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Using Deliberate Cold Exposure for Health and Performance | Huberman Lab Podcast #66



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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we are going to discuss
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the use of deliberate cold exposure
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for health and performance.
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Temperature is a powerful stimulus on our nervous system
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and indeed on every organ and system of our body.
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And cold in particular can be leveraged to improve
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mental health, physical health, and performance,
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meaning for endurance exercise,
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for recovering from various forms of exercise,
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for actually improving strength and power,
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and for enhancing mental capacity.
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In order to properly leverage deliberate cold exposure
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for sake of mental health, physical health, and performance,
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you have to understand how cold impacts the brain and body.
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So today we are going to discuss that.
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We're going to talk about some of the neural circuits
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and pathways, some of the hormones involved.
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I promise to make it all clear and accessible,
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regardless of whether or not
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you have a scientific background or not.
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We are also going to discuss very specific protocols
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that you can apply, which leverage variables
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like temperature, how cold, how to deliver the cold,
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for instance, whether or not you use a cold shower,
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cold immersion, ice bath, circulating water, or still water,
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whether or not you're going for walks outside in a t-shirt
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when it's cold, or whether or not
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you're purposefully using things like cryo,
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if you have access to that or not.
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One thing I can promise you is that
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by the end of today's episode,
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you will know a lot about the biology of thermal regulation.
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That is how your brain and body regulates its temperature.
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You will also have a lot of tools in your arsenal
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that you can use and leverage toward
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improving mental health, physical health,
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reducing inflammation in the body,
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improving athletic performance,
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improving mental performance.
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I promise to spell out all those protocols in detail
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as I go along and to summarize them again at the end.
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I'd like to make a point now that I'm going to make
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several additional times during today's episode,
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and that is that temperature is a very potent stimulus
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for the brain and body.
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That also means that it carries certain hazards
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if it's not done correctly.
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Now, everyone shows up to the table, meaning to protocols,
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with a different background of health status,
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and there's simply no way that I can know
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what your health status is.
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So anytime you are going to take on a new protocol,
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that means a behavioral protocol or a nutritional protocol
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or a supplementation protocol,
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you should absolutely consult a board-certified physician
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before initiating that protocol.
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I don't just say this to protect us.
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I also say this to protect you.
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If you'd like to see our medical disclaimer,
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you can go to our show notes.
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It's described there.
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In fact, I encourage you to please do that.
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And in general, when embarking on new protocols,
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in particular, if they involve strong stimuli
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like changing temperature
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or placing yourself into unusual temperatures,
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I would encourage you to progress gradually.
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I would also encourage you to not look at gradual progression
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as the kind of weak version of a protocol.
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In fact, today I'm going to discuss
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a really beautiful peer-reviewed study
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that involved having people do deliberate cold exposure,
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so they were immersing themselves into water
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up to about their neck,
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and the water was actually not that cold.
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It was only about 60 degrees Fahrenheit,
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which for most people is pretty tolerable,
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so nowhere near the kinds of extreme temperatures
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that one could use in other protocols.
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And the interesting thing is,
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despite that fairly modest cold temperature,
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by simply extending the duration of time
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that people were in that water,
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they experienced enormous increases in neurochemicals
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that ought to translate to improvements in focus and mood,
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and indeed, that's what's been observed
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in subsequent studies.
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So again, please see our medical disclaimer in our show notes
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please proceed with caution always.
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Please also understand that the most potent stimulus
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isn't always the one that you experience
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as the most intense in the moment.
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In fact, I would encourage you
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to find the minimum threshold of stimulus
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that will allow you to derive the maximum benefit
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from each protocol, and indeed,
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I will point out what those thresholds ought to be today.
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I'll give you some simple formulas,
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gauges or guides that you can use
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in order to navigate this extremely interesting
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and potent tool that we call deliberate cold exposure.
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Before we talk about deliberate cold exposure
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and its many powerful applications,
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I'd like to highlight a study
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that I find particularly interesting
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and that I think you will find
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particularly interesting and useful.
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The title of this study is brief aerobic exercise
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immediately enhances visual attentional control
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and perceptual speed,
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testing the mediating role of feelings of energy.
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Now, the reason I like this study is,
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first of all, it's a fairly large size sample group.
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They looked at 101 students.
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These were college age students, and they had two groups.
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One group did 15 minutes of jogging at moderate intensity.
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So when they did measure percent heart rates, et cetera,
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but this would be analogous to zone two cardio,
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which I've discussed on this podcast before.
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Zone two cardio is cardiovascular exercise
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that places you at a level
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where you can hold a conversation
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with a little bit of strain,
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meaning that you can get the words out,
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but every once in a while, you have to catch your breath.
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Whereas if you were to push any harder
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by any mechanism going faster
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or on a steeper incline, et cetera,
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that you would have a hard time
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carrying out a conversation.
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So zone two cardio is a common form
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of describing that level of intensity
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that they call moderate intensity.
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So one group did 15 minutes of jogging
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at moderate intensity,
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which I'm translating to roughly zone two cardio.
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The other group did 15 minutes of relaxation concentration
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that is somewhat akin to mindfulness meditation.
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And then they were analyzed for perceptual speed,
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visual attentional control,
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something called working memory,
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which is your ability to keep certain batches
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of information online.
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Just imagine someone telling you their phone number
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and you have to remember that sequence of numbers
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in your head for some period of time.
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And that's working memory.
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And it depends very heavily
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on the so-called prefrontal cortical networks,
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which are involved in planning and action.
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And they also looked at people's feelings of energy
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and they measured that subjectively,
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how energetic people felt.
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Now, the major takeaways from the study
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that I'd like to emphasize
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are that the 15 minutes of jogging group
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experienced elevated levels of energy
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for some period of time after they ceased the exercise.
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Whereas the group that did mindfulness meditation
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actually reported feeling more calm
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and having less overall energy.
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Now that's very subjective
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and indeed they used subjective measures to analyze energy.
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But what gets interesting is when they looked at performance
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on these various cognitive tasks
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and the two tasks that they use
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were called the trail making tests.
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They have different versions of this,
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version A, version B,
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I don't want to go into too much detail,
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but version A essentially involves having a page of numbers
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that are distributed somewhat randomly.
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So one, two, three, four, five, six, seven, eight,
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and so on, but distributed randomly across the page.
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And people have to use visual search
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to circle those numbers in sequence.
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So this involves visual attention,
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it involves some motor skills,
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involves a number of things
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that certainly require energy and focus.
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The second test was the trail making test part B,
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as I mentioned earlier,
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and this involved also circling numbers in sequence,
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but interspersed between those numbers were letters.
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So rather than just having to circle off numbers
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in sequence, they actually had to connect one,
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then the letter A, then two, then the letter B, et cetera.
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And remember, these are randomly distributed across a page.
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The major takeaway from the study
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is that the group that did the 15 minutes
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of moderate exercise prior to these two tests
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showed significant decreases in the amount of time
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required to complete these tests accurately.
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That is interesting and indeed surprising, at least to me,
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because there have been many studies
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looking at the effects of mindfulness meditation
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on the ability to focus.
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The key variable in the study turned out to be energy,
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this feeling, subjectively measured feeling, I should say,
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of having more energy and thereby the ability to focus,
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especially in these high cognitive demand tasks.
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Now, the takeaway from this study for all of us,
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I think is pretty straightforward.
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If you are going to sit down to do some work
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that requires focus and working memory
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and cognitive attention,
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and especially if it's some visual spatial control,
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meaning you have to search for things on a page,
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you have to organize things on a page,
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so this would be writing, arithmetic,
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basically cognitive work of any kind,
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15 minutes of moderate exercise done prior to that work bout
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could be very beneficial for you.
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This does not mean that mindfulness meditation
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would not be of benefit to you.
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I wouldn't want you to conclude that,
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but if you had to choose between doing
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15 minutes of mindfulness meditation
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and doing 15 minutes of moderate exercise
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prior to a cognitive work bout,
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I would say the 15 minutes of moderate exercise
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would be more valuable,
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at least based on the data in this paper.
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In many previous podcasts,
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I've talked about the powerful effects of doing things like
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mindfulness meditation and other forms of NSDR,
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non-sleep deep rest, so these could be 20 minute naps
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or just lying there quietly with your eyes closed
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or yoga nidra or NSDR scripts are available on YouTube
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and various other places free of cost of any kind.
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You can just go to YouTube, put in NSDR,
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non-sleep deep rest.
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Those protocols have been shown to be very beneficial
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for enhancing neuroplasticity,
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the changes in the brain and body that encode
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or shift the neural circuits that allow for memory to change
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that allow for learning to occur after a learning bout.
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What I'm referring to today in this particular study
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is the use of moderate exercise
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in order to increase one's focus and attention
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in order to trigger that neuroplasticity.
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So the simple sequence here is get energetic and alert,
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do that prior to the learning bout,
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engage in the cognitive work or learning bout,
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and then mindfulness meditation, NSDR and so forth
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should follow.
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And if you would like to access this paper
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and like to look more at the details in the paper,
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we'll be sure to put a link in the show notes.
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The first author is Legrand.
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And again, the title of this paper is
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"'Brief Aerobic Exercise Immediately Enhances
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Visual Attention Control and Perceptual Speed,
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Testing the Mediating Role of Feelings of Energy.'"
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And I also just want to emphasize immediately,
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I think most people out there are interested in tools
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and protocols that work the first time
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and that work every time.
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And indeed, I think this protocol fits that bill.
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I'm pleased to announce that I'm hosting
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two live events this May.
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The first live event will be hosted
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in Seattle, Washington on May 17th.
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The second live event will be hosted
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in Portland, Oregon on May 18th.
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Both are part of a lecture series entitled
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The Brain-Body Contract,
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during which I will discuss science
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and science-based tools for mental health,
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physical health, and performance.
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And I should point out that while some of the material
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I'll cover will overlap with information covered here
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on the Huberman Lab Podcast
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and on various social media posts,
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most of the information I will cover
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is going to be distinct from information covered
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on the podcast or elsewhere.
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So once again, it's Seattle on May 17th,
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Portland on May 18th.
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You can access tickets by going to hubermanlab.com slash tour
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and I hope to see you there.
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Before we begin, I'd like to emphasize
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that this podcast is separate from my teaching
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and research roles at Stanford.
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It is, however, part of my desire and effort
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to bring zero cost to consumer information about science
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and science-related tools to the general public.
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In keeping with that theme,
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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Athletic Greens, also called AG1.
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I started taking AG1 way back in 2012,
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so I'm delighted that they're sponsoring the podcast.
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The reason I started taking AG1
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and the reason I still take AG1 once or twice a day
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is that it covers my foundational vitamin, mineral,
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and probiotic needs.
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It also has adaptogens and things like zinc
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for immune system function,
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but the probiotics are one of the key features in there.
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I've done several podcasts on the gut microbiome,
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which are these trillions of microbiota
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that live in our digestive tract
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and that are crucial for our immune system,
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brain function, and so on.
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One way to enhance our gut microbiome
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Now, the glasses were initially designed
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00:13:40.100
for athletic performance,
link |
00:13:41.140
meaning they were designed to be worn
link |
00:13:42.540
while cycling or running,
link |
00:13:43.940
and indeed you can wear them while cycling or running.
link |
00:13:46.140
If you get sweaty, they won't slip off your face.
link |
00:13:47.840
They're very lightweight.
link |
00:13:48.660
In fact, you hardly ever remember
link |
00:13:50.140
that they're on your face.
link |
00:13:50.980
At least I can't remember that they're on my face.
link |
00:13:52.840
I wear the sunglasses when I drive.
link |
00:13:54.700
I wear readers at night,
link |
00:13:56.140
but they're not just for athletic performance.
link |
00:13:58.220
They have a terrific aesthetic,
link |
00:13:59.660
so you could wear them to the office or to work or to school.
link |
00:14:02.340
They look great.
link |
00:14:03.180
Unlike a lot of high-performance sunglasses out there
link |
00:14:04.940
that make people look like cyborgs,
link |
00:14:06.160
these you would be happy to wear anywhere.
link |
00:14:08.180
If you'd like to try Roca glasses,
link |
00:14:09.700
you can go to roca.com, that's R-O-K-A dot com,
link |
00:14:12.920
and enter the code Huberman
link |
00:14:14.420
to save 20% off your first order.
link |
00:14:16.740
Again, that's Roca, R-O-K-A dot com,
link |
00:14:19.220
and enter the code Huberman at checkout.
link |
00:14:21.220
Today's episode is also brought to us by Helix Sleep.
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00:14:24.020
Helix Sleep makes mattresses and pillows
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00:14:26.140
that are uniquely designed to your sleep needs.
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Everybody knows the importance of sleep
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00:14:30.720
for mental health, physical health, and performance,
link |
00:14:33.140
but probably what everyone doesn't realize
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00:14:35.240
is that you have unique sleep needs.
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00:14:37.620
Your body, and indeed the way you sleep,
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need to be matched to the correct mattress
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in order to get the best possible sleep.
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Helix understands that, and if you go to their website,
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they have a brief two-minute quiz that anyone can take
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00:14:49.220
that will match your body type and sleep preferences
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to the perfect mattress for you.
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00:14:53.420
So they ask questions like, do you sleep on your side,
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00:14:55.260
your back, or your stomach, or maybe you don't know,
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00:14:56.860
do you tend to run hot or cold through the night,
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00:14:58.380
or maybe you don't know.
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I matched to the Dusk mattress, D-U-S-K,
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nor too soft, and I've been sleeping on that mattress
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for over a year now, it's the best sleep I've ever had.
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So if you're interested in upgrading your mattress,
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go to helixsleep.com slash Huberman,
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take their two-minute sleep quiz,
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for 100 nights risk-free.
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00:15:26.020
They'll even pick it up for you if you don't like it,
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00:15:27.580
although I think you will like it.
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00:15:28.940
I certainly love mine.
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00:15:30.140
Again, if you're interested,
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00:15:31.180
go to helixsleep.com slash Huberman
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00:15:33.420
to get up to $200 off your mattress order
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00:15:35.880
and two free pillows.
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00:15:37.260
Okay, let's talk about the use of cold
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00:15:38.860
for health and performance.
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00:15:40.540
I confess I love this topic because it takes me back
link |
00:15:43.580
to my undergraduate years when I worked in a laboratory
link |
00:15:47.380
studying cold physiology,
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00:15:49.540
its effects on the brain and its effects on the body.
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00:15:52.620
And over the years,
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00:15:53.980
I've always kept track of the literature in this area,
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00:15:56.740
and indeed there have been some tremendous discoveries,
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00:15:59.780
both in animal models, so in rodents like mice and rats,
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00:16:02.780
but also in humans.
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00:16:04.540
And today we're going to talk about
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00:16:06.080
both categories of studies,
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00:16:07.740
and I will be careful to point out
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00:16:09.460
when discoveries were made in animal models
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00:16:11.860
and when they were made in humans.
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00:16:15.060
A key point when thinking about the use of cold as a tool,
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00:16:19.740
and the key point is that you have a baseline level
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00:16:23.740
of temperature that is varying,
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00:16:26.480
changing across the 24-hour cycle.
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00:16:29.440
So any use of deliberate cold exposure
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00:16:32.220
is going to be superimposed on that rhythm,
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00:16:36.120
that circadian rhythm, meaning that 24-hour rhythm.
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00:16:39.540
The basic contour of your circadian rhythm in temperature
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00:16:44.700
is that approximately two hours before the time you wake up
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00:16:49.520
is your so-called temperature minimum.
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00:16:51.880
So your temperature minimum is a time
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00:16:54.360
within the 24-hour cycle
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00:16:56.140
when your body temperature is at its lowest, okay?
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00:16:59.860
So if you normally wake up around 6 a.m.,
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00:17:03.200
your temperature minimum is probably about 4 a.m.
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00:17:07.340
If you normally wake up at about 7 a.m.,
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00:17:09.960
your temperature minimum is probably about 5 a.m.
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00:17:13.140
It's not exactly two hours before your wake-up time.
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00:17:16.180
It's approximately two hours before your wake-up time.
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00:17:19.220
Now, as you go from your temperature minimum
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00:17:22.660
to the time in which you are going to awake,
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00:17:25.060
your temperature is rising slightly.
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00:17:27.940
And then at the point where you wake up,
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00:17:30.380
your temperature starts to go up more sharply
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00:17:33.300
and will continue to go up into the early
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00:17:35.820
and sometimes even into the late afternoon.
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00:17:38.580
And then sometime in the late afternoon and evening,
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00:17:41.340
your temperature will start to decline.
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00:17:44.740
And indeed, as you approach sleep,
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00:17:46.720
your body temperature will drop
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00:17:48.220
by anywhere from one to three degrees.
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00:17:50.760
And in fact, that decrease in core body temperature
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00:17:53.980
is important, if not essential,
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00:17:55.700
for getting into and staying in deep sleep, okay?
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00:17:58.980
So temperature rises with waking.
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00:18:01.580
That's easy to remember.
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00:18:02.820
It tends to continue to rise throughout the day.
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00:18:05.580
And in the late afternoon and evening,
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00:18:07.300
your temperature will start to go down
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00:18:09.540
and the drop in temperature actually helps you access sleep.
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00:18:13.860
That background, or what we call baseline circadian rhythm
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00:18:18.260
in core body temperature is important to remember
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00:18:21.160
because it helps us frame both the effects
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00:18:24.300
of deliberate cold exposure
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00:18:26.380
and it helps us frame when you might want
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00:18:29.660
to use deliberate cold exposure
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00:18:31.100
in order to access specific states.
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00:18:33.580
It also points to times within the 24-hour cycle
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00:18:36.740
when you might want to avoid using deliberate cold exposure
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00:18:39.820
if your primary goal is to get to sleep.
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00:18:42.520
Okay, so that's the circadian rhythm in temperature.
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00:18:45.580
Now I just briefly want to touch on thermal regulation
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00:18:48.800
at the level of the body and the brain.
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00:18:51.080
And this will be very surprising to many of you.
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00:18:55.240
Let's do what's called a Gedanken experiment,
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00:18:57.500
which is a thought experiment.
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00:18:58.940
Let's say I send you out into the desert heat
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00:19:01.940
for a jog or a run, and it's very hot outside,
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00:19:05.220
you know, 102 degrees or 103 degrees.
