Welcome to the huberman Lab podcast, where we discuss science and science based tools for everyday life. I'm Andrew huberman, and I'm a
professor of
neurobiology and Ophthalmology at Stanford school of medicine. Today. We are going to discuss the use of deliberate cold exposure for health and
performance. Temperature is a powerful stimulus on our nervous system and indeed on every organ and system of our
body and cold in particular can be leveraged to improve.
Mental health, physical, health, and performance, meaning
for endurance, exercise for recovering, from various forms of exercise,
for actually improving strength and power. And for
enhancing mental capacity,
in order to properly
leverage, deliberate, cold exposure, for sake of mental health, physical, health, and
performance. You have to understand how
cold impacts the brain and body. So today, we are going to discuss that we're going to talk about some of the neural circuits
and Pathways some of the hormones involved. I promise
to make
it all clear and accessible regardless of whether or not you have a scientific background or not. We are also going to discuss a very specific protocols that you can apply, which leverage variables like temperature, how cold, how to deliver the cold for instance, whether or not use a cold shower, cold
immersion, ice bath circulating water or still water
whether or not you're going for walks outside in a t-shirt when it's cold or whether or not your purposefully using things like cryo, if you have access to that or
not.
One thing I can promise you is that by the end of today's episode, you will know a lot about the biology of thermo
regulation. That is how your brain and body regulates its temperature. You also have a lot of tools in Your Arsenal that you can use and leverage toward improving
mental health, physical
health, reducing inflammation in the body, improving athletic
performance, improving mental performance. I promise to spell out all those
protocols in detail as I go along and to summarize them again at the end.
I'd like to make a point now that I'm going to make several.
Additional times during today's
episode. And that is that temperature is a very potent stimulus
for the brain and body. That also means that it carries certain hazards. If it's not done correctly. Now, everyone shows up to the table, meaning to protocols,
with a different background of health status, and there's simply no way that I can
know what your health status is.
So anytime you are going to take on a new protocol, that means a behavioral protocol or nutritional
protocol or supplementation protocol. You should absolutely consult a
Board certified physician before initiating that protocol. I don't just say this to protect us. I also say this to protect you. If
you'd like to see our medical disclaimer. You can go to our show notes. It's
described there. In fact, I encourage you to, please do that.
And in general, when embarking on new
protocols, in particular, if they involve strong, stimuli like changing temperature or placing yourself into unusual temperatures.
I would encourage you to progress gradually. I would also encourage you to not look at gradual progression.
Shin as the kind of weak version of a protocol.
In fact, today, I'm going to discuss a really beautiful peer-reviewed study that involved having people do deliberate, cold exposure. So they were immersing themselves into
water up to about their
neck and the water was actually not that cold. It was only about 60 degrees
Fahrenheit which for most people is pretty tolerable.
So nowhere near the kinds of extreme temperatures that one could use in other protocols. And the interesting thing is despite that fairly modest cold temperature.
By simply extending the duration of time. That people were in
that water. They experienced
enormous increases in neurochemicals
that ought to translate to improvements in focus and mood and indeed that's what's been observed in subsequent studies.
So again, please see our medical disclaimer in our show notes.
Please proceed with caution.
Always, please also understand that the most potent stimulus isn't always the one
that you experience as the most intense in the moment. In fact, I would encourage you to
find the
Minimum threshold of stimulus that will allow you to drive the maximum benefit from each
protocol and indeed, I will point out what those thresholds ought to be today. I'll give you some simple formulas gauges or
guides that you can use in order to navigate this extremely, interesting and potent
tool that we call deliberate cold exposure. Before we talk about deliberate, cold exposure, and its many powerful applications. I'd like to
highlight a study that I find particularly
interesting in that. I think you will find particularly interesting.
Interesting and useful.
The title of this study is brief aerobic exercise immediately, enhances visual attentional
control and perceptual speed testing the
mediating role of feelings of energy.
Now, the reason I like this study is,
first of all, it's a fairly large size, sample group. They looked at 101
students. These were college-age students.
And they had two groups, one group did 15 minutes of
jogging.
Moderate intensity. So when they did
measure percent heart rates Etc, but this would be analogous to zone two
cardio, which I've discussed on this podcast
before zone. Two cardio is cardiovascular. Exercise. That places you at a level where you can hold a conversation with a little bit
of strain, meaning that you can get the words out. But every once in a while, you have to catch your breath, whereas, if you were to push any harder by any mechanism, going faster, or on a steeper incline etcetera.
That you would have a hard time carrying out a conversation. So zone, two cardio is a
common form of describing that level of intensity that
they call moderate intensity. So one group did 15 minutes of jogging at moderate intensity, which I'm translating to roughly Zone to
cardio. The other group did 15 minutes of relaxation concentration. That is somewhat akin to
mindfulness meditation and
then they were analyzed for perceptual speed visual attentional control.
Something called working memory, which is your ability to keep certain
batches of information online. Just imagine someone telling you their phone number and you
have to remember that sequence of numbers in your
head for some period of time
that's working memory. And
it depends very heavily on the so-called
prefrontal cortical networks, which are involved in planning and action.
And they also looked at people's
feelings of energy and they measure that subjectively how energetic people felt. Now, the
major takeaways from this study that I'd like to emphasize our that
The 15 minutes of jogging group experienced elevated levels of
energy for some period of time after they ceased the
exercise. Whereas the group that did mindfulness meditation actually reported feeling more calm and
having less overall energy. Now that's very subjective and indeed they used subjective measures to
analyze energy, but what gets interesting is when they looked at performance on these various
cognitive tasks and the two
tasks that they use were called the
Making tests, they have different versions of this version, a version B. I don't want to go into too much detail. But
version a essentially involves having a page of numbers that are distributed somewhat randomly.
So 1 2 3 4 5 6 7 8 and
so on but distributed randomly across the page and people have to use visual search to Circle those numbers in sequence. So this involves visual attention and involves some motor skills. Involves a number of things that certainly require energy and focus. The second test was the trail making test part.
Be as I mentioned earlier, and this involved also circling numbers in sequence, but interspersed between those numbers were letters. So rather than just having to Circle off
numbers in sequence. They actually have to connect one. Then the letter
A then 2, then the letter B, etcetera. And remember, these are
randomly distributed across a page,
the major takeaway from this study. Is that the group that did the 15 minutes of moderate exercise? Prior to these two tests showed significant decreases in the amount of time,
required, to complete these tests.
Accurately,
that is interesting and indeed surprising
at least to me,
because there have been many studies
looking at the effects of mindfulness. Meditation on the ability to focus. The
key variable in the study, turned out to be energy. This feeling
subjectively measured feeling I should say
of having more energy and thereby the ability
to focus especially in these high cognitive demand
task. Now, the takeaway from this study, for all of us, I think is pretty straightforward. If you are going to sit down to do some
work,
Work, that
requires focus and working memory and cognitive attention and especially if it's some visual spatial control. Meaning you have to search for things on a page, you have to organize things on a page. So this will be writing arithmetic, basically cognitive work of any kind, 15 minutes of moderate exercise done prior to that work.
Bout could be very beneficial for you. This does not mean that mindfulness meditation would not be of benefit to you. I wouldn't want you to conclude that,
but if you had to choose between doing 15 minutes of mindfulness,
Meditation and doing 15 minutes of moderate exercise prior to a
cognitive work bout. I would say the 15 minutes of
moderate exercise would be more valuable, at least based on the data in this paper. In many previous podcasts. I've talked about the powerful effects of doing things, like mindfulness, meditation and other forms of NSD are non sleep deep breath. So, these could be 20-minute naps or just lying there quietly with your eyes, closed, or Yoga Nidra, or an SDR.
Scripts are available on YouTube and various other places free of
cost of any kind. You
just go to YouTube, put in N, SD are non sleep deep, rest.
Those protocols have been shown to be very
beneficial for enhancing neuroplasticity, the
changes in the brain and body, that encode or shift the neural circuits that allow for memory to change
that allow for learning to occur. After a learning about
what I'm referring to today. And in this particular study is the use of
Moderate exercise, in order to increase ones, focus and attention in order to trigger that
neuroplasticity. So the simple sequence here
is get energetic and alert do that prior to the learning about engage in the cognitive work or learning
about and then mindfulness, meditation and SDR and so forth, should follow. And if you would like to
access this paper and like to look more at the details in the paper, will be sure to put a link in the show notes. The first author is Legrand and again the
Title of this paper is brief aerobic exercise immediately, enhances visual attentional control and perceptual speed testing the mediating
role of feelings of energy, and I also just want to emphasize immediately. I think most people out there are interested in tools and protocols, that work the first time in that work every time and indeed. I think this protocol fits that bill. I'm pleased to announce that I'm hosting to Live Events. This may the first
live event will be hosted in Seattle, Washington on May
17th. The second live event will be hosted in Portland, Oregon on May 18th both
Part
of a lecture series entitled, the brain-body contract during which I will discuss science and science based tools for mental health, physical, health, and performance. I should point out that while some of the material, I'll cover will overlap with information covered here on the huberman Lab podcast and on various social media posts.
Most of the information I will cover
is going to be distinct from information covered on the podcast or elsewhere.
So once again, it's Seattle on, May 17th Portland
on May 18th, you can access tickets by going to human lab die.
Calm / tour and I hope to see you there. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford.
It is however, part of my desire and effort to bring zero cost to Consumer information about science and science related tools to the general
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Okay, let's talk about the use of cold for health and performance. I confess, I love this topic because it takes me back to my undergraduate years. When I worked in a laboratory studying cold physiology, its effects on the brain and its effects on the body. And over the years. I've always kept
track of the literature in this area
and indeed there have been some tremendous discoveries.
Both an animal models. So in rodents like mice and rats, but also in humans. And today we're going to talk about both categories of studies. And I will be careful to point out when discoveries were made in animal models and when they were made in humans, a key point, when thinking about the use of cold as a tool and the key point is that you have a baseline level of temperature that is varying changing across the 24-hour cycle. So,
So, any use of deliberate cold, exposure is
going to be superimposed on that
Rhythm that. Circadian rhythm, meaning, that 24-hour Rhythm the basic Contour of your circadian. Rhythm in temperature,
is that approximately two hours before the
time you wake up, is your so-called temperature minimum. So your temperature minimum is a time within the 24 hour cycle when your body temperature is at its lowest.
So if you normally wake up around 6:00 a.m. Your temperature, minimum is probably
about 4 a.m. If you normally wake up at about 7 a.m. Your temperature, minimum is probably about 5:00 a.m. It's not exactly
two hours before your wake-up
time. It's approximately two hours before your wake-up time.
Now, as you go from your temperature, minimum
to the time in which you are going to
awake. Your temperature is rising
slightly. And then at the point where you wake up.
Up, your temperature starts to go up more sharply and
will continue to go up into the early and sometimes even
into the late afternoon and then sometime in the late afternoon and evening. Your temperature will start to
decline. And
indeed, as you approach sleep, your body temperature will drop by anywhere from one to three degrees. And in fact, that decrease in core body, temperature is important, if not essential for getting into and staying in deep Sleep.
Okay, so
Temperature rises with waking that's easy to remember. It tends to continue to rise throughout the day and in the late
afternoon and evening. Your temperature will start to go down and the drop in temperature actually helps you access sleep that background or what we call Baseline circadian rhythm in core body. Temperature is important to remember
because it helps us frame both the effects
of deliberate cold exposure
and it helps us.
Frame, when you might want to use
deliberate cold exposure, in order to access specific States, it also points to times within the 24 hour cycle when you might want to avoid using deliberate cold exposure. If your primary goal is to get to
sleep. Okay, so that's the Circadian rhythm in temperature. Now, I just briefly want to touch on thermal
regulation at the level of the body and the brain, and this will be very surprising to many of you.
Let's do what's called a gedanken experiment, which is a thought experiment. Let's say I send you out into the desert heat for a jog or a run and it's very hot outside, you know, 102 degrees or 103 degrees and you start to move, you
start to sweat and
of course your core body temperature goes up now, then I offer you a cold towel maybe in a really, really cold towel and this towel is saturated with water. So you can actually squeeze the water out of that and
Your body off and our gedanken experiment is for me to say, okay. Where are you going to place the
towel? How are you going to cool yourself off? And I'm guessing that most of you would
think that the best way to cool yourself off would
be to drape that towel over your head. Maybe your neck over your torso, that it would feel really, really good and they will cool you off.
Well, that's exactly
the wrong approach if you want to cool off. And in fact, if you were to use that approach, your body temperature would
continue to increase.
He's even more.
