Full video transcripts:

Patrick McKeown
0:05

Hello everybody, and yeah, delighted to talk with Susanna, who's hailing from Copenhagen, and Daniel just across the water in Malmo, and Susanna, we met about two months ago face to face — we were giving a workshop in Belfast, and the whole topic of conversation came up about ice cold, so it's really topical out there. And Susanna has a PhD thesis on it, so she's an authority on all things cold and brown fat. So, Susanna, it's a pleasure to have you here. It's great, I think the conversation is going to be interesting. Now, as I said, I know nothing about cold, so I'm going to really step back in this one, and for me, sometimes I just can't get my head around why anybody would bother to jump into an ice bath, but I've done it a couple of times. Not so sure, but convert me. But tell us a little bit about your background, how you got into it, and let's get the conversation flowing.

Susanna Søberg
1:08

Thank you, thank you for having me. It was so nice to see you a couple of months ago when I went to one of your workshops. So the cold, the water, and the breathing is really connected, and we can really benefit from learning how to breathe calmly and light doing a cold water immersion. But initially, actually, I started my PhD in the brown fat, the healthy fat, and that was the reason why I started looking into what is actually happening when you go into the cold, cold air, cold rooms, or just getting cold on your skin, but also going into the cold water. So my thesis is actually about our metabolism, and what happened was that I had this science topic of the brown fat, and figuring out how can I do a research study in humans, because there's been some studies done in rodents, and also cell models, saying that if you get cold on your skin, then they will activate your brown fat, because norepinephrine will be released from your nervous system, because you activate the sympathetic nervous system, and that will activate our brown fat cells, which will then increase our heat in our body — so that is to protect us from becoming hypothermic. And then I got the idea — then what about winter swimmers, because they go into the cold water all the time, so do they have more brown fat? Because when you expose yourself to cold all the time, we see in rodent studies that the brown fat can increase in volume, and if we can increase the volume of brown fat in the body, then we will have more cells to increase our metabolism, increase our heat in our body, because when the brown fat is activated, it takes up sugar and fat from the bloodstream, and thereby we can burn some calories. So that is really what researchers are doing right now, it's really a hot topic in metabolism, increasing our brown fat.

Daniel
3:17

Did you actually do winter swimming or ice swimming before you did the study, or did you start doing it because of your study?

Susanna Søberg
3:25

Yeah, exactly. So I would say I was pretty much like Patrick, because I was like, man, I'm going to study something that I really reject, I don't want to go into the cold, I'm comfortable, I feel fine at just neutral temperatures. But I have to say that I was also a person that was really — I can maybe call myself a cold sissy, because I was so scared of the cold all the time, I freeze really easily, so the thought of that was really not something that appealed to me, at least. So going into this research, I was like, okay, if I do this at some point, I will have to try it at least. So yeah, that's — so I did this, I did start up the research, and I did do some field research, just observing winter swimmers, how do they do it in Denmark, noting down how is this a good thing, and how long do they stay in the water. So it took me a year just to get data on how this is actually done in practice. But the winter swimmers were all seeing that I was doing this study, so they were saying, "Oh, Susanna, you cannot study this without trying," so you have to get into the water, and at some point they convinced me. And I must say, the first three times I was not having it, was not something I liked. I know that some get hooked the first time, and I wish I had it like that, but it wasn't like that for me at all. So by the time of four or five times, I was not scared of the water anymore, I was not really scared of getting cold like that anymore, and that is when you start building up your resilience, actually. So, but today I like it.

Daniel
5:16

How cold was it when you jumped in? Because that matters — was it two Celsius or 18 Celsius, or somewhere in between?

Susanna Søberg
5:22

Well, so cold water is 15 degrees and below, and the reason why I say that is because we can see in the literature that by the time the water hits 15 degrees and below, we've seen some observations on people getting activation of the cold shock, and also accidents, so that's the registration we have seen in the records, at least, so 15 degrees and below is where you activate your sympathetic nervous system. By the time I went into the water, it was October, so in Denmark the temperature in the water will be around maybe eight, five — yeah, around that — but this year it's the water is really warm, we had a really warm summer, but usually it's around maybe eight, nine, ten degrees or something like that in October, it could be colder. But yeah, I remember it was super cold, at least.

Patrick McKeown
6:18

It's a lot of diminishing returns, you know — do you get the same effect at 14 degrees as you get at two degrees, or how does that work?

Susanna Søberg
6:26

So there is probably like a dose-response effect on temperature, and you can also feel it on your breathing, because if you go into water that is two degrees, you will have a much larger activation of your sympathetic nervous system, that is your fight-and-flight system. So of course you will have a more rapid increase of all the hormones, so adrenaline, noradrenaline, and cortisol, which will make you — you can say — fight for your life. But that would mean that you can stay in a shorter time, of course, in the water, so you have to adjust to the temperature as well. But most important of all is just to feel how it feels for you, so as soon as you feel too uncomfortable, the body will tell you, now it's enough, now you go up, and you have to listen to that. But building up, you will have to accept that you can only stay for a certain amount of time, and don't compete with anyone, because people are different. So some will be fine with just building up to maybe one minute or two minutes, three minutes, and no reason to stay in longer, no matter what temperature it is, I would say, and then some are just fine with just a short dip, you will get the activation of the sympathetic nervous system anyways. But in the beginning you will not be able to stay for a minute, that is also something people will have to accept, it's like training, it's like going to the fitness center, you have to build this up, your cells will have to adapt.