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00:19:08.680
And you start to move, you start to sweat,
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00:19:12.220
and of course your core body temperature goes up.
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00:19:14.860
Now, then I offer you a cold towel,
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00:19:18.840
maybe a really, really cold towel.
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00:19:21.180
And this towel is saturated with water
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00:19:22.820
so you could actually squeeze the water out of that
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00:19:24.700
and cool your body off.
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00:19:26.320
And our Gedanken experiment is for me to say,
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00:19:28.760
okay, where are you going to place the towel?
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00:19:31.460
How are you going to cool yourself off?
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00:19:33.780
And I'm guessing that most of you would think
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00:19:35.860
that the best way to cool yourself off
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00:19:37.560
would be to drape that towel over your head,
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00:19:39.500
maybe your neck, over your torso,
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00:19:41.980
that it would feel really, really good
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00:19:43.280
and they would cool you off.
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00:19:45.340
Well, that's exactly the wrong approach
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00:19:48.220
if you want to cool off.
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00:19:49.300
And in fact, if you were to use that approach,
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00:19:52.060
your body temperature would continue to increase even more,
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00:19:56.580
yes, even more than had you not placed that cold towel
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00:20:00.300
on your head or your torso.
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00:20:02.540
And here is why.
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00:20:04.460
Thermal regulation, meaning your brain and body's ability
link |
00:20:07.380
to regulate your internal core temperature
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00:20:10.900
is somewhat like a thermostat
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00:20:12.500
and that thermostat resides in your brain.
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00:20:15.140
So if you think about the thermostat
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00:20:16.620
in your home or apartment,
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00:20:18.640
if it's too warm in your home or apartment
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00:20:22.540
and you were to take a bag of ice
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00:20:24.940
and to put it on that thermostat,
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00:20:27.600
what would the thermostat do?
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00:20:29.060
It would register the environment as artificially cool.
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00:20:32.620
It would think that the environment
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00:20:34.640
was actually much colder than it is.
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00:20:37.940
And so as a consequence,
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00:20:39.740
it would trigger a mechanism
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00:20:41.000
to further increase the temperature in the room.
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00:20:43.500
And you have such a thermostat as well.
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00:20:45.500
It's called the medial preoptic area of the hypothalamus.
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00:20:48.500
The hypothalamus is a small region of brain tissue
link |
00:20:52.140
about over the roof of your mouth
link |
00:20:54.060
and a little bit in front of that.
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00:20:56.180
So it's basically right behind your nose
link |
00:20:59.500
and over the roof of your mouth.
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00:21:01.200
And it's a collection of neurons.
link |
00:21:02.620
Those neurons have a lot of different functions
link |
00:21:04.500
that include things like the control of aggression,
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00:21:07.500
the control of sex behavior,
link |
00:21:09.200
the control of temperature regulation and so on.
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00:21:11.680
The medial preoptic area has connections
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00:21:14.960
with the rest of the brain
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00:21:17.240
or areas within the brain, I should say,
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00:21:19.060
and with many areas within the body.
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00:21:21.460
It receives input from receptors in our skin
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00:21:26.100
and inside our body that register temperature,
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00:21:29.560
and it acts as a thermostat.
link |
00:21:31.280
So if the surface of your body is made cool,
link |
00:21:34.540
your medial preoptic area will send signals
link |
00:21:38.380
by way of hormones and by way of chemicals
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00:21:41.700
that will serve to heat your body up.
link |
00:21:44.620
So what this means is that if you want to cool down,
link |
00:21:47.220
the last thing you want to do
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00:21:48.980
is to bring a cold surface of any kind,
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00:21:52.780
towel or splashing water,
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00:21:54.560
to the majority of your body surface.
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00:21:57.180
It might be very, very surprising to you.
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00:21:59.080
And you might say, wait, if I want to cool down,
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00:22:00.900
I should jump into a cold lake or something of that sort.
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00:22:02.940
That's a different thing altogether.
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00:22:05.500
What I'll tell you,
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00:22:06.500
and we'll get into this in more depth later,
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00:22:08.260
is that if you really want to cool down
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00:22:09.920
quickly and efficiently,
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00:22:11.340
you should leverage particular portals,
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00:22:14.780
meaning particular sites on your body
link |
00:22:18.160
where heat can leave your body more readily
link |
00:22:21.660
and where cooling can have a dramatic and fast impact
link |
00:22:26.100
on your core body temperature.
link |
00:22:27.160
It can even save your life if you're going hyperthermic.
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00:22:29.400
We're going to talk more about the specific protocols
link |
00:22:31.940
to reduce core body temperature for sake of performance
link |
00:22:34.620
and avoiding hyperthermia later in the episode.
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00:22:37.500
Hyperthermia, of course, is a very, very dangerous situation
link |
00:22:40.580
because while your body can drop in core temperature
link |
00:22:44.160
somewhat and still be safe,
link |
00:22:45.820
you can't really increase your body temperature that much
link |
00:22:48.460
before your brain starts to cook
link |
00:22:50.020
and other organs start to cook and by cook,
link |
00:22:52.040
I mean the cells actually start to die.
link |
00:22:54.140
So you have to be very, very careful with the use of heat.
link |
00:22:56.900
Heat stroke is no joke.
link |
00:22:58.420
People die from heat stroke all the time.
link |
00:23:00.260
You really want to avoid that.
link |
00:23:02.340
One way to avoid that
link |
00:23:04.700
is to cool the appropriate surfaces of your body
link |
00:23:07.540
and the appropriate surfaces in this case
link |
00:23:10.000
are the upper cheeks,
link |
00:23:11.860
or I would say the upper half of the face,
link |
00:23:14.520
the palms of your hands and the bottoms of your feet.
link |
00:23:16.480
I've talked about this on the podcast before
link |
00:23:18.560
and in the guest episode with Dr. Craig Heller,
link |
00:23:20.900
my colleague in the biology department at Stanford,
link |
00:23:23.860
but just very briefly, these surfaces,
link |
00:23:26.460
the upper half of the face,
link |
00:23:28.340
the palms of the hands and the bottoms of the feet
link |
00:23:31.100
are what we call glabrous skin surfaces,
link |
00:23:34.940
G-L-A-B-R-O-U-S, glabrous.
link |
00:23:38.340
And those surfaces are unique in that just below them,
link |
00:23:42.660
the vasculature is different than elsewhere in the body.
link |
00:23:46.100
Normally, the passage of blood goes from arteries
link |
00:23:48.860
to capillaries to veins,
link |
00:23:50.640
but just beneath the glabrous skin
link |
00:23:53.900
on the bottoms of the feet,
link |
00:23:54.740
the hands and the upper half of the face,
link |
00:23:56.260
you have what are called arteriovenous ostomoses.
link |
00:23:59.960
These are portals of blood
link |
00:24:02.260
that go directly from arteries to veins.
link |
00:24:04.160
And in doing so,
link |
00:24:05.540
allow the body to dump heat more readily, more quickly.
link |
00:24:11.940
So as it turns out,
link |
00:24:13.100
that if you are to cool the palms of the hands,
link |
00:24:15.660
the bottoms of the feet and the upper half of the face,
link |
00:24:17.460
you can more efficiently reduce core body temperature
link |
00:24:20.700
for sake of offsetting hyperthermia
link |
00:24:23.220
and for improving athletic performance
link |
00:24:25.420
and maybe even cognitive performance.
link |
00:24:27.300
So we will return to the specific protocols
link |
00:24:29.180
for doing that later in the episode.
link |
00:24:31.280
I'll give you a lot of details about how to do that,
link |
00:24:34.140
how to do that without the use of any fancy
link |
00:24:36.560
or expensive technology.
link |
00:24:38.260
There are some technologies
link |
00:24:39.400
that are now commercially available.
link |
00:24:41.420
For instance, the so-called Coolmit
link |
00:24:43.060
that will allow you to do that with maximum efficiency,
link |
00:24:45.180
but I'll also give you some at-home methods to do this
link |
00:24:48.580
either in the gym or on runs or for sake of cognitive work.
link |
00:24:51.620
Okay, so the two key themes again
link |
00:24:54.220
are understand that baseline circadian rhythm in temperature
link |
00:24:58.480
and understand that the best way to cool the body
link |
00:25:01.740
is going to be by making sure that something cold
link |
00:25:06.500
contacts the bottoms of your feet,
link |
00:25:08.340
the palms of your hands and the upper half of the face.
link |
00:25:10.500
Ideally all three if your goal
link |
00:25:11.860
is to lower core body temperature quickly.
link |
00:25:13.880
And again, just cooling off the back of your neck
link |
00:25:17.120
or the top of your head or your torso with a towel
link |
00:25:19.340
is going to be the least efficient way
link |
00:25:21.360
to lower core body temperature
link |
00:25:22.900
and might even increase body temperature
link |
00:25:25.780
under certain conditions.
link |
00:25:27.060
Okay, with those two points in mind,
link |
00:25:28.820
we can start to think about
link |
00:25:30.060
directed deliberate cold exposure protocols.
link |
00:25:32.660
And there are a number of different reasons
link |
00:25:34.740
to use deliberate cold exposure.
link |
00:25:36.780
And I want to separate those out for you.
link |
00:25:40.000
There are cold protocols that have been tested
link |
00:25:42.820
in peer reviewed studies
link |
00:25:44.060
that are designed to improve mental performance.
link |
00:25:47.140
They are designed to improve things like resilience
link |
00:25:49.820
or your grittiness or your ability to move through challenge
link |
00:25:52.520
or to regulate your mind and your internal state
link |
00:25:56.260
under conditions of stress.
link |
00:25:57.800
And we can define stress very specifically
link |
00:26:00.260
as times when adrenaline also called epinephrine
link |
00:26:04.820
and or norepinephrine also called noradrenaline
link |
00:26:09.260
are elevated in your body.
link |
00:26:10.560
Forgive me for the noradrenaline nor epinephrine
link |
00:26:13.460
adrenaline epinephrine nomenclature.
link |
00:26:15.260
I didn't make that up.
link |
00:26:16.460
It turns out that every once in a while,
link |
00:26:17.860
scientists disagree, imagine that.
link |
00:26:20.060
And you'll get multiple scientists
link |
00:26:21.740
naming the same molecule different things, okay?
link |
00:26:23.780
So epinephrine and adrenaline are the same thing.
link |
00:26:26.620
I will use them interchangeably.
link |
00:26:28.340
Norepinephrine and noradrenaline are the same thing.
link |
00:26:31.180
I will use those terms interchangeably.
link |
00:26:34.360
Noradrenaline and adrenaline
link |
00:26:36.060
are often co-released in the brain and body.
link |
00:26:38.060
So they work as kind of a pair to increase our level
link |
00:26:41.820
of agitation, our level of focus
link |
00:26:44.100
and our desire and our ability to move.
link |
00:26:47.420
They are often co-released from different sides
link |
00:26:50.420
in the brain and body with dopamine,
link |
00:26:52.860
a molecule that is commonly misunderstood
link |
00:26:56.660
as the molecule of pleasure,
link |
00:26:58.000
but is actually the molecule of motivation,
link |
00:27:00.300
reward and pursuit.
link |
00:27:02.720
So dopamine, norepinephrine and noradrenaline
link |
00:27:04.920
tend to be released together under certain conditions.
link |
00:27:08.180
And today you will learn how deliberate cold exposure
link |
00:27:11.140
can be used to cause increases in the release of several,
link |
00:27:15.260
if not all of these,
link |
00:27:16.340
in ways that can improve your levels of attention
link |
00:27:19.460
and your mood.
link |
00:27:20.980
But the key point is that your mental state is shifted
link |
00:27:26.700
when you are exposed to certain forms of cold.
link |
00:27:29.700
And many people use deliberate cold exposure specifically
link |
00:27:33.340
to shift their body state
link |
00:27:35.340
as a way to train their mental state
link |
00:27:37.660
so that they can better cope with stress in real life.
link |
00:27:40.460
And by real life,
link |
00:27:41.280
I mean when life presents stressful events.
link |
00:27:43.900
And I will give you specific protocols
link |
00:27:45.760
as to how you can do that.
link |
00:27:47.140
In other words, how you can become more resilient
link |
00:27:49.640
through the use of deliberate cold exposure.
link |
00:27:52.160
Now, because of the ways in which deliberate cold exposure
link |
00:27:55.380
can increase this category of chemicals
link |
00:27:57.800
called the catecholamines,
link |
00:27:58.900
that includes dopamine, norepinephrine and epinephrine,
link |
00:28:01.700
it can also be used to elevate mood
link |
00:28:05.820
for long periods of time.
link |
00:28:07.700
And I'm going to discuss a specific protocol
link |
00:28:10.080
that has been shown to increase these chemicals
link |
00:28:13.040
anywhere from 2.5X, so 250%,
link |
00:28:17.060
to as high as 500% five times over baseline.
link |
00:28:23.700
Now you might be asking whether or not it's a good thing
link |
00:28:26.300
to raise chemicals like norepinephrine and dopamine
link |
00:28:29.140
to such a great degree,
link |
00:28:31.140
whether or not that's healthy for us,
link |
00:28:32.460
whether or not they can harm us.
link |
00:28:34.060
But it turns out that these elevations
link |
00:28:36.020
in norepinephrine and dopamine are very long lasting
link |
00:28:39.000
in ways that people report feeling vast improvements in mood
link |
00:28:43.580
and vast improvements in levels of cognitive attention
link |
00:28:47.660
and energy.
link |
00:28:48.720
So by my read of the literature,
link |
00:28:50.880
these seem to be healthy increases
link |
00:28:52.980
in our baseline levels of these chemicals
link |
00:28:56.540
in ways that can really support us.
link |
00:28:57.740
So I'll give you a protocol for that.
link |
00:28:59.780
Now, those are some of the mental effects
link |
00:29:01.720
of deliberate cold exposure.
link |
00:29:03.180
But deliberate cold exposure has also been studied
link |
00:29:05.460
in animal models and in humans
link |
00:29:07.020
in the context of increasing metabolism.
link |
00:29:09.820
Even in converting certain fat cells
link |
00:29:12.940
that we call white fat cells,
link |
00:29:14.280
which are the ones where energy is stored,
link |
00:29:16.080
they're the ones that we typically think of
link |
00:29:17.420
as kind of blubbery fat,
link |
00:29:19.440
to beige or brown fat, which is thermogenic fat,
link |
00:29:23.280
meaning that it can increase core body temperature
link |
00:29:25.380
and serves as kind of the furnace
link |
00:29:27.640
by which we increase our core metabolism.
link |
00:29:31.020
So with a very broad stroke,
link |
00:29:33.140
I can say that white fat is generally the kind of fat
link |
00:29:35.620
that people want less of,
link |
00:29:37.060
and beige fat and brown fat is generally the kind of fat
link |
00:29:40.140
that if you're going to have fat cells
link |
00:29:42.540
and you certainly need fat cells that you want more of.
link |
00:29:45.300
They are thermogenic.
link |
00:29:46.180
They help you stay lean.
link |
00:29:47.560
They actually serve as a reservoir for heating your body up
link |
00:29:50.100
if you're ever confronted with a cold challenge.
link |
00:29:52.140
So we're going to talk about how to use cold
link |
00:29:53.920
for metabolism as well.
link |
00:29:55.540
And of course, people are using deliberate cold exposure
link |
00:29:57.920
to reduce inflammation post-exercise,
link |
00:29:59.980
to reduce inflammation generally,
link |
00:30:02.660
and people are also using cold to enhance performance
link |
00:30:06.500
in the context of strength training,
link |
00:30:08.540
in the context of endurance training,
link |
00:30:10.100
and we'll talk about those data as well.
link |
00:30:12.440
But where I'd like to start is with mental performance,
link |
00:30:14.920
and I'd like to detail what happens
link |
00:30:18.280
when we deliberately expose ourselves to cold.
link |
00:30:21.420
It's key to point out the word deliberate.
link |
00:30:24.620
If I don't say otherwise, then throughout this episode,
link |
00:30:27.620
if I say cold exposure, I mean deliberate cold exposure.
link |
00:30:30.720
And the reason I point that out is that as my colleague,
link |
00:30:33.060
David Spiegel in the Department of Psychiatry at Stanford
link |
00:30:35.180
says, it's not just about the state that we are in,
link |
00:30:38.540
it's about the state that we are in
link |
00:30:39.940
and whether or not we had anything to do
link |
00:30:41.700
with placing ourselves into that state
link |
00:30:43.900
and whether or not we did that on purpose or not.
link |
00:30:45.880
And what he really means by that statement
link |
00:30:48.660
is that there are important effects
link |
00:30:51.380
of what we call mindset.
link |
00:30:53.080
Mindset was a topic discussed in the guest episode
link |
00:30:56.340
with Ali Krum some weeks ago.
link |
00:30:58.620
If you haven't seen that episode, I highly recommend it.
link |
00:31:01.220
And the science of mindset tells us
link |
00:31:03.400
that if we are doing something deliberately
link |
00:31:06.180
and we believe that it's going to be good for us,
link |
00:31:08.580
it actually can lead to a different set
link |
00:31:11.420
of physiological effects than if something is happening
link |
00:31:15.720
to us against our will or without our control.
link |
00:31:18.820
Now, this is different than placebo effects.
link |
00:31:20.620
Placebo effects are distinct from mindset effects.
link |
00:31:23.860
If you want to learn more about that distinction,
link |
00:31:25.320
please see the episode with Ali Krum.
link |
00:31:27.260
But again, when I talk about cold exposure in this episode,
link |
00:31:30.340
I'm talking about deliberate cold exposure,
link |
00:31:33.240
meaning that you are placing yourself
link |
00:31:35.260
into a cold environment on purpose
link |
00:31:37.660
in order to extract a particular set of benefits.
link |
00:31:42.460
When we talk about deliberate cold exposure,
link |
00:31:44.960
almost always that means getting uncomfortable.
link |
00:31:48.060
And one of the most common questions I get
link |
00:31:50.060
when discussing the use of cold for sake of mental
link |
00:31:52.660
or physical performance, metabolism, et cetera,
link |
00:31:54.680
is how cold should it be?
