Cold water is often framed around resilience. In the context of endometriosis, the more useful question is gentler and more precise: can controlled cold exposure help the nervous system relate to pain differently?
Full transcript from the source video, grouped into clickable timestamp sections.
I um I completed my PhD in 2018, so about 8 years ago now, but since then I've had a few career interruptions just due to um having kids and caring responsibilities and things. So having that sort of time taken into account, I'm still sort of within what is considered an early career researcher um role. Well, Dr. Dodds, thank you for joining me on the Uncommon Living Podcast because I have questions. Great. Well, I'm here to answer them. It's been very controversial since Stacy Sims went on the Huberman Podcast. She went on Steven Bartlett's Diary of a CEO Podcast, and she went on Mel Robbins Podcast. And there was a clip from the Mel Robbins Podcast that was the most shared podcast clip of 2025. And it was where Stacy Sims said, "Oh, I don't really like ice baths for women." Now, in context, she acknowledges that cold plunge therapy can be very beneficial for women in lots of ways, but Stacy Sims has trademarked this phrase that women are not small men. And she wanted to make a distinction between temperatures that she thought men should plunge at, temperatures that she thought women should plunge at. And the headlines have said, "Women should never ice bath." The there's been a deliberate misinterpretation of that clip that has discouraged women from finding out what the benefits of ice bath might be. One of the ironies is
ice bath might be. One of the ironies is that Sims mentioned your EndoChill study at University of Adelaide. And this clip was not shared at all. She said, "It looks like the early evidence on cold plunge therapy and women with endometriosis is that the cold plunge will help resolve the endometriosis. And you've sent me some of those results in the poster that you've recently presented and it says key results near measuring a few things that support what Sims was trying to communicate to her audience, but I think I lost in the exaggeration of social media. All of my questions are on behalf of those listeners, the same ones that commented under that Instagram post and said, "I don't understand how this could be true. Um you know, ice baths have saved my life. They've changed everything for me. They're so beneficial. How could they be bad?" And then the other comments that say, "I knew it. That's why I've never taken an ice bath and I never will." And it would be so helpful to my audience to talk about what inspired your investigation, what you're finding so far, and what does the data say, not the the social media headlines. Well, I have to say first of all, I do agree with Sims in that women are not small men. I think that that statement is is
think that that statement is is accurate. We know now know that there are lots of differences in the biology between males and females in terms of their immune system, the way that they process pain, their various susceptibilities to certain diseases. So, um I certainly agree with that because particularly in pain fields, most of the research has been historically done using male subjects and it's just been assumed that it would translate easily into the female domain. Um and we now are generating more and more evidence to suggest that there are fundamentally different sort of pain pathways between males and females. But, in terms of the cold plunging, ice bath therapy, um cold water exposure, um we don't have a lot of evidence, but we are building evidence now, um I guess to make a case that it is beneficial to women as well as men. Um so, this particular study came about oh, back in 2023, I believe. Um so, we were actually approached by a philanthropic organization based here in, um Australia. They're based in Sydney, Australia. And they are, um they sort of have a naturopathic background. They research, or they support research looking at alternative and complementary therapies for various conditions.
for various conditions. Um they have quite an interest in women's health, and they knew about the Wim Hof method, which, um is a a method that comes from Wim Hof himself, based in the Netherlands. Um it's a three-pillar sort of technique that looks at meditation, breathwork, and cold exposure therapy to improve health. And so, they knew about Wim Hof's philosophy. They had an interest in women's health, um and endometriosis pain. And so, they actually put two and two together, and had a call out um in Australia for proposals, um to look at that sort of connection. And so, our team, we have I'm representing a large team today. Most of us are based at Adelaide University, um which is formally called the University of Adelaide. We've now, um merged with another university in South Australia, just this year. Um and so, our team put through a proposal, and it was kind of accepted by foundation who supported our pilot study. And so our proposal was to look at a small group of patients with endometriosis to see whether a 12-week Wim Hof method like intervention could improve their endometriosis symptoms. So I think it's important here to distinguish between
distinguish between endometriosis as a condition and the symptoms associated with endometriosis. I guess if we can backtrack and actually sort of define what we mean by endometriosis. I think that would be helpful. Yeah, this is sort of an evolving sphere as well. It's traditionally been considered chronic inflammatory condition in biological females that manifests with lesions primarily in the pelvis that resemble the lining of the uterus, which is the endometrium. And so that's how the condition gets its name, endometriosis. But these lesions we now know they form not only in the pelvis, but are quite widespread within the abdominal cavity. There have been rare cases reported, for example, in the lungs, in the nasal mucosa, and throughout the body on nerves, for example. And so it's traditionally considered gynecological because the lesions were primarily around the pelvis, but we now know it is more of a systemic condition. Well, let me see if I have this right. This is cells that belong in the uterus that are found growing outside the universe uterus and not just sort of on the outside of the uterus itself, but throughout the body? Yes, that's correct. That sounds kind of scary. I know. Well, the cells themselves, they are endometrial like. They are not what we would consider traditional endometrium, like the exact
traditional endometrium, like the exact same tissue that you find inside the uterus, but it has characteristics that are very similar to the uterine lining. And so, I think primarily they're found around the reproductive tract, and that's probably because of um gravity. You know, we're bipedal animals, we stand up, so things often sink due to gravity, and so these lesions um form in the pelvis, but they do kind of spread elsewhere. Um and the main hypothesis for the development of endometriosis is through a retrograde menstruation. So, this is where it is believed that endometrial tissue at the time of menstruation, instead of exiting out of the vagina, it actually can come back up through the fallopian tubes, which are open-ended, which um a lot of people don't quite know that they are open-ended into the pelvis, and the tissue kind of comes out, and it settles by gravity and starts to form lesions on tissues in the pelvis. Okay, I have an image in my mind that I want to share, so you can tell me if it's totally wrong. But we have an ovary, and then we have the end of the fallopian tube, and a lot of people don't realize these aren't attached. When the ovary is going to release an egg, the fallopian tube has to kind of like suck it up, like has to collect it, and then it has to travel through the tube. So, I think what you're saying is that menstrual fluid could sort of back up through the fallopian tube and