Patrick McKeown
8:01

So a novice like me, you're saying maybe just get in for 30 seconds, and I think that takes the fear response away as well, a little bit, because you're realizing it's only for 30 seconds.

Susanna Søberg
8:10

30 seconds is also long. I mean, your first step will just be a few seconds, you can go in and maybe count to five and then go up, because the next time you can count to 10, and then to 30, and then at some point you will be able to stay in the water until the cold shock subsides, and that will take you around 40 seconds, one minute. Some people, it's one and a half minutes, it's a little bit different, it's a little bit individual, but it seems that if you can get over the cold shock, if you can use your breathing, concentrate on your breathing getting low and light, then you can relax in the water, you can switch from sympathetic activation of your nervous system to the parasympathetic activation, and when you can do that, you can at some point rest, and you will feel the switch. I think it's amazing — I remember the day where I could sit in the water, and I was swimming, but then I was sitting, and actually holding my hands above the water because I get so cold hands. And I remember the first day where I actually got over the cold shock response, and I immediately felt the calmness in my body. It was like getting over to the other side. It was amazing, and it was a very cold day with fog on, it was a lake, I remember, and it was just so beautiful, I have made a core memory about that, it's just — it was so beautiful. So, Patrick, one day you will have to try, and just build it up a bit, and then you will see that something amazing is happening.

Daniel
9:46

Like breathing, because I've — you know, when you get the switch, you get your mouth, and you can just, like with breathing, Patrick, slow breathing, yeah, and it's like breath holding, like if you tell somebody to hold their breath for several minutes, it's too stressful, you start slow. The only difference is that the cold is temperature driven, so you may not be able to do it in the summer, but I think there are many similarities with breathing, as far as you have a little bit of an aversion to breath holding, and some of those exercises are more stressful, but once you get used to it slowly, it's a lot —

Susanna Søberg
10:22

About fear, I think. So fear of getting into the cold, fear of breath hold, it's the feeling of breathlessness, I think. A lot of my subjects — I did a randomized control trial, it was 30 subjects in this study, it's not published yet — but I trained them from never having tried winter swimming before, and of course, we went — me and my team — we went to the sea with them, and had, maybe three, four, five times, because we wanted to make sure that they were not stopping their winter swimming because of fear of the water, because fear is not something we can use for anything, so if they don't want to continue in winter swimming, it should be because they're not having it, they're not feeling it afterwards. But the first few times, the reports coming back to me was that people felt breathless, and that was not a great feeling, of course, but that was the biggest fear, not being able to breathe. So what I really encourage people to do is think about the breathing before you go into the water, so calm yourself down before you go into the water, take some deep breaths on land, and just stand there for a bit, relax yourself, do some breathing techniques, but in a relaxing way. I don't encourage people to hyperventilate, because you're already warm — because you just came from home, where maybe you were running, you're already warm enough — you just have to calm your nervous system so you can go into the water, because then the cold will activate the sympathetic nervous system, but you are already in the training of lowering your breath, and that you can use in the water.

Patrick McKeown
12:12

I think there's something tremendous in terms of mental health here, because in terms of breathing, as Daniel was saying, you surrender to it. Now, I've done a few ice baths, XPT, and they were four minutes in duration, I just never went back to them again. And I have — we've put in ice baths, we've infrared, so we've everything here, and yeah, so shame on me. But it's really about — so what you're saying, Susanna, is when people get into the water, they are feeling breathless in the water —

Susanna Søberg
12:45

Yeah.

Patrick McKeown
12:45

— and this is something that they don't like. So really it's about having some command over your breathing, that here you're in the face of adversity, and your breathing is getting fast, which is going to happen in any situation that's stressful.

Susanna Søberg
12:57

Yes, exactly.

Patrick McKeown
12:58

Any physiological, any mental stressful situation, and it's really about developing the tools then to be able to take control, to self-regulate, whether it's in the water or whether it's in situations outside of the water. So there's a lot going on, and even though I have to say your book, Winter Swimming, and I'll show it towards the end as well, it's a beautifully crafted book.

Susanna Søberg
13:19

Thank you.

Patrick McKeown
13:20

And what you've included in it, with photographs of real people, not just Instagram people, which can be very much a turn-off, that you're making it accessible to normal populations. The degree to which this has been practiced around the world — because we had this conversation with Daniel and yourself beforehand — that very often we think it's only isolated, say, for example, for Finland, for Sweden, for the Nordic countries, for Denmark, etc, but it's actually practiced worldwide, internationally, and this is not just a movement at the moment, this has been practiced for decades.

Susanna Søberg
13:55

Yeah, there's —

Patrick McKeown
13:55

Nothing new about this.