link |
00:31:57.300
How cold should the water be?
link |
00:31:58.440
How cold should the environment be?
link |
00:32:00.900
And I just will tell you now,
link |
00:32:02.260
and I'm going to say this again and again
link |
00:32:03.720
throughout the episode,
link |
00:32:04.560
because it will continue to be true throughout the episode
link |
00:32:06.820
and long after the episode is over,
link |
00:32:09.580
how cold depends on your cold tolerance,
link |
00:32:12.820
your core metabolism, and a number of other features
link |
00:32:15.900
that there is simply no way I could know or have access to.
link |
00:32:20.440
So I would like you to use this rule of thumb.
link |
00:32:24.580
If you are using deliberate cold exposure,
link |
00:32:27.340
the environment that you place yourself into
link |
00:32:30.780
should place your mind into a state of,
link |
00:32:33.340
whoa, I would really like to get out of this environment,
link |
00:32:36.820
but I can stay in safely.
link |
00:32:39.240
Okay, now that might seem a little bit arbitrary,
link |
00:32:41.220
but let's say you were to get into a warm shower
link |
00:32:43.560
and it would feel really, really nice,
link |
00:32:45.140
and you were to start turning down the warm
link |
00:32:47.100
and turning up the cold,
link |
00:32:48.360
there would be some threshold
link |
00:32:49.700
at which it would feel uncomfortable to you.
link |
00:32:52.560
And if you were to continue
link |
00:32:53.700
to make a little bit colder than that,
link |
00:32:55.540
you would really want to get out of the shower,
link |
00:32:57.580
but you were confident that you could stay in
link |
00:33:00.120
without risking your health, right?
link |
00:33:02.580
Without risking a heart attack.
link |
00:33:04.040
Now that's very different
link |
00:33:05.060
than jumping into a very, very cold lake,
link |
00:33:07.820
or I've seen these images of people
link |
00:33:10.560
that will cut holes into frozen over lakes
link |
00:33:13.700
and they'll get into that cold water.
link |
00:33:16.000
If you are trained to do that
link |
00:33:17.200
and you have the right conditions, et cetera,
link |
00:33:19.140
that can be done reasonably safely,
link |
00:33:21.220
but that's certainly not what I would start with.
link |
00:33:23.740
And for many people, that will be too cold.
link |
00:33:25.540
And indeed, some people can go into cold shock
link |
00:33:28.620
and can die as a consequence of getting
link |
00:33:30.140
to that extremely cold water very quickly.
link |
00:33:32.220
Now that's not to scare you away
link |
00:33:33.400
from deliberate cold exposure.
link |
00:33:34.860
It's just to say that there's no simple prescriptive
link |
00:33:38.260
of how cold to make the environment
link |
00:33:39.820
in order to extract maximum benefit for mental
link |
00:33:43.840
or physical performance.
link |
00:33:46.220
So the simple rule of thumb is going to be,
link |
00:33:49.220
place yourself into an environment
link |
00:33:51.120
that is uncomfortably cold,
link |
00:33:53.540
but that you can stay in safely, okay?
link |
00:33:55.260
And you'll have to experiment a bit.
link |
00:33:56.380
And that number, meaning that temperature
link |
00:33:58.860
will vary from day to day.
link |
00:34:00.180
It will vary across the 24 hour cycle
link |
00:34:03.420
because of that endogenous, meaning that internal rhythm
link |
00:34:06.880
in temperature that I talked about earlier,
link |
00:34:09.200
low early in the day, rises into the afternoon,
link |
00:34:11.300
drops at night.
link |
00:34:12.460
You can actually do this experiment if you like.
link |
00:34:14.860
Try getting into a cold shower at 11 o'clock at night,
link |
00:34:17.700
if you want, versus try doing it
link |
00:34:20.480
in the middle of the afternoon.
link |
00:34:21.980
It's quite a different experience.
link |
00:34:24.260
And by quite a different experience,
link |
00:34:25.580
I mean it requires quite a different degree of resilience
link |
00:34:29.580
and leaning into the practice.
link |
00:34:31.060
Your willpower will have to be higher, I suspect,
link |
00:34:35.620
late in the day as compared to early in the day.
link |
00:34:39.800
But that will vary, of course, between individuals as well.
link |
00:34:42.700
So the most common question I get
link |
00:34:43.940
about deliberate cold exposure is,
link |
00:34:45.800
how cold should the water be?
link |
00:34:48.060
And we've answered that with uncomfortably cold
link |
00:34:50.820
to the point where you want to get out,
link |
00:34:51.920
but you can safely stay in.
link |
00:34:53.780
The second most common question I get
link |
00:34:55.480
about deliberate cold exposure is whether or not
link |
00:34:57.840
cold showers are as good, better,
link |
00:35:00.140
or worse than cold water immersion up to the neck.
link |
00:35:03.420
For instance, I also get a lot of questions
link |
00:35:05.400
about whether or not cryo chambers are better
link |
00:35:08.180
than all the others, et cetera, et cetera.
link |
00:35:10.260
I'm going to make all of that very simple for you
link |
00:35:12.700
by saying cold water immersion up to the neck
link |
00:35:15.580
with your feet and hands submerged also
link |
00:35:18.220
is going to be the most effective.
link |
00:35:20.940
Second best would be cold shower.
link |
00:35:23.700
Third best would be to go outside
link |
00:35:26.020
with a minimum amount of clothing,
link |
00:35:28.700
but of course clothing that is culturally appropriate
link |
00:35:32.060
and that would allow you to experience cold
link |
00:35:35.100
to the point where you would almost want to shiver
link |
00:35:37.040
or start shivering.
link |
00:35:38.420
Now, there are a number of different important constraints
link |
00:35:41.340
that are going to dictate whether or not you use
link |
00:35:43.340
one form of cold exposure or the other.
link |
00:35:45.380
For instance, some people don't have access
link |
00:35:46.980
to cold water immersion.
link |
00:35:48.000
They don't have access to ice baths or cold water tanks,
link |
00:35:53.140
cold ocean or cold lakes, et cetera.
link |
00:35:55.180
In that case, showers would be the next best solution.
link |
00:35:58.760
I do want to emphasize that there have been very few,
link |
00:36:01.180
if any, studies of cold showers,
link |
00:36:04.360
and you can imagine why this would be the case.
link |
00:36:07.220
In a laboratory, you want to control
link |
00:36:08.620
for as many variables as possible.
link |
00:36:10.980
So placing people into a cold water immersion
link |
00:36:15.440
or an ice bath up to the neck and insisting
link |
00:36:17.260
that they keep their hands and feet under
link |
00:36:19.420
is very easy to control.
link |
00:36:21.240
It means that everyone can do essentially the same thing.
link |
00:36:23.580
Whereas with cold showers, people are different size bodies.
link |
00:36:27.280
Some people are going to put their head under.
link |
00:36:28.580
Some people are going to lean forward.
link |
00:36:31.260
Measuring the amount of cold water exposure on the body
link |
00:36:33.980
is very hard to do.
link |
00:36:35.180
And so there aren't a lot of studies of cold showers,
link |
00:36:38.220
but of course, a lot of people don't have access
link |
00:36:40.540
to cold water immersion, so they have to use cold showers.
link |
00:36:43.420
And if you don't have access to both, of course,
link |
00:36:45.400
then going outside on a cold day can be of benefit.
link |
00:36:49.500
But I will point out that the heat transfer
link |
00:36:53.400
from your body into water is much higher,
link |
00:36:56.980
four times greater, if not even greater,
link |
00:37:00.720
depending on the temperature of the water,
link |
00:37:02.400
in water, as opposed to in air.
link |
00:37:04.360
So it's going to be much more efficient
link |
00:37:05.900
to do cold water immersion than anything else,
link |
00:37:07.760
cold showers after that,
link |
00:37:09.140
and put yourself into a cold environment
link |
00:37:11.680
would be the third best thing.
link |
00:37:13.380
I'm not going to get into cryochambers
link |
00:37:15.000
because they carry quite a high degree of cost.
link |
00:37:18.240
And again, there aren't many studies of them.
link |
00:37:20.620
So if you have access to cryochambers,
link |
00:37:23.060
I'm sure that the cryochamber facility
link |
00:37:24.740
has told you about all these incredible benefits,
link |
00:37:26.340
and I don't doubt that some of those benefits truly exist,
link |
00:37:29.040
but most people just don't have the resources
link |
00:37:31.340
or the access to those.
link |
00:37:32.380
So we're going to leave cryochambers
link |
00:37:33.640
out of today's discussion.
link |
00:37:34.940
And of course, I realize there's a fourth category
link |
00:37:37.100
of cold exposure out there.
link |
00:37:38.400
People who are wearing ice vests,
link |
00:37:39.860
believe it or not, those exist.
link |
00:37:40.860
Ice underwear, yes, those exist.
link |
00:37:44.340
You can look for them on Amazon if you like.
link |
00:37:46.740
They are putting cold packs in their armpits
link |
00:37:49.340
or in their groin or elsewhere
link |
00:37:50.660
in order to stimulate some of the effects of cold
link |
00:37:54.460
on mental and physical performance.
link |
00:37:56.780
I'm not going to address those in too much detail today.
link |
00:37:59.940
They can be efficient in certain ways,
link |
00:38:02.420
but as you'll learn about later in the episode,
link |
00:38:04.900
cooling the palms, the upper face,
link |
00:38:07.460
and the bottoms of the feet
link |
00:38:08.620
is going to be far more efficient.
link |
00:38:10.400
And unfortunately, I think most of the people
link |
00:38:12.860
that are using ice packs to increase their core metabolism
link |
00:38:15.360
are not aware of the glabber skin cooling
link |
00:38:18.420
and how it can be a very, very potent stimulus.
link |
00:38:20.820
So we'll return to that later.
link |
00:38:23.100
Unless I say otherwise, I'm mainly going to be focusing
link |
00:38:25.820
on cold water immersion and cold showers.
link |
00:38:28.000
So let's talk about protocols for enhancing mental health
link |
00:38:30.820
and performance using deliberate cold exposure.
link |
00:38:34.460
What happens when we get into cold
link |
00:38:37.460
is that we experience an increase in norepinephrine,
link |
00:38:41.440
in noradrenaline release and in adrenaline release.
link |
00:38:44.500
The fact that cold exposure, deliberate or no,
link |
00:38:47.180
increases norepinephrine and epinephrine
link |
00:38:50.140
in our brain and body
link |
00:38:51.740
means that it is a very reliable stimulus
link |
00:38:54.380
for increasing norepinephrine and epinephrine.
link |
00:38:56.540
That's sort of an obvious statement,
link |
00:38:58.400
but that obvious statement can be leveraged
link |
00:39:02.020
to systematically build up what we call resilience.
link |
00:39:05.540
Now, when we experience a stressor in life,
link |
00:39:08.660
whether or not it's something bad happens
link |
00:39:10.820
in our relationship or something bad happens in the world,
link |
00:39:14.220
and we feel stress, that stress is the consequence
link |
00:39:17.820
of increases in norepinephrine and epinephrine
link |
00:39:21.020
in our brain and body.
link |
00:39:21.980
Very similar, if not identical,
link |
00:39:23.660
to the kinds of increases
link |
00:39:24.720
that come from deliberate cold exposure.
link |
00:39:27.180
So deliberate cold exposure is an opportunity
link |
00:39:29.940
to deliberately stress our body.
link |
00:39:32.940
And yet, because it's deliberate
link |
00:39:34.520
and because we can take certain steps,
link |
00:39:36.000
which I'll describe in a moment,
link |
00:39:38.340
we can learn to maintain mental clarity.
link |
00:39:41.860
We can learn to maintain calm
link |
00:39:44.300
while our body is in a state of stress.
link |
00:39:47.500
And that can be immensely useful
link |
00:39:49.800
when encountering stressors in other parts of life.
link |
00:39:53.300
And that's what we call resilience or grit,
link |
00:39:55.540
our ability or mental toughness,
link |
00:39:57.460
our ability to lean into challenge or to tolerate challenge
link |
00:40:01.580
while keeping our heads straight, so to speak.
link |
00:40:04.140
So one simple protocol for increasing resilience
link |
00:40:07.700
is to pick a temperature that's uncomfortable,
link |
00:40:10.400
of shower or cold immersion,
link |
00:40:12.540
and then to get in for a certain duration of time,
link |
00:40:15.820
and then to get out.
link |
00:40:17.200
Now, it's important to understand
link |
00:40:18.220
that people will experience different levels
link |
00:40:20.160
of norepinephrine and adrenaline release
link |
00:40:22.320
when getting into cold water.
link |
00:40:24.140
Some people, because they dread the cold so much,
link |
00:40:27.980
will actually experience norepinephrine
link |
00:40:29.900
and epinephrine increases
link |
00:40:31.040
even before they get into the cold water
link |
00:40:33.580
or under the cold shower.
link |
00:40:35.100
Now, you may have experienced this.
link |
00:40:36.220
I've certainly experienced this.
link |
00:40:37.900
I'm dreading it, I don't want to do it,
link |
00:40:39.540
and I have to force myself to do it.
link |
00:40:41.820
And indeed, epinephrine and norepinephrine and its surges
link |
00:40:45.580
can be thought of as sort of walls
link |
00:40:47.840
that we have to confront and go over.
link |
00:40:49.920
And I'd like you to conceptualize them that way
link |
00:40:52.020
because it allows us to build protocols
link |
00:40:54.580
that can be very objective
link |
00:40:57.300
and can allow us to monitor our progress
link |
00:40:59.400
in terms of building resilience.
link |
00:41:01.260
So one option is to simply say,
link |
00:41:03.780
okay, I'm going to force myself
link |
00:41:05.260
to get into the cold shower for one minute.
link |
00:41:07.700
How cold?
link |
00:41:08.540
Again, uncomfortably cold, but you can stay in safely.
link |
00:41:10.420
Or I'm going to get into the ice bath for one minute.
link |
00:41:13.680
Ice baths are very cold inevitably.
link |
00:41:16.820
And what is also inevitable is that when you get
link |
00:41:20.020
into the cold, you will experience a surge
link |
00:41:22.360
in epinephrine and norepinephrine.
link |
00:41:24.080
That's non-negotiable because it's mediated
link |
00:41:26.660
by cold receptors on the surface of your body and your skin
link |
00:41:30.060
and the way that they trigger the release
link |
00:41:32.060
of norepinephrine and epinephrine,
link |
00:41:33.580
not just from the adrenals,
link |
00:41:35.260
from the adrenal glands above your kidneys,
link |
00:41:37.220
but also from regions of your brain,
link |
00:41:38.780
like the locus coeruleus,
link |
00:41:39.940
which cause increases in attention and alertness,
link |
00:41:42.900
and from other locations in your body
link |
00:41:45.260
where epinephrine and norepinephrine are released.
link |
00:41:47.140
In other words, cold is a non-negotiable stimulus
link |
00:41:51.740
for increasing epinephrine and norepinephrine.
link |
00:41:55.100
Even if you are the toughest person in the world
link |
00:41:57.980
and you love the cold, that increase in epinephrine
link |
00:42:01.780
and norepinephrine is going to happen.
link |
00:42:04.020
So the way to think about norepinephrine and epinephrine
link |
00:42:06.700
in this context of building mental resilience
link |
00:42:09.220
is that you have two options.
link |
00:42:11.440
You can either try to extend the duration of time
link |
00:42:15.340
that you are in the deliberate cold exposure.
link |
00:42:17.440
So going from one minute to 75 seconds to two minutes
link |
00:42:20.980
and so on over a period of days,
link |
00:42:23.380
or one way to approach this
link |
00:42:26.120
and the way that I particularly favor
link |
00:42:27.840
is to take the context of the day and the moment
link |
00:42:31.540
into account, meaning we have different levels of grit
link |
00:42:35.020
and resilience on different days
link |
00:42:37.160
and depending on the landscape of our life at the time,
link |
00:42:39.740
even the time of day that we're doing these protocols,
link |
00:42:42.100
and start to be able to sense the release
link |
00:42:45.540
of epinephrine, excuse me,
link |
00:42:47.380
and norepinephrine in our brain and body,
link |
00:42:49.620
and see those as walls that we want to climb over
link |
00:42:52.500
in order to build resilience,
link |
00:42:53.900
and to start counting the number of walls that we traverse
link |
00:42:57.900
and the distance between those walls
link |
00:42:59.760
as we do deliberate cold exposure.
link |
00:43:01.680
Let me give you an example of the timed protocol
link |
00:43:05.260
because that one is very straightforward,
link |
00:43:06.840
although I do not think it is as powerful
link |
00:43:09.560
for building mental resilience.
link |
00:43:11.000
The time protocol would be Monday,
link |
00:43:12.880
I do one minute of deliberate cold exposure
link |
00:43:15.320
at a given temperature.
link |
00:43:16.160
Wednesday, I extend that by 50%.
link |
00:43:18.400
And Friday, I do deliberate cold exposure
link |
00:43:21.680
for twice as long as I did on Monday.
link |
00:43:23.800
And if I were to continue that every week,
link |
00:43:26.200
Monday, Wednesday, Friday,
link |
00:43:27.060
I would continue to either increase the duration
link |
00:43:29.480
or I would lower the temperature and reduce the duration,
link |
00:43:34.120
this kind of thing,
link |
00:43:34.960
very much like sets and reps in the gym.
link |
00:43:36.480
Now that option is very objective, right?
link |
00:43:38.680
You could even log it in a book.
link |
00:43:40.280
And as you develop the ability to stay in cold temperatures,
link |
00:43:46.120
even progressively colder and colder temperatures
link |
00:43:48.160
for longer and longer periods of time,
link |
00:43:50.200
you will become more resilient.
link |
00:43:52.440
What do I mean by that?
link |
00:43:53.600
Well, my operational definition of resilience
link |
00:43:55.600
is that you are able to resist escape from the stressor,
link |
00:43:59.120
the cold, by virtue of your willpower,
link |
00:44:02.880
which is really your prefrontal cortex
link |
00:44:05.760
causing top-down control on your reflexes
link |
00:44:08.800
and your limbic system and your hypothalamus,
link |
00:44:10.800
which are basically telling you
link |
00:44:11.820
to get out of that cold water,
link |
00:44:13.920
get out of that cold environment.