up through the fallopian tube and escape, uh beginning around the ovary, but then travel through the body because that fallopian tube is not tightly sealed, and it's not meant to be. Mhm. Okay. That's correct. All right. Yes. So, that's the main theory for, I guess, the or originating sort of mechanism for endometriosis, but it doesn't seem to explain all cases. So, there are alternative hypotheses as well around how endometriosis does develop. Um that's sort of like a whole another topic. So, I guess in terms of this interview, I won't go into all those different theories, but it is important to say as well on this topic that of the retrograde menstruation, um a long time ago there was a study looking into um sort of the proportion of of menstruating women that this happens in, and it was estimated to occur in around 70 to 90% of of menstruating females. That sounds enormous. It is a lot, but only a subset go on to develop these endometriosis lesions. So, it's thought that in in the majority of cases, this menstrual effluent or menstrual fluid is um sort of gobbled up by the immune cells that sit in the pelvis and the peritoneum, and it's cleared away, and there are no lesions that form. But in some women, the lesions are sort of evade immune clearance. Um
are sort of evade immune clearance. Um there's something unique about the tissue, there's something unique about the immune system, maybe the hormonal environment, genetic susceptibility. For some reason, this subpopulation of women go on to develop lesions. Um and this is a subject of intense investigation, and it's likely to be multifactorial. Um so, yeah, there's a very big immune component to that. Okay, bear with me um because I'm an engineer. I build machines. And when we're talking inside the body, you know, my understanding is somewhat rudimentary. But it sounds like what you're saying is this retrograde menstruation is actually normal. Many women experience this. That does not mean it becomes pathological. That ordinarily some of this backflow of menstrual fluid is no big deal because your body knows how to handle it. But in some cases, it becomes problematic because the immune system or some other function hasn't kicked in and it allows these cells to travel throughout the body or allows them to flourish in a way that becomes pathological because it can be very painful. Am I getting that right? Perfect. Yeah. That's right. Um I'm glad that you were able to interpret that, Thomas. Thank you. That everything I'm saying is making sense so far. Yeah. Yes, so that's sort of the manifestation of the lesions. But um I guess the main
of the lesions. But um I guess the main clinical complaint, the main reason why um [clears throat] women with the condition present clinically is because of the pain that is generated from the condition. Sort of the two key areas are fertility and pain. Um but in terms of this particular study, we were focusing on pain because I guess this is what impacts daily life for these patient population. Um and the pain itself is quite difficult to study because it is highly heterogeneous between individuals. Um it can present as sort of menstrual pain. It can be non-cyclical pain, um bowel pain, bladder pain. Um it can manifest as sort of like nerve pain, muscular spasm. The patients can often experience migraine and other somatic symptoms like nausea, fatigue, sleep disturbances. Um lots and lots of different um symptoms are associated with the condition. Okay, so this is a surprise. This is not just uh premenstrual or menstrual cramps like my daughters might experience. This could be more general. It could show up in areas that aren't associated with the pelvis, the way that you just described it. And maybe it doesn't just show up at a certain time during the cycle or a certain time during the month. It could
certain time during the month. It could show up at other times, too. That's right. So for some patients it is um kind of clockwork sort of dysmenorrhea, so bad period pain. Um but for other patients it can be everyday, all sorts of different symptoms. Um and for some patients they don't have any pain at all and they don't actually know that they've got endometriosis until, for example, they try um to conceive and start a family and and some investigations happen into why they might be subfertile or infertile and then it's found that they have endometriosis and it's causing scar tissue um on their reproductive organs and and therefore they they can't actually conceive. Um so the fact that there is such a um such a wide variety of of presentation, clinical presentation, um it's it makes it really hard to study, but it also um I guess emphasizes the fact that this condition needs to have a personalized approach to treatment. So depending on the exact symptoms that someone is experiencing, um there are different sort of treatment methodologies that can be um investigated. So with our Endo Chill trial, we were interested in endometriosis patients that had pain because there have been um sort of studies in the past and evidence to support that um it can impact the nervous system. Like uh practicing the Wim Hof method or sort of the components
Wim Hof method or sort of the components of the Wim Hof method in terms of breath work and cold therapy can um modulate nervous system responses, um, including pain. And so, that's what we wanted to study is if this particular intervention should could impact, hopefully improve, pain symptoms in this patient population. Um, and by what mechanisms would that happen? Because there's a lot of anecdotal evidence, you know, um, most of the ways that we obtain sort of pain severity scores from patients is a self-reported survey, but we wanted to know is there something biological happening in these patients that could sort of account for their changes in symptoms. So, in our study, we were also looking at, um, we took a few blood samples to see if we could measure whether anything was happening to their, um, sympathetic nervous system responses that could account for a change in pain, as well as looking at their immune system responses because there is this really, um, really defined, uh, connection between the nervous system and immune system and how they work together to influence pain. Okay, so it sounds like right now you're recruiting subjects to your study and you're looking for certain characteristics that would be, uh, make them eligible as part of your, uh, cohort. Pain is one of them because that's what you want to study.
that's what you want to study. All right, but here's something ironic. Um, the cold pressor test has been used in psychology for decades now. It's a standardized, you know, psychological instrument for measuring tolerance to pain. So, I've got to ask like you're recruiting these women who are in pain and you know, here's what we're going to do. We're going to use some cold therapy on these women who are already are in pain. Well, the psychologist would tell you, "Look, Dr. Dodds, don't do that because we [clears throat] use cold stimulation to create pain and they're already in it. And so, I'm I'm going to be a a little naive or maybe a little provocative for on the sake of my skeptical members of the audience. What are you thinking about recruiting these people who are in such pain and it can be generalized to participate in a cold plunge study? Mhm. That's a great question. So, we did actually have uh some of the endometriosis community when we started to put out our call for recruitment, um they were quite skeptical. You know, a lot of them would say, um you know, taking Endone doesn't um influence my pain at all. What on earth is cold water going to do? Um and I understand that. I I do. I totally get that, but um I think one thing that's really important to know about the endometriosis population, particularly those with pain that is not managed by existing therapies, they're almost willing to try anything.
