Are Cold Plunges Actually Good For You?

A researcher who studies the effects of extreme cold on the body throws a few drops of icy water on the social media trend. Also, why mammoths make great mascots.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  WNYC is supported by Bear. Science is about asking questions, testing, trying again. It's not easy, but it's relentless. It evolves, and that's why science delivers. Learn more at sciencedelivers.com.

• 0:14Ira Flatow?

  Science Friday is supported by MathWorks, creator of MATLAB and Simulink software for technical computing and model-based design. MathWorks, accelerating the pace of discovery in engineering and science. Learn more at mathworks.com.

• 0:31Speaker 02

  Support for Science Friday comes from USA for UNHCR, the UN Refugee Agency. Here's a problem. How do you keep a house above freezing when the windows are gone and the power is out for 16 hours a day? In Ukraine this winter, the answer fits in a box. Reflective insulation, plastic sheeting to cover broken windows, draft blockers for the doors. Simple materials installed the same day a team arrives. Your gift delivers them, and until December 31st, it's matched. Donate at unrefugees.org/friday.

• 1:09Flora Lichtman?

  I'm Flora Lichtman, and you're listening to Science Friday.

• 1:15Flora Lichtman?

  Today on the show, sorting fact from fiction on cold plunges, the hottest wellness trend.

• 1:22Speaker 04

  Morning, guys. It is day 87 of taking a nice bath every single day.

• 1:25Speaker 00

  Let's cold plunge together. Woo!

• 1:30Speaker 05

  I can't move. I don't know if that was smart. But I just did 20 minutes.

• 1:38Flora 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 Hamon, who studies human performance and cold exposure at the University of Ottawa. Francois, welcome to Science Friday.

• 2:04Speaker 06

  Thank you so much for having me.

• 2:06Flora Lichtman?

  All right, let's dive in. Should I be plunging? That's my burning question.

• 2:11Speaker 06

  So, 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.

• 2:33Flora Lichtman?

  Really? Tell me about them.

• 2:35Speaker 06

  So the dangers are more related to the fact that ice water is at 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.

• 3:02Flora Lichtman?

  Hmm.

• 3:03Speaker 06

  And if you do it on a regular basis, you can actually develop what we call non-freezing cold injuries. And these non-freezing 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.

• 3:38Flora Lichtman?

  What do we know about the benefits?

• 3:40Speaker 06

  So the first benefit, which is kind of the obvious one, is the fact that when I go into ice water, it's a stimulant. You know, 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, like, why do you do it? Uh, doing some work in Switzerland, 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.

• 4:15Flora Lichtman?

  Hmm.

• 4:15Speaker 06

  Uh, 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. It's not clear. And it's mainly because the research is not well standardized. On the immune system side, there's no proof at all that cold 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. You know, people that might be, you know, suffering maybe from depression

• 4:58Speaker 06

  that are staying inside or 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, uh, pushing the limits are also some of the benefits that are very, very clear when it comes to ice water dipping.

• 5:17Flora Lichtman?

  What about brown fat? What is it? Do I need to care about it? And how is it related to this conversation?

• 5:23Speaker 06

  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 brown fat 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 burnt are below five calories per hour and even less. Which means that it doesn't, it doesn't burn a lot of calories.

• 6:07Speaker 06

  And if you don't control your diet, you're never going to be able to modify your, 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.

• 6:21Flora Lichtman?

  Okay. You mentioned working with militaries in different countries. Tell me about this work and why they're interested in cold plunging.

• 6:30Speaker 06

  Well, there's a few reasons. I mean, uh, 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 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 condition, which is something that has been kind of left on the back burner for the last few years, and now is really coming back.

• 7:16Flora Lichtman?

  And what's your work about? Is it about, is it training soldiers? Is it studying them?

• 7:21Speaker 06

  So I did both. Uh, so again, as a researcher, studying is always something we're interested in doing. Uh, but I've kind of combined it also with workshops where I'm working with soldiers and working on, okay, how do we improve cold shock response? How do we improve the, 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, uh, chances of success?

• 7:49Flora Lichtman?

  Well, can you give us some tips that we can look forward to using in, you know, six months? When it gets cold again?

• 7:55Speaker 06

  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, 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 in your body's responses if you're able to do this.

• 8:37Flora Lichtman?

  You know, 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, like, is there something to that argument?

• 8:53Speaker 06

  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 thermally mutual 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

• 9:37Speaker 06

  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 condition. 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.

• 10:05Flora Lichtman?

  Okay, I know we're just about out of time. Two quick questions. If I want to safely explore cold plunging, what are your like, top quick recommendations?