link |
00:44:16.040
And in doing so, you are basically getting better
link |
00:44:19.000
at controlling your behavior when your brain and body
link |
00:44:21.840
are flooded with norepinephrine and epinephrine.
link |
00:44:24.000
That's a very reductionist way to explain resilience
link |
00:44:26.600
or grit or mental toughness,
link |
00:44:28.100
but it's a reductionist way of explaining it
link |
00:44:30.500
that is very closely tied to the biology
link |
00:44:32.320
and to the psychology.
link |
00:44:33.640
And it is a fact that norepinephrine and epinephrine release
link |
00:44:38.160
in the brain and body
link |
00:44:39.160
are the generic universal code for stressor.
link |
00:44:43.500
There is no unique chemical signature
link |
00:44:45.480
for different forms of stressors.
link |
00:44:46.840
That is the only one.
link |
00:44:48.380
Although, of course,
link |
00:44:49.220
there are other chemicals involved as well.
link |
00:44:50.800
So you could go for time
link |
00:44:52.200
and you could try and reduce the temperature
link |
00:44:53.720
and increase the time over a period of days or weeks.
link |
00:44:57.440
Now that's an attractive way to approach things,
link |
00:45:00.000
but the problem is that you don't have
link |
00:45:02.180
an infinite amount of room with which to lower temperature
link |
00:45:06.000
because eventually you will get into temperatures
link |
00:45:08.100
that are either so-called that they are dangerous,
link |
00:45:10.840
or you have to stay in cold temperatures
link |
00:45:13.360
for such long periods that it becomes impractical
link |
00:45:16.940
because presumably you also have to
link |
00:45:18.920
take care of other aspects of your life.
link |
00:45:20.440
You can't just sit all day in the ice bath.
link |
00:45:23.020
Now, for that reason,
link |
00:45:24.220
I favor a protocol in which you build mental resilience
link |
00:45:27.600
and mental toughness
link |
00:45:28.760
through two different types of protocols.
link |
00:45:31.060
The first one involves counting walls.
link |
00:45:33.380
Now, what do I mean by walls?
link |
00:45:34.400
I mean, the sensation of, no, I don't want to do this,
link |
00:45:38.640
and the idea or the sensation in your brain and body
link |
00:45:42.520
that you actually want to leave that environment
link |
00:45:44.320
and go warm up.
link |
00:45:45.520
Now, again, for some people,
link |
00:45:46.680
that will be even before getting into
link |
00:45:48.520
the ice bath or cold shower.
link |
00:45:50.080
So if you are feeling very resistant
link |
00:45:52.700
to getting into the ice bath or cold shower
link |
00:45:54.800
and you manage to do that,
link |
00:45:56.320
that's going over what I would call one wall, okay?
link |
00:46:00.180
Then for some period of time,
link |
00:46:01.640
you might actually feel comfortable in the ice bath,
link |
00:46:05.560
cold water, or cold shower,
link |
00:46:07.760
and you feel like you could stay there
link |
00:46:09.520
for some period of time,
link |
00:46:10.420
that you could stay there for a minute or two minutes,
link |
00:46:12.240
but inevitably the next wall will arrive.
link |
00:46:15.840
And I would encourage you to pay attention
link |
00:46:17.620
to when that next wall arrives
link |
00:46:19.300
and actually having an awareness,
link |
00:46:20.960
that so-called interoceptive awareness, as we call it,
link |
00:46:24.340
of when that next surge in adrenaline epinephrine comes
link |
00:46:27.640
or whether or not it reaches a certain threshold
link |
00:46:30.360
in your brain and body that you feel you want to get out,
link |
00:46:32.400
and you're able to stay in for even just 10 seconds longer,
link |
00:46:36.240
that means you've traversed yet another wall.
link |
00:46:39.240
And if you continue to stay in that cold environment,
link |
00:46:42.140
you will find that the next wall will come
link |
00:46:44.120
and the next wall will come.
link |
00:46:45.040
Now, eventually, of course, you will get very, very numb,
link |
00:46:48.260
depending on how cold it is,
link |
00:46:49.360
and you could also place yourself into danger.
link |
00:46:51.180
So you have to maintain cognitive control,
link |
00:46:54.000
counting these walls, traversing these walls,
link |
00:46:56.260
but getting out at some point, of course.
link |
00:46:59.120
So my favorite protocol for building mental toughness,
link |
00:47:03.880
AKA grit, AKA resilience, is to take into account
link |
00:47:07.440
that some days just getting into the ice bath
link |
00:47:10.120
or cold shower represents a wall.
link |
00:47:11.560
Some days it doesn't.
link |
00:47:12.640
Some days you get in
link |
00:47:13.480
and you feel like you could go 10 minutes.
link |
00:47:15.700
Other days you get in
link |
00:47:16.540
and you feel like you could only go a minute.
link |
00:47:18.640
And setting a designated number of walls
link |
00:47:20.880
before you start the protocol
link |
00:47:22.980
is going to be very beneficial here.
link |
00:47:24.640
So you say, as long as I can do it safely,
link |
00:47:27.060
I'm going to do three walls today.
link |
00:47:29.360
The first wall is getting in,
link |
00:47:30.480
the second wall will arrive when it arrives,
link |
00:47:32.760
and the third wall will arrive when it arrives,
link |
00:47:35.380
and I'll get over that wall and then I'll get out.
link |
00:47:37.080
The next day, you might do five walls.
link |
00:47:38.700
The next day, you might do three walls again,
link |
00:47:41.920
but you might lower the temperature.
link |
00:47:43.480
This gives you tremendous flexibility,
link |
00:47:45.880
and indeed, it gives you much more latitude
link |
00:47:48.800
to be able to use the same temperatures in different ways,
link |
00:47:52.480
or to reduce the temperature only a little bit
link |
00:47:54.700
and still get a lot of stimulus,
link |
00:47:56.760
meaning a lot of results out of a given protocol.
link |
00:48:00.140
Whereas people who are just going for temperature and time
link |
00:48:02.880
eventually become cold adapted.
link |
00:48:04.920
They get very, very good at doing three minutes
link |
00:48:07.760
or six minutes or even 10 minutes at a given temperature.
link |
00:48:10.720
And so then they feel like they have to lower the temperature
link |
00:48:12.880
even more and even more,
link |
00:48:14.480
and eventually they just bottom out.
link |
00:48:16.240
There's nowhere else to go.
link |
00:48:17.280
There's nowhere to get improvements out of the protocol,
link |
00:48:21.100
at least not in terms of mental resilience.
link |
00:48:24.240
Of course, there's still the positive effects on inflammation
link |
00:48:27.480
and metabolism, et cetera,
link |
00:48:28.520
that we'll talk about in a little bit.
link |
00:48:30.800
But the key thing here is to design protocols
link |
00:48:33.520
that are going to work for you over time.
link |
00:48:35.600
And for you very, very hardy,
link |
00:48:37.380
very, very tough guys and gals out there
link |
00:48:39.520
that can get right into an ice bath
link |
00:48:41.520
or a very, very cold immersion,
link |
00:48:43.080
and you can just grind it out for six or 10 minutes,
link |
00:48:45.480
or you can even do that by remaining peaceful.
link |
00:48:48.680
Well, more points to you, but guess what?
link |
00:48:51.060
That's the equivalent of already having loaded up
link |
00:48:53.240
the barbell with 600 pounds and done your 10 reps.
link |
00:48:56.320
There's not a whole lot more variable space
link |
00:48:58.960
with which to get benefits from that stimulus.
link |
00:49:02.300
And in the weight room,
link |
00:49:03.400
people understand that you can adjust, for instance,
link |
00:49:05.280
the speed of the movement,
link |
00:49:06.480
or you can start combining that movement
link |
00:49:07.960
with pre-exhaustion, et cetera.
link |
00:49:09.620
With cold exposure,
link |
00:49:11.080
you don't have as much variable space to play with.
link |
00:49:13.580
So if your goal is to build resilience,
link |
00:49:15.660
either go for time as a function of temperature,
link |
00:49:18.520
or what I suggest is to start recognizing these walls
link |
00:49:23.240
as an experience of resistance in you
link |
00:49:25.920
and going over those walls,
link |
00:49:27.400
set a certain number of walls
link |
00:49:28.840
that you're going to go over on a given day
link |
00:49:31.320
and do that at a given temperature,
link |
00:49:32.760
and then to mix it up.
link |
00:49:34.680
And ideally, you might even throw in one more wall
link |
00:49:38.440
at the end if you're really feeling bold and brave,
link |
00:49:41.120
because that's going to build out further resilience.
link |
00:49:43.460
But if you want cold exposure to work for you
link |
00:49:45.500
for sake of building up resilience
link |
00:49:46.920
and mental toughness over time,
link |
00:49:48.500
you're going to want to vary this parameter space
link |
00:49:51.360
in some sort of way,
link |
00:49:52.760
and you don't have to be super systematic about it.
link |
00:49:56.080
That's the beauty of this kind of approach,
link |
00:49:58.320
because you're relying on the fact
link |
00:49:59.920
that those walls really represent times
link |
00:50:02.880
in which you are forcing your top-down control,
link |
00:50:05.400
your prefrontal cortex, to clamp down on your reflex,
link |
00:50:08.160
and you're learning behavioral control
link |
00:50:10.240
in the context of your body having elevated levels
link |
00:50:12.960
of these catecholamines, norepinephrine and epinephrine.
link |
00:50:15.520
And that translates to real life
link |
00:50:17.500
in a much more realistic way, I believe,
link |
00:50:19.880
because in real life,
link |
00:50:21.520
you're not really engaging in stressors
link |
00:50:24.280
for a given amount of time
link |
00:50:26.240
that you know how long it's going to last,
link |
00:50:28.000
and you know the context.
link |
00:50:28.920
No, most stressors arrive in the form of surprises
link |
00:50:31.800
we don't like, text messages that deliver bad news,
link |
00:50:34.800
information about the outside world
link |
00:50:36.640
or real world and online interactions
link |
00:50:38.880
that send our system into a state
link |
00:50:40.680
of increasing norepinephrine and epinephrine.
link |
00:50:42.800
And if you start to think of those as walls
link |
00:50:44.620
that you can tolerate and climb over
link |
00:50:46.060
while staying calm and clear of mind,
link |
00:50:48.480
then you can really imagine how the ice bath
link |
00:50:52.120
and other forms of cold exposure
link |
00:50:53.760
are really serving to train you up for real life stressors.
link |
00:50:57.760
Okay, the next question that I always get
link |
00:50:59.620
is what should my mental state be
link |
00:51:02.180
while I'm exposing myself to this uncomfortable
link |
00:51:04.920
yet safe condition of cold?
link |
00:51:07.640
Well, you have two options,
link |
00:51:09.560
and there are probably other options as well.
link |
00:51:11.600
One is to try and calm yourself
link |
00:51:13.960
to remain as mentally still as possible.
link |
00:51:17.640
The other is to lean into that challenge
link |
00:51:21.080
and so to grind it out.
link |
00:51:22.600
And here, I have to say that this is a lot
link |
00:51:24.760
like teaching someone to drive on a gravel road.
link |
00:51:27.360
For any of you that have driven on a gravel road,
link |
00:51:29.880
you know that there is no optimal speed
link |
00:51:32.840
for all gravel roads.
link |
00:51:33.960
It depends on the density, the gravel, et cetera,
link |
00:51:36.120
and the vehicle, et cetera.
link |
00:51:37.720
So for instance, on some gravel roads,
link |
00:51:40.100
when you start to drive and the dust starts to kick up,
link |
00:51:42.960
your best option is to drive fast
link |
00:51:44.660
and put that dust cloud behind you.
link |
00:51:46.680
On other gravel roads, if you try and do that,
link |
00:51:49.080
the dust actually kicks up around the vehicle
link |
00:51:50.760
and it makes it hard to see,
link |
00:51:51.960
and sometimes you have to slow down.
link |
00:51:53.920
The same thing is true for getting
link |
00:51:55.520
through deliberate cold exposure.
link |
00:51:57.480
Sometimes it's easier to calm yourself.
link |
00:51:59.480
One way to do that is through double inhales
link |
00:52:01.700
through the nose and extended exhales through the mouth,
link |
00:52:03.960
or simply by trying to control your breathing
link |
00:52:06.760
and reduce the pace of your breathing
link |
00:52:08.680
and increase the volume of your breathing.
link |
00:52:11.200
I have to say that everyone experiences
link |
00:52:14.880
a shortening of breath
link |
00:52:15.780
when they get into uncomfortably cold water.
link |
00:52:18.300
That is a universal physiological response.
link |
00:52:21.580
Everyone also experiences a 30 to 80% decrease
link |
00:52:26.160
in cognitive function,
link |
00:52:27.480
in particular of the frontal cortex.
link |
00:52:29.400
The metabolism of your frontal cortex goes down,
link |
00:52:31.400
the metabolism, meaning the activity of brain areas
link |
00:52:34.400
associated with stress and panic goes way up.
link |
00:52:36.920
And so anchoring your mind in cognitive activities
link |
00:52:41.400
as you get into the cold can be very, very helpful
link |
00:52:44.180
for maintaining clarity of mind.
link |
00:52:46.800
In fact, one thing that I sometimes recommend
link |
00:52:48.780
is that people try and engage
link |
00:52:50.640
in some sort of cognitive exercise while in the cold,
link |
00:52:53.680
not as a form of distraction,
link |
00:52:55.560
but as a way to maintain clarity of thinking
link |
00:52:57.600
and to learn how to do that when the body is flooded
link |
00:52:59.840
with all these chemicals that make us stressed.
link |
00:53:02.240
So for instance, you could do math problems
link |
00:53:04.200
and not two plus two equals four,
link |
00:53:06.000
not three times three equals nine,
link |
00:53:08.200
but things that require a little bit more focus
link |
00:53:10.700
and attention, working memory and so forth.
link |
00:53:13.360
You could also start to have thoughts
link |
00:53:16.440
that you deliberately impose a full sentence structure on.
link |
00:53:20.560
That's actually quite tough.
link |
00:53:22.120
You could try and recall specific bouts of information
link |
00:53:25.280
that are challenging.
link |
00:53:26.120
This is teaching your mind how to stay online,
link |
00:53:29.240
or rather I should say,
link |
00:53:30.080
this is you teaching your prefrontal cortex
link |
00:53:32.460
how to stay engaged
link |
00:53:33.980
while you have high levels of stress in your body.
link |
00:53:36.840
Years ago, I had a friend who works in the neuroscience
link |
00:53:40.760
world, research neuroscientist,
link |
00:53:42.440
who is obsessed with this very bizarre sport
link |
00:53:45.680
that I don't necessarily recommend at all,
link |
00:53:47.660
which is the combination of boxing and chess.
link |
00:53:50.600
You may have seen this on YouTube
link |
00:53:51.800
where people will box around, legitimate boxing around,
link |
00:53:54.560
they're sparring all out often.
link |
00:53:56.520
And then at the end of the round,
link |
00:53:58.200
instead of resting in the corner,
link |
00:53:59.260
they actually sit down and play chess.
link |
00:54:01.000
And then they go back to boxing and back to chess.
link |
00:54:03.060
Again, not a sport that I recommend,
link |
00:54:05.560
but the reason he was obsessed with this
link |
00:54:07.120
is because he studies the impact of stress
link |
00:54:10.280
on cognitive performance.
link |
00:54:11.360
And what that particular very bizarre sport was doing
link |
00:54:14.320
was toggling back and forth
link |
00:54:15.600
between different states of mind.
link |
00:54:17.580
Now it's used both to increase cognitive clarity
link |
00:54:22.040
for the fighter when they box
link |
00:54:23.600
because staying calm and clear thinking
link |
00:54:25.420
is very important to winning boxing matches.
link |
00:54:27.840
Believe it or not, it's not an all outrage.
link |
00:54:29.760
It's a very calculated game of mental chess
link |
00:54:32.200
and physical chess that's quite high stakes,
link |
00:54:34.520
as you can imagine.
link |
00:54:36.480
It's also used in some circles as a way to teach people
link |
00:54:40.700
how to engage in cognitive performance
link |
00:54:42.640
when their body is simply filled with stress.
link |
00:54:44.360
So in the boxing chess example,
link |
00:54:46.820
the replacement for the cold water
link |
00:54:49.040
is actually the boxing, right?
link |
00:54:50.320
It's the thing that's supposed to induce the stress
link |
00:54:52.280
because getting hit is stressful
link |
00:54:53.700
and the risk of getting hit is stressful for most people.
link |
00:54:56.960
So again, if you think about deliberate cold exposure
link |
00:55:00.700
as a way of just systematically
link |
00:55:02.540
and reliably inducing epinephrine
link |
00:55:04.400
and norepinephrine release and delivering stress,
link |
00:55:07.000
well, then this idea of maintaining cognitive clarity
link |
00:55:09.720
and actually engaging in cognitive tasks
link |
00:55:11.600
while in the ice bath or cold shower
link |
00:55:14.240
can actually be very beneficial,
link |
00:55:15.600
even though it might sound a little bit silly.
link |
00:55:16.940
You're really training up your ability
link |
00:55:18.640
to keep your brain working
link |
00:55:20.400
when the reflex is to shut down the parts of your brain
link |
00:55:24.160
that are involved in deliberate planning and thinking.
link |
00:55:26.300
Now, another important aspect of deliberate cold exposure
link |
00:55:29.280
that I rarely, if ever hear discussed,
link |
00:55:32.240
but is vitally important
link |
00:55:34.480
is whether or not you move around or not.
link |
00:55:37.640
And here's the reason.
link |
00:55:38.860
When you get into cold water
link |
00:55:41.600
and you remain there for some period of time,
link |
00:55:44.240
your body is generating heat
link |
00:55:46.520
and that heat generates what's called a thermal layer
link |
00:55:49.340
that surrounds your entire body.
link |
00:55:52.220
So if you stay still,
link |
00:55:54.360
you are actually warmer than if you move around.
link |
00:55:57.240
You can try this the next time
link |
00:55:58.440
you're doing your deliberate cold exposure.
link |
00:55:59.920
If you're submerged up to the neck,
link |
00:56:01.160
sit there for about 10, 30 seconds
link |
00:56:03.680
and be very, very still of body.