Susanna Søberg
13:57

No, there's nothing new about it, but I mean, there's been more — you can see more research on it the last maybe 20 years, and also metabolism-wise, which I've been studying — but also there's been a pandemic, which apparently also really took off during the pandemic, right, and it really builds into what you just said about mental health, because the lockdown didn't really do anything good for us, I would say, mentally. So people are more stressed, and they have more anxiety, and they feel more lonely, I think. So going out to the water, and getting this increase in neurotransmitters, such as dopamine — increase by 250%, or even more, just by a short dip, actually — and also norepinephrine, and endorphins increasing too, which makes us happy, it's our happiness hormones, and it makes us more calm, because when you submerge in the water, you activate the parasympathetic nervous system, and serotonin goes up, and that is what you need for the mental balance, and that holds on for hours after your cold dip. So what people did was actually, they were seeking excitement, I think, also maybe people were a bit bored, but then they found out, well, this is actually making me more happy and more joyful, more relaxed afterwards. So in relation to mental health, I think this is really interesting when it comes to maybe curing depression and also anxiety, or holding it at bay, you can say. So I have seen that people use this, but this is, of course, on anecdotal evidence, if you can call it that, or stories, yeah, but —

Patrick McKeown
15:47

It has to start somewhere, in terms of you're seeing the observations, and in time then the science will show the connection, or at least will uncover it. But you're saying that initially, when you get into the water, you're activating a sympathetic response, so you're feeling distressed there, and then you're surrendering to it, so that's transforming then from a sympathetic activation to a relaxation response.

Susanna Søberg
16:08

Yes, so okay, but what people need is a tool to know how to do this, because the fear starts when you don't know what to do, you don't know how to breathe, you don't know what to do when you go into the water. So I think it's really important, and that was also important for my studies in my research — when I guided them into the water, I told them exactly before, so they knew how to go into the water. Empty your lungs, I always say, so when they go in they should exhale, because then they make capacity to breathe in more air, because when you go in and you're not adapted, you will have activation of your sympathetic nervous system, and that will increase hyperventilation, and then you will have a very high and shallow breathing, you cannot get the air down. But if you exhale completely before the first step in the water, you will have a bigger capacity to breathe deeply. So that is one thing. The other thing is doing the light breathing before you go into the water, so standing on the beach or jetty, or before your bath, whatever it is you're using, and just practice getting your activation of your parasympathetic nervous system, then it will be easier for you going into that breathing again as soon as you step into the water.

Daniel
17:36

We spoke a little bit earlier here before the podcast about measuring — have you used any measuring devices? Because if you have, like myself, the Oura ring, for example, you can see that switch when you become calmer after a certain — and it doesn't happen to me every time — but have you used any of that on yourself or the ones you've taught?

Susanna Søberg
17:57

Yeah, so we've used a Garmin watch, and with that we can see the heart rate, and also the swim strokes, how many strokes did they take, and we can see how much the pulse actually went up, and also how fast it actually declined again, because what is normally said is that you have an increase in heart rate as soon as you go into the water, and you will definitely have that if you are an unexperienced winter swimmer, also because you are a bit anxious and nervous about going into the water, and it's probably mostly that. But because the cold shock is so short, you will — because of the activation of the parasympathetic nervous system and the vagus nerve — you will have a decrease in the heart rate as well, and that is why you can see people sitting in water for maybe a minute, two minutes, three minutes, and not hyperventilate, that is because they have calmed their nervous system to the parasympathetic activation. So you can definitely use your breath to get into that state, and you can use that in your everyday as well, so that is another thing.

Daniel
19:11

Do you — so you actually mostly swim, you don't sit still, because there's a —

Susanna Søberg
19:17

I do both. I do, yeah, I do both. Well, it's because sometimes if I can't reach the bottom of the sea, then of course I would have to do a swim, but sometimes I just like to swim as well, because then I activate my muscles, and you have two systems in your body that can activate the heat — that is the brown fat, which will be activated at first, but at some point that will not be enough to defend your core temperature, and then the muscles will, of course, help you. But if you are swimming, then the muscles will help you immediately to keep yourself warmer, and actually, so swimming is actually a good thing, because then you will have more heat in your body, but you will also have changing temperature, because of the thermal layer, will be cold all the time, so it's like a balance.

Daniel
20:11

Like we said earlier, if you dig into it, like there's a heat layer, if you sit completely still, and also if you take your hands and even your feet outside, there's a difference if you really want to get into it, so — but I really —

Susanna Søberg
20:24

Want to make a point there, because there are some people thinking that taking your hands out of the water is like cheating, and I really don't think it is, because you don't have to submerge your whole body to get benefits of this, or get your activation right, you can say it's not necessary, because we've done studies — not only me, but other researchers as well — where we see that submerging just a hand or a foot in cold water at four degrees for four minutes, which is a long time, but we could see immediately that there is an activation of the brown fat. And there was also studies done in fishermen, where we can see that because they work with the hands in cold water all the time, during cleaning the fish and stuff, what they do — but we can see that they have a cold adaptation in other places in the body, it's not just the hands, they can have a long time in cold water, it's also the legs and rest of the body. So cold adaptation is not necessarily the whole body, of getting your head submerged, you don't really have to. And because I get so cold on my hands — sorry — I take them up, because then I can sit in the water a longer time. Of course, I do a swim, but then I take them up afterwards, because then I'm able maybe to sit a little bit longer, and get my two, three minutes of how long I want to sit there.