• 10:15Speaker 06

  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 non-freezing cold injuries. 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 do ice water versus then just doing lake water. Uh, you know, at fifty or sixty degrees. You're still gonna get benefits. It's gonna be more comfortable and you're still getting benefits of cold. And you're gonna be able to to stay in longer. So that's uh another thing. You should never do it alone.

• 10:59Speaker 06

  You should always make sure that you have safety procedures in place. Uh, especially if you're doing it in lakes, especially if we're doing in the winter when there's ice. You gotta make sure you're able to come out of the uh the ice just in case uh 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 a risk of cardiac arrest.

• 11:43Flora Lichtman?

  Do you partake in in cold plunging?

• 11:46Speaker 06

  Yeah, I've been doing it uh regularly since twenty seventeen. 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 uh cold showers.

• 11:57Flora Lichtman?

  Why do you do it? What what's in it for you?

• 12:00Speaker 06

  I I I love it. I just enjoy it. I do it with friends. Uh, we go hang out. Uh, I love doing it in the winter. I love uh uh feeling the cold, which is kind of interesting. Uh, so I so I love feeling it on my body. I love can coming out of the 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 uh in a group. And we never exceed two minutes and we always supervise each other to make sure that everything's good.

• 12:29Flora Lichtman?

  It's like the soldier said, it feels good.

• 12:31Speaker 06

  It feels good. And you know, 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.

• 12:45Flora Lichtman?

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

• 12:49Speaker 06

  Thank you so much.

• 12:51Flora Lichtman?

  Dr. Francois Hamon, professor at the University of Ottawa.

• 12:58Flora Lichtman?

  Don't go away after the break. We're going to stay cool with a trip to the Ice Age to hang out with some especially charismatic megafauna.

• 13:06Speaker 07

  They have so much charisma. They've got riz, as the kids like to say these days.

• 13:10Flora Lichtman?

  Stay with us.

• 13:15Speaker 00

  Science Friday is supported by PBS, presenting Going Wild. If you love learning about the natural world and meeting the scientists who help us understand it, be sure to check out the new season of Going Wild with Dr. Ray Wynn Grant. It's the chart-topping and Webby Award-winning podcast from the folks at Nature on PBS, now with a video companion series. In this season of Going Wild, host acclaimed wildlife ecologist Dr. Ray Wynn Grant heads out into the field to explore the animals, people, and stories that make nature worth saving. Stops include a hibernating black bear den in Arkansas and an underwater shipwreck site off the Florida coast. If you're looking for a place to start, check out the season's debut episode, where Ray joins beloved biologist and influencer Jordan King in the Florida Everglades to learn about

• 14:00Speaker 00

  his unlikely journey into science and how to study a wetland when it's not very, well, wet. So don't miss out. Follow Going Wild with Dr. Ray Wynn Grant on Apple Podcasts, Spotify, YouTube, or wherever you get your podcasts. WNYC is supported by Bear. Every day in America, science delivers. Not just in the headlines, but in the moments that matter most. Science is a journey, one of curiosity, persistence, and progress. It's about asking questions, testing, learning, and improving again and again. Science delivers harvests that feed families, tools that help farmers grow more with less, and new ways to protect land for generations to come. Let's keep asking, keep testing, keep discovering, so science can keep delivering.

• 14:45Speaker 00

  Learn more at sciencedelivers.com.

• 14:48Speaker 08

  Support for Science Friday comes from the Heising Simons Foundation. Unlocking knowledge, opportunity, and possibilities. More at hsfoundation.org.

• 15:02Flora Lichtman?

  You might remember back in 1993, when the original Jurassic Park was released, it set off an explosion of dino mania in popular culture. Toys, theme park rides, even a basketball team. The expansion Toronto Raptors took their name and mascot from the film's Philosaraptors. Now, it seems another prehistoric animal might be having its mammoth moment.

• 15:26Speaker 09

  Ready or not, here come the moon mammoths. Erie Sewell's latest name change.

• 15:31Flora Lichtman?

  With the help of the show last week tonight, a minor league baseball team in Pennsylvania rebranded themselves the Erie Moon Mammoths. That comes just a few months after the Utah NHL franchise renamed itself the Mammoth as a nod to the state's paleontological past. So, why are mammoths back? And do they really have what it takes to be a successful team mascot? We'll ask an expert on these woolly wonders. Dr. Advite Zooker is curator of vertebrate paleontology at the Florida Museum of Natural History, based in Gainesville, Florida. Welcome to Science Friday.

• 16:08Speaker 07

  Thank you. It's great to be here.

• 16:09Flora Lichtman?

  Okay, so you study mammoths. Let's get this out of the way.