link |
00:56:05.480
In fact, this is the way that most people
link |
00:56:07.360
start to do deliberate cold exposure.
link |
00:56:09.080
They give this very stoic look.
link |
00:56:10.420
They don't blink.
link |
00:56:11.260
They look very peaceful.
link |
00:56:12.080
Some of them even look tough,
link |
00:56:13.780
or they make a very even, A, emotional face
link |
00:56:17.760
and so it looks like they're really tough,
link |
00:56:20.140
but they are so still that, believe it or not,
link |
00:56:22.360
they're not providing the most potent stimulus.
link |
00:56:26.520
If they or you were to move around in that water,
link |
00:56:30.660
what would happen is you'd break up the thermal layer
link |
00:56:32.680
and that you actually experienced that as much colder.
link |
00:56:35.960
So if you really want to push the resilience aspect,
link |
00:56:39.120
or for instance, if you want to use a given temperature
link |
00:56:42.040
that you're comfortable in,
link |
00:56:43.240
but that you want to increase the stimulus
link |
00:56:45.520
and you want to get some more benefit
link |
00:56:47.360
for mental resilience training,
link |
00:56:49.160
well, then get into the cold water,
link |
00:56:51.560
move your body around continuously,
link |
00:56:53.800
but try and keep your mind still
link |
00:56:55.340
or even do some sort of cognitive task.
link |
00:56:57.540
So as you're starting to realize
link |
00:56:59.160
there are a bunch of different variables
link |
00:57:00.320
that you can play with
link |
00:57:01.240
while maintaining the same temperature of water,
link |
00:57:03.720
and in doing so, really keep you in the zone
link |
00:57:06.920
of what should and absolutely has to be safe for you
link |
00:57:10.820
without having to just continually drop the temperature
link |
00:57:13.120
from say 60 degrees to 55 to 40 to 33,
link |
00:57:15.720
because as I mentioned before,
link |
00:57:16.640
eventually you're going to bottom out.
link |
00:57:18.240
So if you're one of those people that likes to look tough
link |
00:57:20.720
or really relaxed while you're in the ice bath
link |
00:57:22.880
or cold water immersion,
link |
00:57:24.080
just realize that you're actually cheating yourself
link |
00:57:26.760
out of part of the stimulus.
link |
00:57:28.320
Keep those limbs moving,
link |
00:57:29.840
and of course, limbs under the water, feet and hands,
link |
00:57:33.600
is going to be a more potent stimulus
link |
00:57:35.720
than hands and feet out
link |
00:57:37.640
for reasons that should be obvious
link |
00:57:39.180
based on what we talked about
link |
00:57:40.160
in terms of glab or skin cooling.
link |
00:57:42.320
So keep those submerged, move your body, pedal,
link |
00:57:45.420
maybe move your knees up and down,
link |
00:57:47.040
pedal your feet, and trust me,
link |
00:57:48.740
it's going to feel a lot colder
link |
00:57:50.080
than were you to remain stone still.
link |
00:57:52.260
Another very common question
link |
00:57:53.440
is how often to do deliberate cold exposure.
link |
00:57:56.720
It's tough to make a recommendation on that
link |
00:57:59.340
based on any peer reviewed study,
link |
00:58:01.720
although there are a few in humans
link |
00:58:03.240
that point to a threshold of 11 minutes total per week.
link |
00:58:07.520
So that's total throughout the week,
link |
00:58:09.400
divided into two or four sessions
link |
00:58:11.600
of two or three minutes or so.
link |
00:58:13.540
Now that 11 minute cutoff is not a strict threshold
link |
00:58:16.320
and is actually geared more towards increases in metabolism.
link |
00:58:20.100
We'll get into this a little bit later in the episode,
link |
00:58:22.920
but I think the 11 minute threshold,
link |
00:58:25.600
meaning 11 minutes total of deliberate cold exposure per week
link |
00:58:29.020
is a pretty good number to use
link |
00:58:31.440
if you need a number in order to keep you consistent.
link |
00:58:34.940
But as we talked about earlier,
link |
00:58:36.400
some of you are going to be in the ice bath
link |
00:58:39.480
or cold immersion or cold shower for one minute.
link |
00:58:42.020
Others of you will be in there for 10 minutes
link |
00:58:44.120
depending on how frequent and how high, if you will,
link |
00:58:47.560
those walls of adrenaline are coming.
link |
00:58:50.160
So for some of you getting into a cold shower
link |
00:58:53.180
for three minutes total for the whole week
link |
00:58:54.960
will represent a tremendous achievement
link |
00:58:58.080
in terms of willpower and overcoming the resistance
link |
00:59:00.800
to doing that, overcoming those walls.
link |
00:59:02.360
For others of you, three minutes is nothing.
link |
00:59:04.960
So what do I recommend?
link |
00:59:06.880
I recommend that you get at least 11 minutes total per week,
link |
00:59:11.080
but at the point where 11 minutes total per week
link |
00:59:13.240
is very easy for you or is no longer representing
link |
00:59:15.760
a significant mental challenge,
link |
00:59:17.160
meaning you're not experiencing many of these walls,
link |
00:59:19.080
you're excited to get into the cold shower or immersion,
link |
00:59:21.760
you're going through it easily, you're cruising basically,
link |
00:59:24.560
then I would say either lower the temperature safely,
link |
00:59:27.800
of course, extend the duration safely, of course,
link |
00:59:31.400
or increase the frequency so that you're doing this
link |
00:59:33.840
perhaps every day or maybe five days a week
link |
00:59:36.660
or three days a week.
link |
00:59:37.520
I personally get tremendous benefit
link |
00:59:39.320
from doing deliberate cold exposure three times a week
link |
00:59:42.480
and using the walls method that I described earlier
link |
00:59:45.560
as my gauge for how long to stay in.
link |
00:59:47.440
And typically that means that I'm staying in for anywhere
link |
00:59:50.320
from two minutes to six minutes per session.
link |
00:59:53.880
And that averages out to about 11 to 15 minutes total
link |
00:59:58.600
per week.
link |
00:59:59.580
So again, I do not think that you need to be super strict
link |
01:00:02.880
about these guidelines.
link |
01:00:04.200
It's most important when embracing a protocol,
link |
01:00:06.920
A, that you do it safely,
link |
01:00:08.220
but secondarily that you do it consistently.
link |
01:00:11.340
So find what you can do consistently
link |
01:00:13.120
and then vary the parameters that will allow you
link |
01:00:15.120
to continue to do deliberate cold exposure consistently,
link |
01:00:18.360
regardless of whether or not you have access to a shower
link |
01:00:20.520
or a cold immersion, et cetera.
link |
01:00:22.160
Okay, so we've been talking about mental effects
link |
01:00:24.400
and the use of deliberate cold exposure
link |
01:00:26.280
for sake of building resilience,
link |
01:00:28.040
which I do believe can be tremendously powerful.
link |
01:00:30.600
Look, it's no coincidence that the screening
link |
01:00:35.040
and the training for Navy SEALs involves a lot of exposure
link |
01:00:38.900
to cold water.
link |
01:00:40.080
One could argue that it is deliberate
link |
01:00:41.780
because they elect to go to BUDs,
link |
01:00:43.720
but when they get into the cold water at BUDs
link |
01:00:46.400
is dictated by the instructors.
link |
01:00:48.660
And the reason they use cold water exposure as the stressor
link |
01:00:52.260
is that it does offer considerable leeway
link |
01:00:55.200
in terms of duration and temperature,
link |
01:00:58.000
in terms of how you can use it as a stressor,
link |
01:01:00.780
whereas things like heat don't offer much variable space.
link |
01:01:04.000
As we say, there isn't a lot of room
link |
01:01:06.640
beyond which you start injuring or even killing people
link |
01:01:09.600
by using heat.
link |
01:01:10.720
So there are a lot of forms of stressors out there,
link |
01:01:12.540
but cold is one that we can titrate,
link |
01:01:14.540
that we can adjust in ways that can allow us
link |
01:01:16.440
to continually build up and or maintain mental toughness.
link |
01:01:21.840
Now, deliberate cold exposure also has many effects
link |
01:01:25.600
on chemicals other than norepinephrine and epinephrine,
link |
01:01:28.760
most notably the neuromodulator dopamine,
link |
01:01:32.000
which is involved in elevating our mood,
link |
01:01:34.400
making us feel energized and enhancing our ability to focus.
link |
01:01:38.120
And that has a lot to do with how dopamine engages us
link |
01:01:41.160
in motivated states, tends to narrow our thinking
link |
01:01:44.560
and our behavior into a particular trench
link |
01:01:46.720
of goal-directed behavior.
link |
01:01:47.980
If you want to learn more about dopamine,
link |
01:01:50.560
you can learn a lot about dopamine
link |
01:01:52.360
in our episode about dopamine.
link |
01:01:54.120
It's at hubermanlab.com.
link |
01:01:55.300
You can find it.
link |
01:01:56.140
It's a two and a half hour plus kind of deep dive
link |
01:01:59.280
into all things dopamine, focus, motivation, et cetera.
link |
01:02:04.820
Deliberate cold exposure has a very powerful effect
link |
01:02:08.700
on the release of dopamine in our brain and body.
link |
01:02:11.060
And this is one of the main reasons
link |
01:02:13.000
why people continue to do deliberate cold exposure.
link |
01:02:17.040
Basically, it makes us feel good
link |
01:02:19.160
and it continues to make us feel good
link |
01:02:21.280
even after we get out of the cold environment.
link |
01:02:23.760
In fact, some people would say
link |
01:02:25.440
they don't feel good in the cold environment.
link |
01:02:26.980
It's all stress for them, but afterwards they feel great.
link |
01:02:30.140
One of our previous guests, Dr. Anna Lempke,
link |
01:02:32.280
who's a medical doctor
link |
01:02:33.440
at Stanford University School of Medicine,
link |
01:02:34.920
she's a close colleague of mine,
link |
01:02:37.280
described the use of dopamine in her book,
link |
01:02:39.520
dopamine nation, an incredible book
link |
01:02:41.260
about addiction and dopamine, I should mention,
link |
01:02:43.400
and the use of dopamine elicited by cold water exposure
link |
01:02:49.480
by one of her patients.
link |
01:02:50.600
What I'm referring to is the fact that one of her patients
link |
01:02:53.800
helped themselves get and stay sober off drugs
link |
01:02:57.080
by using deliberate cold exposure to increase dopamine.
link |
01:03:01.000
So a healthier form of dopamine release
link |
01:03:03.080
than they were engaged in prior to getting sober.
link |
01:03:07.020
Now, the basis for dopamine release
link |
01:03:09.900
in response to cold exposure
link |
01:03:11.440
is that the catecholamines, norepinephrine, epinephrine,
link |
01:03:14.040
and dopamine tend to be co-released
link |
01:03:16.560
by the same sorts of stimuli,
link |
01:03:18.640
but most stressors, and in particular things
link |
01:03:21.380
that evoke stress or our feelings of stress internally
link |
01:03:24.800
that we don't like, do not increase dopamine.
link |
01:03:27.980
They only increase norepinephrine and epinephrine,
link |
01:03:30.520
but deliberate cold exposure
link |
01:03:32.200
seems to cause a dramatic increase in dopamine,
link |
01:03:36.040
and this has actually been substantiated
link |
01:03:37.800
in a really beautiful study
link |
01:03:39.640
entitled Human Physiological Responses to Immersion
link |
01:03:42.520
into Water of Different Temperatures.
link |
01:03:44.640
The first author is Sramek.
link |
01:03:46.940
I'm almost certainly pronouncing that poorly,
link |
01:03:49.760
if not incorrectly, S-R-A-M-E-K.
link |
01:03:54.200
This was published in the European Journal
link |
01:03:55.800
of Applied Physiology in the year 2000.
link |
01:03:58.400
Really a beautiful study.
link |
01:03:59.480
I love this study.
link |
01:04:00.660
They took people and they had them sit in chairs underwater,
link |
01:04:04.480
but their head was out and so they were immersed
link |
01:04:06.720
up to the neck in either of three different temperatures,
link |
01:04:11.320
excuse me, 32 degrees Celsius,
link |
01:04:13.960
which is 89 degrees Fahrenheit, 20 degrees Celsius,
link |
01:04:17.440
which is 68 degrees Fahrenheit, or 14 degrees Celsius,
link |
01:04:21.000
which is 57.2 degrees Fahrenheit.
link |
01:04:23.720
So not super cold, but then what they did
link |
01:04:27.380
is they measured people's core body temperature throughout.
link |
01:04:29.960
They measured their metabolism
link |
01:04:31.520
and they looked at serum levels
link |
01:04:33.720
of things like norepinephrine, epinephrine,
link |
01:04:36.280
dopamine, and cortisol, serum meaning within the blood.
link |
01:04:39.360
So a really nice and quite thorough study.
link |
01:04:43.240
There were not a huge number of subjects in the study,
link |
01:04:46.240
but nonetheless, it was a very thorough study
link |
01:04:48.460
in terms of the number of variables that they explored.
link |
01:04:52.600
So I just want to briefly highlight some of what they saw
link |
01:04:55.580
or what they observed in this study.
link |
01:04:57.720
First of all, all the groups were in the water
link |
01:05:01.640
of a given temperature for one hour,
link |
01:05:04.480
which is much longer than most
link |
01:05:06.220
of the deliberate cold exposure protocols
link |
01:05:08.080
that anyone is using at home.
link |
01:05:09.460
I mean, maybe you're taking one hour long cold showers.
link |
01:05:12.200
Maybe you're getting into the ice bath for an hour,
link |
01:05:14.440
although I don't recommend that.
link |
01:05:15.500
I think you'd probably get badly hypothermic.
link |
01:05:18.360
Or maybe you're getting into a cold water immersion
link |
01:05:21.420
for some period of time,
link |
01:05:22.480
but I have a hard time imagining that it would be an hour
link |
01:05:24.980
and I don't suggest that if it's very cold.
link |
01:05:27.100
So this study focused on actually
link |
01:05:28.900
somewhat moderately cool temperatures,
link |
01:05:31.800
not what I think most people would consider
link |
01:05:33.960
very, very cold temperatures,
link |
01:05:35.640
but extended the duration for quite a while.
link |
01:05:38.380
So again, 32 degrees Celsius, 20 degrees Celsius,
link |
01:05:42.120
or 14 degrees Celsius, here's what they observed.
link |
01:05:45.700
The group that was immersed up to the neck
link |
01:05:48.720
in 32 degrees Celsius, that is 89 degrees Fahrenheit,
link |
01:05:51.920
water did not experience a shift in metabolism
link |
01:05:55.380
nor a significant increase in dopamine norepinephrine
link |
01:05:58.960
or these other catecholamines.
link |
01:06:01.020
The group that was in 20 degrees Celsius,
link |
01:06:03.640
meaning 68 degree Fahrenheit water for an hour,
link |
01:06:08.120
experienced a 93% increase in metabolic rate,
link |
01:06:12.040
which is remarkable given that the water wasn't that cold
link |
01:06:15.920
and yet an hour is a pretty long time to be in there.
link |
01:06:18.520
And again, it speaks to the dramatic effect
link |
01:06:21.280
of heat transfer that water has,
link |
01:06:23.680
which I mentioned earlier as opposed to being out
link |
01:06:25.580
in the air at 68 degrees,
link |
01:06:27.340
it would certainly not cause that increase
link |
01:06:29.580
in metabolic rate.
link |
01:06:31.520
The group that was at 14 degrees Celsius,
link |
01:06:34.980
meaning 57.2 degrees Fahrenheit water for an hour,
link |
01:06:39.120
experienced a 350% increase in metabolism.
link |
01:06:42.780
So huge increases in metabolism.
link |
01:06:45.240
Now, the most interesting data to me,
link |
01:06:48.680
at least in terms of mental effects
link |
01:06:50.520
of deliberate cold exposure,
link |
01:06:52.400
were that the plasma or serum levels of norepinephrine
link |
01:06:58.160
in the blood increased 530%.
link |
01:07:01.640
These are huge increases in norepinephrine.
link |
01:07:04.360
So it suggests that this is a stressful stimulus,
link |
01:07:07.240
at least neurochemically speaking, stressful,
link |
01:07:10.020
despite the fact that it's not super, super cold,
link |
01:07:12.280
although 57.2 degrees Fahrenheit, 14 degrees Celsius
link |
01:07:15.960
is not a, you know, it's not a warm environment,
link |
01:07:20.360
but it's not a ultra, ultra cold environment,
link |
01:07:22.560
but an hour is a very long time to be in there.
link |
01:07:26.560
The subjects also experienced a 250% increase
link |
01:07:31.680
in dopamine concentrations, which while not 530%,
link |
01:07:36.880
as it was with norepinephrine,
link |
01:07:38.080
is still a very large increase
link |
01:07:40.640
in baseline levels of dopamine.
link |
01:07:42.480
And what was interesting is that those increases
link |
01:07:44.780
in dopamine persisted for a very long period of time
link |
01:07:48.160
and afterwards, even out to two hours, okay?
link |
01:07:51.520
And they stopped the study after 120 minutes
link |
01:07:54.400
of getting out of the cold, but nonetheless,
link |
01:07:58.200
these increases in norepinephrine are huge and long lasting,
link |
01:08:01.800
and these increases in dopamine
link |
01:08:03.320
are very large and long lasting.
link |
01:08:05.800
And I do believe that these documented effects in humans
link |
01:08:08.880
explain much of the enhancement of attention
link |
01:08:12.320
and of feelings of wellbeing and mood
link |
01:08:14.360
that people typically experience
link |
01:08:16.400
after doing deliberate cold exposure.
link |
01:08:19.080
And the reason I say that is that if you were to go back
link |
01:08:22.800
to the episode that I did on dopamine,
link |
01:08:24.720
or you were to go back to the episode that I did
link |
01:08:27.040
with Dr. Anna Lemke on addiction and dopamine,
link |
01:08:29.740
what you would find is that increases in dopamine
link |
01:08:32.840
of the sort evoked by deliberate cold exposure
link |
01:08:35.840
are actually very similar to the kinds of increases
link |
01:08:38.100
in dopamine that are elicited by things like nicotine
link |
01:08:41.400
or from other behaviors that are known to be addictive
link |
01:08:44.720
and bad for us because they lead to other effects
link |
01:08:47.620
on the brain and body that we simply don't want.