Daniel
21:55

Yeah, I think that's a good point you made there, because some people can sit, but they can't have their — sometimes their feet or their hands, because they have problems with it — so they can still get that benefit while doing so. These little tips and tricks that people may not necessarily know, so it's good to know that if you do it that way, at least you can get the benefit, even though your hands are not in the water.

Susanna Søberg
22:17

Exactly, you can wear gloves as well, and also neoprene shoes — I do that all the time, but that's also because of my fear of touching the ground in the sea, because I can't see it, and that's a little bit — maybe just me, I don't know — but I wear the shoes, because then I don't have to think about that, I can concentrate on my breathing, and I could do a little swim, because I really love that, and sit there for longer if I take my hands off, I get the benefits. So, yeah.

Daniel
22:49

How long would you normally — I mean, it's individual, but would you recommend somebody to be in until they're calm, their breathing, or — because you said an exhale before you go in and breathe light — what do you kind of tell them when you're in the water? Do you have any certain protocol for people?

Susanna Søberg
23:10

Yeah, well, I always tell them to lower their breath, of course, and try to calm themselves down by doing a deep inhalation, and try to do it slow as well, so deep and light and slow, actually. So by doing that, they will get the activation of the parasympathetic nervous system quicker, and they also, of course, will have a vessel dilation as well, which will mean, in the beginning, it will be like a struggle between getting cold adapted and also opening your veins, so you will actually quickly get cold by the parasympathetic activation, but at some point you will be able to vasoconstrict well in your skin, that you will not get that cold by activating your parasympathetic activation with slow breathing. So it's like there's also a building up and a switch the way the body needs to get.

Patrick McKeown
24:14

So you're kind of saying, listen to your body.

Susanna Søberg
24:17

Yeah.

Patrick McKeown
24:17

It's not always an easy one, because you could say to yourself — and I'm going to be macho here — so I'm going to keep on saying to myself I should stay in longer and longer and longer, and then one overdoes it, and sometimes extremes — sometimes I feel with people with breathing, they can push it to the extremes, that there's different personality types, and I could understand that the individuals who do the long breath holds are also the ones that are going to jump into the water as well. So how would you know if you're overdoing it? Would you know by your shivering afterwards, that it takes you so long to get back to normal temperature?

Daniel
24:50

Yeah, I know —

Patrick McKeown
24:51

Daniel's looking at Oura ring and things like that, but say for a normal individual, how would they know?

Susanna Søberg
24:56

Yeah, so that's a really good question. And I think that is right, if you feel bad in the water, and you start shivering, that is definitely your cue to get off. You should not shiver in the water, because then you know your temperature has decreased too much. And I did, like, a small table in my book, where it says exactly what is happening, what can you feel when the temperature reaches 36, decreasing one degree in your core, and also what happens at 35 degrees, and when it reaches 35 you will have the shivering, and you should not have that, there is absolutely no reason to go there. So when you feel a little bit like the tingle in your skin has gone away, and you feel like a cold shiver towards your core, it's like a feeling, it's something you can feel, then it's definitely time to get up, because one thing you need to know is when you are in the water, that is not when you are the coldest in your core. You will have what is called the after-drop — when you have been in the water, so when you get up from the water, the blood vessels will dilate, and the blood in your core will, of course, go to your tissues and your skin, and that will decrease the temperature of the blood, and that goes back to your core, and then the temperature receptors will, of course, pick that up, send a signal to the temperature regulating center in the brain, and then it feels, well, now we're getting even colder. So when you get up from your cold dip, you will have a decrease in your temperature after that, so don't stay until you absolutely feel this is getting too much, don't push it. There's absolutely also no reason, because we see the health benefits happening within a few minutes, and after that it plateaus, so there's no reason to stay longer, and this is everything to do with hormesis as well, I don't know if we should talk about that, but yeah —

Patrick McKeown
27:03

Why not, I think —

Daniel
27:07

But I think, Patrick, that it goes back to — you do link to breath holds, like diaphragm — if you do breath holds, your diaphragm will start contracting more and more, if you're experienced it will take longer. Same with if you're in the cold, you feel these downs after, whatever, a minute, and then after a minute, when they come more and more often, just like the contractions of the diaphragm, it's kind of telling you you're stressing the system, so at least for me, so you have these subjective measures as well, with experience, I would say.

Susanna Søberg
27:39

Yeah, but also, when you are a new winter swimmer or cold dipper, you will have shivering afterwards, and the shivering is not in itself anything dangerous, it's just the muscle warming you up, which is a good thing, but if you experience that many times, or all the time, actually, then you would know, maybe you just stay in for a short amount of time, because then you will learn — the body will learn to heat itself up, but not to extremes, because I mean, then it doesn't feel that great to feel that shivering for hours afterwards, so you will have to adjust it to yourself. It's all about body composition, and it's really difficult to say, this is how you should do it, this is just the protocol, you cannot do that, but we can set up some advice around how much you should do, but as far as the literature goes, you shouldn't stay in the water for 10 minutes, 15 minutes, which some very competitive people would do, pushing it to the extreme, too.