almost willing to try anything. Um and that's sort of where this complementary and alternative medicine approach comes in is because, you know, traditional pharmacology, um so, using a lot of hormonal contraceptives or hormonal manipulating drugs as well as traditional um nerve-based drugs, um they don't work for a lot of the patients. Um and they have a lot of side effects. Yeah. So, we see patients in chronic pain routinely report that people want non-pharmacological interventions if they can get them. They're tired of taking all these pain drugs that sort of work a little bit when you first start taking them and then you got to fool around with the dose and it feels like you never get it right and you're going to be on it forever. Patients don't want that. And so, it sounds like some you had some skepticism in this community, but you also had some people saying, "Look, I'll try anything at this point. I'm looking for relief." Did you describe like the basis for this hypothesis to them? Yes, well that was part of the recruitment process. So we have a as part of our ethical obligations, we do need to describe some of the reasoning or the scientific justification behind the study. And so that is sort of um reasoning for them to be involved in sort of part of the um consent process of them being involved in the study. But also when we started the intervention,
also when we started the intervention, what's really important and this kind of this came from the Wim Hof team directly who we consulted with before we started the study was that it's really important for the participants to have training before engaging in the breath work and the cold therapy um because there is a certain way to do it to get the most benefit out of it. And so one of the members of our study team was a certified breath work and cold therapy um practitioner. And we had a training session with all of our participants before we began and he went through a very sort of comprehensive introduction into what the breath work was about, how it was thought to contribute to biological changes in the body. Um it was important for us not for for the participants not to have an expected outcome. Um so we did make it very clear that this is something that works um in some people but it may not work in others and it depends um largely from what you put in. So the sort of more regularly that you do it, you're likely to get more benefits um than someone who does it very occasionally. Um but um to not sort of expect that this is going to fix their pain. But, yes, I did I do want to say that we had someone who went through training and explained the process and the sort of hypotheses around how it would work
hypotheses around how it would work before they then went into training for the breath work and the cold therapy. And our coach, um, our cold therapy coach, when we had these training sessions, he, um, sort of coached them through the, um, the ice bath or the cold bath. So, he sat with them whilst they were immersed and sort of talked them through, um, what they would be sensing, um, and allowed them to sort of maintain in that cold bath, um, for the 3-minute duration that we were hoping to get. So, um, yeah, they were kind of led through quite intimately with a coach on how exactly to practice the techniques so they got it right. You said something really interesting that you're targeting the nervous system, not the metabolism. Some people might do ice bath because they want to recruit brown fat and improve their insulin sensitivity and this is all very wonderful. We have good science on that. Some people might do it because, uh, they want to treat or reduce delayed onset muscle soreness from their workout. And you're explaining it differently. You're saying we're working on the nervous system, not the muscles, not the metabolism. What is the mechanism by which, and and it can be the breath work and the cold plunge together? What How does this, um, modify the nervous system? Um, okay, this is a good question. So, um,
okay, this is a good question. So, um, the hypothesis, so we don't have direct evidence, but the main hypothesis based on the evidence that we do have is that the cold plunge is like a controlled stressor on the body. So, it's something that we actively engage in and it's something that we know that's going to end within a certain short time frame, but it is stressful on the body. So, when you go into a cold plunge, there are temperature receptors in your skin that are going to be firing electrical signals like crazy because of this temperature change. And those signals reach the brain and activate the sympathetic nervous system. So, the fight or flight um sympathetic nerves in your body. And one of the main outputs of the sympathetic nervous system is to release noradrenaline. Um and so the the nerves will release noradrenaline throughout the body onto various different organs and it can also activate the um adrenal glands, which release more adrenaline and noradrenaline into the blood. And it's this um release Oh, so when I say adrenaline and noradrenaline, I do know that in the US, you call those epinephrine and norepinephrine. So, they're kind of like the same thing. Although most people are familiar with both terms and I'm glad you're clarifying. Yeah. Oh, no, I said So, these two sort of neurotransmitters and hormones, um they work throughout the body to increase heart rate and they have
increase heart rate and they have various effects in the body. And um as I mentioned before, they can also act on the immune system. So, um going back to how they work in terms of pain, it's thought that the release of noradrenaline is part of a descending inhibition. So, this is where um sort of like from the brain to the peripheral tissues, there's like a a blocking signal. So, it prevents pain signals from reaching the brain and you consciously perceiving pain. So, there's an increase in descending inhibition, so there's almost like a an endogenous analgesic effect. Um, and that um, happens sort of in conjunction with the release of serotonin and dopamine as well. And, um, there's also this interaction with the immune system. So, it's thought that there's an, um, Well, actually the hypothesis is is that there's some change in the immune system, but we're working on the exact details. But, what we think happens is that it actually, um, shifts the immune response to a like pro-resolving rather than a, um, sort of reactive immune state. And, this, um, impacts the inflammatory environment around the endometriosis lesions, and it also, um, acts to lower the sensitization of the
acts to lower the sensitization of the peripheral nerves that are sending those pain signals to the brain. Because this is one of the, uh, I guess key points around, um, why we think, um, these whole-body symptoms develop in endometriosis. So, perhaps there is this, um, original development of lesions in the pelvis, but over time the body becomes sensitized. Um, so we believe that there is a central sensitization that happens where when there are continuous peripheral, um, sort of pain-related signals and inflammatory signals reaching the brain, it actually alters the, um, molecular, um, sort of chemistry of the nerves in the central nervous system so that they become hypersensitive to pain signals. So, you end up getting these chronic pain, um, you end up experiencing chronic pain as well as these, um, additional somatic symptoms. And, the way that we, um, I guess one of the pieces of evidence for this is that even when, um, many endometriosis patients have their lesions removed by surgery, it doesn't always alleviate the pain. So, it indicates that there is this sort of um, ongoing sensitization of their their nervous system. And so, we believe that with this cold therapy, if there's this release of noradrenaline, um, it's impacting the immune system, downregulating and sort of resolving the inflammation in the pelvis, then those sort of sensitizing signals start to decline. The other component is, um, that I think