link |
01:08:50.240
And yet deliberate cold exposure, provided it's done safely,
link |
01:08:53.840
can create similar, if not greater, increases in dopamine
link |
01:08:58.560
that are not just fleeting,
link |
01:09:00.680
that don't just occur during, say,
link |
01:09:02.080
the consumption of some deleterious drug or activity,
link |
01:09:05.180
but that are very long lasting
link |
01:09:06.440
and that can be leveraged toward activities
link |
01:09:09.520
other than deliberate cold exposure.
link |
01:09:11.820
So I want to emphasize this.
link |
01:09:13.100
I'm not suggesting that people do deliberate cold exposure
link |
01:09:15.680
for an hour a day,
link |
01:09:16.840
and unfortunately there are not many studies
link |
01:09:19.680
yet exploring how shorter,
link |
01:09:22.240
colder temperature environment exposure,
link |
01:09:25.000
say one minute or three minutes or six minutes
link |
01:09:28.140
at 55 degrees or at 50 degrees,
link |
01:09:32.140
whether or not that leads to similar,
link |
01:09:34.640
greater or reduced levels of dopamine in the brain and body.
link |
01:09:38.780
And yet almost everybody who does deliberate cold exposure
link |
01:09:42.580
will say, yeah, it was stressful, I didn't enjoy it,
link |
01:09:45.660
or I eventually grew to like it,
link |
01:09:47.360
but that I always feel better afterwards.
link |
01:09:49.640
And then that feeling lasts a very long period of time.
link |
01:09:52.680
And I think it's almost certain that those experiences
link |
01:09:56.100
that people report relate to these increases in dopamine
link |
01:09:58.820
and in concert with the increases in norepinephrine
link |
01:10:02.000
also explain the other effect that's commonly reported,
link |
01:10:04.480
which is an enhancement in mental acuity
link |
01:10:06.960
and the ability to focus.
link |
01:10:09.160
Now, here we can extrapolate to the study
link |
01:10:11.720
that I discussed at the early part of the episode
link |
01:10:14.860
where I was talking about the use
link |
01:10:15.900
of short 15 minute exercise,
link |
01:10:18.120
kind of moderate intensity exercise,
link |
01:10:19.760
and how that was shown to increase levels of energy
link |
01:10:22.760
and mental acuity
link |
01:10:23.760
in these working memory visual attention tasks.
link |
01:10:26.320
And there again, we have to assume somewhat
link |
01:10:29.320
because they weren't doing neurochemical measurements,
link |
01:10:31.440
but we can reasonably assume
link |
01:10:34.040
that those improvements in cognitive performance
link |
01:10:36.640
were due at least in part to the increase in catecholamines
link |
01:10:39.760
known to accompany moderate intensity zone to cardio.
link |
01:10:43.720
So what you're starting to see here is a theme.
link |
01:10:45.800
The theme is that virtually any stimulus
link |
01:10:49.240
that delivers more norepinephrine, epinephrine,
link |
01:10:51.660
and dopamine to our system will sharpen our mental acuity
link |
01:10:54.640
and elevate our mood,
link |
01:10:55.640
and will do so for some period of time.
link |
01:10:58.280
Deliberate cold exposure, it turns out,
link |
01:11:00.480
is a very potent way to increase these catecholamines,
link |
01:11:03.480
this category of chemicals,
link |
01:11:04.800
and thereby to improve mood, mental acuity,
link |
01:11:07.640
and levels of alertness.
link |
01:11:09.160
And as we'll next see, it not only has that effect,
link |
01:11:13.040
which can be very beneficial for many people
link |
01:11:15.080
in a bunch of different circumstances,
link |
01:11:16.920
but it also has the positive effects
link |
01:11:19.680
that many people seek in terms of metabolism
link |
01:11:22.560
in lowering inflammation in the body
link |
01:11:24.320
and other physiological effects as well.
link |
01:11:26.600
And forgive me, I was almost ready to move on
link |
01:11:28.840
to effects of deliberate cold exposure
link |
01:11:31.560
on metabolism and inflammation and so forth,
link |
01:11:34.280
but I neglected to point out
link |
01:11:35.640
one of the other very interesting aspects
link |
01:11:38.600
of the study showing deliberate cold exposure
link |
01:11:41.680
can increase norepinephrine and dopamine,
link |
01:11:44.160
which is that they observed no significant increases
link |
01:11:48.120
in the stress hormone cortisol.
link |
01:11:50.240
And that is both surprising, interesting, and important,
link |
01:11:53.640
because what it means is that the quality of stress
link |
01:11:57.460
that deliberate cold exposure is creating in the body
link |
01:12:00.740
is likely to be one of what we call eustress.
link |
01:12:04.520
Hans Selye, the great physiologist,
link |
01:12:07.400
won a Nobel Prize for distinguishing between distress,
link |
01:12:10.800
which is stress in the brain and body
link |
01:12:13.200
that causes the release of things like cortisol
link |
01:12:16.560
along with the other catecholamines
link |
01:12:17.960
and that we experience as negative happening to us
link |
01:12:20.720
and can lead to negative health outcomes.
link |
01:12:22.880
And he distinguished that from eustress,
link |
01:12:25.400
which was stress that we now understand
link |
01:12:27.880
is associated with increases in things
link |
01:12:29.720
like norepinephrine and dopamine,
link |
01:12:31.440
but no increases or minimal increases in cortisol,
link |
01:12:35.000
and that can lead to positive health outcomes.
link |
01:12:37.560
So it appears that deliberate cold exposure
link |
01:12:40.380
can create what we call,
link |
01:12:42.100
or what Hans Selye called eustress.
link |
01:12:44.800
In other words, it can create a condition
link |
01:12:46.560
in the brain and body in which we are stressing ourselves,
link |
01:12:49.860
we are training up resilience,
link |
01:12:51.200
and yet we are creating a neurochemical milieu
link |
01:12:54.160
that actually has many health benefits.
link |
01:12:56.360
Now I'd like to shift our attention
link |
01:12:57.600
to the effects of deliberate cold exposure on metabolism.
link |
01:13:00.780
And I'd like to start by detailing a study
link |
01:13:03.320
that was performed on humans
link |
01:13:05.160
and published just at the end of last year.
link |
01:13:07.740
The title of the study is
link |
01:13:08.800
Altered Brown Fat Thermoregulation
link |
01:13:10.840
and Enhanced Cold Induced Thermogenesis
link |
01:13:13.620
in Young Healthy Winter Swimming Men.
link |
01:13:15.980
And I should point out that
link |
01:13:17.760
while the study was only performed on male subjects,
link |
01:13:20.600
there's no reason to think that
link |
01:13:22.300
the effects that they discovered
link |
01:13:23.560
would only pertain to men.
link |
01:13:25.160
I would hope that they would also do a study on women
link |
01:13:27.120
at some point in the future,
link |
01:13:28.800
but the effects that they describe
link |
01:13:30.840
are very basic core physiological processes.
link |
01:13:34.700
What they did is they looked at deliberate cold exposure
link |
01:13:37.200
in this group of young men,
link |
01:13:38.720
and they used that 11 minute threshold per week.
link |
01:13:42.960
So in other words, they had them get into cold water
link |
01:13:46.760
for approximately 11 minutes per week.
link |
01:13:50.160
And again, that's 11 minutes total per week.
link |
01:13:53.600
They divided that into two sessions,
link |
01:13:56.000
although in speaking with the first author of the study,
link |
01:13:58.760
Dr. Susanna Soberg,
link |
01:14:00.000
I learned that it probably is not important
link |
01:14:02.320
that it be two sessions.
link |
01:14:03.500
It could be three or even four sessions
link |
01:14:06.280
as long as it reaches that 11 minute threshold.
link |
01:14:09.880
What they discovered was that
link |
01:14:11.520
by going into these cold environments,
link |
01:14:14.840
in this case, cold water immersion up to the neck
link |
01:14:17.960
for 11 minutes total per week,
link |
01:14:21.240
that these men experienced increases
link |
01:14:23.800
in so-called brown fat thermogenesis.
link |
01:14:26.660
I'll talk more about what that is in a moment
link |
01:14:28.720
and increases in core body temperature
link |
01:14:30.800
that translate to increases in core body metabolism.
link |
01:14:34.920
Now, the overall increases in core body metabolism
link |
01:14:37.820
that they experienced were not extremely large.
link |
01:14:42.840
They were statistically significant,
link |
01:14:44.600
but they weren't extremely large.
link |
01:14:45.960
However, the changes in brown fat stores
link |
01:14:50.400
are perhaps what's most interesting about this study.
link |
01:14:53.080
And I'll tell you why.
link |
01:14:54.420
The metabolic increases of deliberate cold exposure
link |
01:14:57.580
are both acute, meaning happening in the short term,
link |
01:15:00.280
when you get into the cold and immediately after,
link |
01:15:02.900
one does experience an increase in core metabolism.
link |
01:15:06.440
You burn some calories, in other words.
link |
01:15:09.680
And while those might not be very significant increases,
link |
01:15:14.520
or I should say they can be statistically significant,
link |
01:15:17.740
but they are not enormously large numbers
link |
01:15:20.720
of calories burned,
link |
01:15:22.620
the longer lasting effects of deliberate cold exposure
link |
01:15:27.200
on metabolism seem to take place by changes that occur
link |
01:15:30.680
in the types of fat that we store in our body
link |
01:15:34.100
and the way that that fat impacts our metabolism
link |
01:15:36.680
at other times throughout the 24-hour cycle.
link |
01:15:41.800
This actually has a somewhat anecdotal basis,
link |
01:15:44.660
in particular in Scandinavia.
link |
01:15:46.880
I don't speak Swedish nor I speak Danish,
link |
01:15:49.440
nor do I speak Norwegian, but I do have Danish relatives.
link |
01:15:52.960
And they were able to help me decipher
link |
01:15:55.400
a common Swedish saying,
link |
01:15:58.020
which essentially translates to the fact that
link |
01:16:01.120
in preparation for the summer, they say,
link |
01:16:05.320
one should expose themselves to warm environments
link |
01:16:09.000
so that one is comfortable
link |
01:16:11.080
in warm environments in the summer.
link |
01:16:13.120
That's one half of this traditional Swedish
link |
01:16:16.440
and also Danish saying.
link |
01:16:17.940
The other half of this traditional Danish Swedish saying
link |
01:16:22.380
is that in preparation for winter,
link |
01:16:24.800
in order to not feel too cold in cold environments,
link |
01:16:28.760
one should prepare for those in the fall
link |
01:16:31.300
by not wearing a jacket and exposing oneself
link |
01:16:34.240
to cold environments.
link |
01:16:36.200
Now, of course, this is just anecdotal cultural lore,
link |
01:16:40.120
but it actually has a physiological basis,
link |
01:16:42.200
which is by exposing oneself to cold environments
link |
01:16:46.400
on a repeated basis in anticipation of exposure
link |
01:16:50.040
to more extreme cold environments,
link |
01:16:52.100
one can feel more comfortable in those extreme
link |
01:16:54.920
cold environments.
link |
01:16:56.000
And that's exactly what they observed
link |
01:16:58.180
in this study by Soberg et al.
link |
01:17:00.380
The men felt more comfortable in extreme cold
link |
01:17:03.940
if they had trained through deliberate cold exposure,
link |
01:17:07.380
which might not seem surprising at all,
link |
01:17:09.880
but based on what we talked about earlier,
link |
01:17:12.280
whereby deliberate cold exposure evokes this discomfort
link |
01:17:16.040
and this experience of norepinephrine release,
link |
01:17:18.640
at least in the short term,
link |
01:17:20.700
then you would say, well, shouldn't that deliberate
link |
01:17:22.680
cold exposure also make them feel uncomfortable,
link |
01:17:25.240
like they really want to get out?
link |
01:17:26.680
Well, that is true at the beginning
link |
01:17:29.600
of a deliberate cold exposure protocol,
link |
01:17:31.420
meaning in the first week or in the second week
link |
01:17:33.480
or the third week, but what one finds and what you will find
link |
01:17:36.320
if you do deliberate cold exposure consistently
link |
01:17:38.980
is that you will then become more comfortable
link |
01:17:42.400
at cold temperatures away from the deliberate cold exposure.
link |
01:17:46.720
So, whereas you might have previously been the person
link |
01:17:49.160
who was always cold in the room with air conditioning
link |
01:17:51.160
or always seeking a sweater, always wanting to bundle up,
link |
01:17:54.000
you will be more comfortable in those cold environments.
link |
01:17:56.040
And the reason for that is well substantiated
link |
01:17:59.960
from this study and from animal studies
link |
01:18:03.240
whereby deliberate cold exposure
link |
01:18:06.240
converts one particular kind of fat cell,
link |
01:18:09.520
the white fat cell,
link |
01:18:11.080
which is a very low metabolic output cell,
link |
01:18:15.280
it's basically a storage site for energy in the body,
link |
01:18:17.800
fat cells to a different type of fat cell,
link |
01:18:21.240
which is the beige fat cell called beige
link |
01:18:24.400
because it's actually beige or slightly brown
link |
01:18:26.980
under the microscope, or even to brown fat cells,
link |
01:18:30.440
which are very dark under the microscope
link |
01:18:32.420
and dark because they contain mitochondria
link |
01:18:35.920
and are very metabolically and thermogenically active.
link |
01:18:40.500
In other words, white fat doesn't burn many calories,
link |
01:18:43.860
it's basically a storage site,
link |
01:18:45.520
it's a bank account for energy,
link |
01:18:47.600
it's filled with lipids and those lipids can be used
link |
01:18:52.240
if the body needs energy
link |
01:18:53.480
and if it goes into a caloric deficit.
link |
01:18:55.680
Beige fat and brown fat acts as sort of a furnace
link |
01:18:59.680
or the sort of fat that you would find in a candle,
link |
01:19:03.400
a fuel that can increase core body temperature.
link |
01:19:06.080
So beige fat and brown fat is very good
link |
01:19:09.520
at raising our metabolism and helps burn white fat.
link |
01:19:13.320
Now, of course, it does that only in the context
link |
01:19:16.400
of a caloric deficit,
link |
01:19:18.340
but it can actually help create that caloric deficit.
link |
01:19:21.960
Having more beige fat and brown fat
link |
01:19:24.560
can increase your overall core metabolism.
link |
01:19:27.320
In other words, the number of calories
link |
01:19:29.040
that you burn per day and therefore the number of calories
link |
01:19:31.700
that you need to either maintain or to lose weight.
link |
01:19:35.800
The simple translation of this is that getting
link |
01:19:38.240
into cold water for a total of 11 minutes, perhaps more,
link |
01:19:43.040
but at least 11 minutes per week,
link |
01:19:45.000
divided into two or four sessions
link |
01:19:47.720
can increase your core metabolism in part
link |
01:19:50.520
by increasing your beige and brown fat stores.
link |
01:19:54.200
And we know how that works, at least in animal models.
link |
01:19:57.400
And there's now reason to suspect
link |
01:19:59.280
that the exact same mechanisms are occurring in humans.
link |
01:20:02.320
The primary way in which deliberate cold exposure
link |
01:20:05.340
converts white fat cells into these more metabolically,
link |
01:20:08.480
thermogenically active metabolism increasing beige
link |
01:20:12.120
and brown fat cells is because norepinephrine
link |
01:20:18.240
released when we get into the cold,
link |
01:20:20.920
binds to receptors on the surface of white fat cells
link |
01:20:25.000
and activates downstream pathways such as UCP1.
link |
01:20:30.000
So this is an uncoupling protein one
link |
01:20:32.640
that acts on the mitochondrial metabolism of cells
link |
01:20:35.520
and increases the mitochondrial output of those cells
link |
01:20:39.060
and the mitochondrial density of those cells.
link |
01:20:41.360
In other words, it takes a cell that has a kind
link |
01:20:44.840
of a weak engine or no engine for generating energy,
link |
01:20:48.880
although every cell has some mitochondria,
link |
01:20:51.040
it takes cells that have very few mitochondria
link |
01:20:53.600
and increases the engine size.
link |
01:20:56.320
It kind of stokes the furnace of those particular cells
link |
01:20:59.960
and actually can change gene expression in those cells.
link |
01:21:03.480
So that's what's really interesting.
link |
01:21:04.640
Deliberate cold exposure causes increases in norepinephrine,
link |
01:21:08.420
which bind to receptors on the surfaces of white fat cells,
link |
01:21:12.680
which triggers the release of things like UCP1.
link |
01:21:16.320
It also causes the release of things like PPAR gamma
link |
01:21:19.680
and cofactor PGC1.
link |
01:21:22.040
I'm going to refer you to a review
link |
01:21:23.540
if you want to learn more about these.
link |
01:21:25.440
For those of you that don't want to learn more,
link |
01:21:26.840
all you need to know is that the downstream of all that
link |
01:21:29.600
are increases in mitochondria and metabolism
link |
01:21:32.400
and actual genetic changes in the white fat cells
link |
01:21:36.240
that convert them into beige and brown fat cells.
link |
01:21:39.480
This is especially important for adults
link |
01:21:41.400
because babies and young children
link |
01:21:44.740
actually don't have the ability to shiver
link |
01:21:47.760
or they have a less robust capacity to shiver.
link |
01:21:51.540
Very small babies really can't shiver,
link |
01:21:53.440
so they have a lot of brown fat in order to keep them warm.
link |
01:21:57.440
Young children eventually develop the ability to shiver
link |
01:22:01.200
and maintain these brown fat stores,
link |
01:22:02.920
mainly around the clavicles, the heart, the upper spine,
link |
01:22:05.960
and in the upper back.
link |
01:22:07.660
And it's no coincidence that kids can often run around
link |
01:22:10.840
with a minimal of clothing
link |
01:22:11.880
and be comfortable in environments
link |
01:22:13.120
that adults would be cold in.