Yes, even more than had, you not placed that cold towel on your head or your torso. And here is why thermoregulation, meaning your brain and body's ability to regulate your internal core. Temperature is somewhat like a thermostat and that thermostat resides in your brain. So if you think about the thermostat in your home or apartment, if it's
too warm in your home or
apartment, and you were to take a bag of ice,
And to put it on that thermostat,
what would the thermostat do it would register the environment as artificially? Cool, right? It would think that the environment was actually much colder than it
is. And so, as a consequence, it would trigger a mechanism to further, increase the temperature in the
room, and you have such a thermostat as well. It's called the medial preoptic area of the hypothalamus. The
hypothalamus is a small region of brain tissue about over the roof of your mouth a little bit.
It in front of
that. So it's basically
right behind your nose
and over the roof of your mouth. And it's a collection of neurons. Those neurons have a lot of different functions that include things like the control of aggression, the control of sex Behavior, the control of temperature regulation, and so, on the medial, preoptic area
has connections with
the rest of the brain or areas within the brain. I should say, and with many areas within the body, it receives
input from
Is in our skin and inside our body, that register temperature
and it acts as the thermostat. So if the surface of your body
is made, cool, your medial preoptic area will send signals by way of hormones and by way of chemicals that will serve to heat your body up.
So what this means is that if you want to cool
down the last thing you want to do is to bring a cold surface of any kind towel or splashing water.
To the majority of your body surface might be very, very surprising to you and you might say wait if I want to cool down I should jump into a cold lake or something of that sort. That's a different thing altogether. What I'll tell you and we'll get into this in more depth later. Is that if you really want to cool down quickly and efficiently, you should leverage
particular portals, meaning particular
sites on your body, where heat can leave your body more
readily. And we're
cooling, can have a dramatic.
And fast impact on your core body. Temperature can even save your life. If you're going hyperthermic. We're going to talk more about the specific, protocols to reduce core body, temperature for sake of performance. And avoiding hyperthermia later in the episode. Hyperthermia, of course, is a very, very dangerous situation because while your body can drop in core temperature somewhat and still be
safe. You can't really
increase your body temperature that much before your brain starts to cook and other organs start to cook and buy coke. I mean, the cells actually start to die. So you have to be very
Very, very careful with the use of heat. Heat stroke is no joke. People died from heatstroke all the time. You really want to avoid that
one way to avoid that
is to cool, the appropriate surfaces of your body and the appropriate surfaces. In this case, are the upper cheeks or the I would say the upper half of the face. The palms of your hands and the bottoms of your feet. I've talked about this on the podcast before and in the guest episode with dr. Craig Heller. My colleague in the biology
department at Stanford, but just very briefly.
These surfaces the upper half of the
face, the palms of the hands and the bottoms of the feet are what we call, glabrous skin, surfaces GLA, be Rous glabrous.
And those surfaces are unique in that, just below them. The
vasculature is different than elsewhere in the body. Normally the passage of blood goes from arteries, capillaries devane's, but just beneath the glabrous skin on the bottom of the feet.
Hands in the upper half of the face. You have
what are called? Arteriovenous
anastomoses. These
are
portals of blood that go directly from arteries to veins and in doing so allow the body to dump heat more readily more quickly. So as it turns out that if you are to cool, the palms of the hands, the bottoms of the feet and the upper half of the face, you can more efficiently. Reduce core body, temperature for sake of offsetting hyperthermia and for improving athletic.
Performance and maybe even cognitive performance. So we will return to the specific protocols, for doing that. Later in the episode. I'll give you a lot of details about how to do that. How to do that without the use of any fancy or expensive technology. There are some technologies that are now commercially available. For instance, the so-called cool MIT that will allow you to do that with maximum efficiency, but I'll also give you some at home methods to do this either in the gym or on runs or for sake of cognitive work. Okay. So the two key themes
again our
First and that Baseline circadian rhythm in temperature and understand that the best way to cool.
The body is going to be by making sure
that something
cold contacts, the bottoms of your feet, the palms of your hands and the upper half of the face. Ideally, all three. If your goal is to lower core body temperature, quickly. And again, just cooling
off the back of your neck or the top of your head, or your torso with a towel
is going to be the least efficient way to lower core body, temperature and might even increase.
Body temperature under certain conditions,
okay? With those two points in mind, we can start to think about directed
deliberate cold, exposure, protocols
and there are a number of different reasons to use.
Deliberate cold, exposure, and I want to separate those out for
you.
There are cold
protocols that have been tested in peer-reviewed studies
that are designed to improve
mental performance. They are designed to improve things like resilience, or your grittiness, or your ability to move through challenge, or to regulate your mind and your internal State under conditions of stress. And we can Define stress very
specifically as times when adrenaline also called epinephrine and or
norepinephrine also called noradrenaline are
Didn't your body, forgive
me for the nor adrenaline and norepinephrine, adrenaline epinephrine nomenclature? I didn't make that up. Turns out that every once in a while scientists disagree. Imagine that. And you'll get multiple scientists naming. The same molecule different things. Okay. So epinephrine and adrenaline are the same thing. I will use
them interchangeably,
norepinephrine and noradrenaline are the
same thing. I will use those terms
interchangeably noradrenaline and adrenaline or often Co released in the brain and body. So
they work as kind of
A pair to increase our level of agitation, our level of focus
and our desire. And our ability to move.
They are often KO released from different sites in the brain and body with dopamine. A molecule that is commonly misunderstood as
the molecule of pleasure, but is actually the molecule of
motivation reward and pursuit. So dopamine norepinephrine and
noradrenaline tend to be released together under certain conditions. And today you will learn how
Deliberate, cold exposure can be used to cause increases in the release of several. If not all of these in ways that can improve your levels of attention and your mood. But the
key point is that your
mental state is shifted when you are exposed to certain forms of cold and many people use deliberate cold, exposure, specifically, to shift
their body State, as a way to train their mental state, so that they can better cope with
stress.
In real life. And by real life, I mean when life presents stressful events and I will give you specific protocols as to how you can do that. In other words, how you can become more resilient through the use of deliberate cold exposure. Now, because of the ways in which deliberate cold exposure can increase this category of chemicals called the catecholamines that includes dopamine norepinephrine and epinephrine.
It can also be used to elevate mood for long periods of
time and I'm going to discuss a specific
Call that has been shown to increase these chemicals anywhere from
2.5 x. So, 250 percent to as high as five hundred percent.
Five times over Baseline.
Now, you might be asking whether or not it's a good
thing to raise chemicals like norepinephrine and dopamine to such a great degree whether or not that's healthy for us whether or not they can harm
us, but it turns out that these elevations in norepinephrine and dopamine
are very long lasting in ways that people report feeling vast
improvements in
mood and vast improvements in levels of cognitive attention and energy.
So by my reading of the literature
of the
Seem to be healthy increases in our Baseline levels of these chemicals in ways that can really support us. I'll give you a protocol for that.
Now, those are some of the Mental
effects of deliberate cold exposure.
But, deliberate cold exposure has also been studied in animal models, and in humans, in the context of increasing metabolism, even in converting, certain fat cells that
we call white fat cells, which are the ones where energy is stored, the ones that we typically think of, as kind of blubbery
fat to beige, or brown.
On fat, which is thermogenic
fat, meaning that it can increase core body, temperature and serves as a kind of the
Furnace by which we increase
our core metabolism. So with a very broad stroke, I can say that white fat is generally the kind of fat that people want less of and beige fat and brown fat is generally, the kind of fat that, if you're going to have fat cells and you certainly need fat cells that you want. More of their thermogenic, they help you stay lean. They actually serve as a reservoir for heating your body up if you're ever confronted.
With a cold challenge, so we're going to talk about how to use cold for metabolism as
well. And of course, people are using deliberate cold exposure to reduce inflammation. Post exercise to reduce inflammation, generally and people are also using cold to
enhance performance in the context of strength
training in the context of endurance training and we will
talk about those data as well.
But where I'd like to start is
with mental performance. And I'd like to
detail what happens when we deliberately expose ourselves to cold.
Hold its key to point out the word, deliberate. If I don't say otherwise then, throughout this episode, if I say cold exposure. I mean,
deliberate cold exposure.
And the reason I point that out, is that as my colleague, David Spiegel in the department of Psychiatry at Stanford says, it's not just about the state that we are in, it's about the state that we are in and whether or not we had anything to do with placing ourselves into that state and whether or not we did that
on purpose or not. And what
he's really means by that statement is that there are important
X of what we call mindset mindset, was the topic discussed in the guest episode with Ali crumb some weeks ago. If you haven't seen that episode of highly recommend it. And the signs of mindset tells us that if we are doing something deliberately and we believe that it's going to be good for us. It actually can lead to a different set
of physiological effects.
Then if something is happening to us
against our will or without our control.
Now, this is different than Placebo
effects, plus you
So effects are distinct from mindset effects. If you want to learn more about the distinction, please see the episode with Ali Chrome.
But again, when I talk about
cold exposure in this episode, I'm talking about deliberate cold exposure, meaning
that you are placing
yourself into a cold environment on purpose in order to extract a particular set of benefits.
When we talk about deliberate cold exposure, almost always, that means getting uncomfortable and one of the, most common questions I get when discussing the
Of cold forsake, a mental or physical performance. Metabolism Etc. Is how cold should it be?
How cold should the water be? How cold should the environment be? And I just will tell you now, and I'm going to say this again, and again, throughout the episode because it will continue to be true throughout the episode and long after the episode is over,
how cold depends on your cold tolerance, your core metabolism and a number of other features that there
is simply no way I could know or have access to. So I
I'd like you to use this rule of thumb.
If you are using deliberate cold
exposure, the environment that you place yourself into
should place your mind into a
state of. Whoa. I would really like to get out of this environment, but I can stay in safely.
Okay. Now, that might seem a little bit arbitrary but let's say you were to get into a warm
shower and it would feel really, really nice and you were just
start turning down the warm and turning up the cold, there would be some Threshold at which it would feel.
Comfortable to you. And if you were to continue to make a little bit colder than that, you would really want to get out of the shower. But you were
confident that you could stay in without risking your health, right without risking a heart attack. Now, that's very different than jumping into a very, very cold lake. Or, you know, I've seen these images of people that will cut holes into, you know, frozen over
lakes, and they'll get into that cold water. If you are trained to do that and you have the right conditions, Etc, that can be done reasonably safe.
Flee, but that's certainly not what I would start with. And for many people that will be too cold and indeed. Some people can go into
cold shock and can die as a consequence of getting to that extremely cold water, very quickly. Now, that's not to scare you away from deliberate cold exposure. It's just to say that
there's no simple prescriptive of how cold
to make the environment in order to extract maximum benefit for mental or physical performance.
So the simple rule of thumb is going to be Place yourself
into an environment.
That is uncomfortably cold, but that you can stay in safely.
Okay, and you'll have to experiment a bit. And that
number, meaning, that temperature will vary from day-to-day. It will vary across the 24-hour cycle because of that endogenous, meaning that
internal rhythm in temperature, that I
talked about earlier low early in the day, Rises into the afternoon. Drops at night. You can actually do this experiment. If you,
like try getting into a cold shower at
11:00 at night, if you want
versus, try doing it in the middle.
Of the
afternoon. It's quite a different experience and by quite a different experience. I mean,
it's it requires quite a different degree of resilience
and leaning into the practice. Your willpower will have to be higher. I suspect late in the day as it compared to early in the day, but that will vary, of course, between individuals, as well.
So, the most common question I get about deliberate cold. Exposure, is how cold should the water be? And we've answered that with uncomfortably cold.
Point where you want to get out, but you can safely stay in the second. Most common question. I get about deliberate. Cold exposure
is whether or not cold showers are as good better or worse than cold, water
immersion up to the neck. For instance. I also get a lot of questions about whether or not cryo Chambers are
better than all the others, etc. Etc. I'm going to make all of that. Very simple for you by saying Coldwater immersion up to the neck with your feet and hands. Submerged also is going to be the most effective.
Second best would be cold shower. Third, best would be to go outside with a minimum amount of clothing. But of course, clothing that is culturally appropriate, and that would allow you
to experience cold to the point where you would almost want to shiver or start shivering.
Now, there are a number of different important constraints that are going to dictate whether or not you
use one form of cold exposure or the other. For instance. Some
people don't have access to
Coldwater immersion. They don't have access to ice baths.
Or cold, water tanks, cold ocean or cold Lakes
etcetera. In that case showers
would be the next best solution. I
do want to emphasize that there have been very few if any studies of cold
showers and you can imagine why this would be the case in a laboratory. You want to control for as many variables as possible.