Daniel
28:48

So how would you tell somebody — now is a perfect time to start, or maybe a month ago — but how would you tell them to build the habit, if it is in the middle of the winter, do you have a general, like, just go down to the knee for 30 seconds — so you have a certain protocol or adaptation for somebody who's a complete beginner?

Susanna Søberg
29:12

Well, if it's a complete beginner, I would say start after summer, or just continue your summer swimming into the winter, because then the season, the temperature in nature and weather will just do the conditions for you. So if you can swim in the summer and you just continue that, then it will be much easier for you to adapt to the temperature decreasing just slowly, because then you don't have to get the immediate cold shock if you start in December or January when winter is at its peak, so it's easier for yourself to start in the summer. It's also more safe, because there's also, of course, some safety around this, so people with heart diseases or high blood pressure not treated — that is people usually told not to do winter swimming, or they should go to their doctor and talk to them about it, because it is really difficult to say that everybody can just start winter swimming, because, as I told you before, the conflict of the sympathetic and the parasympathetic nervous system — one raises the heart rate and blood pressure, and the other one brings it down, and that makes the conflict to the heart. And you can almost, if you try winter swimming, dipping, you can remember that the heart is like, oh, it's like struggling the first few seconds of it, and if you have heart problems, I would say you should be careful about that, but starting out from summer would definitely be less stressful for your cardiovascular system.

Patrick McKeown
30:47

And in terms of when we're looking at breathing exercises, people with anxiety, we have to go really, really gentle, because especially when we give them air hunger, because that air hunger can put them into a stress response. Is there anybody who would say predisposition towards anxiety or panic disorder, that they have to go even easier than somebody without those issues? Do you see that difference, or not?

Susanna Søberg
31:12

I haven't really trained a group of people with anxiety or depression as such, so I cannot really talk about that on a scientific level, but my observation is that people with anxiety and depression are doing winter swimming, and they start out slow, but I would say it would be the same for everybody, because it's all individual, you have to feel it yourself, how much can I do. But relaxing before you go in, having anxiety or not, having a slow breath before you go in and exhale completely will help you in the water, but everybody will have an increase in their heart rate in the first few seconds, and everybody will have an activation from the cold shock, so having anxiety could trigger even more anxiety with going in, so they maybe have to take it even more slow, is my — sure —

Patrick McKeown
32:17

Sure.

Susanna Søberg
32:17

Yeah. So —

Daniel
32:20

What about, as far as dipping the face in cold water, or even submerged — are there any benefits from that, or should you not do it? What's your experience?

Susanna Søberg
32:34

The face can be very good, to put cold water in your face, because that is also giving you this energy boost, and also noradrenaline release from your nervous system. But I mean, you don't have to dunk your head under the water to get the benefits of dipping in cold water, so I usually say that we don't have to. There's also a safety around it, because when you submerge your body up to your neck, you will have — studies show that you will have a decrease of blood flow to the brain of 30% or even more, so dunking your head even more, that will increase that shock, and you have the risk of, of course, hitting your head or drowning, and you don't really need that. So for safety, I always say there's no need to, and for health benefits there's also no need to, but sometimes when I'm out in the sea, and we have really clean water here, so I take some water and just splash it in my face, because then I get that refreshing feeling afterwards, because it's also very much calming yourself, but it's also because it activates the parasympathetic nervous, the vagal nerve, by putting cold water in your face, that could be nice too.

Daniel
33:53

Mammalian reflex as well, if you get the heart rate down, so there's — maybe not something you do the first day, but it's interesting to maybe use as well. So just wanted to get your input on that.

Patrick McKeown
34:12

Yeah, it's very interesting in terms of the reduced blood flow to the brain. So I'm assuming that's — the body is conserving energy, and the heart rate is really slowing down, bradycardia, as Daniel was talking about — but is there any positives as a result of reducing blood flow to the brain like that? Because, for example, when we're doing breath holding, we would advise never lower your blood oxygen saturation to below 50%, because this is when you can have a reduction of blood flow to the brain, but if you hold your breath until you drop to about 80%, you can actually have an increase of blood flow to the brain. So I'm kind of surprised, with the cold, that it would actually cause a reduction of blood flow, and you would think that the body is going to look after the brain and the heart, so that the peripheral circulation is going to constrict, and this blood is diverted to the more essential organs to maintain survival. So that's not the case?

Susanna Søberg
35:05

No, I'm surprised as well, I must say — that is maybe why those studies were actually also performed in Denmark, I was quite surprised when I saw it, I was like, this is really interesting, because I would think that the brain must be very vital for us to increase the blood flow, and people always say that, oh, when you go into the cold water you have an increase in blood flow to the brain, but it's quite opposite, apparently. And these studies were performed in a laboratory, where they had this big tub that they put people in, for exactly 30 seconds, and then took them up again, and at zero degrees, so it was really, really cold as well, zero Celsius. But what is important here, I think, is that that is why we should be a bit cautious around dunking the head in the water, and also going alone, because the low blood flow to the brain can cause people to faint in the water as well, so I always say never go alone.

