Alison Stewart: Ice baths have emerged as one of the latest wellness trends. However, the practice has been around long before. Practitioners in ancient Greece prescribed cold water for high fevers and snow for open wounds. Therapeutic hypothermia was used to treat injuries in ancient Egypt over 5,000 years ago. In the late 1800s, some sanitariums treated mental illness with hydrotherapy. Then there's the fun of it, witnessed on Wednesday as thousands of people welcomed the new year with the annual Coney Island Polar Plunge, including our next guest, the host of New York Presbyterian Hospital's Health Matters podcast, Courtney Allison.

She spoke about her experience on the most recent episode with Dr. Asad Siddiqi, the chief of rehabilitation medicine at New York Presbyterian Brooklyn Methodist Hospital, an assistant professor at Weill Cornell Medicine who specializes in sports medicine. The two of them are joining me in studio. Thank you for joining us.

Dr. Asad Siddiqi: Thank you so much for having us.

Alison Stewart: Listeners, did you participate in the annual Polar Plunge? Maybe a tradition you share with your family or friends or as a bucket list item, what convinced you to run into the cold water? How did you feel after? 212-433-9692, 212-433-WNYC or you can hit us up on social media @allofitwnyc. Okay, Courtney, this is your second year in a row of participating in the plunge. How did this become a tradition for you?

Courtney Allison: Last year some coworkers were doing it and it just sounded like so much fun. I'd been intrigued by it and I thought, "Okay, let's do this."

Alison Stewart: Can you describe what it felt like after the plunge?

Courtney Allison: After the plunge I felt exhilarated, invigorated. Like I told Dr. Siddiqi on the podcast, I just felt very clear-headed cause you just can't think of anything else. I felt a boost to my mental health that day.

Alison Stewart: What did you think of before you went in the water?

Courtney Allison: Luckily I was with a really excited crowd that was hyping us up. My friend screamed, "Let's go," and then we all just held hands and ran in. I mostly just felt excitement and terror.

Alison Stewart: Terror?

Courtney Allison: Yes, a little terror.

Alison Stewart: What did you think the day before you first ever did it? Not the day of, because you're all excited. There's a crowd out there. The day before.

Courtney Allison: I didn't know I was doing it the day before. I didn't really decide until 10:00 PM that night or in the morning to just go.

Alison Stewart: Oh my God. Wow. Then why did you want to talk about it on the podcast?

Courtney Allison: We did the plunge, and like I said, I felt all these mental health benefits, and it was so much fun. I've heard anecdotally that it's good for your health, and like you said, there's possibly all these benefits. We were curious to talk to a doctor, and luckily we have that luxury to say, "What are these health benefits? What was actually happening in my body when we did this?"

Alison Stewart: Dr. Siddiqi, what are the actual health benefits of cold water plunging, the ones that have been backed by research?

Dr. Asad Siddiqi: That's an important caveat, particularly because the body of research may not be applicable to every way that someone would engage with a cold plunge. Some people do it, like Courtney, once a year as a ritual. Some people make this a part of their daily practice or weekly practice. It becomes a part of their routine. When we look at some of the benefits that have been described in the literature, certainly impacts on mood, impacts on inflammation, it's a great way to-- because physiologically, what it's doing to the blood in the limbs, it's shunting blood back to the heart to keep your core temperature up.

It's a useful way to address swelling and inflammation and things of that nature, but it really depends on how you're engaging with the activity.

Alison Stewart: Did you feel any of that that he just described?

Courtney Allison: Yes. I definitely felt refreshed after. I guess I don't know exactly 100% what was going on in my body, but I did feel those things. Yes.

Alison Stewart: It's interesting because there's a lot of myths around cold plunges. The founder of the Coney Island Polar Bear Club, of the organization, he was dubbed the father of American physical culture. That's just a joke, I guess. What are some strange myths that you've heard about cold plunging?

Dr. Asad Siddiqi: What's interesting about when these things take on a life of their own as a phenomenon, I think a lot of the myths that come out may have a kernel of truth or may be grounded in something that has been described somewhere by someone, and then they just get extrapolated. Building off of the impacts on mental health or mood, some people will take it to the extreme and say it cures depression o its impacts on cancer because of the way that it affects with cellular metabolism.