So,
Placing people into a
Coldwater immersion or an ice bath up to the neck and insisting, that they keep their hands and feet under is very
easy to control. It
means that everyone can do essentially the same thing,
whereas, with cold showers people are different sized bodies. Some people are
gonna put their head under. Some people are going to are going to lean
forward measuring. The amount of cold water exposure. On the body is very hard to
do, and so there aren't a lot of studies of cold showers. But of course, a lot of people don't have access to Coldwater immersion, so they have to use
Showers, and if you don't have access to both, of course, then going outside on a cold
day can be of benefit. But I will point out that the heat transfer from your body
into water is much
higher for X greater. If not
even greater depending on the temperature of the water in water as opposed to an air.
So it's going to be much more efficient to do
Coldwater immersion than anything else, cold showers after
that and put
yourself into a cold environment, would be the third.
Best thing
I'm not going to get into cryo Chambers because they
carry quite a high degree of cost. And again, there aren't many studies of them. So if you have access to crowd Chambers, I'm sure that the crowd chamber facility is told you about all these incredible benefits. And I don't doubt that some of those benefits truly exist, but most people just don't have the resources or the access to those who were going to leave, cryo Chambers, out of today's
discussion. And, of course, I realize there's a fourth category of cold exposure out there. People are wearing ice vests, believe or not those
exist, ice underwear.
Yes.
Those exist.
You can look for them on Amazon. If you like.
They are putting cold packs in their armpits or in their groin or elsewhere, in order to stimulate some of the effects of
cold on mental and physical performance.
I'm not going to address those in too much detail. Today. They can be efficient in certain ways. But as you'll learn about later in the episode cooling, The Palms, the upper face and the bottoms of the feet is going to be far more efficient. And unfortunately, I think
Of the people that are using ice packs to increase
their core metabolism, are not aware of the glabrous skin Cooling and how it can be a very, very potent stimulus will return to that later.
Unless I say otherwise, I'm mainly going to be
focusing on Coldwater, immersion, and cold showers.
So, let's talk about protocols for enhancing mental health and performance, using deliberate cold exposure.
What happens when we get into
cold? Is that we experienced an
increase in norepinephrine in noradrenaline.
Release an adrenaline release, the fact that cold exposure, deliberate or no
increases norepinephrine and epinephrine
in our brain. And body
means that it is a very reliable stimulus, for increasing norepinephrine and epinephrine, that sort of an obvious statement. But that obvious statement can be leveraged to systematically, build
up what we call resilience.
Now, when we experience a stressor in
life, whether or not, it's something bad happens in our relationship or
something.
Bad happens in the world and we feel stress that stress is the consequence of increases in norepinephrine and epinephrine in our brain and body. Very similar. If not
identical to the kinds of increases that come from deliberate cold
exposure. So, deliberate cold exposure is an opportunity to deliberately stress our
body and yet because it's deliberate and because we can take certain steps, which I'll describe in a
moment.
We can learn to maintain mental Clarity. We can learn to maintain calm while our body is in a state of stress and that can be immensely useful when encountering
stressors in other parts of life. And
that's what we call resilience, or grit, our ability, or
mental toughness,
our ability to lean into challenge, or to tolerate
challenge while keeping our head straight, so to speak.
So, one simple protocol for increasing resilience.
Is to pick a temperature that's uncomfortable of shower or called immersion and then to get in for a certain duration of time and then to get out. Now, it's important to understand that people experience different levels
of norepinephrine and adrenaline release,
when getting into
cold water, some
people because they dread the cold. So much will actually experience norepinephrine and epinephrine increases even before
they get into the cold water or under the cold shower. Now, you may have experienced this. I've certainly experienced this
I'm dreading it. I don't want to do it. And I have to force myself to do it and indeed, epinephrine and norepinephrine. And it's surges can be thought of as sort of walls that we
have to confront and go over.
And I'd like you to conceptualize them that way, because it allows us to build protocols, that can be very objective and can allow us
to monitor our progress in terms of building resilience.
So one option is to Simply say, okay. I'm going to force myself to get into the cold shower for one minute.
How cold again, uncomfortably cold
but you can stay in safely
or I'm going to get into the ice bath for one minute. Ice baths are very cold inevitably and what is also inevitable is that when you get into the cold,
you will experience a surge in epinephrine and norepinephrine.
That's non-negotiable because it's mediated by Cold receptors on the surface of your body and your skin and the way that they trigger the release
of norepinephrine and epinephrine, not just
from the adrenals from the adrenal glands above your kidneys, but also,
So from regions of your brain, like the locus coeruleus,
which caused increases in the tension and
alertness and from other
locations in your body where epinephrine and norepinephrine are
released. In other words, cold is a non-negotiable stimulus, for increasing
epinephrine and norepinephrine.
Even if you are the toughest person in the
world and you love the cold that increase in epinephrine and norepinephrine is going to happen. So the way to think about norepinephrine and epinephrine in this context.
Building mental resilience, is that you have two options.
You can either try to extend the
duration of time that you are in the deliberate cold exposure. So going from one minute to 75 seconds
to two
minutes. And so on, over a period of days
or one way to approach this, and the way that I particularly favored is to take the context of the day, in the moment into account, meaning we have different levels of
grit and resilience on different days, and
Adding on the landscape of our life at the time, even the time of day that we're doing these protocols
and start to be able to sense the release of
epinephrine epinephrine. Scuse me and norepinephrine in our brain and body and see
those as walls that we want to climb over in order to build resilience and to start counting the number of Walls that we Traverse and
the distance between those walls as we do deliberate cold
exposure. Let me give you an example of the timed
protocol because that one is very straightforward, although I do
I think it is as powerful
for building mental resilience.
The time protocol would be Monday. I do one minute of deliberate, cold, exposure, at a given temperature, Wednesday.
I extend that by 50% and Friday. I do deliberate, cold exposure for twice as long as I did on
Monday. And if I were to continue that every week, Monday, Wednesday, Friday, I would continue to either increase the duration or I would lower the temperature
and reduce the duration
this kind of thing very much like sets and Reps in the gym. Now that option is
Very objective, right? You could even log it in a book. And as you develop the ability to stay in cold temperatures,
even progressively colder and colder temperatures for longer and longer periods of time. You will become more resilient. What do I
mean by that? Well, my operational definition of resilience is that you are able to resist escape from the stressor the
cold by virtue of your willpower, which is really your prefrontal cortex causing top-down control.
On your reflexes and your limbic system and your hypothalamus which are basically telling you to get out of that cold water, get out of that cold
environment and in doing so you are basically getting better at controlling your behavior when your
brain and body are flooded with norepinephrine and epinephrine. That's a very reductionist way to explain resilience or greater mental toughness,
but it's a reductionist way of explaining it. That is very
closely tied to the biology and to the psychology
and it is a fact that norepinephrine and
epinephrine.
And released in the brain and body
are the generic universal code. For stressor. There is no unique chemical signature for different forms
of stressors. That is the only one. Although, of course, there are other chemicals involved as well.
So you could go for time and you can try and reduce the temperature and increase the time
over a period of days or weeks. Now that's an
attractive way to approach things. But the problem is that you don't have an infinite amount of room with which to lower temperature because eventually you will get into
Jurors that are either so cold that they are dangerous or you have to stay in cold temperatures for such
long periods that it becomes impractical. Because presumably, you also have to take care of other aspects of your life. You can't just sit all day in the ice bath.
Now, for that reason, I favor a protocol in
which you build, mental resilience and mental toughness
through two different types of protocols. The first one involves counting walls. Now, what do I mean by walls? I mean the sensation of no, I
want to do this and the idea or the sensation in your brain and body that you actually want to leave
that environment and go warm up.
Now, again, for some people, that will be even before
getting into the ice bath or cold shower.
So if you are feeling very resistant to getting into the
ice bath or cold shower and you manage to do that, that's
going over, what I would call one wall. Okay, then for some period of time, you might actually feel
comfortable in the ice bath cold water or cold shower.
And you feel like you could stay there for some period of time that you could stay there for a minute or two minutes, but inevitably the next wall will arrive and I would encourage you to pay attention to when that next wall arrives. And actually having an
awareness that so-called interoceptive awareness as we call it of. When that next surge in Adrenaline epinephrine comes or whether or not it reaches a certain threshold in your brain and body that you feel you want to get out and you are able to stay
in for even just 10 seconds, longer, that means you've traversed.
Yet another wall. And if you continue to
stay in that cold environment, you will find that the next wall will come in. The next wall will come now.
Eventually, of course, you will get very, very numb depending on how cold it is. And you could also Place yourself into danger. So you have to maintain cognitive control, counting these walls, traversing these walls, but getting out at some point, of course, so my
favorite protocol for building mental toughness, AKA grit AKA
resilience is to take into account.
Some days just getting into the ice bath or cold, shower represents a
wall, some days. It doesn't some days you get in and you feel like you could go 10 minutes, other days, you get in and you feel like you could only go a minute and setting a designated number of
Walls before you start. The protocol is going to be very beneficial here. So you
say, as long as I can do, it safely. I'm going to
do three walls today. The First wall is getting in the second wall will arrive when it arrives. And the third
wall will arrives when it arrives and I'll get over that wall. And then I'll get
out the next.
Day, you might do five walls. The next day. You might do
three walls again, but you might lower the temperature. This gives you tremendous flexibility and indeed, it gives you much more latitude to be able to use the same temperatures in different ways, or to reduce the temperature, only a little bit and still get a lot of stimulus. Meaning a lot of
results out of a given protocol.
Whereas people who are just going for temperature and time, eventually become cold-adapted, they get very, very good at doing three.
And it's are six minutes or even 10 minutes at a given temperature. And so then they feel like they have to lower the temperature
even more and even more
and eventually they just bought him out. There's nowhere else to go. There's no
way to get improvements out of the protocol at
least not in terms of mental resilience. Of course, they're still the positive effects on inflammation and Metabolism, Etc. That
we'll talk about in a little bit.
But the key thing here is to design protocols that are going to work for you over time. And for you very, very Hardy.
Very, very tough guys. And gals out there that can get right into an ice bath or a very, very cold immersion. And you can just grind it
out for six or ten minutes, or you can even do that by remaining peaceful.
Well more points to you. But guess what? That's the equivalent of already having loaded up the barbell with 600 pounds and done your 10 reps. There's not a whole lot more variable
space, with which to get benefits from that stimulus. And in the weight room, people
understand that you can adjust for instance, the
speed of the movement or you can start combining.
Movement with pre-exhaustion
Etc with cold exposure. You don't have as much variable
space to play with. So if
your goal is to build resilience, either go for time as a function of temperature or what I suggest is to start recognizing these walls as an experience of resistance in you and going
over those walls set, a certain number of Walls that you're going to go over on
a given day and do that at a given temperature and then to mix it up and ideally you might even throw in
In one more wall at the end, if you're really feeling
bold and brave because that's going to build out further resilience. But if you want cold exposure to work for you for sake of building up, resilience and mental toughness over time. You're going to want to vary this parameter space in some sort of way and
you don't have to be super systematic about it. That's the beauty of this
kind of approach because you're relying on the fact that those walls
really represent times in which you are forcing your top down, control your prefrontal cortex to clamp down on.
Reflex and you're learning behavioral control in the context of your body,
having elevated levels of these catecholamines, norepinephrine and epinephrine and that
translates to real life in a much more, realistic way, I believe. Because in real life, you're not really engaging in stressors for a given amount of time that, you know,
how long it's going to last and you know, the
context know most dressers arrived in the form
of surprises. We don't like text messages that deliver bad news
information about the outside
world or real.
Old and online interactions, that send our system into a state of
increased norepinephrine and epinephrine.
And if you start to think of those as walls that you can
tolerate and climb over while staying calm and clear of
mind. Then you can really imagine how the ice bath and other forms of cold exposure are really serving to train you up for real
life stressors.
Okay. The next question that I always get is, what should my mental state be?
While I'm exposing myself to this uncomfortable yet safe condition of cold.
Well, you have two options and they're probably other options as well. One is
to try and calm yourself to remain as mentally still as possible.
The other is
to lean into that challenge and so to grind it out. And here I have to say that this is a lot like teaching someone to drive on a gravel road for any of you that have driven on a gravel
road. You know that there is no optimal speed, for all gravel
roads. It depends on the density, the gravel Etc and the vehicle
Etc.
Yeah, so, for instance, on some gravel roads, when you start to drive in the dust starts to kick up your best option is to drive fast
and put that dust cloud behind you on other gravel roads. If you try and do
that, the dust actually kicks up around the vehicle and
it makes it hard to see. Sometimes you have to slow down.