link |
01:22:16.920
As life goes on, we tend to lose beige and brown fat,
link |
01:22:21.000
but this mechanism that I'm referring to
link |
01:22:23.680
points to the plasticity of white fat,
link |
01:22:25.640
meaning the ability for white fat
link |
01:22:27.040
to actually convert its identity
link |
01:22:28.580
into this metabolically thermogenically
link |
01:22:30.960
enhancing form of beige and brown fat.
link |
01:22:33.900
So deliberate cold exposure is a terrific way
link |
01:22:36.520
to increase your core metabolism.
link |
01:22:38.440
And oftentimes critics will say,
link |
01:22:39.880
well, the increase in metabolism isn't that significant,
link |
01:22:42.540
although I do want to point out again,
link |
01:22:44.440
the 93% and the 350% increases in metabolism
link |
01:22:49.520
from that previous study.
link |
01:22:51.040
But critics then will say,
link |
01:22:53.180
well, that doesn't really translate to that big
link |
01:22:56.680
of a caloric burn during the deliberate cold exposure.
link |
01:23:00.960
But to that, you should say, ah,
link |
01:23:02.680
but that's only limiting your optics
link |
01:23:04.840
to just a portion of the effects
link |
01:23:06.280
of deliberate cold exposure,
link |
01:23:07.780
because deliberate cold exposure
link |
01:23:09.080
can also convert white fat to beige fat and brown fat
link |
01:23:12.820
and lead to these more lasting increases in metabolism.
link |
01:23:17.000
So for any of you interested in increasing your metabolism
link |
01:23:19.680
and or being comfortable in cold environments
link |
01:23:22.480
and or being comfortable
link |
01:23:24.400
in terms of being able to combat stress mentally,
link |
01:23:27.500
deliberate cold exposure, I do believe is a powerful tool.
link |
01:23:30.960
And there is simply no reason why you couldn't
link |
01:23:33.560
and shouldn't use the same protocols
link |
01:23:35.800
that I described earlier for building resilience
link |
01:23:38.520
to increase metabolism.
link |
01:23:39.920
Provided you're hitting that 11 minute per week threshold,
link |
01:23:43.400
you ought to be stimulating both mechanisms,
link |
01:23:46.160
increases in resilience and increases in core metabolism.
link |
01:23:51.800
As I mentioned earlier, most of the detailed studies
link |
01:23:53.820
on the conversion of white fat to beige fat and brown fat
link |
01:23:57.080
through the use of cold have been done in animal models,
link |
01:23:59.520
but the human data are starting to emerge.
link |
01:24:01.480
And if you'd like to do the deep dive into these mechanisms,
link |
01:24:04.200
things like UCP-1, PPAR-gamma, et cetera,
link |
01:24:07.220
there's a beautiful review that was published recently
link |
01:24:09.640
in the journal Cell,
link |
01:24:10.600
which is one of the three apex journals,
link |
01:24:12.120
Nature Science Cell.
link |
01:24:13.680
And the title of that paper
link |
01:24:15.400
is Adipose Tissue Plasticity in Health and Disease.
link |
01:24:18.140
I love this review.
link |
01:24:19.440
It has beautiful diagrams detailing all of the pathways
link |
01:24:22.780
from cold to norepinephrine through UCP-1,
link |
01:24:26.460
downstream of things like cyclic AMP.
link |
01:24:28.200
If none of those names mean anything to you,
link |
01:24:30.240
don't worry about it.
link |
01:24:31.080
You certainly don't need to know these mechanisms
link |
01:24:32.840
to benefit from deliberate cold exposure protocols.
link |
01:24:35.760
If those names do mean something to you,
link |
01:24:38.140
or you're interested in exploring the downstream effects
link |
01:24:41.160
of deliberate cold exposure,
link |
01:24:42.400
and something else that's really nice
link |
01:24:44.200
that's covered in this paper
link |
01:24:45.600
is how deliberate cold exposure interacts
link |
01:24:48.040
with fasted states and fed states.
link |
01:24:51.720
I think you'll also find this review very interesting.
link |
01:24:54.280
I don't want to go too deeply into fasted states
link |
01:24:56.320
and fed states right now.
link |
01:24:58.080
Suffice to say that when we are fasted,
link |
01:25:00.440
meaning when we haven't eaten for some period of time,
link |
01:25:03.020
our baseline levels of norepinephrine and epinephrine
link |
01:25:07.100
are already elevated.
link |
01:25:08.960
And so cold exposure at those times
link |
01:25:11.360
ought to have an even greater effect
link |
01:25:13.880
on metabolism and resilience and so on.
link |
01:25:16.460
So for you fasters or your intermittent fasters out there,
link |
01:25:20.400
if you really want to get fancy,
link |
01:25:21.860
you can do your deliberate cold exposure
link |
01:25:24.120
when you are fasted.
link |
01:25:25.560
I certainly wouldn't recommend doing it
link |
01:25:27.120
with a very full stomach in any case.
link |
01:25:29.460
And as I mentioned before on this podcast,
link |
01:25:32.960
intermittent fasting is but one way,
link |
01:25:36.200
and certainly there are other ways
link |
01:25:37.520
to limit total caloric intake
link |
01:25:39.660
for sake of maintaining or losing weight,
link |
01:25:41.580
if that's your goal.
link |
01:25:43.120
I know many people are using and benefit
link |
01:25:45.480
from intermittent fasting, however,
link |
01:25:47.400
and so it certainly can be combined
link |
01:25:49.660
with deliberate cold exposures
link |
01:25:51.160
in order to get even greater increases
link |
01:25:53.000
in norepinephrine and epinephrine.
link |
01:25:54.860
So for those of you that are primarily interested
link |
01:25:57.100
in using deliberate cold exposure
link |
01:25:58.560
to increase dopamine levels in your brain and body,
link |
01:26:02.220
you can also do a combined protocol
link |
01:26:05.480
whereby you ingest caffeine 60 to 120 minutes
link |
01:26:09.140
before the deliberate cold exposure.
link |
01:26:11.720
This is based on a study that I've talked about before
link |
01:26:14.660
entitled Caffeine Increases Striatal Dopamine D2D3
link |
01:26:18.360
Receptor Availability in the Human Brain.
link |
01:26:20.400
And as the title suggests, this study was done on humans.
link |
01:26:23.760
Looking at the density and or efficacy
link |
01:26:27.560
of these dopamine receptors in an area of the brain
link |
01:26:29.840
called the striatum, which is involved in planning and action
link |
01:26:32.500
and also suppressing planning and action.
link |
01:26:34.320
It's involved very closely with whether or not
link |
01:26:37.580
we can engage in behavior and withhold behavior,
link |
01:26:41.080
the so-called go and no-go pathways in the brain.
link |
01:26:44.240
Dopamine plays a critical role in that
link |
01:26:45.840
and many other things as well, as you now know.
link |
01:26:49.240
So why would you want to ingest caffeine 60 to 120 minutes
link |
01:26:52.640
before deliberate cold exposure?
link |
01:26:55.020
Well, as I talked about earlier,
link |
01:26:57.760
dopamine can increase quite substantially
link |
01:27:00.260
in response to deliberate cold exposure,
link |
01:27:02.160
but dopamine on its own doesn't do anything.
link |
01:27:04.000
It has to bind to receptors.
link |
01:27:05.960
And this paper shows quite definitively
link |
01:27:08.680
that ingesting caffeine, in this case,
link |
01:27:10.320
it was 300 milligram dose of caffeine,
link |
01:27:12.360
which is about the dose of caffeine
link |
01:27:14.160
in two or three cups of coffee.
link |
01:27:15.440
It depends on the strength of the coffee, of course,
link |
01:27:17.560
but it's not an outrageous amount of caffeine.
link |
01:27:19.800
That increases the density and or efficacy
link |
01:27:23.800
of these receptors,
link |
01:27:24.640
which would allow that dopamine to have its greatest effect.
link |
01:27:28.820
And for those of you that want to get really, really fancy,
link |
01:27:31.120
I suppose you could do this fasted.
link |
01:27:32.580
So you get the further increase in norepinephrine,
link |
01:27:35.000
then you get the dopamine increase from the cold exposure,
link |
01:27:37.200
the binding of the dopamine.
link |
01:27:38.880
Although I do want to point out that at some point
link |
01:27:42.120
you start layering together enough protocols
link |
01:27:44.080
that you would be spending your entire day
link |
01:27:45.680
trying to get this dopamine pulse.
link |
01:27:47.080
And I would hope that you would have other activities
link |
01:27:49.560
that you would engage in.
link |
01:27:50.780
But if you're getting up in the morning and you're fasted
link |
01:27:53.760
because you haven't eaten all night
link |
01:27:55.040
and you have a cup of coffee,
link |
01:27:56.140
and then 60 minutes later you take your cold shower,
link |
01:27:59.160
or two hours later you do your cold immersion
link |
01:28:01.820
or your cold shower,
link |
01:28:02.880
you would be layering together these different mechanisms
link |
01:28:05.840
of dopamine receptors, epinephrine, and so forth
link |
01:28:07.940
in a way that at least to me doesn't seem incompatible
link |
01:28:11.240
with having some other life,
link |
01:28:12.440
like going to school and having relationships, et cetera.
link |
01:28:15.040
And this increase in dopamine,
link |
01:28:16.720
particularly in the striatum, is not a trivial one.
link |
01:28:20.740
I do want to point out, as the authors do,
link |
01:28:23.160
that preclinical studies have shown
link |
01:28:24.860
that increases in striatal dopamine
link |
01:28:27.340
induced by things like modafinil,
link |
01:28:29.400
which is used to treat ADHD and treat narcolepsy,
link |
01:28:33.280
is necessary for their wake promoting actions.
link |
01:28:36.120
What this really says is that
link |
01:28:37.400
just having elevated levels of dopamine from a drug
link |
01:28:39.800
or from an ice bath or what have you
link |
01:28:42.300
is not sufficient to get the effects of dopamine.
link |
01:28:44.560
You really need the receptors to be available,
link |
01:28:47.400
and you need those receptors to be available
link |
01:28:49.040
in the appropriate density,
link |
01:28:50.440
and you need those receptors to be available
link |
01:28:52.560
in the appropriate density in the striatum in particular.
link |
01:28:55.320
So I think there are a number of reasons why,
link |
01:28:57.500
if it's compatible with the other aspects of your health,
link |
01:29:00.560
because of course always you have to consider this
link |
01:29:02.280
on a background of cardiovascular health
link |
01:29:03.920
and blood pressure, et cetera,
link |
01:29:05.160
that ingesting a cup or two of coffee
link |
01:29:07.240
an hour before your ice bath, maybe fasted as well,
link |
01:29:11.240
could be quite beneficial for increasing dopamine
link |
01:29:13.520
over quite extended periods of time.
link |
01:29:15.640
A couple of key points that you'll want to pay attention to
link |
01:29:18.380
in thinking about deliberate cold exposure and metabolism.
link |
01:29:21.280
In the Soberg study, they also explored the use of sauna
link |
01:29:25.240
and how to use sauna, meaning deliberate heat,
link |
01:29:27.960
in conjunction with cold.
link |
01:29:30.400
We are going to do an entire episode
link |
01:29:32.240
about the use of heat for health and performance.
link |
01:29:34.640
So that is not the focus now.
link |
01:29:37.160
However, it does raise an important point
link |
01:29:40.160
that we do need to address at this moment,
link |
01:29:42.120
which is if you are using sauna
link |
01:29:44.960
or if you are taking warm showers,
link |
01:29:47.320
or if you're simply using deliberate cold exposure
link |
01:29:50.040
of any kind, should you get into the heat afterward
link |
01:29:54.000
or before or not at all?
link |
01:29:55.840
And this is where we can point
link |
01:29:58.440
to the so-called Soberg principle,
link |
01:30:00.680
at least I call it the Soberg principle.
link |
01:30:02.320
The Soberg principle named after first author
link |
01:30:04.240
of this study I referred to earlier, Dr. Susanna Soberg.
link |
01:30:08.060
In science, it is appropriate to take a key piece of data
link |
01:30:12.940
and call it a principle,
link |
01:30:14.460
if in fact it translates to something larger,
link |
01:30:16.500
which I believe it does.
link |
01:30:18.140
It is generally not appropriate
link |
01:30:20.020
for people to name a principle after themselves,
link |
01:30:21.940
although there are a few scientists that have done that.
link |
01:30:25.380
So I have named it the Soberg principle,
link |
01:30:27.020
but I did that to give it appropriate credit
link |
01:30:30.260
to Dr. Susanna Soberg, who discovered that
link |
01:30:33.740
and pointed out quite appropriately
link |
01:30:36.240
that to achieve the greatest increases in metabolism
link |
01:30:40.380
through deliberate cold exposure,
link |
01:30:42.720
you want to force yourself to reheat on your own
link |
01:30:47.460
after the deliberate cold exposure,
link |
01:30:49.240
meaning you wouldn't want to go
link |
01:30:51.060
from the cold shower to a hot shower
link |
01:30:53.380
or from the cold shower to a sauna.
link |
01:30:54.820
Rather, if you were going to start with a hot shower
link |
01:30:57.140
or you're going to start with a sauna,
link |
01:30:58.720
that you would end with the cold
link |
01:31:00.980
and then you would reheat naturally.
link |
01:31:03.780
Now, I personally take a cold shower
link |
01:31:06.100
a few times a week or do cold immersion.
link |
01:31:08.300
And because I'm not specifically focused
link |
01:31:10.700
on increasing metabolism, although I probably should be,
link |
01:31:13.900
that's not what I'm using it for now,
link |
01:31:16.440
I will take a hot shower afterwards.
link |
01:31:18.060
And in doing so, I'm short-circuiting
link |
01:31:19.880
some of the further metabolic increases
link |
01:31:21.820
that I would achieve were I to just end with the cold.
link |
01:31:25.180
So the Soberg principle is
link |
01:31:27.700
if you want to increase your metabolism, end with cold.
link |
01:31:31.520
And we can take this a step further and say
link |
01:31:34.580
that if you want to use deliberate cold exposure
link |
01:31:36.980
to increase metabolism, that you should make sure
link |
01:31:40.940
that you get to the point where you shiver.
link |
01:31:43.620
And the reason for this is that
link |
01:31:44.980
there are a series of studies, but in particular,
link |
01:31:47.080
one study published in the journal Nature,
link |
01:31:48.960
excellent journal in the year 2018,
link |
01:31:51.740
showing that deliberate cold exposure
link |
01:31:55.700
that evokes shivering from the muscles
link |
01:31:59.160
causes the release of a molecule called succinate
link |
01:32:02.080
from the muscles, and that succinate plays a key role
link |
01:32:06.140
in activating brown fat thermogenesis,
link |
01:32:08.820
which you now have heard about and understand
link |
01:32:10.940
as critical to the increases in metabolism
link |
01:32:13.100
caused by deliberate cold exposure.
link |
01:32:15.860
So what this means is if you want to increase
link |
01:32:17.500
your metabolism, end on cold, that's the Soberg principle,
link |
01:32:20.260
and as best you can, try and get to the point
link |
01:32:23.160
where you are shivering either when you are
link |
01:32:25.940
in the cold exposure or immediately afterwards.
link |
01:32:29.240
Now, one efficient way to do this is to, for instance,
link |
01:32:32.580
you could get into the cold shower
link |
01:32:35.340
for a minute or two minutes or three minutes,
link |
01:32:37.500
uncomfortably cold, but safe to stay in.
link |
01:32:40.060
Remember, that's our general rule of thumb.
link |
01:32:42.260
Then turn off the water and stand there,
link |
01:32:45.420
make sure that you're not holding yourself
link |
01:32:47.820
close to your body, you're not hugging yourself
link |
01:32:49.700
to try and keep yourself warm,
link |
01:32:50.760
but rather your limbs are extended at your sides.
link |
01:32:53.900
And then if that fails to induce shiver,
link |
01:32:56.860
then to turn on the cold water again
link |
01:32:59.660
and then turn it off again.
link |
01:33:00.920
So alternating perhaps a minute to three minutes
link |
01:33:03.020
of cold exposure followed by a minute to three minutes
link |
01:33:05.520
of drying out in air and going back
link |
01:33:08.380
into the cold exposure, et cetera.
link |
01:33:10.620
I can tell you this from experience,
link |
01:33:12.140
this is a pretty brutal protocol.
link |
01:33:15.160
If you have never tried getting into an ice bath
link |
01:33:18.700
or cold water immersion or cold shower for one minute
link |
01:33:21.580
and then getting out and trying to stand there
link |
01:33:23.340
with your arms extended in cool or cold air
link |
01:33:26.080
for one minute and then getting back into the cold shower
link |
01:33:28.780
or water immersion, you are in for an experience
link |
01:33:32.420
because even for those of you
link |
01:33:34.260
that are pretty shiver resistant,
link |
01:33:36.060
you will find that it is much, much harder
link |
01:33:38.240
to get out of that cold water and stand their arms extended
link |
01:33:41.880
and drying off by evaporation,
link |
01:33:43.780
which further draws heat from the body
link |
01:33:46.580
than it is to wrap yourself in a towel,
link |
01:33:48.260
get in a warm shower or a sauna.
link |
01:33:50.180
So there's certainly no requirement to end on cold.
link |
01:33:54.060
There's certainly no requirement to induce shiver,
link |
01:33:57.620
but if your primary goal is to induce increases
link |
01:34:01.740
in metabolism, both in the short-term and in the long-term
link |
01:34:05.140
following the cold exposure,
link |
01:34:06.660
well, then you'll want to end on cold
link |
01:34:07.980
and you'll want to find a way to shiver
link |
01:34:10.540
provided that the level of cold
link |
01:34:12.780
that you're exposing yourself to
link |
01:34:14.100
is still safe for you overall.
link |
01:34:15.860
So up until now, I've been talking
link |
01:34:17.100
about deliberate cold exposure as a potent stimulus
link |
01:34:20.020
for the release of norepinephrine in the brain and body.
link |
01:34:22.820
And indeed it is, but the way I've been describing it
link |
01:34:26.700
has been in the context of circulating plasma levels
link |
01:34:30.740
of norepinephrine, meaning circulating within the blood.
link |
01:34:34.620
What I haven't mentioned, but is absolutely true
link |
01:34:37.660
is that the fat cells themselves
link |
01:34:41.700
actually receive input from neurons.