Daniel
36:09

But I think, Patrick and Susanna, maybe it's got something to do with the temperature — there's a big difference between zero and 15 Celsius, there's a big difference between going down to 80% oxygen saturation or 50%, same as training, it's a big difference between jogging for one hour or going all out for 20 seconds. So the intensity of the temperature, the intensity of a breath hold matters, you can't — in my opinion, you can't just say, well, if you're at 15 for 20 minutes, it's not the same, it's very, very cold, it's same with training, that's why you get a different effect, and maybe that is the reason — down to a certain point you get increased, but below that it goes into a different gear, and for me that makes — it wouldn't make sense, not knowing, but I know from experience it's like when people say burning calories, it's very different doing low intensity, high intensity, the shock of your body and different gears come into play, so maybe there's something gradually there happening, of course.

Susanna Søberg
37:07

So the warmer the water is, the more blood flow you will have in your brain when you go into the water, but I think that because that is really hard for people to distinguish — when should I then dunk my head and not dunk my head — I just say that there is no reason to, there is absolutely nothing showing that this is going to do anything good for you. So, but I think that 15 degrees and below is very cold, and also it's relative, there's also something relative to this, so if your skin is very warm, you can get a cold shock at a higher degree, but if you are a bit cold already, then the cold shock will be less, and some people are just warmer than other people, so it's —

Patrick McKeown
38:01

So this then is going to matter, then, if you're going from a hot sauna into the cold bath and then back into the hot sauna again — so what's the difference between that, and normal temperature, the atmospheric temperature, going into the water?

Susanna Søberg
38:14

Sorry, once again?

Patrick McKeown
38:16

So say you're going from a hot sauna —

Susanna Søberg
38:18

Yeah.

Patrick McKeown
38:19

You're feeling really, really hot —

Susanna Søberg
38:20

Yeah.

Patrick McKeown
38:21

And now you're jumping into a cold bath, and you're going from one extreme right down to the other extreme —

Susanna Søberg
38:26

Yeah, so that's going to increase your cold shock, of course, because the relative difference is quite big at this moment when you come straight from the very hot sauna, and that is also why I think it's not really that important if it's 15 degrees or 12 degrees, but there's a difference in 15 and zero, of course, but if you just look at the relative difference, then you will have a cold shock response no matter what. So, yeah, again, the blood flow to the brain will decrease.

Daniel
38:58

You do that as well — what is there, a difference between doing just going down, doing a cold exposure, versus doing sauna first, cold and then sauna again, or the various combinations ending with a sauna? Have you noticed a difference in what happens with people when they mix it, versus just doing cold exposure?

Susanna Søberg
39:18

So that I haven't really done any studies where I have compared this, so not on a scientific level I cannot tell you, but what I did in my research was based on all the observations that I did, and also what is happening in your metabolism. I would say that because of my hypothesis saying that the cold would activate your metabolism, I said that my protocol should be that people should start in the cold to decrease the skin temperature, and then they go into the sauna and back to the cold, back to the sauna, and then they end on cold, because if you end on cold, then you force your body to reheat itself, and that will, of course, take energy, and the energy comes from activating your brown fat and activating your muscles. Eventually, when you get home, you will maybe start shivering a bit, and that is really good for your health, so if you don't overdo it or do it extremely, then it's good, and it's really good for you.

Daniel
40:14

I learned the hard way that it's not necessarily good to go from cold to heat, cold to heat, when the contrast is 90 Celsius too quickly, it actually — you have to be very careful about that.

Susanna Søberg
40:26

I always say that people should just stand on the bridge, or just wait a bit to cool down in the wind, so they have what we talked about, so the cold shock response to submerging yourself will be a little bit less, so it should, of course, be done carefully, but also never alone, so that is also for safety, really important.

Daniel
40:47

But luckily, Patrick, you got a mile or two down to the ocean from yourself.

Patrick McKeown
40:54

So envious, I can see it, it's a bit — I can almost see Galway Bay, but it's a little bit overcast at the minute, we have an infrared sauna down there as well, so there's no excuses —

Susanna Søberg
41:07

You should have definitely tried —

Patrick McKeown
41:11

Me totally — so I'm feeling so guilty having this podcast, you know, I'm sitting here and I say no contribution whatsoever to make —

Daniel
41:17

We'll do a repeat podcast in a few weeks, and we'll see what —

Patrick McKeown
41:21

No other choice, Susanna. For somebody who wouldn't be familiar with brown fat, and what's the benefits, and what's the comparisons, and do some people naturally have more brown fat than others —

Susanna Søberg
41:35

Yeah.

Patrick McKeown
41:36

And what's the whole aspect in terms of weight loss and things like that?