The same thing
is true for getting through deliberate, cold
exposure. Sometimes it's easier to calm yourself. One
way to do that is through double inhale, through the nose and extended exhales through the mouth or simply by trying to control your breathing and reduce.
The pace of your breathing and increase the volume of your
breathing.
I have to say that everyone experiences a shortening of
breath, when they get into uncomfortably cold water.
That is a universal physiological response. Everyone also experiences a 30 to 80 percent, decrease, in cognitive function, in particular
of the prefrontal cortex, the
metabolism your frontal. Cortex goes
down the metabolism, meaning the activity of brain areas associated with stress and panic goes way up
and so anchoring your mind in cognitive activities as you get.
The cold can be very, very helpful for maintaining Clarity of Mind.
Fact. One thing that I sometimes recommend is that people try and engage in some sort of cognitive exercise
while in the cold, not as a form of distraction,
but as a way to maintain Clarity of thinking and to learn how to do
that when the body is flooded with all these chemicals that make us stressed. So for instance, you could do
math problems and not two plus two equals four
not, you know, three times three equals nine but
things that require a little
bit more focus and attention working memory.
Marie and so forth. You could also
start to have thoughts
that you deliberately impose a full
sentence structure on. That's actually quite tough.
You could try and recall
specific bouts of information that are challenging. This is teaching your mind how to stay online or rather I
should say this, is you
teaching your prefrontal cortex how to stay engaged, while you have high levels of
stress in your body years ago. I had a friend who
works in the Neuroscience World research neuroscientist.
Who is obsessed with this very
bizarre sport that? I don't necessarily
recommend at all, which is the combination of boxing and chess. You may have seen this on YouTube where people will
box around legitimate, boxing around their sparring, all
out often. And then, at the end of the round, instead of resting in the corner, they
actually sit down and play chess and then they go back to boxing and back to chess again, not a sport that I
recommend, but the reason he was obsessed with this is
because he studies the impact of stress on cognitive performance. And what that
Circular very bizarre sport was doing was
toggling back and forth between different states of mind.
Now, it's used both to increase cognitive Clarity for the fighter when they
box because staying calm and clear thinking is very important to Winning boxing matches believe or not. It's not an all outraged. It's a very calculated game of mental chess and physical chest. That's quite high stakes as you can imagine.
It's also used in some circles as a way to
teach people how to engage in cognitive.
Performance when their body is simply filled with stress. So, in the boxing chest example, the replacement for the cold water is actually the boxing, right? It's the thing that supposed to induce the stress because getting hit is stressful and the risk of getting hit as stressful for
most people. So again, if you think about deliberate cold
exposure as a way of just systematically and reliably inducing epinephrine and norepinephrine release and delivering
stress will, then this idea of maintaining
cognitive Clarity and actually engaging in cognitive tasks while in the
Ice bath or cold shower can actually be very beneficial even though it might sound a little bit silly. You are really training up your ability to
keep your brain working. When the
reflex is to shut down the parts of your brain that are involved in deliberate planning and thinking. Now, another important aspect of deliberate cold
exposure that I rarely if ever hear discussed, but is vitally important is whether or not you move around or
not. Here's the reason when you get into cold
water.
And you remain
there for some period of time, your body is generating heat
and that heat generates what's called a
thermal layer that surrounds your entire body.
So if you stay still, you are actually warmer than, if you move around, you can try this. The next
time you're doing your deliberate cold exposure. If you're submerged up to the neck sit there for about ten thirty seconds
and be very, very still of Body. In fact. This is the way that most
people start to do deliberate cold exposure. They give this very stoic, look, they don't blank, they
A peaceful some of them even look tough like the where they make a very, you know, even a emotional face. And so it looks like they're, they're
really tough, but they are so still that. Believe it or not. They are not
providing the most potent stimulus
if they or you or to move around in that water, what would happen is you'd break up the thermal
layer and that you actually experience that as much colder.
So if you really want to push the resilience aspect, or for instance, if you want to use a
Given
temperature that you're comfortable in, but that you want to increase the stimulus and you want to get some more benefit for mental resilience training.
Well, then get into the cold water. Move your body around continuously,
but try and keep your mind still or even do some sort of cognitive tasks. So as you're
starting to realize, they're a bunch of different variables that you can play with while maintaining the same temperature of water and in doing so, really keep you in the zone of what should and absolutely has to be safe for you without having
To
just continually drop the temperature from say 60 degrees to 55 to 4233. Because as I mentioned before, eventually you're going to bottom out.
So if you're one of those people that likes to
look tough or really relaxed while you're in the ice bath or Coldwater immersion just realize that you're actually cheating yourself out of part of
the stimulus, keep those limbs moving. And of course, limbs under the water feet and hands is
going to be a more potent stimulus than hands and feet out for reasons. That should be obvious based on what we talked about in terms of glabrous skin.
In
cooling to keep those submerge, move your body pedal, maybe move your knees up and down, pedal your feet. And
trust me. It's going to feel a lot colder than where you to remain Stone,
still another very common question is, how
often to do deliberate, cold exposure.
It's tough to make a recommendation on
that based on any peer-reviewed study.
Although there are a few in humans that point to a threshold of 11 minutes, total per week. So that's total throughout the week divided into two or four sessions.
Of two or three minutes or. So
now that 11-minute cutoff is not a strict threshold and is actually
geared more towards increases in metabolism will get into this a little bit later in the
episode. But I think the 11 minute threshold, meaning 11 minutes total of deliberate cold exposure per week is a pretty good number to use. If you need a number in order to keep you consistent, but as we talked about earlier, some of you are going to be in the
ice bath or cold immersion or cold shower.
For one minute. Others of you will be in there for 10 minutes depending on how frequent and how high if you will those walls of adrenaline are coming.
So for some of you getting into a cold shower for three minutes total for the whole week will represent a tremendous achievement in terms of willpower and
overcoming the resistance to doing that overcoming those walls for
others of you. Three minutes is nothing. So what do I recommend? I recommend that you get at least 11 minutes total per week, but
Point where 11 minutes total per
week is very easy for you or is no longer representing a significant mental challenge. Meaning you're not experiencing many of these walls. You're excited to get into the cold shower or immersion. You're going through it. Easily. You're
cruising basically, then I would
say, either, lower the temperature safely, of course, extend the duration safely, of course or
increase the frequency.
So that you're doing this perhaps every day or maybe
five days a week or three days a week. I personally get
tremendous benefit from doing deliberate cold exposure.
Three times a week and
using the walls method that I described earlier as my gauge for how long to
stay in. And typically that means that I'm staying in for anywhere
from 2 minutes to 6 minutes per session and that averages out to about 11 to 15
minutes total per week.
So again, I do not think that you need to be super strict about these guidelines. Its most important when embracing a protocol a that you do it safely but secondarily that you do it consistently.
So find what you can do consistently and then vary the parameters that will allow you to
continue to do deliberate, cold exposure, consistently regardless of whether or not you have access to a shower or cold immersion Etc.
Okay. So, we've been talking about Mental
effects and the use of deliberate, cold, exposure, for sake of building resilience, which I do believe can be tremendously powerful. Look. It's no coincidence. That the
screening and the training for Navy
Seals, involves a lot of exposure to cold water. One could argue that it is.
Deliberate because they elect to go to buds,
but when they get into the
cold water at buds, is dictated by the instructors and the reason they use cold
water exposure, as the stressor is that it does offer considerable leeway in terms of duration and temperature in terms of how you can use
it as a stressor. Whereas things like heat don't offer much variable space as we say, there isn't a
lot of room Beyond which you start injuring or even killing
people by using heat. So they're a lot.
Forms a stressors out there, but cold is
one that we can titrate that we can adjust in ways that can
allow us to continually build up
and or maintain mental toughness.
Now, deliberate cold exposure also
has many effects on chemicals, other than norepinephrine and epinephrine.
Most notably, the neuromodulator
dopamine which is involved
in elevating our mood, making us feel
energized and enhancing our ability to focus. And that has a lot to do with how dopamine engages us.
In motivated States tends to
narrow our thinking and our Behavior into a particular trench of goal-directed behavior. If you
want to learn more about dopamine, you can learn a lot about dopamine in our episode about dopamine. It's a huberman labs.com. You can find it. It's a two-and-a-half hour plus kind of Deep dive into all things dopamine Focus motivation etcetera.
Deliberate cold exposure has a very powerful effect on the
release of dopamine in our brain and body. And this is one of the main reasons why people continue to do deliberate, cold exposure.
Basically, it makes us feel good and it continues to make us feel good. Even after we get
out of the cold environment. In
fact, some people would say they don't
feel good in the cold environment. It's all stressed for them. But afterwards, they feel great. One of our previous guest. Dr. Anna Lemke. Who is a medical doctor at Stanford University School.
Medicine. She's a close colleague of mine. Described the use of dopamine in her book, dopamine nation, and
incredible book about addiction and dopamine. I should mention
and the use of dopamine, elicited by cold water at exposure. By one of her patients. What I'm referring to is the fact that one of her patients help themselves get and stay sober off drugs, by using
deliberate cold exposure, to increase dopamine. So, a healthier form of dopamine release. Then they were
aged in prior to getting sober. Now, the
basis for dopamine release in response to cold exposure,
is that the catecholamines norepinephrine epinephrine
and dopamine tend to be Co released by the same
sorts of stimuli, but most
stressors and in particular things, that evoke stress where our
feelings of stress internally that we don't like
do not increase dopamine. They only
increase in our epinephrine and epinephrine,
but deliberate cold exposure seems to
cause a dramatic.
Increase in dopamine and this is actually been substantiated in a
really beautiful study entitled, human physiological responses to immersion into water of different temperatures. The first author is ceramic. I'm almost
certainly pronouncing that poorly. If and if not incorrectly SRA M. EK this
was published in the European Journal of Applied physiology in the year 2000, really a
beautiful study. I love this study.
They took people and they had them sit in chairs underwater.
But their head was out and they were so they were immersed up
to the neck and either three
different either of three different temperatures. Scuse me 32 degrees Celsius, which is 89 degrees Fahrenheit, 20 degrees Celsius, which is
68 degrees Fahrenheit or 14 degrees Celsius, which is 57.2 degrees Fahrenheit.
So not super cold, but then what they did is they measured people's core body temperature throughout, they measured their metabolism and they looked at serum levels of things.
Norepinephrine epinephrine dopamine and cortisol to see remaining within the blood. So a really
nice and quite thorough study. There were not a huge number of
subjects in the study. But
nonetheless it was a very thorough study in terms of the
number of variables that they explored.
So I just want to briefly
highlight some of what they saw or what they observed in this study.
First of all, all the groups were in the water of a given
temperature for 1 hour, which
Much longer than most of the deliberate, cold, exposure, protocols, that anyone is using
at home. I mean, maybe you're taking one hour, long, cold showers. Maybe you're getting into the ice
bath for an hour. Although I don't recommend that, I think you'd probably get badly hypothermia.
Cold temperatures, but extended the duration for quite a
while. So again, 32 °C 20 degrees Celsius or 14 degrees
Celsius. Here's what they observed.
The group that was immersed up to the neck and 32 degrees
Celsius. That is 89 degrees. Fahrenheit water did not experience a shift in metabolism,
nor a significant increase in
dopamine norepinephrine, or these other catecholamines.
The group that was in 20
°C meaning 60.
°F water for an
hour experience. A 93 percent increase in
metabolic rate,
which is remarkable given that the water is in
that cold and yet an hour is a pretty long time to be in there. And again, it speaks to
the dramatic effect of heat
transfer that water has, which I mentioned earlier as opposed to being out in the air at 68 degrees. It wouldn't certainly not caused that increase. In metabolic rate the group that was at 14 degrees
Celsius.
Meaning, 57.2
degrees, Fahrenheit water for an hour
experience, a 350 percent increase in metabolism. So huge increases in metabolism. Now, the most interesting data to me at least in terms of Mental effects
of deliberate, cold
exposure were that the plasma or serum levels of norepinephrine in the blood increased, five hundred and thirty percent. These are huge increases in norepinephrine. So,
Suggest that this is a stressful stimulus. At least nor chemically speaking stressful.
Despite the fact that it's not super, super cold or the
57.2 degrees Fahrenheit, 14 degrees. Celsius is not a, you know, it's not a
warm environment, but it's not
a Ultra Ultra cold environment. But an hour is a very long time to be in there.
The subjects also experienced a 250% increase in dopamine
concentrations, which
while not five hundred and thirty percent. As it was with norepinephrine is still a
very large increase in Baseline levels of dopamine.
And what was interesting is that those increases in dopamine, persisted
for a very long period of time afterwards
even out to two hours.