• 16:12Speaker 07

  Yep.

• 16:13Flora Lichtman?

  Are they or are they not mascot material?

• 16:17Speaker 07

  They are totally mascot material. They are huge. The ones in North America were about 12 or 13 feet high at the shoulder. They weighed more than a big African elephant. They had these massive 12 to 14 foot long tusks. Big, massive, powerful creature. It's got everything that your team needs.

• 16:35Flora Lichtman?

  Do they have charisma?

• 16:37Speaker 07

  They have so much charisma. They've got riz, as the kids like to say these days.

• 16:42Flora Lichtman?

  Were the mammoths here woolly?

• 16:44Speaker 07

  You know, the mammoths down south in the US were probably not quite as woolly as the ones up in Alaska and Siberia. The species that we have down here, the Colombian mammoth, was probably hairless.

• 16:56Flora Lichtman?

  Hairless? Like an elephant?

• 16:58Speaker 07

  Just like a big elephant. Yeah, they ranged all the way from Central America all the way up to the Great Lakes. And if you're down in Florida, or Mexico, or Central America, it gets pretty hot. And I'm not sure if you want to have a big furry coat when you live down there.

• 17:14Flora Lichtman?

  That makes sense. Now that you say it, of course, it makes sense. Tell me a little bit about mammoth life. Reintroduce me to them.

• 17:21Speaker 07

  Mammoths are very much like elephants. They probably lived in matriarchal herds, just like modern day African elephants and Asian elephants. They were large grazing animals, so they had these specialized teeth that were quite well adapted for feeding on grass. But that also meant that they could eat pretty much anything that they wanted to on the landscape. Mammoths show up in North America about one and a half million years ago, and they're here on the continent up until about 12,000 or 13,000 years ago, when they finally go extinct.

• 17:54Flora Lichtman?

  Thanks to humans, or do we know?

• 17:56Speaker 07

  Probably because of humans. This is a huge debate in paleontology and archaeology. And what we can say for sure, based on the evidence, is that you can't explain all of these extinctions without humans.

• 18:11Flora Lichtman?

  Is there anything big happening in the mammoth field right now?

• 18:14Speaker 07

  There absolutely is. So you mentioned Jurassic Park, and one of the hallmarks of that movie is that they managed to extract DNA. Now, that's not really possible for extinct dinosaurs, but we do have ancient DNA from mammoths. The oldest ancient DNA that we have from a mammoth comes from Siberia, and it's about 1.2 million years old. I think it is the oldest ancient DNA that we've ever extracted directly from a species. And we have ancient DNA from the Huntington mammoth, which was the basis for the Utah Mammoth mascot. What we've found out kind of blew all of our minds.

• 18:52Speaker 07

  The Colombian mammoth, which is the species found in the Lower 48 in Central America, is a hybrid species. About half of its DNA comes from woolly mammoths, and half of its DNA comes from a lineage of stepmammoths that came down into North America about one and a half million years ago. That paper came out in 2021, so this kind of blew up our conventional paleontological definitions for what this species is.

• 19:19Flora Lichtman?

  What do you hope this extra attention brings to mammoths?

• 19:24Speaker 07

  I hope that it just rekindles people's appreciation for our deep past. I think there's a lot to learn about our past from these fossils and a lot we can learn about the future from the extinction of these animals as well. So I think if we pay attention to what went on in the past, we can do a much better job of conserving our future.

• 19:48Flora Lichtman?

  Okay, I'm sold. Major League Baseball, we're coming for you with the mammoth. I mean, what is, what's a Met, anyway?

• 19:55Speaker 07

  Yeah.

• 19:56Flora Lichtman?

  Do you have a team you would, you would pick to sub in the mammoth for?

• 20:00Speaker 07

  Uh, maybe not the mammoth, but I live in Gainesville and Gainesville High School, I think, should change its mascot to the Gompther. And a Gompther is a cousin of a mammoth. I mean, doesn't the Gainesville Gompther sound awesome?

• 20:15Flora Lichtman?

  That's a whole other segment.

• 20:17Speaker 07

  Absolutely. And a Gompther is a four-tusked elephant, and that's pretty rad.

• 20:21Flora Lichtman?

  Okay, that's awesome, too. Thanks for coming on.

• 20:24Speaker 07

  Thank you so much.

• 20:25Flora Lichtman?

  Dr. Advite Zuckur, curator of vertebrate paleontology at the Florida Museum of Natural History. Thanks for listening. Don't forget to rate and review us wherever you listen, but only if you like the show. It really does help us get the word out and get the show in front of new listeners. Today's episode was produced by Dee Peterschmidt. I'm Flora Lichtman. Thanks for listening.