The other component is, um, that I think the Wim Hof team really, um, believe in, is that uh, when you um, actively engage in these controlled stressors, over time, with practice, you become better able to control sympathetic outflow in your body. So, you almost don't become as physically reactive to a stressful stimulus. Um, so, you the the fight or flight response, um, you know, you don't get that extreme change in heart rate and and that sort of thing. So, you're able to almost control the amount of adrenaline noradrenaline being released in your body. And so, when someone is undergoing a pain flare-up, they do get sympathetic activation, they do get stressed, um, they, um, you know, that they are reacting to being in pain, but by practicing the Wim Hof technique and being able to control their sympathetic sort of outflow, it's thought that they might not react to their pain flare-ups as much as they previously would. So, they're better able to manage their responses to pain throughout the day and maybe better able to manage, um, sort of like their day-to - day activities, where previously they were, you know, they they might have been restricted to beds um, because of, you know, the extreme pain that they were in, but they're better able to manage their day by controlling this
manage their day by controlling this sympathetic outflow. So, it's it's a multi-faceted sort of hypothesis around why the cold plunge in particular would be beneficial for this patient population. The breath work side of it is about it's an it's another controlled stressor. So, when I talk about breath work, particularly when I was presenting this work on the other week as you mentioned Thomas at the Australian Pain Society meeting, when we spoke about breath work, a lot of sort of the audience thought that I meant sort of meditative breath work. And but that's not what the Wim Hof method sort of promote. It's actually a more of a hyperventilation and a breath hold approach. So, that again almost makes your body quite hypoxic but in a controlled way, you're controlling the breathing, but it's a controlled stressor on the body as well. And by practicing that technique, there are components of what we call interoception where you can really notice changes happening in your body in almost a relaxation meditation kind of way. And so by practicing the breath work and really taking note of of how your body is reacting to this activity, it's also thought that that interoceptive process when you're having a pain flare-up can help you manage your pain as well cuz you can sort of really
sort of really uh understand or better understand and better take note of reactions happening in your body and almost suppress them over time. You're really onto something. There's a lot of people who report experiences that corroborate what you're saying. There's clinical data on people, the very short-term studies, always freak out the research subjects. But when they go longer, for say 2 weeks, we notice that the physiological measures of stress become muted in response to the same cold. So there's less of a cortisol spike. There's less of a gasp reflex. There's fewer changes in the pulse. People become acclimated to the stress. But That's right. Almost habituated to it. Correct. And there's good psychological reasons for it, but there's also physiological reasons for it. The The training for the cold is similar to training for the weight room. When you, you know, lift weights, you get sore, but then your body will respond to that hormetic stress by adapting. And there are physiological adaptations that happen to our subjects who will do cold plunge therapy for more than days. Whether that's improvement in their basal constriction or improvements in their thermoregulatory processes, they become more than habituated, although that's true. They become physiologically acclimated, and this cannot help but
acclimated, and this cannot help but also impact their psychology. Mhm. I had a man named Andrew Sheridan on the podcast, and he has one of these thermal contrast spas where people do sauna and they do cold, and he's in Ohio. He developed his own method, and he pointed of coaching people through the cold plunge, and he pointed something out that I thought was really insightful. Almost every sympathetic activation or hormetic stressor that we have experience with tends to get worse over time. My own experience was I did a VO2 max test. My VO2 max is terrible, but when I started the test, you know, I'm walking on this incline treadmill and I'm like, "Oh, well, this isn't so bad." And I've got, you know, a little breath thing so it can measure all my oxygen. And then they go a little steeper and a little faster. I'm like, "I can handle this." I stayed on that treadmill until I thought I was going to throw up in that mask and then I collapsed on the floor. Almost all of our stressful events get worse over time. And so, our catastrophizing mind creates a scenario. It's, you know, this isn't so bad, but oh my gosh, it's going to be really bad in a minute. I'll never be able to sleep in 5 minutes. He pointed out that the cold plunge is the opposite. The worst part of getting into the cold plunge is the first 15 seconds. You experience the gasp reflex. You get that sympathetic
gasp reflex. You get that sympathetic activation. But, then the parasympathetic takes over. And this is the difference between the gasp reflex and the dive reflex. Now, your subjects are in there for 3 minutes. And if you're measuring Okay. If you're measuring their heart rate, you're probably seeing their heart rate is coming down. If you were going to measure uh blood glucose, you would see an initial spike when they first get in and that's the liver releasing its glucagon. And you know, that's part of the sympathetic activation, but then it will clear fast and it will come down. This is the parasympathetic or what they call the rest and digest system coming over. Do you also see that in your subjects? That would be really interesting if we did. It's not something that we measured, but I wouldn't be surprised if we did see more parasympathetic inputs over time. The more that it was practiced, the technique was practiced. I um I would think that that would get more parasympathetic into activation over time. We did see that the total accumulated time of cold therapy was indicative of the improvement in pain. You're getting a dose-response curve. This This is wonderful because this is helping reinforce your hypothesis. Yeah, we did. So, those that So, I don't mean spending longer than 3 minutes at a time in the bath, but those
minutes at a time in the bath, but those that did it more frequently and had a total accumulated time that was greater ended up having a better improvement in pain. And I think this speaks to sort of all the mechanisms that I mentioned before that there's increased dopamine release, they have better mood, you know, they're more motivated to get in the ice or the sort of the cold plunge the further they move along. So, it's it's difficult to start, but then once you get into like the routine of doing it, it does have significant improvements in in pain symptoms. There are other studies that will use terms like vagal tone because the vagus nerve is sort of a conduit of the parasympathetic nervous system. The ones that are most convincing to me are heart rate variability. Heart rate variability is a good physiological measure of psychological resilience because your pulse has to constantly adjust. If you breathe in, if you breathe out, if you go upstairs, I mean, you're not aware of it, but the the space between the beats of your heart is constantly moving to adapt to whatever the stresses or demands of the system are. When heart rate variability is low, it's like the psychological system is brittle. When heart rate variability is high, it's resilient. You have a lot of adaptive capacity. And so, I think that what you've created is training or like
what you've created is training or like a workout for the nervous system. You activate the sympathetic, you activate the parasympathetic, and in this analogy of a workout, it is no wonder that the nervous system comes out stronger and better prepared both physiologically and psychologically to deal with when the pain starts coming. Some people will begin that catastrophic cascade. Oh, this isn't so bad, but in an hour it's real I better cancel that appointment. I don't And then it starts to [clears throat] to make it. Yeah. Right. I do agree that the psychology around pain I mean that that's a whole field in itself. But the way that someone perceives their pain and and the catastrophization component of it has significant impacts on how they're able to manage their pain and their day. And that's why in Adelaide in particular we have a really big research community on pain education and how to allow pain patients to learn about why their body is reacting the way that they do and sort of rationalize why they're thinking the way that they're doing the way that they're thinking about their pain and how they can almost trick their brain into into not thinking about it the way that they previously had. Pain is a signal. It's trying to communicate something. And some people will block it out especially men who are in a hyper-competitive environment.