Okay, and they did they stopped the study after 120 Minutes of getting out of the cold.
But nonetheless, these increases
in norepinephrine are
huge and long lasting. And these increases in dopamine
are very large and long-lasting.
And I do believe that these documented effects in humans, explain much of the enhancement of attention and of feelings of
well-being and mood that people typically
experience
after doing deliberate cold exposure.
And the reason I say that is that if you were to go
back to the episode that I did on dopamine or you were to go back to the episode.
A I did with dr. Anna Lemke on addiction and dopamine. What you would find is that
increases in
dopamine of the sort evoked by deliberate. Cold exposure
are actually very similar to
the kinds of increases in dopamine, that are listed by things like nicotine or from other behaviors that are known to be addictive, and bad for us, because they lead to other effects on the brain and body that we simply don't want. And yet
deliberate, cold exposure, provide is done safely can create similar if not greater.
Increases in dopamine, that are not just fleeting that, don't
just occur during say the consumption of some deleterious, drug or activity, but that are very long lasting, and that can be leveraged toward activities other than deliberate cold exposure. So, I want to emphasize this. I'm not suggesting that people do deliberate
cold exposure for an hour a
day. And unfortunately, there are not
many studies yet.
Exploring, how shorter colder and
temperature, environment, exposure
say, one
And or three minutes or six
minutes at, you know, 55 degrees or it 50 degrees,
whether or not that leads to similar greater, or reduce levels of
dopamine in the brain and body. And
yet, almost everybody who does deliberate, cold exposure will say, yeah, it was stressful. I didn't enjoy it or I eventually grew to like it, but that I always feel better afterwards. And then that feeling lasts a
very long period of time and I think
it's almost certain that those experiences that people.
Report relate to these increases in dopamine,
and in concert with the increases in norepinephrine, also, explain the other effect that's
commonly reported, which is an enhancement in mental acuity and the ability to focus. Now, here we can extrapolate to the study that I discussed at the early part of the episode where I was talking about the
use of short 15-minute
exercise, kind of moderate intensity exercise and how that was shown to
increase levels of energy and mental acuity. In
these working memory visual attention task.
And there again, we have to assume somewhat
because they weren't doing neurochemical
measurements, but we can reasonably assume that those improvements in cognitive performance. We're due at least in part to the increase in catecholamines known to accompany
moderate-intensity Zone to cardio. So what you're starting to see here is a theme,
the theme is that virtually any stimulus that delivers more norepinephrine epinephrine and dopamine to our system will sharpen our mental acuity and Elevate, our mood and will do. So,
For some period of time,
deliberate cold exposure. It turns out is a very potent way to
increase these catecholamines. This category of chemicals and thereby to improve mood, mental acuity and levels of
alertness. And as will next, see, it not only has that
effect, which can be very beneficial for many people and a bunch of different
circumstances, but it also has the
positive effects that many people seek in terms of metabolism
in lowering inflammation in the body and
other physiological effects as well.
Well,
and forgive me, I was almost ready to move on to effects of deliberate cold exposure on metabolism and inflammation and so forth,
but I neglected, to point out one of
the other very interesting
aspects of the study showing deliberate cold, exposure can increase in our epinephrine and
dopamine, which is that they observed no
significant increases in the stress hormone
cortisol, and that is both surprising interesting and important. Because what it means, is that the
Quality of stress that deliberate cold, exposure is
creating in the body is likely to be one of what we call you stress, Hans selye. A the great physiologist won a Nobel Prize for distinguishing between
distress, which is stress in the brain and body, that
causes the release of things like cortisol along with the other catecholamines and that we experience as
- happening to us and can lead to negative Health outcomes. And he distinguished that from you
stress which was stressed.
That we Now
understand is associated with increases in things like norepinephrine and
dopamine, but no increases or minimal
increases in cortisol and that can lead to positive Health outcomes.
So it appears that deliberate cold exposure, can create what we
call or what Hans selye a called you stress.
In other words. It can create a condition in the brain and body in which we are stressing ourselves. We are training up
resilience and yet, we are creating a neurochemical milieu that actually has many health benefits.
Now, I'd like to shift our attention to the effects of deliberate cold exposure on metabolism. And I'd like to start by detailing a study that was performed on humans and published just at the end of last year. The title of the study is altered, Brown fat, thermoregulation and enhanced cold-induced thermogenesis in young healthy
winter, swimming men. And I should point out that while the study was
only performed on male subjects. There's no reason to think that the effects that they discovered would only
pertain to men. I would hope that they would also do.
A study on women at some point in the future,
but the effects that they describe our very basic core physiological. Processes. What they did is they looked at deliberate, cold exposure in this group of young men and they used that 11-minute threshold per week. So in other words, they had them get into cold water for approximately 11 minutes per week.
And again, that's 11 minutes. Total per week.
They divided that into two sessions.
In speaking with the first author of the study. Dr. Susanna Solberg. I learned that it probably is not important that it be two sessions. It could be three or
even four sessions as long as it reaches that 11-minute threshold.
What they discovered was that by going into these cold environments, in this case,
Coldwater immersion up to the
neck for 11 minutes total per week that these men experienced increases in so-called Brown fat.
A Genesis, I'll talk more about what that is in a moment and increases in core body, temperature that translate to increases
in Core Body metabolism.
Now, the overall increases in Core Body metabolism that they experienced. We're not extremely large. They were statistically significant, but they weren't extremely large. However, the change is in brown, fat stores are perhaps,
what's most interesting about this study? And I'll tell you why
the metabolic
increases of
Cold exposure are both
acute. Meaning happening in the short term, when you get into the cold and
immediately after one does experienced an increase in core metabolism. You burn some calories in other words.
And while those might not be very significant
increases, or I should say they can be statistically significant, but they are not
enormous lie. Large numbers of calories burned. The longer lasting effects of
deliberate cold exposure on metabolism seem to take place by changes that occur in the types of fat that
we store in our body. And the way that that fat impacts our metabolism at other times throughout the 24 hour
cycle.
This actually has a somewhat anecdotal basis. In particular in Scandinavia.
I don't speak Swedish. Nor I speak Danish. Nor do I speak Norwegian? But I do have
Danish relatives, and they were able to help me decipher a common, Swedish saying, which essentially translates to the fact that in preparation for the summer. They say one should expose themselves to warm environments. So that one is comfortable
in.
Environments in the summer. That's one half of this traditional Swedish. And also Danish saying the
other
half of this traditional Danish Swedish saying
is that in preparation for winter in order to not feel too cold in cold environments, one should prepare for those in the fall by, not wearing a jacket and exposing oneself
to cold environments. Now, of course, this is just anecdotal
cultural lure, but it actually has a physiological
Logical basis which is by exposing oneself to cold
environments on a
repeated basis in anticipation of exposure to more extreme cold environments, one can feel more comfortable
in those extreme cold environments.
And that's exactly what they observed in this study by sober. Get all the men felt more comfortable in extreme cold if they had trained
through deliberate cold exposure,
which might not seem surprising at all, but based on what we talked.
About earlier, where by deliberate cold exposure, evokes this discomfort? And this experience of norepinephrine release at least in the short-term. Then you would say, well, shouldn't that deliberate cold exposure
also make them feel uncomfortable. Like, they really want to get
out. Well, that is true at the beginning
of a deliberate cold exposure protocol, meaning in the first week, or in the second week of the third week, but what one finds and what you will find. If you do deliberate, cold exposure, consistently is
that you will then become
I'm more comfortable at cold temperatures away from the deliberate cold exposure. So, whereas you might have previously, been the person who is always cold in the room with air
conditioning or always seeking a sweater always wanting to bundle up. You will be more comfortable in those cold environments. And the reason for
that is well, substantiated from this study and from animal studies, where by deliberate cold, exposure, converts one particular, kind of fat cell,
the white fat cell,
which is
A very
low metabolic output cell. It's basically a storage site for energy in the body fat
cells, to a different
type of fat cell, which is the beige fat cell called beige because it's actually beige or slightly Brown under the
microscope or even to Brown fat cells,
which are very dark under the microscope and dark because they contain mitochondria
and are very metabolically and thermogenic Ali active. In other words.
White fat doesn't burn many calories. It's basically a
storage site. It's a bank account for energy. It's filled with lipids and those lipids can be used if the body needs energy and if it goes into a caloric deficit,
beige fat, and brown fat acts as sort
of eight furnace or the sort of fat that you would find in a candle
a fuel that can increase core body temperature. So, beige fat and brown fat is very good at raising our metabolism and
Burn white fat. Now. Of course, it does that only in the
context of a caloric deficit, but it can actually help create that caloric deficit,
having more beige fat, and brown fat can increase your overall
core metabolism. In other words, the number of calories that you burn per day and therefore, the number of calories that you need to either maintain or to lose weight.
The simple translation of this. Is that getting into cold
water for
a total of 11.
11
minutes, perhaps more, but at least 11 minutes per week, divided into two
or four sessions can increase your core metabolism in part by increasing your beige
and brown fat stores,
and we know how that works, at least in animal models and there's now reason to
suspect that the exact same mechanisms are occurring in humans,
the primary way in which deliberate cold exposure, converts, white
fat cells into these more metabolically.
Thermogenic Lee Active Metabolism increases
Beige and brown fat cells is because norepinephrine
released when we get into the cold
binds to receptors on the
surface of white fat cells,
and activates Downstream Pathways such as you see p 1. So this is an uncoupling protein one that acts on the mitochondrial metabolism of cells and increases the mitochondrial output of those
cells and the mitochondrial density of those cells.
In other words, it takes a cell that has a kind of a weak engine or no engine
for generating energy. Although every cell has
some mitochondria. It takes cells that have very few mitochondria and increases the engine size. It kind of Stokes the furnace of those particular cells and actually can change gene expression in those cells. So, that's what's really interesting. Deliberate cold exposure causes increases in norepinephrine, which bind to receptors on the surfaces of
White fat cells which triggers the release of things like you cp1. It also causes the release of things like ppar gamma and cofactor PGC one.
I'm going to refer you to a review. If you want to learn more about these for those of you that don't want to learn more. All you need to know is that the downstream of all that
are increases in mitochondria and metabolism and actual genetic changes in the white fat cells that convert them into beige and brown fat cells. This is
especially important for adults.
Because babies and young children, actually don't have the ability to shiver or they have a less robust capacity
to shiver. Very small babies. Really can't shiver. So they have a lot of brown fat in order to keep them warm
young children eventually developed the ability to shiver and maintain these Brown fat stores, mainly around the clavicles, the heart, the upper spine, and in the upper back and it's no coincidence. That kids can often
run around with a minimal.
Clothing and be comfortable in environments, that adults would be cold in
as life goes on. We tend to lose Bayesian Brown fat. But this mechanism that I'm referring to points to the plasticity of white fat. Meaning the ability for
white fat, to actually convert its identity into this metabolically. Thermogenic Ali enhancing form of beige and brown fat.
So deliberate cold exposure is a terrific way to increase your core metabolism. And oftentimes critics will say, well, the increase in metabolism.
Um, isn't that significant? Although I do want to point out again, the
93% and 350% increases metabolism from that previous study, but
critics then we'll say, well, that doesn't really translate to that
big of a caloric burn during the deliberate cold exposure. But
to that you should say, ah, but that's only limiting your Optics
to just a portion of the effects of deliberate, cold exposure. Because deliberate cold, exposure can also convert white fat.
He's fat and brown fat and lead to these more lasting increases in metabolism.
So for any of you interested in increasing your metabolism and or being comfortable in cold environments
and or
being comfortable in
terms of being able to combat stress, mentally
deliberate, cold exposure. I do believe is a powerful tool and there is simply no reason why you couldn't and shouldn't use the same. Protocols that I described earlier for building resilience to increase metabolism provided. You're hitting that 11.
Minute per week threshold, you ought to be
stimulating. Both mechanisms increases in
resilience and increases in core metabolism. As I mentioned earlier, most of the detailed studies on the
conversion of white, fat to beige fat and brown fat through the, use of
cold have been done in animal models, but the human data are starting to
emerge and if you'd like to do the Deep dive into these mechanisms things, like you see
p, 1 P bar, gamma Etc. There's a beautiful review that was published recently in the journal cell,
which is one of the
Apex journals nature science cell and the title of that paper is adipose tissue plasticity in health and disease. I love this review. It has beautiful diagrams detailing. All of the pathways from cold the norepinephrine through you cp1 Downstream of things like cyclic amp e, if none of those names mean anything to you, don't worry about it. You certainly don't need to
know these mechanisms to benefit from deliberate cold exposure, protocols. If those names
do mean something to
you, or you are interested in
exploring the downstream effects of
Deliberate cold exposure and something else. That's really nice. That's covered in this paper is how deliberate cold, exposure, interacts with fasted States and fed States. I think you'll also find
this review. Very interesting. I
don't want to go too deeply into
fastest States and fed
States right now. Suffice to say that when we are fasted, meaning, when we haven't eaten for some period of time, our Baseline levels of norepinephrine and epinephrine are already elevated. And so cold, exposure, at those times.
