happening more in warm areas, there was less focus on looking at cold, per se. But now that the war in Ukraine has started, there’s been more emphasis at how do we improve our capacity to operate in cold conditions, which is something that has been kind of left on the back burner for the last few years and now is really coming back.

FLORA LICHTMAN: And what’s your work about? Is it training soldiers? Is it studying them?

FRANCOIS HAMAN: So I did both. So again, as a researcher, studying is always something we’re interested in doing. But I’ve kind of combined it also with workshops, where I’m working with soldiers and working on, OK, how do we improve cold shock response? How do we improve the capacity through self-awareness to operate better in the cold? How do I make them understand, how can I sleep, how can I eat, and what are the behaviors that will optimize chances of success?

FLORA LICHTMAN: Well, can you give us some tips that we can look forward to using and six months when it gets cold again?

FRANCOIS HAMAN: Yeah, so one of the most important things is to do an exposure that is gradual. One thing that’s interesting is we tend to be too warm in the cold, and we want to stay really, really warm. But the best way to survive and do well and actually be able to even enjoy cold is to realize that, in the cold, you might be cold a little bit. And just be able to tolerate that cold will allow your body to respond differently next time and actually improve your acclimation and actually be able to operate better.

So I think one of the advices I would say is try to endure a bit of cold because there will be benefits to your body’s responses if you’re able to do this.

FLORA LICHTMAN: Some of the rhetoric around cold plunging online is that it’s good because it stresses your body. And I confess that I don’t totally understand the logic of that. But maybe you can help me understand, is there something to that argument?

FRANCOIS HAMAN: Well, there is, for sure. So one thing to keep in mind is that there are benefits of stressing your body. We live in very thermoneutral conditions, and that could actually promote some of the chronic diseases that we see because people are not really exposing themselves to various conditions. So if we think about the benefits of stressing ourselves, it’s often what we do– we’re looking for comfort. We’re trying to feel good. We’re trying to stay in a very controlled environment.

And generally, what we do is just kind of hilarious. I don’t know the way it happens in the US, but in Canada we use a lot of AC to be super cold. And then in the winter, we’re going to use a lot of heat to be super warm.

But the reality of it is, stressing your body out actually allows your body to work to its maximum and be able to create plasticity in your responses. So if anything goes wrong, your body’s going to be able to respond to whatever changing conditions you’re going to be facing. And I think one of the issues is people are not looking for these changes in conditions. And this is something that needs to be developed, and it’s a bit developed through stressing your body out. And again, done in a controlled way, in a safe way, but this will allow your physiology to improve when you’re exposing yourself.

FLORA LICHTMAN: OK, I know we’re just about out of time. Two quick questions– if I want to safely explore cold plunging, what are your top quick recommendations?

FRANCOIS HAMAN: So the first thing is to start gradually. One of the things is to really protect your hands and feet at all times. You should not cool your hands and cool your feet. You will create damage. Anytime you cool your hands and feet, you increase the chance of developing nonfreezing cold injury. So that’s one very important one.

The other part is you don’t need to start with ice water. You can actually start with water that is warmer and gradually come to colder temperatures. So there’s no real benefit to ice water versus than just doing lake water at 50 or 60 degrees. You’re still going to get benefits. It’s going to be more comfortable, and you’re still getting benefits of cold. And you’re going to be able to stay in longer. So that’s another thing.

You should never do it alone. You should always make sure that you have safety procedures in place, especially if you’re doing it in lakes, especially if you’re doing it in the winter when there’s ice. You got to make sure you’re able to come out of the ice just in case something happens. So you do have to follow some safety procedures.

And I think what you have to be careful about is all these gurus on social media that are giving you advice on doing this with no real research, understanding, or research background and don’t really understand the effects on the body, you do have to be tremendously careful about the advice that you get and make sure that you go to the right places to get your advice. I do fully encourage people to get medical clearance before going into ice water. There is a risk of cardiac arrest.

FLORA LICHTMAN: Do you partake in cold plunging?

FRANCOIS HAMAN: Yeah, I’ve been doing it regularly since 2017. I do it about three times a month, and generally, if I’m having very stressful weeks, I will tend to skip it and just go for cold showers.

FLORA LICHTMAN: Why do you do it? What’s in it for you?

FRANCOIS HAMAN: I love it. I just enjoy it. I do it with friends. We go hang out. I love doing it in the winter. I love feeling the cold, which is kind of interesting. So I love feeling it on my body. I love coming out of the hole and feeling the sun warming my body. So for me, it’s really because I really enjoy it and I really enjoy the time when in a group. But we never exceed two minutes, and we always supervise each other to make sure that everything’s good.

FLORA LICHTMAN: It’s like the soldier said, it feels good.

FRANCOIS HAMAN: It feels good. And we don’t put enough emphasis on this component. And sometimes, we should listen to the little voice inside and our intuition and what our bodies are telling us. If it doesn’t feel good, don’t do it. Simple as that.

FLORA LICHTMAN: That is the perfect advice. Francois, thank you for taking the time, and happy plunging.

FRANCOIS HAMAN: Thank you so much.

FLORA LICHTMAN: Dr. Francois Haman, Professor at the University of Ottawa.

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