in a hyper-competitive environment. They'll block out the pain so that they can perform. And nothing wrong with this. And then as soon as that performance is over, oh my gosh, the pain might come flooding in. But pain is a signal that something is amiss and needs correction. And the psychology of it that is training people to be aware of it and to say, "Huh, what is this pain trying to tell me in this moment? Not only might it help them distract from some of their catastrophizing thoughts, but they could explore the pain, what the triggers are, and the responses that they get to choose to it in a way that could be really constructive. This is what I love about my ice bath. We say, you must go in of your own volition. There's no bullying, there's no coercion. You have to go in because you're choosing to go in. And it's going to hurt. I don't know any of my customers who actually enjoy my product, because you know I invented this Morozko. But they do it because it's hard. And they say likes to be uncomfortable, do they? No. Why would we sign up for that? Except [laughter] that we know this is going to help train us to do the uncomfortable things. And so some of my customers will adopt a mantra. One of my favorites is, this is what cold feels like. This is not death, this is not catastrophe, this is just cold. Some of my customers will talk to different body parts. Hey, you hang in there toes. This is going to be really rough on you for a couple of minutes. You hang in there fingertips. You know, we're going to be fine. You're on the team. We're just working on
on the team. We're just working on something here. And then they come out. Because they've chosen this for themselves, they feel victorious. They feel like supernatural, like they could do anything now. Mhm. So, what I want to ask you is, what changes in overall lifestyle, besides pain, do your research subjects report to you? Well, based on what we asked them in this study, so there was only I mean, we did generate a lot of data, but um we were limited by sort of the key survey criteria that that we asked them. We did find that those that on the days that participants engaged in cold therapy, they had improvements in what we call their somatic symptoms. So, they had um less fatigue, better sleep, they felt well rested, they felt more mental clarity, they felt less nausea. Um so, I guess their general well-being was better. Well, better better on the days that they had cold therapy. This is something that we want to explore further because the participants always um completed their surveys at the end of the day. And so, um we're trying to separate out whether they engaged in the cold therapy because they were feeling better on those days or um so, that you know, they felt more motivated to engage in the cold therapy or was doing the cold therapy in the
was doing the cold therapy in the morning, did that have impacts throughout the day that that improved their symptoms. So, that is one I guess one of our findings, but we do need to fine-tune um exactly where that connection comes from. Um so, we didn't ask them necessarily about their long-term improvements. The only thing that we did ask is if they once they finished the intervention, were they likely to continue after the study. And we again, we found that those that had the better sort of accumulated time um of the cold plunge, they were more likely to continue it later on. I guess um and that kind of feeds into the more that you do it, the better you feel, the more motivated you are, and you kind of continue onwards. So, those that engaged less with the cold therapy and almost sort of intermittently did it and didn't see the benefits that other participants did, they kind of said, "No, this is not for me." And that's fine. It's It's not going to be something that is for everyone. But um for those participants that really or those people that really benefit from it, um it seems to have significant improvements on their daily well-being. Are you familiar with Heather Massie? Do you know her work? No, sorry. I've never met her, and so I can't introduce you, but she's at the University of Portsmouth in the United Kingdom. Okay. And she did a survey almost a thousand British women, and this was cold water swimming. So, these are women who form clubs, and then they'll go jump in the North Sea or something. They'll do this winter swimming.