Ought to have an even greater effect on metabolism and resilience and so on. So
for you fasters or your intimate, and faster is out
there. If you really want to get fancy, you can do your deliberate cold exposure when you are
fasted. I certainly wouldn't recommend doing it with a very full
stomach in any case, and as I mentioned before on this podcast, intermittent fasting is, but one way, and certainly, there are other ways to limit total caloric intake
for sake of maintaining or lose.
Wait, if that's your
goal, I know many people are
using and benefit from intermittent fasting. However, and so it certainly can be combined with deliberate called exposures in order to get even greater increases in norepinephrine and epinephrine.
So for those of you that are primarily
interested in using deliberate cold exposure, to increase dopamine levels in your brain and body. You can also do a combined
protocol, whereby you ingest caffeine 60
to 120 minutes before the deliberate cold
exposure.
This is based on a study that I've talked about before entitled. Caffeine increases striatal dopamine
D2 D3 receptor, availability in the human brain. And as the title suggests, this study was done on
humans. Looking at the density and or efficacy of these dopamine receptors in an area of the brain
called the striatum, which is involved in planning and action, and also suppressing planning and action. It's involved, very
closely with whether or not, we can engage in behavior and withhold Behavior.
The so-called
Go and no go Pathways in the brain. Dopamine plays a
critical role in that and many
other things as well as you now know.
So, why would you want to ingest caffeine 60 to 120 minutes before deliberate cold exposure? Well, as I talked about earlier, dopamine can increase quite substantially in response to deliberate cold exposure, but dopamine on its own, doesn't do anything. It has to bind to receptors and this paper shows quite definitively that ingesting caffeine. In this case. It was 300.
Gram dose of caffeine, which is about the dose of
caffeine in two or three cups of coffee. It depends on the strength of the coffee, of course, but it's not an outrageous amount of caffeine
that increases the density. And or efficacy of these receptors, which you would
allow that dopamine to have its greatest effect. And for those of you that want to get really, really fancy, I suppose you could do this fasted. So you get the further increase in
norepinephrine and you get the dopamine increase from the cold exposure, the body of the dopamine, although I do want to point out that
Some point you start layering together enough
protocols that you would be spending your entire day. Trying to get this dopamine pulse and I would hope that you had would have other activities that you would engage in.
But if you're getting up in the morning and you're fasted, because you haven't eaten all night and you have a cup of coffee and then 60 minutes later, you take your cold shower
or two hours later.
You do your cold immersion or your cold shower. You would be layering together these different
mechanisms of dopamine receptors epinephrine and so forth, in a way that at least, to me, doesn't seem incompatible with
having some other life like going to school and having relationships,
Etc. And this increase in dopamine, particularly in the, striatum is not a trivial one. I do want to point out as the authors do, that preclinical Studies have shown that increases in striatal, dopamine induced by things like modafinil, which is
used to treat ADHD and treat, narcolepsy is necessary for their wake promoting
actions. What this really says is that just having elevated levels of dopamine from a drug, or from an
ice bath or
Have you is not sufficient to get the effects of
dopamine. You really need the receptors to be available. And you need those receptors to be available in the appropriate density.
And you need those receptors to be available in the appropriate, density in the striatum in particular. So, I think there are a number of reasons
why if it's compatible with the other aspects of your health. Because of course, always you have to consider this on a background of cardiovascular, health and blood pressure
Etc. That ingesting a cup or two of coffee an hour before your ice bath. Maybe fasted as
well.
It'd be quite beneficial for increasing dopamine over quite extended periods of time. A
couple of key points that you'll want to pay attention to and thinking about
deliberate cold exposure and
Metabolism in the so Burke study. They also explored the use of sauna and how to use sauna meaning deliberate heat in conjunction with cold. We are going to do an entire episode about the use of heat
for health and performance. So that is not the focus now,
however, it does raise an important point that we do need to address at this.
Moment, which is if you are using sauna, or if you are taking warm showers, or if you are simply using deliberate cold exposure of any kind, should you get into the heat afterward or before or not at all? And this is where we can point to the so-called. So Berg principal least I call it, the sobered principle to sober principal named after first author
of this study. I referred to earlier. Dr. Seuss anise oberg.
In science, it is appropriate to take a key piece of data and call it a principle. If in fact, it translates to something larger, which I believe it does. It
is generally not appropriate for people to name a principal after themselves. Although there are a few scientists that have done that. So I have named it, the sober principle, but I did that to give it
appropriate credit
to dr. Susanna. So Berg who discovered that and pointed out quite appropriately that to achieve the greatest increases.
Metabolism through, deliberate cold exposure.
You want to force yourself to reheat on your own after
the deliberate cold exposure.
Meaning you wouldn't want to go from
the cold shower to a hot shower
or from the cold shower, to a sauna rather. If you were going to start with a
hot shower where you going to start with a sauna that you would end with the cold and then you would reheat naturally.
Now, I personally take a cold shower, a few times a week, or do cold immersion and
Because I'm not specifically focused on increasing
metabolism. Although I probably should be, that's not what I'm using it for now.
I will take a hot shower afterwards and in doing. So, I'm short circuiting some of the further
metabolic increases that I would achieve. Were I to just end with the cold.
So, the sobered principle is, if you want to increase your metabolism and with cold, and we can take this a step further and say that, if you want to use deliberate cold exposure to increase metabolism.
That you should make sure that you get to the
point where you shiver. And the
reason for this is that there are a series of studies. But in particular, one study, published in the journal Nature, excellent journal
in the year
2018, showing that deliberate cold exposure. That evokes shivering from the muscles causes the release of a molecule called succinate from the muscles and that succinate plays a key role in activating Brown fat thermogenesis.
Which you
now have heard about and understand as critical to the increases in metabolism caused by deliberate cold exposure.
So what this means is, if you want to increase your metabolism and on cold, that's the sobered principal. And as best, you can try and get to the point where you are shivering either. When you are
in the cold exposure or immediately afterwards.
Now one efficient way to do this is to, for instance you could get into the cold shower for a
minute or two minutes or three
minutes uncomfortably cold.
But safe to stay in. Remember, that's our general rule of
thumb, then turn off the water and stand there. Make sure that you're not
holding yourself close to your body. You're not hugging yourself to try and keep yourself warm, but rather, your limbs are extended at your sides.
And then if that
fails to induce shiver then to
turn on the cold water again, and then turn it off again. So, alternating perhaps a minute to three minutes of cold
exposure, followed by a minute, to three minutes of drying out in air and going back into the
Cold exposure
Etc. I can tell you this from experience. This is a pretty brutal protocol. If you have never tried getting into an ice bath or cold water immersion or cold, shower for one minute and then getting out and trying to stand there with your arms, extended in
cool or cold air for one minute and then getting back into the
cold shower or water immersion, you
are in for an
experience. Because even for those of you that are pretty shiver resistant, you will find that it is much much
harder to get out.
That cold water and stand their arms extended and drawing off by
evaporation, which further draws
heat from the body.
Then it is to wrap yourself in a towel, get in a warm
shower or a sauna. So there's certainly no
requirement to end on cold. There's certainly no requirement to induce shiver. But if your primary
goal is to
induce increases in metabolism, both in
the short term and in the long term,
following the cold exposure. Well, then you'll want to end on cold and you'll fall.
Want to find a way to shiver
provided that the level of cold that you're exposing yourself to is still safe for you overall.
So up until now I've been talking about
deliberate cold exposure as a potent stimulus for the release of norepinephrine in the brain and body. And indeed, it
is. But the way I've been describing, it has been in the context of circulating
plasma levels of norepinephrine, meaning circulating within the blood
What I haven't mentioned, but is absolutely true, is that the fat cells themselves, actually receive input from neurons. So, there are
neurons that release norepinephrine in response to cold directly into the
fat. So, I want to give you this picture of how the architecture of all this works
because I think it can help you navigate and indeed build better, deliberate cold, exposure, protocols. Your adrenal glands, release norepinephrine, and epinephrine.
Your brain has sites within it like the locus coeruleus, that release norepinephrine and
epinephrine but there are also neurons within your skin that sends cold and other neurons
that can directly release norepinephrine into the fat stores and cause those white fat cells to convert to beige and brown
fat. And I think this particular aspect of our physiology is often overlooked in studies, and when people say, oh well, the increases in metabolism, aren't that great? The circulating
Levels of norepinephrine those are very large, but they're very transient. And so on that fails to understand that neurons that actually sense cold are in a position to communicate via other neurons directly to the fat cells and release norepinephrine into those fat cells, which is I pointed out earlier set off a huge set of immediate and long-term
Cascades of even gene expression changes.
So, the picture that I'd like you to have in your mind, is that when you get into the cold,
Of course you experienced that as a experience of, I don't want to do this. I'm going to overcome this. I'm going to climb over these mental walls, that represent adrenaline release in my brain and body,
but also that your fat cells are receiving, signals norepinephrine signals that are changing those
fat cells in the way that they metabolize energy.
Now, I'd like to shift our attention to the use of deliberate cold exposure, for
sake, of physical performance.
And there are a lot of opinions out there about the use of deliberate
cold whether or not it should be done for instance, before.
For or after exercise. Whether or not if done immediately after strength training, or
hypertrophy training, meaning training designed to grow muscles
or make them stronger, whether or not, it can inhibit that process and so on and so forth. I think today in looking over the literature and trying to bring forward the simplest
and most straightforward and yet
scientifically grounded. Protocols. We can set up some general guidelines that will allow most, if not all of
you to still extract the benefits of deliberate cold, exposure on
physical.
Four minutes without getting too neurotic,
about the exact timing, but for
sake of discussion and because it's a prominent
theme in many online communities.
Let's just start with the big one out there. Meaning, the question of whether or not doing an ice bath or doing deliberate cold, exposure, or taking a cold shower. After strength, /
hypertrophy training,
meaning training designed to increase strength or and or I should say the size of muscles.
Will somehow short circuit or diminish that process, whether or not
it will reduce or eliminate those strength gains and hypertrophy gains. And the
short answer that I was able to arrive at on the basis of a review article that I'll talk about in a moment and some other studies as well. Is that if your main goal is hypertrophy and strength, it is probably best to avoid cold water immersion and ice bath immersion in the four hours.
Immediately following that strength and or hypertrophy training
again. If your main goal is
to achieve hypertrophy or
strength or some combination of those probably best to avoid Coldwater immersion up to the neck or ice bath immersion up to the neck. Immediately after strength and hypertrophy training and extending out to about four hours. After that training.
If you're really neurotic about this, then
perhaps you'd want to move the cold water exposure to a different day
entirely, but it all depends on how
neurotically attached you are to getting every last bit of strength and hypertrophy, and if that's your goal, terrific, well, then probably moving the cold
exposure for hours or more
away from that training is going to be necessary for you. Now, you'll notice I did not talk about
cold showers. And the reason I did not talk about cold showers, is that there simply are not very many studies of deliberate
cold exposure.
Through cold showers for the reasons. I talked about at the beginning of the episode.
It's hard for me to imagine that taking a brief cold
shower. After a strength or hypertrophy training session would completely reverse or Short Circuit, the effects of that strength and hypertrophy
training. But again, if you're neurotically attached to getting every last bit of strength and
hypertrophy out of your training sessions,
then by all means err on the side of
caution and wait for hours or more to do your cold shower just as you would wait for hours or more to do your cold.
Our immersion
now, there are nice data pointing to the fact that doing Coldwater immersion after a hard run. So endurance training, or even Sprint an interval training
or after a Weight Workout where your main focus is on
performance of those movements or after a skill training
workout, where your main focus on
performance of those movements that there's no reason to think that that Coldwater immersion or ice bath or cold shower would inhibit the progress
or the
Less that would lead to progress that occurred during that training session.
In other words. I don't see any reason based on the literature
to avoid deliberate cold exposure immediately after training again, unless your goal is hypertrophy and strength.
And in fact, there's a very nice review that was recently published on deliberate, cold exposure,
and how it can Impact Physical
performance, whether or not it's done before, or after different types, of training and so forth. The paper.