When you look at how the literature is conducted or how the research around this topic and other topics in the wellness space are conducted, it's hard to make those conclusions from a causal perspective. It can be very challenging to separate fact from fiction, which is why it's useful to have someone to help you guide the way that you engage with it.

Alison Stewart: A new episode of New York Presbyterian Hospital's Health Matters podcast, Taking on the Cold Water Plunge. We're here discussing the potential benefits with Courtney Allison, the host, and Dr. Asad Siddiqi. Listeners, did you participate in the annual Polar Plunge? Call us and tell us about it. 212-433-9692, 212-433-WNYC or you can hit us up on social media, @allofittwnyc. You said that you felt refreshed. Is that what you said how you felt afterward, your mental health?

Courtney Allison: Yes. Clear-headed.

Alison Stewart: Clear-headed. Why do you think you felt so clear-headed? Was your brain somewhere else that it all came into focus? I'm curious about the clear-headedness.

Courtney Allison: I have a bit of an active mind. It's hard to turn my mind off. I think something about running into the ocean on January 1st is the one thing that will turn that faucet off for a little bit. Then I just was on a high the rest of the day.

Alison Stewart: Extreme athlete and fitness guru Wim Hof developed a cold plunging technique that pairs cold exposure with breathing and meditation. He says it's to help manage anxiety and stress. How could cold water plunging help someone dealing with stress or anxiety?

Dr. Asad Siddiqi: Fundamentally that's what it is. It is a stress on the body. When you think about, again, fundamentally what our bodies are, they're sensory organs. We're a brain connected to a bunch of nerves that experience the environment around us. I think foundational or very key to Wim Hof's method in particular is the amount of mental preparation that goes into something like that. These kinds of things can be done on a whim. I would say that the riskiest version of the cold plunge is the one that you're not prepared for mentally or physically.

That's where we talk about some of the risks of the activity, including cold shock and even potentially death. The prepared mind and the prepared body is the one that is probably the safest to engage with something like this.

Alison Stewart: Let's take a caller. Carter is calling us from Manhattan. Hi, Carter, you're on the air.

Carter: Hi. How are you?

Alison Stewart: Doing great.

Carter: I lived in Denmark during 2018. I had the privilege to have a contract there and engaged in the Danish tradition of ice baths, and that is waking up every morning and going to the harbor and breaking through the ice. They have saunas there, and you jump in and take the plunge, and you do it two or three times every morning as a wake-up. One of the best things I've ever done.

Alison Stewart: You said one of the best things you've ever done?

Carter: Oh, yes. Oh, my gosh. The best day ahead of you. Your head is so clear and your mind is so clear, and you really get focused on what it is you want to accomplish that day, and you go and hang out with your friends in the sauna and warm back up, and then you go out together and jump in again.

Alison Stewart: Thanks for sharing that. What's, either of you can answer this, the difference between these ice baths and a cold plunge? Are they same thing?

Dr. Asad Siddiqi: Essentially the same thing. It's basically the mechanism by which the cold is being transmitted to your body. Whether it's ice or the liquid form that you would get in something like a cold water immersion or a cold tub, fundamentally, they're the same thing. Cold water may be a little bit more effective at heat transfer, and it might actually work a little bit faster.

Alison Stewart: Courtney, after you did the plunge the first time, how was the second time?

Courtney Allison: It was harder.

Alison Stewart: Harder?

Courtney Allison: I don't know why. I'm still processing, but I guess because, again, it was so exhilarating last year, I had that in my head. I forgot the water was going to be cold. Maybe I should have mentally prepared more, but I ran in and I was like, "This is terrible. Where are the endorphins? Hurry." It was a little bit different this year.

Alison Stewart: Did you enjoy it less or more?

Courtney Allison: A little bit less, actually.

Alison Stewart: You think? You think it's the last time you're going to do it?

Courtney Allison: No, I'm definitely going to do it again because I'm curious to see how it'll evolve and it'll be different each time.

Alison Stewart: Let's talk to Howard from Forest Hills. Hi, Howard. You're on the air with All Of It.

Howard: Hi. Always brings this to my mind about in Finland, they have a tradition of going in ice water, and after they finish being in ice water, they run into the sauna bath, and they beat each other with some trees. It's a Finnish tradition.

Alison Stewart: Thank you so much for calling. What were you going to say?