winter swimming. And they reported spectacular results in in a array of different quality of life measures, including menstrual cramps, dysmenorrhea, and post menopausal symptoms. And it sounds like the two of you would have a lot to talk about because she's asking different questions, and she's got a different It's sort of epidemiological the way that she's doing it, and you have this more structured clinical study. But, the two of you would be able to compare notes, and you might come to a deeper understanding of what's going on inside the woman's body. Yeah, thank you. I I really appreciate that. And I know anecdotally from people here in Australia who do like ocean swims in the morning that they find that it just has such beneficial impacts on their pain as well as sort of their mental clarity, their stress levels. And so, there's something in it. I think a lot of people who just engage in sort of ocean swimming anyway, it's the salt water, it's being outside, it's the cold. All of those factors sort of feed into it. The mental health benefits are wonderful. There are some good case studies on major depression that resisted drug intervention, resisted conventional talk therapy, and was resolved with cold water immersion. Whether it was outside or inside, both were successful. And I think that's part of what she was tapping into because some of these studies were done by a colleague of hers at the University of
colleague of hers at the University of Portsmouth named Mike Tipton. He really studies drowning, but he's got this extreme environments lab, and he'll dunk people into, you know, cold water, and then ask them how they feel. And this is kind of similar to what you're doing. [laughter] [laughter] We do also have like plans now to sort of scale up [snorts] into a larger study. So a large part about our inter-trial was figuring out whether this would be feasible in in the patient population because it does involve sort of regular practice. And I think that's one thing that's quite difficult for the endo community at least getting started with this practice because they are in a lot of pain. And so it's it's very hard to get started on anything when you're in pain. Speaking to that motivation component and also just feeling up to it. So we were wanting to know is it is this going to be feasible in this patient population? And we found that at least for a subset of the population, it does seem to be extremely beneficial and so it's worthwhile scaling up to a larger more long-term study at least to see if if that patient population yeah, to look at some more outcome measures and I guess we have more evidence supporting its use more globally. But one of the things that we didn't find in this pilot study that we really want to know is our biological data and all of the survey data that we kind of collected from baseline, we were not able to predict before beginning which patients
predict before beginning which patients would benefit from the therapy versus which ones that would not. So at the moment if we do scale up into a larger study, it is going to be everyone trialing it again until we're able to I guess find the signal that will tell us who will benefit from this or who is likely to benefit from this versus who would would rather not sort of recommend it for them. The nervous system might not give up its secrets to you. You can probe it and you can look and it might still stay a mystery even after you've tried to decode it. Yeah, it may not be simple. It It may be many, many years of work, but um this pilot data at least has been very promising. We're on the topic of pain. Have you been reading about green light therapy for migraine, for fibromyalgia, for relief of chronic pain? Cuz I got this device. I call it the migraine lamp. It's based upon clinical trials at Harvard University and the University of Arizona that says green light through the eyes will reduce the frequency and severity of migraine headaches. It will even provide relief to fibromyalgia patients. And this Wow. The These results aren't aren't anywhere near well known enough in the pain community. No, I haven't heard of that. I have heard um about sort of light therapy in terms of green space um exposure. Yeah.
green space um exposure. Yeah. Um And in green green space being outdoors, you know, getting natural light and how that can impact pain. But in terms of like actually colored light therapy, I have not read into that yet. The Japanese college Shinrin Yoku, which translates to forest bathing. You go out into the forest and there's some good data on particularly the coniferous forest. So these are might be cedar trees and they they put out the aroma and there's a chemical kind of fact. If I remember it correctly, it's a phytoncide. And if you isolate the phytoncide and use it in isolation, it will provide an immune system boost. But independent of that and independent of exercise, just being out in the light environment of the forest will boost the immune system, will improve mood, will help speed wound healing. And there are two wavelengths of light. Green, which should be pretty clear, and red near infrared, which is a bit of a surprise. But these are the the wavelengths that the trees emit. And so, the hypothesis here is that we ought to be able to create non-invasive, non-pharmacological pain interventions based upon light. The The story that I tell is that it brings the forest into your apartment, into your home. I live in Phoenix, Arizona. So, forest bathing requires me to drive 3 hours. So, I bring the forest into me.
3 hours. So, I bring the forest into me. Two other questions. We must make a distinction between PCOS, which just got renamed, and endometriosis. Will you help us with that distinction? Okay. So, um PCOS, which is now PMOS, um very recently it got changed the name. I think it was in the last four Not that that happened, which has been a long time coming. Formerly PCOS was a systemic condition that sort of manifested with cysts, um multiple cysts on the ovaries, which we now know are actually follicles, not cysts per se, um but are are different types of follicles. Um and there were other metabolic components that manifested as insulin resistance, and had a highly androgenic sort of effect. So, um I think one of the I guess clinical symptoms of PCOS PMOS was that um there was sort of excessive hair production in some um women. There was an insulin resistance that impacted fertility. There were these um multi-cystic, which are now what we consider follicles. And so, it's been changed from polycystic ovarian syndrome to more of a metabolic syndrome that better encompasses um I guess all the different components of of that condition. Endometriosis is this condition associated with
is this condition associated with lesions. Lesions that actually resemble the uterine lining, so endometrial tissue, that are spread throughout the pelvis but can also spread more widely throughout the body and is primarily associated with pain. Think PCOS PMOS. Um there is not a large pain component, whereas in endometriosis there is a huge pain and somatic sort of symptom-related component. But yeah, there's there's a key difference between these follicles, which are formally called cysts on the ovaries, versus endometriosis lesions in endometriosis. Endometriosis as well though, um there is some research into um metabolic changes that could happen in those particular patients. I won't get far into the research, but there has been some evidence recently, for example, using GLP-1 inhibitors in um managing endometriosis. So there does seem to be a metabolic component, but that is not as well known as the metabolic changes that we see in PMOS. One of the big physiological differences between men and women is testosterone and the androgenic aspects of PMOS that you were talking about they're associated with excess testosterone because the ovaries are making testosterone. But the interesting thing about women, even though testosterone is the dominant