Is entitled impact of Coldwater. Immersion compared with passive recovery following a single bout of strenuous exercise on athletic performance in Physically, Active participants, a systematic review with meta-analysis
and meta-regression.
So this is a meta-analysis of 52 studies that looked at a tremendous number of variables and context as you would expect
in a meta-analysis of 52
studies. I'm going to read you, the conclusions of the study and I will provide a link. We certainly don't have the
To go through all the details of the study. I will
highlight a few specific outcomes that I found particularly interesting. But here I am
paraphrasing their conclusions. That
Coldwater immersion. I want to emphasize immersion, not cold showers, but
Coldwater immersion, they say wasn't effective recovery tool after high intensity exercise. They observed positive outcomes. Meaning improvements in
certain
variables for muscular power muscular soreness meaning,
Has muscular soreness, increase muscular power
perceived recovery after 24 hours of exercise.
However, there were certain forms of exercise
that were not benefited by
Coldwater. Immersion, such as eccentric
exercise exercise,
focusing only on the
lowering component or the so-called eccentric component of resistance exercise.
They saw some very interesting dose-response relationships for things like endurance training, meaning, the longer, the
Cold exposure, post endurance training, the more Improvement in endurance performance, reductions in circulating
creatine, kinase has and things that relate to muscle damage under certain conditions. Some point in the future. By the way, we will do an entire episode on Creatine creatine kinase which are important not just for muscular function, but also for
brain function, but the basic takeaway was that cold, water immersion performed after high intensity
exercise was beneficial from a number of different standpoints.
And indicated that shorter duration, cold exposure, and lower temperatures can improve
the efficacy of cold water exposure if used after high intensity exercise.
Okay there I'm directly pulling from their conclusions. So what this says is that it's not just those
longer duration 30 45 minute and 60 Minute, Protocols of Coldwater immersion that we discussed earlier,
but also shorter duration, 1 minute 3 minute 5 minute exposures to
Lower temperatures temperatures that would make. You
psychologically, want to get out as
soon as you possibly can? But again, that you can safely stay in done, after training really have been shown to
improve outcomes in terms of reducing soreness and
improving training.
Efficacy, meaning your ability to get back into training more quickly and thereby
deliver more training, stimuli to a given muscle
or in your endurance training,
protocol, translate to English. What this means is that
That taking a cold shower or getting into an ice bath or some other form of Coldwater immersion within the immediate minutes. Or even the amid
mediate hours following your training has been shown to be beneficial.
I'm sure a number of you have questions. For instance. How long
should you be in that cold exposure? Is it the same as the 11-minute threshold described earlier.
To be honest with you. There are not enough studies to really point to the critical threshold for eliminating or reducing delays.
Onset muscle soreness or forgetting
maximal, results from power and endurance training, but this study does make a couple of
key points. And here, I will just
paraphrase. For instance, that Coldwater. Immersion is more likely to positively influence, muscular power performance to reduce muscle soreness to reduce serum, creatine kinase, and to improve perceived recovery, after high intensity exercise as compared with passive recovery. This can be translated to
Cold water exposure after training is beneficial and probably better than passive
recovery from a number of standpoints.
In addition. They say that dose-response relationships,
meaning the amount and the
degree of cold that people are exposed to and how often they did that.
In particular in lower temperature called immersion. So these would be the sorts of cold immersion. Protocols, that are one minute or two minutes, three minutes, maybe five minutes, but that one couldn't stay in there longer because it feels stressful and one wants to get out. Maybe more effective after high intensity exercise
for removal of serum creatine kinase
as well. That these shorter duration. Coldwater
immersion approaches may be more effective after
high-intensity endurance performance as well. So,
This can be translated to say that, unless your main goal is hypertrophy and strength that cold exposure. Ideally called immersion in cold water, ice bath. But if you don't have access to that, then cold showers is likely going to be beneficial if done
immediately after or in the minutes or hours after your training, especially high intensity training.
One particularly. Nice thing about this meta-analysis
is that it included some studies that involve the use of cooling.
Hacks. So again, vests that can hold essentially ice packs
and indeed even cryotherapy Chambers. And so on. There's a nice table in the study. If you want to get really detailed and go and look
specifically at those studies. I invite you to do that will put a link to this study in the caption for this
episode. But all in all what this study shows is that deliberate cold exposure can be very useful for Recovery likely through
reductions in inflammation in muscle and connective tissue.
And while this study did not look specifically at the mechanisms of reduced
inflammation caused, by deliberate, cold
exposure. Those mechanisms are somewhat known. There are a number of
studies that have pointed to the fact that
deliberate cold and cold. Generally can reduce inflammatory cytokines such as il-6 interleukin 6, it can increase anti-inflammatory, cytokines such as interleukin 10 and so on.
Without getting into all those details. I think it's sufficient to say that if you are somebody who experiences a lot of delayed onset, muscle soreness taking a cold shower after your training or getting into a cold immersion after your training, even if it's a few hours later ought to help. And if you are doing particularly intense training, then you probably want to
ratchet up the number of cold exposure, sessions that you're
doing. Even if those have to be done
on separate days from your training because a lot of the inflammatory effects of training,
Ernst and strength training or actually occurring some hours away from the training stimulus, so it's not just that inflammation goes up radically during training, which it often
can, but that it can occur even in
the days and even weeks afterwards, depending on how intense and how long duration that training is.
So delivery. Cold exposure
is very powerful as an anti-inflammatory tool.
Now, I'd like to emphasize the topic that we touched on, in the beginning of the episode,
which are those glabrous skin surfaces, the hands, the upper face, and the bottoms of the
feet.
Through which heat is especially good at leaving the body. And another way of putting that is that one can cool. The body
much more efficiently through the glabrous skin surfaces. Now, if
you want to understand all of the science behind this and all of the various applications, I invite you to, please listen to the episode that I did with. Dr. Craig Heller again, in the biology department at Stanford for sake. Of this episode. I'm just going to detail a couple
Of findings from his laboratory. The first one, dealing with exercise-induced hyperthermia, because I think this is very
interesting and it can even save lives. If you understand the way this works.
There's a particular paper that focuses on this and we will put a link to this as well. The title of this paper is novel application of chemical, cold packs for treatment of exercise. Induced hypothermia, a randomized control trial. This is a pretty brutal, study brutal for
the subjects. That is what
this study.
Dad was having subjects walk on a treadmill at a pretty significant incline. Anywhere from 9 to 17 percent, wearing a substantial amount of
clothing that was not. Well
ventilated and the room was kept to 40
degrees celsius, which is 104 degrees Fahrenheit.
This is definitely not something to do at home. This study was designed to induce hypothermia, which as I mentioned earlier, can be quite dangerous and they compared to types of cooling and the first form of cooling.
That they call traditional cooling, they had ice packs on their neck, in their armpits and in their groin. And in the other group, there was the so-called glabrous skin cooling. So the Palms, the soles of the
feet, which were actually,
so they were cooling inside the boots or inside of gloves and on the upper portion of the face.
And the basic takeaway of this study is that by cooling the glabrous skin. The subjects were able to sustain this walking on these incline treadmills for much longer than where the
people who receive traditional Cooling and also the return to Baseline temperature was much faster in the glabrous skin, cooling
group. So how this translates to the real world is that if ever you are hyperthermic or someone else's hyperthermic?
One way to cool them down quickly is to cool these Palmer glabrous,
soles of the feet glabrous and upper portion of the face glaber has portions of the body using cool Rags using ice packs, or using any number of different cold objects or temperatures.
One key thing. If you're going to use glabrous Skin cooling, is that whatever you use to cool? Those surfaces cannot be so cold that it causes vasoconstriction.
Friction. Because as I mentioned earlier, the arteriovenous anastomoses, these portals of arteries
directly to veins that
exist only
in these glabrous skin
surfaces. The way that they are able to cool, the
body and essentially pass cool into the body. Although that's not really what they're doing. They're actually extracting heat from the body to be
technical. They're extracting heat from the body. The only way they can do that is if those veins don't collapse and veins.
Will collapse
if they were made very,
very cold. So if you want to use
glabrous Skin cooling to offset hyperthermia, or for the other forms of performance, which we will talk about in a
moment. You need to use a cool object or Surface, that is not so cold that causes vasoconstriction. And this can be a little bit tough to dial in. Meaning. It can be tough to identify such an object. And for that reason, dr. Heller. And some of his colleagues have developed a commercial product, called the cool
mint. You can actually go to their website. Cool mint.com. I don't have any Financial.
Other relationship to them. I know they've been developing this technology for some period of time. It involves a
glove that you put your hand into it, circulates water of a given temperature, and it does so and does. So at a temperature that is sure to not cause vasoconstriction of the palm, and you may be asking, how
can you just put your hand into one glove and have this work? Well, that's how powerful these glabrous skin. Surfaces are even just by cooling one. Palm, the core body temperature drops radically.
Now, that's their commercial technology. I know that some people out there have started to experiment with a home version of this,
which would be taking a package,
for instance, of frozen blueberries, or some other cold, drink, or
cold metal object, and actually bringing it into the
gym or out on a run. There are even people who are now developing cooled. Psych bicycle, handles for long rides. This might seem a little kooky or crazy to you. But as you'll soon hear in the study, I'm about to describe the increases in.
Endurance and in the volume of strength training that people can conduct if they
appropriately. Cool, their body through this, these glabrous skin. Portals is actually quite significant. So
again, as it relates to hyperthermia have someone is overheating by all means try and get them out of that heat, get them to
stop exercising, you can
die from hypothermia, try and cool. The bottoms of the feet, the palms of their hands and the upper portion of their face. That does not mean that it would be a bad idea.
Idea to
put cold water on the top of their head, that probably would also help. And perhaps on their neck.
What is probably
not going to be a good idea is to do
the more standard thing of draping. Someone in cold
towels on the surface of their body because as I mentioned the beginning of the episode that thermostat in the hypothalamus, the medial preoptic area will typically react to
that by increasing
core body. Temperature further
the effects of glabrous skin, cooling on physical performance. Are truly
remarkable provided. The glabrous skin cooling is done correctly.
And I want to point out that the main degree of effect is on
volume
or the ability to do more work. And I want to point this out because I think that many people certainly in the exercise science Community. But even in the general public, when they hear about some of these effects that are measured in the laboratory, they sort of look a at those effects of bit of scans and they think well,
that's not possible, Right? Effects, for instance, that have been
documented showing doubling or tripling of the number of
dips that
at one can do in a relatively short amount of time
or doubling of the number of pull-ups one can do or 14 percent increases in strength or even comparable
degrees in increase in weight training output to people who are on performance-enhancing drugs, etc. Etc.
Part of the confusion is that the effects of proper Palmer,
cooling. Because it almost always is done by Palmer, Cooling and less often in these experiments by cooling of the bottoms of the feet and the upper portion of the face, but those are
Facts tend to be the ability to do more work overtime and just to illustrate some of the major effects that the hell, our lab is seen and that are documented in this manuscript that I'll share with you in a moment. The typical protocol is to have people come in and do some endurance training, so running on a treadmill and to have a condition where one group is actually doing Palmer cooling while they are on a bike or on a treadmill. And inevitably the outcome is that
They can do more work. They can pedal further at a given speed
or they can run longer at a given speed than people who are not doing Palmer
cooling or who are receiving cooling by way of, you know, cold compress to the back of the neck or ice pack to the armpits. Etc. So the effects of polymer cooling are very clear and very robust and in the context of endurance. Exercise, almost always allow people to do more work to go longer with less perceived effort and to quit later so to speak.
In terms of strength training, they've looked at the capacity to perform sets of dips. So, one of the more famous examples of
this that dr. Heller shares in the episode that we did earlier and that you can find it. Human lab.com, involves
someone coming in and doing sets of dips, maybe 40 dips. This person actually could do 40 dips on there for a set then resting for a period of two to
three minutes and then doing 35. And then resting for a period of two or three minutes and then doing progressively
fewer and fewer.
Fewer to the point where over a period of time, they add up, the total number of dips that they can do and then they have them come back after a period of recovery.
So not immediately after but take a couple
of days come back and do it effectively the same protocol but during the rest periods. They're doing two minutes to pull more
cooling, which accept essentially allows heat to move out of the body lowering core body temperature. In other words,
and what they find is that they see enormous increases in the total number of
Of dips that people can do. But that doesn't mean that the person goes from being
able, to do 40 dips, to being able to do 50 dips, or 60 dips on that first
set. What it means is that they're able to do 40 on the first set than 40 on the second than 38 on the third and so on and so forth. So that the total duration of the workout is extended and yet they're doing much more work, even though it takes more time. So that's an important point and I think a point that perhaps wasn't as clear or as
clearly made by me in the previous episodes that discuss this
But
for those of you that are interested in exploring Palmer, cooling, first of all, I recommend taking a brief glance or even a deep dive into this study, which is entitled work, volume and strength, training, responses to resistive exercise, improve with periodic heat extraction from the Palm in this study. They describe
Big increases in anaerobic, meaning strength, training output, things like
Improvement, in dips
Improvement, in bench, press Improvement in pull ups Etc, in human subjects, and it's a really nice study and points to some of the protocols that you might be able to adapt
in your own setup.