Susanna Søberg
41:41

So the brown fat is a very remarkable tissue that we have in our body, nobody really knows about it, it's really something new that we started researching, but we have known about it since — I think it was the 1500s or something — there was this research of finding brown fat in this animal, and it's a hibernating animal, and they saw that it was activated with cold, but then the researchers found that it was also in animals that were not in hibernation, and then they got confused, and they put down the research, and didn't want to look at it again, because it was very confusing. But what the brown fat does, and we found out a little bit later, was that when it's activated with cold, it increases the metabolism by taking in sugar and fat from the bloodstream, and then it releases heat, as the product, and it's activated immediately as soon as the skin gets cold, so that is because of norepinephrine release. So when we're cold, it activates norepinephrine from the brain and the brown fat, which is located very close to the central nervous system, so in humans at least, it's up here under the supraclavicular bone, and down the spine and around the kidneys, a little bit around the heart, which also makes sense. So when it's activated, it keeps our vital organs warm, and it happens within like minutes or seconds — actually, I could tell from my studies doing measuring with an infrared thermography camera, I could see the activation immediately. But what it does is that when it's activated, it takes up sugar and fat from the bloodstream as fuel to keep it activated and keep us warm from the inside, and some people have more than others, which we started looking into by the millennium, actually, and we saw that some people have more, and that is apparently — the younger you are, and when you reach around 40, 50 years old, we can see a decrease, also at the same time when we see that obesity goes up. So we don't really know if obesity is happening because you have a reduction in your brown fat, or the obesity is making the brown fat shrink, so we don't really know which way it really goes, but there is so much research showing also that the brown fat is very dependent on insulin, like the muscles, so if you are insulin resistant, you will have a difficulty activating the brown fat. So it could be that if you are above normal BMI, you will have less of the brown fat, and if you are younger and normal BMI, you have more. We see in babies, babies have a lot of brown fat, and before the millennium we thought that, well, the brown fat is only for babies, because they have a lot, and we can see it on the back of them — they have that because they cannot shiver in the muscles in the first, I don't know, six months or something like that, so they need the brown fat to keep themselves warm, and then it vanishes a bit, it shrinks with age, but we can activate the brown fat and keep it alive, you can say, and use it for increasing our metabolism if we go into some kind of cold. And I know that I took the model of winter swimming, but studies also show that if you sleep in a cold room at 19 degrees for a month, studies show that these subjects increase the amount of brown fat, it's not that big, but they got more — they got a higher insulin sensitivity, and also a faster blood sugar reduction in the bloodstream. And when the same subjects then slept in a room at 24 degrees, and the later months at 27 degrees, they saw that the amount of brown fat is shrunk again, so it's definitely something that we can build the brown fat if we go into the cold, or sleep in the cold, or go in the cold wind, because when we do that, we activate it, and that will increase the amount of mitochondria in the cells, and also we can maybe brown some of the white fat cells into what we call beige fat cells. Now we have the whole color scale of beige, brown and white fat cells, but they are very distinguished, the white fat cell and the brown fat cell, because the brown fat cell has lots of mitochondria, and can use the white fat as fuel, but the white fat is not that easily activated, and we know that also from exercise, it's really hard to get it activated and get rid of it, or empty the white fat cells, but we can do that with the cold, because the brown fat is going to use it as fuel, we want more of it.

Patrick McKeown
47:29

It's so cool. So it's almost as if it's going back to basics, like our ancestors would have been exposing themselves to colder environments, and we now — we're so comfort creatures —

Susanna Søberg
47:41

Yeah.

Patrick McKeown
47:42

That we don't do that. So does disorder have the opposite effect, or is that a stupid question?

Susanna Søberg
47:47

It's not a stupid question, it's a really good question, and I love it, because now we've been talking about the brown fat as a tissue that is only activated by the cold, but actually it's also activated by heat, so you can maybe look at — yeah, because you also have an increase in norepinephrine — but it's also, I think we should look at the brown fat as like a temperature-balancing organ in our body, it's just trying to make you survive, it doesn't really want anything else, it has to use fuel to heat you up and keep you warm, but if you get too warm, it activates, so you can dilate your vessels and get rid of your heat, so it's also —

Patrick McKeown
48:27

That's music. This is absolutely music for my ears, because I was in the sauna this morning, and yesterday morning, and all those mornings. Now you're saying I don't even need to go to the cold, I'll have to —

Susanna Søberg
48:37

You should do both, I think, because my studies actually show that — but it makes sense going into the heat, because it shows that you will have an increase in insulin sensitivity, and also you will get faster rid of the sugar in your bloodstream, but doing the contrast therapy shows exactly the same, which my studies showed, I published last year. So doing both, you will have an increase in mitochondria from going into the cold, but when you go into the heat, the heat will help you use those mitochondria in an efficient way, so they kind of complement each other.

Patrick McKeown
49:24

Complement each other, yeah, exactly. What about afterwards — have you, what have you seen in subjects or yourself as well, once you come up, what happens in your body physically, and how long does the dopamine effect last, and so on, because I guess for most people they want the after-effect. So what happens once you get up?