even though testosterone is the dominant sex hormone in women, they have much less testosterone than men, we know this, and they have multiple sources. It's not just the ovaries. It's also the skin cells, the adrenal glands, and shoot, what was it? And fat cells. Now, what better way could there possibly be to stimulate activity in the skin and the fat and the adrenal glands than to get into a cold plunge? And so, there was a study of Czech army soldiers, men and women. And they all started this program of cold water swimming and then a little bit of exercise afterwards. And they reported big jumps in libido and sexual satisfaction. And I'm theorizing they did not measure testosterone, but I'm theorizing that it was because in women and men, uh men have to exercise afterwards, but women will get an immediate testosterone boost just from being in the cold plunge. I know this because one of those cold pressure tests, this is a woman who is comparing men and women. And of course, these are undergraduate students like everybody else. You pay them 25 bucks and as long as you can get it past your IRB, you can do anything you want, right? And [laughter] they were just just one hand in ice water and they were measuring saliva so that they could uh measure the testosterone. Their hypothesis was that women with higher levels of testosterone would have better pain tolerance. That hypothesis was not
pain tolerance. That hypothesis was not supported in the least. But what they noticed was the women who put their hand in the ice water got a boost in salivary testosterone in exactly the way we would expect. It's consistent with the mechanism of testosterone uh manufacture. All testosterone begins in the mitochondria as pregnenolone. And then it is further metabolized into testosterone. The men saw a drop, which is consistent again with the fact that men have to exercise afterwards to get the same boost. It doesn't sound like you're interested in cortisol or testosterone so much, but I wouldn't be surprised if some of your women who are consistent with their program are experiencing higher levels of testosterone because I have good lab data from case studies that have been reported to me. And we know that testosterone is one of these motivation hormones. It pushes you to to meet the challenges of your life and compete. It's really good for mood. Perhaps some of the improvements in quality of life are happening in your subjects because they've stimulated their mitochondria, they're producing more testosterone, and they have more of that zest, of that competitive drive. What's your reaction to that? Well, I I think that makes a lot of sense to me because we do actually have a theory. It hasn't been, I guess, published a lot yet, but there actually
published a lot yet, but there actually is a theory in the endometriosis or pelvic pain population, at least, that increasing testosterone levels will improve pain. And so, even though it wasn't supported by the study that you just mentioned, Thomas, there is some anecdotal evidence coming out about testosterone patch use, particularly like peri - and post-menopausally, and how that can obviously improve libido and other sort of well-being symptoms, but also potentially using testosterone patches or boosting sort of endogenous testosterone to improve pain symptoms. And I think um Yeah, I think it there is a really big connection there, but I wouldn't be surprised if we did see a testosterone boost in these participants or any participant that female participant or someone with low testosterone would have from engaging in the cold cold water therapy. We did measure cortisol levels in our um participants. Wonderful. We did not find any significant links, but um as again we it was a pilot study. It was a small population and we only took four time points throughout the entire 20 week intervention. So it may be that on the particular time points that we measured the cortisol, we just didn't sort of capture the full variability that they would have experienced. We may have lost it simply due to those time points. But yeah, in this study we didn't see an overall improvement or
didn't see an overall improvement or change in in cortisol levels at all, but I'm not surprised. The the whole cortisol bugaboo on social media is way overblown. The best work on cortisol and cold plunge is done at the Sports University of Lithuania. This is Marius Bruscitas and a former student of his Rima Solnianik. I'm saying her name wrong. But they put their subjects into the cold plunge. We finally got a Morozko so they could go super cold, you know, not just this 10 ° C stuff, but let's go all the way down to two those subjects who are willing. And they will measure blood cortisol, not saliva, so they'll get good reliable measurements. What they noticed is that cold will modulate cortisol. If you're low, it'll bring it up. But if you're high, it won't make it any higher. It might actually help you come down. Yeah. And this is really satisfying to our intuition. If you're already starting with high cortisol, your body knows. You know, the body knows you don't need more. You know, sort of in a constant state of stress. Right. Most of the studies that are looking at the interaction of cortisol with testosterone or the effects of cortisol, especially the animal animal models, they will inject exogenous cortisol. And then they'll say, "Oh,
Endogenous and exogenous are two different things. When your body is making its own, it is subject to all the systemic feedback loops and regulatory mechanisms. And when you inject a rat with cortisol, of course you mess it up. Now, everything else in the body has to change. So, the cortisol research, except for what Myer Peristalsis and Rima Solianic are doing, is not it's not definitive. It's not good and it shouldn't be over simplified and then exaggerated on Twitter or something like that. People will get the wrong idea. I do want to draw on something that you just mentioned, Thomas, about the actual temperature of the cold water plunge. We did use our cold plunge at 10 ° C. Celsius. That's good. And but even though we didn't have when we consulted with the Wim Hof team, they did suggest around 5 ° I'm not surprised. I've talked to the Wim Hof team. And you're colder than these 14 ° C. My customers don't think 14 ° C is even cold. They're like, maybe it's a cool bath. It's a tepid bath, you know? And then you just throw that research out. They're not interested. You get down to 10 and we're starting to get something that most people will get the gasp reflex from. But of course, my customers are operating, a lot of them, at 1 or 2. And them and his sort of his students are going to push you to go as cold as your equipment can get. The unfortunate thing is these aquarium chillers that come from China, you can't
chillers that come from China, you can't take them down below 10 or you'll break them. Well, we the reason why we kind of settled on 10 ° C, is really due to our climate. And I think this is something that might have to be taken into consideration when we're doing sort of cold plunging on a global scale. So, in Australia, where it's quite hot. 10 ° C is very cold, particularly for South Australia. You mentioned we have this Mediterranean climate. It's that's true. So, 10 ° is is very cold to us and our climate is is different to the Netherlands. So, you know, 5 ° C is is quite cold for them. They they used to having snow and very cold temperatures. We don't have that in Australia. So, looking at these different sort of um regional populations and sort of the temperatures that we're acclimatized to may have an impact on the sort of temperatures that we consider cold and and what we use in a therapeutic range in this sort of setting. This is really important. This brings us back to the beginning of the podcast because Stacy Sims is drawing very broad distinctions based upon sex. This is the wrong way to think about it because what is most important is not the sex of the individual, but their prior state of cold training. And so, you could take a woman who's been practicing cold training. Maybe she's been surfing at Bondi Beach your whole life. I don't know exactly what it she's doing, right? But she's acclimated to the cold and she