For instance, over six weeks of pull up training Palm Cooling in between sets improved volume by 144 percent and this was an
experience subjects. So that's interesting.
Because a lot of studies of strength training and improvements in hypertrophy and strength are done in inexperienced untrained athletes, which can changes the picture somewhat compared to experienced athletes.
They found that strength. Meaning the one repetition maximum increased 22% over 10 weeks in bench, press training and they point to the particularly strong effects of using polymer, cooling, when people reach plateaus in endurance and strength training and there, I think it's an important point. I think that if you're going to
To explore Palmer cooling. It's probably not the sort of thing that you're going to do in every run or
in every bout of cycling or in
every strength training session, but that it might be used to vastly increase your volume and or vastly increase your endurance in a
given session or a set of sessions in order to push through
plateaus a particularly interesting point in light of that is, dr. Heller has observed again. And again that Palmer cooling reduces delayed onset muscle soreness.
Or can eliminate it entirely and that's very interesting because it also points to the fact that reducing core body temperature May somehow be involved in short-circuiting the normal
mechanisms of delight delayed onset muscle soreness. And you might say, well, how
would temperature be involved in delayed onset muscle soreness? Well, I want to refer you back to the meta-analysis. That we talked about earlier where the short duration, very cold temperature, exposure. After training did indeed reduce delayed onset muscle
soreness in part through reduction skus.
Me and creatine kinase, so
it's not
inconceivable that temperature and delayed onset muscle soreness are related and that raises.
Perhaps the most important point, which is the way that Palmer cooling can improve performance by way of reducing core body temperature is known. And that is because when one engages in
exercise or muscular output of any kind, strength, or endurance, exercise
the range of temperatures under which a
So can perform is actually very narrow. There's an enzyme called pyruvate kinase, which is critical to muscle contractions and pyruvate kinase can only
function in a very narrow range of
temperatures if that temperature gets too hot. Meaning if the muscle heats up locally, whether or not by running, or cycling or swimming, or weight lifting, the ability for that muscle to continue to contract is reduce and eventually is short circuited
completely. And I think this is a
much underexplored or at
least.
A much under discussed
aspect of so-called muscular failure or the failure of one to continue to endure in running. So for instance, when you run as compared to a bench press or something,
you don't stop running because you can't actually contract the
muscles further. But somehow signals about the heating up of muscular, tissue are conveyed to the
brain. There's a crosstalk there. It's probably bi-directional and people stopped. They quit, right? This is the quitting reflex
in strength training.
Then one can no longer perform a repetition or set of repetitions in part because of heating up of the muscle locally. There are other mechanisms as
well, of course, and I realize that.
But what's very clear from the Palmer cooling work? Is that by simply holding on to a cool object? Remember, not an object? So cold, that it constricts. The vessels of the palms or constricts. The vessels on the bottoms of the feet, but by holding onto a relatively cool
object in one or both hands in between sets for 2 minutes or so.
You can very efficiently
Lee reduce your core body temperature and in doing so reduce the temperature of the muscles that are doing the work, increase the capacity for pyruvate kinase to continue to allow your muscles to contract and thereby allow you to do more volume
of endurance and strength
training. So a simple protocol that dr. Heller passed to me is find a relatively cool objects. So you could, for instance, fill two bottles with cold water. Maybe put a few ice cubes in there, right?
This is not exact.
As we're not talking about the commercial. Cool mint product here. We're talking about an at-home version
or use a pack of frozen, blueberries, or broccoli, sort of pact of
those is what he described and
then in between sets to put your hands and ideally you'd put the bottoms of your feet, but that's
not always feasible in most gyms where they won't let you. Take off your shoes and so forth, but to put your
palms of your hands on that cool surface for a minute or two minutes between sets
and then returning to your sets of work.
Now if you are heating up,
Up through other mechanisms like you're wearing a stocking cap in your in a very warm environment. This might not have as potent
effect. As if you were to do this Cooling in a more moderate environment, wearing lighter clothing Etc.
So by all means, warm
up to do your exercise, lubricate your joints and get into a place where you're not going to injure yourself, doing whatever form of exercise you do. But then, if you'd like to
explore Palmer, cooling, I know a number of people who have written to me saying they heard about Palmer
cooling on the episode with dr. Heller, they've tried this and they see quite
excellent results. It does take some
Appling, right. It's one thing to just kind of hang out in the gym and play on your phone. In between sets. It's another to do deliberate cooling with your palms or the bottom of your feet or the upper portion of your
face, might get some weird looks
but of course, you'll be the one doing some
significantly more volume not experiencing delayed onset, muscle soreness and achieving better endurance and strength gains. Where you to do this properly.
Now as a final topic related to the use of deliberate cold, exposure, for improving health and performance. I'd like to touch on this theme that exists online.
I'm on social media on YouTube, and in various Fitness communities of using deliberate cold exposure to the groin, in particular, to the testicles, in order to try and increase
testosterone. And while this might sound really kooky. Indeed. This practice exists, indeed. If you were to go on the Amazon, there are actually ice
pack underwear that have that are being marketed for sake of increasing testosterone. Now, I am not aware of any
specific. Well, controlled
He's that showed that this indeed works. I can imagine based on what I know
about the nervous system testosterone and cold, Etc, that there are a couple of mechanisms by which one might experience
increases in testosterone as a consequence of deliberate cold exposure. First off. Let me say, there is no reason why you would have to apply these ice packs in the way that I just described
one could, of course, take a cold shower. One could, of
course, use cold immersion a various kinds and you're still going to get that.
Bossier of the groin and the testicles too cold.
Now I should point out that people do report. At least anecdotally increases in testosterone, as a consequence of this
practice and I have to imagine that they are measuring their serum testosterone that they're not just guessing that they're just tossed. Her own went
up. If you know of a study exploring this directly, please, let me know
put in the comments section on YouTube or even just email me. We have a email that you can find it huberman lab.com.
Please email me. The reference, I wasn't able to find a reference,
but I can imagine to reasonably plausible mechanisms by which deliberate cold exposure, to the groin. In particular. The testicles would increase testosterone. The first is somewhat direct, which is that anytime you cool? A body surface that if its cold enough, you're going to get vasoconstriction and then subsequently, you're going to get a rebound increase in vasodilation. Meaning, you're going to constrict the blood vessels in that area.
And then after the cold is removed, there's going to be
more blood flow to that area. And of
course blood flow relates to organ health and tissue Health generally, so perfusion of that region and
those and the gonads to be
specific with additional blood. You could imagine in some ways increasing
testosterone, that's reasonably plausible. The other
probably more likely mechanism relates to the dopamine
increases caused by cold exposure that we talked about earlier.
Again, any time,
I have a somewhat stressful stimulus, but in particular with cold exposure, it seems that the catecholamines norepinephrine epinephrine and dopamine all increase, and dopamine is known to be in the pathway that can stimulate
testosterone.
And so, while there isn't a direct relationship between dopamine, stimulating testosterone, there is an interesting pathway, whereby dopamine increases can trigger increases in things like luteinizing hormone, which
can trigger increases in testosterone as well as estrogen for,
That matter.
So I know that there are a lot of people out there that are
interested in the use of cold exposure for increasing testosterone and some of those people in communities are indeed using cold exposure directly on the gonads on the testes. In order to do this.
I'm not certain that that direct contact is necessary and in some cases
it might actually be quite dangerous. Or are you at least should be careful in terms of tissues there
and avoiding damage, but nonetheless, I think
Eight, dopamine impact on testosterone is very likely, given the 250 percent increases in dopamine that have been
observed with cold water
immersion and all of that points to the fact that Coldwater immersion very likely increases testosterone, but as a downstream consequence of the Coldwater immersion effects on dopamine and luteinizing hormone, and again, there's no reason to think that the increases in luteinizing hormone would also increase estrogen probably not too.
Dangerous or levels. That one would want to
avoid, but I don't think that there's anything particularly
specific about cold for inducing testosterone and not other hormones. I think it's very likely to increase his a number of different hormones. I do hope that there will be a systematic study on this in the not too distant future. I also hope to not be a subject in the cooling of the gonads experiment. Now, I promised you. The last topic was the last topic, but
there's one other really important point that I think everyone should be aware of
if you're going to use to
Brick cold, exposure.
And that brings us back to the very first thing
that we discussed today. Along the lines of deliberate cold exposure, which is that your Baseline temperature is going to be
lowest about two hours before you wake up. It's going to increase in the morning
and as you wake up
and increase throughout the day and afternoon and then start to drop in the evening and come down at night as you head to sleep.
I also want you to remember that if you are to cool, the external portion of your body in particular, your torso,
the net effect of that is going to be an
increase in body temperature.
So for many people, not all. But for many people, if you are going to do deliberate, cold exposure, you are going to increase
your core body temperature, and
that makes sense. If you think
about how deliberate cold exposure can increase metabolism by increasing thermogenesis.
What that all means
is that
if you are doing your deliberate cold exposure, early in the day, you are going to get yet a
further increase in core body temperature, that would be associated with wakefulness. Your ability to be alert that morning or throughout the day and so on.
It also means that if you do
your deliberate cold exposure, very late in the evening or at night, so 6:00 p.m. And 7:00 p.m. 9
p.m. And so on, you are going to
Increase your core body temperature and it, if you
recall,
a decrease in core body, temperature of 1 to 3 degrees, is not just beneficial but is necessary in order to
get into deep sleep and remain in deep sleep. So the takeaway from this is
deliberate cold, exposure done properly will increase your core
body temperature and make you feel more alert.
So, if you're doing it early in the day,
that's probably terrific. Given that most of us want to be alert during the day.
However, if you do it, too,
Late in the day evening or night, it can disrupt sleep by way of
disrupting your core body temperature.
Now the caveat to that is, I myself tend to do my deliberate, cold exposure early in the day. Maybe not first thing in the morning, but mid-morning maybe as late as 3:00 or 4:00 in the afternoon. And some cases in the longer days of summer.
I might do it even later 5 or 6 p.m. And have no trouble sleeping.
I have done deliberate cold exposure, very
late at night, 10 p.m. 11
p.m. And so on as part of
A 30 day
challenge of doing deliberate cold exposure, every day for 30 days. And I got sloppy with my timing and then in order to not miss a day. I would do it at 11:00 at
night. And I must say, I found that I could still fall asleep very easily even doing
deliberate cold exposure, very late at night. However, on those particular
days, I was particularly busy and so, I was particularly
exhausted when I arrived at the deliberate cold exposure, and I had no trouble falling asleep after doing deliberate cold exposure, and then taking a nice warm shower.
I'm going to sleep, but I could imagine that because of the increases in core
body, temperature caused by deliberate cold exposure,
that were 12 do that too late in the day evening or night. That it could indeed disrupt your sleep. So my recommendation would be for most people only do deliberate, cold exposure. If you are prepared to be fairly alert for the next one to four
or maybe even six hours following that deliberate cold exposure. So, for today's episode as is the case with most episodes of the human Lab
podcast. I covered
A lot of
material we talked about mechanisms of
catecholamines and stress and pulsatile release of epinephrine, metabolism, Mental effects performance, glabrous skin, Cooling, and on, and on and on. And while the goal, of course, is to make sure that everyone arrives at specific, very clear mechanistic and actionable protocols. I do realize that it is an immense amount of information. And for that reason, I've created a list of deliberate, cold, exposure, protocols aimed at improving mental toughness.
Listen, resilience mood performance metabolism, reducing inflammation, and so on and so forth. All of those have been condensed into succinct form and can be found at the huberman lab neural network newsletter. This is a monthly or semi monthly newsletter that we release that includes takeaways from the podcast and protocols. You can access those protocols zero cost by simply going to huberman lab.com signing up for the neural network newsletter. It's very easy to do. You just
Supply, your email and you will receive the newsletter. We do, not share your email with anybody
else. In fact, we have our privacy
policy laid out on the human Lab.com website so you can find that there and the protocols that I've designed should make it very straightforward for you to create a set of protocols that you could use with cold showers with cold immersion with or without ice in combination with exercise, specifically, for one goal or another, or to
accomplish multiple goals simultaneously, if
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