Susanna Søberg
49:49

So the effects of the higher release of norepinephrine and dopamine and serotonin lasts for hours afterwards, I believe it could be two hours up to four hours after your dip, so that is also when people report back, they say, I feel really really good in the hours after my winter swim or my sound sauna, and it really makes sense when it comes to what the literature shows regarding dopamine and norepinephrine. So I think it's really something where we can put on the neurotransmitters afterwards, but also warming the body afterwards, you get this really comforting warmth in your body, it feels like — I think it feels like just after I've been training, I get this really relaxing feeling in my body, like I've used it in a really, really good way, I get the same feeling from using the contrast therapy going into the cold and heat. So I think it pretty much does the same, you can say hormesis in the cells, where the cells are trained to become stronger, and that is also what you do when you go for a run or you go training, so it's exercise for your body when you use the cold and the heat.

Patrick McKeown
51:08

It's really interesting, and I was reading as well in your book about the baroreflex, that you're going to have to strengthen it, so you've got a very strong influence on the autonomic nervous system to make one more resilient through that. How does the process work, though, in terms of strengthening the baroreflex — it's something as well I never get my head around, the interrelationship between the vagus nerve and the baroreflex, interconnected, and how that's influencing then heart rate variability. But in terms of the cold, because I'm conscious just in terms of time, we're nearly drawing to a close, but the baroreflex is an interesting phenomenon, because if we can strengthen that, we can improve the autonomic nervous system, and we can bring everything into balance.

Susanna Søberg
51:52

Yeah, in —

Patrick McKeown
51:52

Terms of people with mental and physical issues, so the cold goes way beyond it's applicable, so pretty much everybody with any sort of issue, if that's the case —

Susanna Søberg
52:04

Yeah, it seems like that, I mean, again, going back to people with heart problems or high blood pressure, there is, of course, some precautions there, but I think that people should — people are different, of course, and if they don't follow like a certain protocol, they have to feel how it —

Patrick McKeown
52:29

Yeah.

Susanna Søberg
52:29

How it is for themselves. It's not really something that you can just say that everybody should do it in the same way, but people increase their resilience in different ways, and also, what you are talking about, the mental health, it's going to be a different protocol for people, but there are some studies showing how much you could do to get the health benefits. Yeah, but the question about the baroreceptors — well, I think we need more research on exactly that, and also regarding the breathing and the cold, that could be really interesting going further, yeah.

Patrick McKeown
53:02

It's what actually different breathing techniques applied in terms of what's doing to the autonomic nervous system — yeah, that's really cool. I'm just conscious — sorry, Daniel.

Daniel
53:13

No, I just had a final question. When you said that — it would have been interesting, because you said, you know, you go down and you go in normally to a winter swim fairly relaxed, but if you came from a hard workout, like two minutes before, like an early football team or whatever, then your heart rate is already ramped up, then of course your body heat is — but that's a little bit different, at least for me. Do you have any thoughts on that, like you come in from a different angle if you have a really, really tough workout and go straight in — is the response different?

Susanna Søberg
53:48

I wouldn't recommend that you go straight in. I've seen people just jumping in, young people, and maybe that is more okay, but I actually think that people should be a bit cautious around that, because, as we talked about, the relative difference is also in skin temperature, because they are really hot at this point, and also already have a high heart rate. So maybe spend some time just standing there, lowering your heart rate, and getting into that state of mind where you're thinking, now I'm going into the cold, and the purpose of that is actually to lower my breathing and to activate my parasympathetic nervous system, and not to just get the excitement of the cold water. Other means it could be that people just want that, and then that's fine too, but if you want to get that mental balanced feeling afterwards, and also use the benefits of the chemicals in the brain, I think that people should try and build up the resilience and get calm in the water, and then they will have really good after-feeling of the neurotransmitters afterwards. So I don't think that people should jump into the water, definitely not if they are very hot from a run or a training or something like that, just getting a little bit chilled on the bridge would be good, yeah.

Patrick McKeown
55:15

Yeah. So, in terms of bringing it to a close, I just like to show Susanna's book, and you see the cover of it here, it's called Winter Swimming, and the one thing I love about this book is, aside from the fact that it's really well put together, it's very informative, there's real people, we're not just talking about Instagram and these sculpted bodies that typically, when we see a photograph nowadays, we don't see real people — we've actually a guy who's totally naked there, so no. And yeah, so I would — I think this is a great resource for anybody who wants to delve into this a little bit more. Where would people get your book, Susanna?

Susanna Søberg
55:58

So people can get my book on Amazon, and you can just type in Amazon, and just my name, and it will pop up. But also on Instagram, I have a link in my bio where you can click, and you can have multiple choices for where to get the book as well.

Patrick McKeown
56:16

What's your Instagram?

Susanna Søberg
56:16

It's my name, Susanna Søberg, with an OE, so S-U-S-A-N-N-A, and S-O-E-B-E-R-G.

Patrick McKeown
56:27

Excellent. Well, it's been an absolute pleasure talking to you, it was great meeting you back two months ago, and I think, Daniel, this is a great conversation, all things cold.

Daniel
56:35

Many more questions, but I mean, pressed for time, so I'm conscious of that, so we'll do a repeat when you feel comfortable, Patrick, doing the cold bath, so no pressure, no pressure.

Daniel
56:49

Thanks very much, guys.

Susanna Søberg
56:51

Thank you for having me, was fun, nice stuff.

Patrick McKeown
56:54

Stuff.

Susanna Søberg
56:55

Good stuff, bye, bye, bye.