But she's acclimated to the cold and she might do way better at lower temperatures than a man who's been indoors his whole life. More important than the sex of the subject is the prior state of training of the subject. And so, I don't want women to get the wrong idea that, you know, cold is bad for them because it's a logical fallacy to reason from the ensemble to say, well, this population in general on average responds in this way. That means nothing to an individual to you can't go from the ensemble to the individual. You can only go the other way around. And this is one of those subtleties that gets lost, you know, if I take this to Instagram, I'll get 22 likes because we can only communicate science in the most exaggerated, oversimplified terms or nobody seems to pay attention. Yeah. I think, you know, generalizable claims are are important cuz they do provide some sort of guideline, but for conditions like endometriosis, which are very individual to to each patient, having the sort of personalized approach and and considering the patient um the whole environment of the patient and not generalizing them is actually very important. I think that's why in the past there's been so much trial and error um for some patients regarding their their pain management and their kind of condition management cuz it's like, "Well, this is what we try first, and this is what we try second." And um sort of moving along
try second." And um sort of moving along that path without really really considering them their unique situation. Um and that's something that we're working on in the endometriosis community is and particularly in the research and the clinical space is how we can really personalize um their treatment approach to get better outcomes. Last question. Uh I'm 60. I've been at this for I don't know, 35 years. Um uh raised millions of dollars in grant funding and things like that in engineering. And now I'm very concerned about health. And so, I've never been funded by the National Institutes of Health in the United States. I put in a couple of proposals with a colleague. They are the worst reviews I've ever gotten. My faculty colleagues think I'm nuts. They think I'm wrong and I'm foolish to even have these hypotheses. And so, I want to ask you when you go and you present your posters and your data and your, you know, at this early career stage and you're talking to your senior colleagues, is this career suicide for you, Dr. Dodds, or are you getting a good reception from your colleagues? It is quite a good reception, at least in Australia, because we know that the patients are looking for something new. Now that we have our pilot study under wraps, we do have some of the biological sort of blood-related data, and we can sort of correlate that with other studies in in the literature and sort of
studies in in the literature and sort of build up a case for being able to sort of take this further and really drill down to the mechanisms. And as I mentioned before, to to try and figure out if we can predict which patients will respond to this as opposed to others. But yeah, I I don't think we've had too Well, I don't feel like we've had too much kickback from the research community so far. I think they're very open. They're open to it. It was more so in the beginning, the actual patients themselves that thought, "Hold on. What are you talking about? Is this real science?" But I do know there's another study. I'm not sure who they're funded by, but a study in the UK I saw very recently. They're looking at this contrast therapy that you mentioned before. So the hot sauna, cold water plunge, contrast therapy for endometriosis patients to see if that can improve pain and well-being symptoms. I believe that's in Cardiff, in Wales. They're currently recruiting. So I feel like there is sort of traction being gathered across the world in in terms of this sort of hot cold therapy, at the cold plunge, the the breathwork and meditation. The other great thing about it is this is something that every person kind of has control over. It's something that you can do in your own time. You can do it at home. If you don't have access to a bath, like a cold cold plunge bath, you can still have cold showers. And a lot of gyms, particularly in Australia, I'm sure it's
particularly in Australia, I'm sure it's the same in the US, but a lot of gyms in terms of recovery from exercise are starting to plumb in their own cold plunge bath. So, if you have, you know, access to a gym gym membership, you might be able to do cold plunges that way. And so, it is becoming more accessible and it's something that you can try and integrate within your daily routine. There are two people in Australia whom I can introduce you to who have laid some of the scientific groundwork to sort of soften up those who might be skeptical. One of them is Mark Cohen. He used to be a faculty member, now he's retired from his faculty career. He's an MD PhD. And the other one is a former advisee of his, Lauren Burns. She was an Australian Taekwondo Olympic gold medal champion. And so, when she's going to do her dissertation, of course she wants to study highly competitive athletes and say, "What's the difference, you know, between the gold medal and not medaling at all?" One of the things that Lauren Burns discovered was that those athletes who did more ice baths were generally more successful in their chosen fields. Talk about a dose-response relationship. And she hypothesized that it wasn't physiological, that it was exactly what you're talking about. It was a psychological advantage that they gained, preparing them for the super high-stakes competitions. Yeah.
high-stakes competitions. Yeah. Mark Cohen is a delight. I've never met Lauren Burns in person, but these are two people who I think would be supportive of your work in general. And, you know, when you go to submit your paper, you might put Mark or Lauren down as a suggested reviewer. [laughter] Right. They are knowledgeable, but they're also they want to see you do well. They want to see good science instead of mythology and misconceptions come out in this area. They want um hard supportive evidence. Thank you for all your time. Oh, I was going to say, no, thank you for having me on. It's really um really nice to talk about our our results now that the study has sort of wrapped up and we've got our final final reports together and now thinking about the future. How are we going to um expand on this and and what are we going to focus on? I think we do have some plans to look more into the immune responses in our participants. We we feel like that might be a way that we can separate out the responders versus the non-responders. So, that's something that we're um wanting to pursue. Um and also if it will impact um sort of other other patient populations. You have been a wonderful spokesperson for your large research group. If people have listened this far, they're probably curious. Can they find you or your work online somewhere? So, this work um it is the manuscript is
So, this work um it is the manuscript is under under production currently. We plan to have it published this year. So, um when it is out, Thomas, I can flick it to you and and you might be able to distribute that to your listeners. Um but currently, um no, the results are not um sort of published anywhere currently. Okay. Then, uh I will help disseminate them at least in the United States and the other English-speaking quarters that might listen to me uh when they come out. I'd be delighted to. Thank
Transcript auto-generated by YouTube. Verbatim — duplicates intentionally preserved.
Endometriosis pain involves inflammatory, hormonal, neurological, and psychological layers. Cold water may help by changing how the nervous system processes threat and sensation.
A cold plunge creates a controlled stress response. With breath and safety, the body practices returning from alarm toward steadiness.
Clinical work matters because pain deserves more than anecdotes. The emerging question is not whether cold feels intense, but whether repeated exposure can support meaningful relief and agency.
The best protocol is not the hardest one. It is the one your body can adapt to, recover from, and return to with trust.
Start with the smallest dose that changes your state, then repeat it consistently before increasing intensity.
Track the after-effect: sleep, mood, energy, pain, focus, and training quality the next day.
Respect medical context, especially around cardiovascular conditions, pregnancy, fainting, chronic illness, medication, or persistent pain.