Dr. Asad Siddiqi: No, I was going to say it's very fascinating to hear. You alluded to the long history of this in different cultures and the cultural and social element to this activity. I think that's a big part of some of the perceived benefits that people have.

Alison Stewart: We got a text that says, "Thanks for mentioning William Hoff. I realize this is similar to a Russian banya going from steam to cold and back." What about this idea of going from one extreme to the other?

Dr. Asad Siddiqi: We talk about this a little bit in the podcast. I think it is important to be mindful of extremes generally. Even with just the cold itself, graded exposure is something that we recommend with both heat therapy or cold therapy. As you're getting into it, I've definitely heard anecdotally that people-- it's a pleasurable experience to go from something extremely cold and exhilarating to something warm to help you warm back up.

In terms of the health benefits and what was born out of the research, there have been some studies that indicate that in terms of the physiologic benefits, you do retain more of that by allowing yourself to warm up a little bit more naturally and not jump from the cold directly into the sauna or the heat. Some folks who are a little bit more engaged on this in a daily way will recommend doing sauna first and then finishing it off with cold and then allowing yourself to warm up a little bit more naturally.

Alison Stewart: How did you warm up, Courtney?

Courtney Allison: With a towel, shivering. Eventually, they got some hot chocolate.

Alison Stewart: Let's talk to Sassy calling in from Jamaica, Queens. Hi, Sassy, how are you?

Sassy: Hi. Shout out to NPR. Love you guys. Thank you for taking my call.

Alison Stewart: I want to hear your story.

Sassy: I wanted to do something difficult for New Year's. I was tired of the drinking, tired of going crazy. I wanted to do something difficult. I was put onto this by a friend. She couldn't make it, but I made some friends in that line. Boy, I'll tell you, it was an exhilarating experience, not realizing what the city offered. The opportunity to really reconnect back to nature. It was amazing. I'm definitely doing it time and time again. Lo and behold, I went to work today, and one of my coworkers was there as well, and it was a beautiful experience. I love Coney. Love it. Love it.

Alison Stewart: You did this at Coney Island? Yes?

Sassy: Yes. I was right on Coney Island. I think I went in at about 11:30 something. The band was playing. Mermaids were everywhere. I got French fries after. My hair was soaking wet. My car seat was wet. I would do it again.

Alison Stewart: Thanks for calling in. She's describing the unity of people doing this together. What did you think?

Courtney Allison: That's my favorite part, and I think that's what's going to keep me coming back. Everything she described. I think we must have done it around the same time. There's a drum band. There's people dancing. There's music. It's just this really fun community experience. I had the same experience. I've run into people who have all told me they were also there.

Alison Stewart: I did want to get into some of the health benefits. Talk about the health benefits. Get into some of the possibilities this isn't for everyone. What should people consider?

Dr. Asad Siddiqi: For the majority of the generally healthy population, who, again, is doing this in a deliberate fashion, where they are doing it thoughtfully and in ways that are safe, this can be beneficial, but there are folks with certain medical comorbidities or diagnoses, particularly heart conditions, respiratory conditions, neurologic conditions, especially the ones that affect your protective sensation in your limbs, your hands and feet.

That protective sensation is particularly important in warning you when enough is enough, and if you have an impairment of that, it can be difficult. Generally, you want to apply water safety principles that you would apply for any water activity. It's always better to be in groups, to have someone watching you, someone know where you are, and then ideally be around people who are familiar with basic life support, CPR, those kinds of things.

Alison Stewart: You're doing a third year. Have you done it, Doctor?

Dr. Asad Siddiqi: I have not. We talk about this on the podcast. I have a ton of respect for people who will push their boundaries in this way. It does inspire me to maybe explore it. Being a sports medicine physician and even in the rehabilitation medicine space, we're constantly dealing with people at the limits of their function and trying to help them understand how to optimize it. That involves pain, that involves discomfort, that involves stress, and we want to make sure that that stress is good stress and not distress.

Alison Stewart: I've been speaking with Courtney Allison, the host of the New York Presbyterian Hospital's Health Matter podcast, and Dr. Asad Siddiqi. Thank you so much for coming to the studios.

Dr. Asad Siddiqi: Thank you so much for having us.

Courtney Allison: Thank you for having us.