link |
01:34:44.700
So there are neurons that release norepinephrine
link |
01:34:47.500
in response to cold directly into the fat.
link |
01:34:51.060
So I want to give you this picture
link |
01:34:53.440
of how the architecture of all this works
link |
01:34:55.820
because I think it can help you navigate
link |
01:34:57.980
and indeed build better deliberate cold exposure protocols.
link |
01:35:01.780
Your adrenal glands release norepinephrine and epinephrine.
link |
01:35:05.300
Your brain has sites within it like the locus coeruleus
link |
01:35:08.900
that release norepinephrine and epinephrine.
link |
01:35:12.020
But there are also neurons within your skin
link |
01:35:14.620
that sense cold and other neurons
link |
01:35:17.260
that can directly release norepinephrine
link |
01:35:19.380
into the fat stores and cause those white fat cells
link |
01:35:22.640
to convert to beige and brown fat.
link |
01:35:24.420
And I think this particular aspect of our physiology
link |
01:35:26.920
is often overlooked in studies.
link |
01:35:29.700
And when people say, oh, well,
link |
01:35:31.140
the increases in metabolism aren't that great,
link |
01:35:33.600
the circulating levels of norepinephrine,
link |
01:35:35.340
those are very large, but they're very transient and so on,
link |
01:35:39.180
that fails to understand that neurons
link |
01:35:42.960
that actually sense cold are in a position
link |
01:35:45.620
to communicate via other neurons
link |
01:35:48.500
directly to the fat cells
link |
01:35:49.940
and release norepinephrine into those fat cells,
link |
01:35:51.860
which as I pointed out earlier,
link |
01:35:53.540
set off a huge set of immediate and long-term cascades
link |
01:35:56.820
of even gene expression changes.
link |
01:35:59.840
So the picture that I'd like you to have in your mind
link |
01:36:02.040
is that when you get into the cold,
link |
01:36:04.140
yes, of course you experience that as a experience of,
link |
01:36:07.760
I don't want to do this, I'm going to overcome this,
link |
01:36:09.540
I'm going to climb over these mental walls
link |
01:36:11.300
that represent adrenaline release in my brain and body,
link |
01:36:14.020
but also that your fat cells are receiving signals,
link |
01:36:17.940
norepinephrine signals that are changing those fat cells
link |
01:36:21.020
and the way that they metabolize energy.
link |
01:36:22.860
Now I'd like to shift our attention
link |
01:36:24.180
to the use of deliberate cold exposure
link |
01:36:26.260
for sake of physical performance.
link |
01:36:28.740
And there are a lot of opinions out there
link |
01:36:30.400
about the use of deliberate cold,
link |
01:36:32.440
whether or not it should be done, for instance,
link |
01:36:33.980
before or after exercise,
link |
01:36:36.180
whether or not if done immediately after strength training
link |
01:36:39.700
or hypertrophy training,
link |
01:36:40.800
meaning training designed to grow muscles
link |
01:36:43.460
or make them stronger,
link |
01:36:44.340
whether or not it can inhibit that process
link |
01:36:46.140
and so on and so forth.
link |
01:36:47.600
I think today in looking over the literature
link |
01:36:50.640
and trying to bring forward the simplest
link |
01:36:52.700
and most straightforward
link |
01:36:53.600
and yet scientifically grounded protocols,
link |
01:36:55.980
we can set up some general guidelines
link |
01:36:58.060
that will allow most, if not all of you
link |
01:37:00.140
to still extract the benefits of deliberate cold exposure
link |
01:37:03.300
on physical performance without getting too neurotic
link |
01:37:06.900
about the exact timing.
link |
01:37:08.380
But for sake of discussion,
link |
01:37:10.660
and because it's a prominent theme
link |
01:37:13.240
in many online communities,
link |
01:37:14.860
let's just start with the big one out there,
link |
01:37:18.140
meaning the question of whether or not doing an ice bath
link |
01:37:21.980
or doing deliberate cold exposure
link |
01:37:23.660
or taking a cold shower after strength
link |
01:37:26.140
slash hypertrophy training,
link |
01:37:28.260
meaning training designed to increase strength
link |
01:37:30.660
and or I should say the size of muscles
link |
01:37:34.120
will somehow short circuit or diminish that process,
link |
01:37:37.800
whether or not it will reduce
link |
01:37:39.340
or eliminate those strength gains and hypertrophy gains.
link |
01:37:42.100
And the short answer that I was able to arrive at
link |
01:37:45.060
on the basis of a review article
link |
01:37:47.500
that I'll talk about in a moment
link |
01:37:48.980
and some other studies as well
link |
01:37:51.140
is that if your main goal is hypertrophy and strength,
link |
01:37:56.300
it is probably best to avoid cold water immersion
link |
01:38:00.460
and ice bath immersion in the four hours
link |
01:38:04.340
immediately following that strength
link |
01:38:06.860
and or hypertrophy training.
link |
01:38:08.660
Again, if your main goal is to achieve hypertrophy
link |
01:38:12.860
or strength or some combination of those,
link |
01:38:15.900
probably best to avoid cold water immersion up to the neck
link |
01:38:20.140
or ice bath immersion up to the neck
link |
01:38:23.020
immediately after strength and hypertrophy training
link |
01:38:26.100
and extending out to about four hours after that training.
link |
01:38:31.100
If you're really neurotic about this,
link |
01:38:32.940
then perhaps you'd want to move the cold water exposure
link |
01:38:35.480
to a different day entirely,
link |
01:38:37.140
but it all depends on how neurotically attached you are
link |
01:38:39.800
to getting every last bit of strength and hypertrophy.
link |
01:38:42.380
And if that's your goal, terrific,
link |
01:38:44.060
well then probably moving the cold exposure
link |
01:38:47.160
four hours or more away from that training
link |
01:38:49.040
is going to be necessary for you.
link |
01:38:50.700
Now you'll notice I did not talk about cold showers.
link |
01:38:53.700
And the reason I did not talk about cold showers
link |
01:38:55.820
is that there simply are not very many studies
link |
01:38:59.340
of deliberate cold exposure through cold showers
link |
01:39:01.940
for the reasons I talked about
link |
01:39:03.040
at the beginning of the episode.
link |
01:39:05.100
It's hard for me to imagine that taking a brief cold shower
link |
01:39:08.380
after a strength or hypertrophy training session
link |
01:39:11.020
would completely reverse or short circuit
link |
01:39:13.260
the effects of that strength and hypertrophy training.
link |
01:39:15.480
But again, if you're neurotically attached
link |
01:39:17.860
to getting every last bit of strength and hypertrophy
link |
01:39:21.100
out of your training sessions,
link |
01:39:22.580
then by all means, err on the side of caution
link |
01:39:24.800
and wait four hours or more to do your cold shower
link |
01:39:27.460
just as you would wait four hours or more
link |
01:39:29.880
to do your cold water immersion.
link |
01:39:31.580
Now there are nice data pointed to the fact
link |
01:39:33.900
that doing cold water immersion after a hard run,
link |
01:39:37.540
so endurance training, or even sprint and interval training,
link |
01:39:41.660
or after a weight workout where your main focus
link |
01:39:45.660
is on performance of those movements,
link |
01:39:47.500
or after a skill training workout
link |
01:39:49.180
where your main focus on performance of those movements,
link |
01:39:52.260
that there's no reason to think
link |
01:39:54.200
that that cold water immersion or ice bath or cold shower
link |
01:39:57.380
would inhibit the progress or the stimulus
link |
01:40:01.540
that would lead to progress that occurred
link |
01:40:03.820
during that training session.
link |
01:40:05.260
In other words, I don't see any reason
link |
01:40:07.460
based on the literature to avoid deliberate cold exposure
link |
01:40:10.560
immediately after training,
link |
01:40:12.060
again, unless your goal is hypertrophy and strength.
link |
01:40:15.900
And in fact, there's a very nice review
link |
01:40:17.340
that was recently published on deliberate cold exposure
link |
01:40:21.580
and how it can impact physical performance,
link |
01:40:24.720
whether or not it's done before or after
link |
01:40:27.740
different types of training and so forth.
link |
01:40:30.260
The paper is entitled impact of cold water immersion
link |
01:40:33.500
compared with passive recovery
link |
01:40:35.260
following a single bout of strenuous exercise
link |
01:40:37.780
on athletic performance in physically active participants,
link |
01:40:41.300
a systematic review with meta-analysis and meta-regression.
link |
01:40:45.080
So this is a meta-analysis of 52 studies
link |
01:40:49.540
that looked at a tremendous number of variables
link |
01:40:51.900
and contexts as you would expect
link |
01:40:54.300
in a meta-analysis of 52 studies.
link |
01:40:56.820
I'm going to read you the conclusions of the study
link |
01:40:58.640
and I'll provide a link.
link |
01:40:59.880
We certainly don't have the time
link |
01:41:00.900
to go through all the details of the study.
link |
01:41:02.700
I will highlight a few specific outcomes
link |
01:41:05.120
that I found particularly interesting,
link |
01:41:07.060
but here I am paraphrasing their conclusions
link |
01:41:10.380
that cold water immersion,
link |
01:41:13.420
I want to emphasize immersion, not cold showers,
link |
01:41:16.460
but cold water immersion,
link |
01:41:18.080
they say was an effective recovery tool
link |
01:41:20.040
after high intensity exercise.
link |
01:41:22.300
They observed positive outcomes,
link |
01:41:23.860
meaning improvements in certain variables
link |
01:41:27.360
for muscular power, muscular soreness,
link |
01:41:30.260
meaning reduced muscular soreness, increased muscular power,
link |
01:41:33.300
perceived recovery after 24 hours of exercise.
link |
01:41:36.720
However, there were certain forms of exercise
link |
01:41:39.340
that were not benefited by cold water immersion,
link |
01:41:43.320
such as eccentric exercise,
link |
01:41:45.800
exercise focusing only on the lowering component
link |
01:41:49.220
or the so-called eccentric component
link |
01:41:51.020
of resistance exercise.
link |
01:41:52.700
They saw some very interesting dose response relationships
link |
01:41:56.620
for things like endurance training,
link |
01:41:58.400
meaning the longer the cold exposure
link |
01:42:01.720
post-endurance training,
link |
01:42:02.780
the more improvement in endurance performance,
link |
01:42:05.300
reductions in circulating creatine kinases
link |
01:42:08.740
and things that relate to muscle damage
link |
01:42:11.260
under certain conditions.
link |
01:42:13.100
At some point in the future, by the way,
link |
01:42:14.240
we'll do an entire episode on creatine
link |
01:42:16.260
and creatine kinases,
link |
01:42:17.220
which are important not just for muscular function,
link |
01:42:19.700
but also for brain function.
link |
01:42:21.580
But the basic takeaway was that cold water immersion
link |
01:42:25.300
performed after high-intensity exercise
link |
01:42:27.700
was beneficial from a number of different standpoints
link |
01:42:30.740
and indicated that shorter duration cold exposure
link |
01:42:36.020
and lower temperatures can improve
link |
01:42:38.500
the efficacy of cold water exposure
link |
01:42:40.540
if used after high-intensity exercise, okay?
link |
01:42:42.940
There I'm directly pulling from their conclusions.
link |
01:42:45.400
So what this says is that it's not just those
link |
01:42:47.860
longer duration 30, 45-minute and 60-minute protocols
link |
01:42:52.420
of cold water immersion that we discussed earlier,
link |
01:42:54.860
but also shorter duration, one-minute, three-minute,
link |
01:42:58.100
five-minute exposures to lower temperatures,
link |
01:43:02.460
temperatures that would make you psychologically
link |
01:43:04.740
want to get out as soon as you possibly can,
link |
01:43:07.700
but again, that you can safely stay in,
link |
01:43:09.980
done after training really have been shown
link |
01:43:12.640
to improve outcomes in terms of reducing soreness
link |
01:43:15.940
and improving training efficacy,
link |
01:43:18.700
meaning your ability to get back into training more quickly
link |
01:43:22.460
and thereby deliver more training stimuli to a given muscle
link |
01:43:26.620
or in your endurance training protocol.
link |
01:43:29.060
Translating to English, what this means is that
link |
01:43:30.800
taking a cold shower or getting into an ice bath
link |
01:43:33.620
or some other form of cold water immersion
link |
01:43:35.760
within the immediate minutes
link |
01:43:37.100
or even the immediate hours following your training
link |
01:43:40.300
has been shown to be beneficial.
link |
01:43:43.100
I'm sure a number of you have questions, for instance,
link |
01:43:45.820
how long should you be in that cold exposure?
link |
01:43:49.020
Is it the same as the 11-minute threshold
link |
01:43:51.160
described earlier?
link |
01:43:52.700
To be honest with you, there are not enough studies
link |
01:43:55.720
to really point to the critical threshold
link |
01:43:58.180
for eliminating or reducing delayed onset muscle soreness
link |
01:44:01.800
or for getting maximal results
link |
01:44:04.480
from power and endurance training,
link |
01:44:06.560
but this study does make a couple of key points,
link |
01:44:09.220
and here I will just paraphrase.
link |
01:44:11.180
For instance, that cold water immersion is more likely
link |
01:44:15.180
to positively influence muscular power performance,
link |
01:44:18.660
to reduce muscle soreness, to reduce serum creatine kinase,
link |
01:44:22.700
and to improve perceived recovery
link |
01:44:24.920
after high-intensity exercise
link |
01:44:26.780
as compared with passive recovery.
link |
01:44:29.260
This can be translated to cold water exposure
link |
01:44:32.260
after training is beneficial and probably better
link |
01:44:35.420
than passive recovery from a number of standpoints.
link |
01:44:38.640
In addition, they say that dose-response relationships,
link |
01:44:42.860
meaning the amount and the degree of cold
link |
01:44:47.100
that people were exposed to and how often they did that,
link |
01:44:51.220
in particular in lower temperature cold immersion,
link |
01:44:53.740
so these would be the sorts of cold immersion protocols
link |
01:44:57.020
that are one minute or two minutes,
link |
01:44:59.040
three minutes, maybe five minutes,
link |
01:45:00.820
but that one couldn't stay in there longer
link |
01:45:02.780
because it feels stressful and one wants to get out,
link |
01:45:05.580
may be more effective after high-intensity exercise
link |
01:45:08.240
for removal of serum creatine kinase,
link |
01:45:11.380
as well that these shorter duration
link |
01:45:13.420
cold water immersion approaches may be more effective
link |
01:45:16.100
after high-intensity endurance performance as well.
link |
01:45:19.820
So all of this can be translated to say
link |
01:45:22.260
that unless your main goal is hypertrophy and strength,
link |
01:45:27.140
that cold exposure, ideally cold immersion
link |
01:45:31.060
in cold water or ice bath,
link |
01:45:32.540
but if you don't have access to that,
link |
01:45:34.220
then cold showers is likely going to be beneficial
link |
01:45:37.180
if done immediately after or in the minutes or hours
link |
01:45:40.740
after your training, especially high-intensity training.
link |
01:45:44.260
One particularly nice thing about this meta-analysis
link |
01:45:46.540
is that it included some studies
link |
01:45:48.180
that involved the use of cooling packs,
link |
01:45:50.740
so again, vests that can hold essentially ice packs
link |
01:45:55.400
and indeed even cryotherapy chambers and so on.
link |
01:45:59.000
There's a nice table in the study
link |
01:46:00.340
if you want to get really detailed
link |
01:46:01.860
and go and look specifically at those studies,
link |
01:46:03.780
I invite you to do that.
link |
01:46:04.800
We'll put a link to this study
link |
01:46:06.460
in the caption for this episode.
link |
01:46:08.600
But all in all, what this study shows
link |
01:46:10.340
is that deliberate cold exposure can be very useful
link |
01:46:14.100
for recovery, likely through reductions in inflammation
link |
01:46:18.140
in muscle and connective tissue.
link |
01:46:20.660
And while this study did not look specifically
link |
01:46:22.900
at the mechanisms of reduced inflammation
link |
01:46:25.860
caused by deliberate cold exposure,
link |
01:46:27.860
those mechanisms are somewhat known.
link |
01:46:30.460
There are a number of studies that have pointed to the fact
link |
01:46:32.660
that deliberate cold and cold generally
link |
01:46:34.840
can reduce inflammatory cytokines,
link |
01:46:37.360
such as IL-6, interleukin-6.
link |
01:46:39.520
It can increase anti-inflammatory cytokines,
link |
01:46:43.120
such as interleukin-10 and so on.
link |
01:46:46.260
Without getting into all those details,
link |
01:46:48.000
I think it's sufficient to say that if you are somebody
link |
01:46:51.320
who experiences a lot of delayed onset muscle soreness,
link |
01:46:54.260
taking a cold shower after your training
link |
01:46:56.020
or getting into a cold immersion after your training,
link |
01:46:58.340
even if it's a few hours later, ought to help.
link |
01:47:01.020
And if you are doing particularly intense training,
link |
01:47:04.560
then you probably want to ratchet up
link |
01:47:06.660
the number of cold exposure sessions that you're doing,
link |
01:47:10.180
even if those have to be done on separate days
link |
01:47:12.380
from your training.
link |
01:47:13.220
Because a lot of the inflammatory effects of training,
link |
01:47:15.860
endurance and strength training,
link |
01:47:16.900
are actually occurring some hours away
link |
01:47:19.420
from the training stimulus.
link |
01:47:20.660
So it's not just that inflammation goes up radically
link |
01:47:22.820
during training, which it often can,
link |
01:47:25.060
but that it can occur even in the days
link |
01:47:27.220
and even weeks afterwards, depending on how intense
link |
01:47:29.540
and how long duration that training is.
link |
01:47:31.300
So deliberate cold exposure is very powerful
link |
01:47:33.820
as an anti-inflammatory tool.
link |
01:47:36.420
Now I'd like to emphasize a topic that we touched on
link |
01:47:38.540
at the beginning of the episode,
link |
01:47:40.380
which are those glabrous skin surfaces,
link |
01:47:43.100
the hands, the upper face and the bottoms of the feet,
link |
01:47:45.780
through which heat is especially good at leaving the body.
link |
01:47:50.420
And another way of putting that is that
link |
01:47:53.740
one can cool the body much more efficiently
link |
01:47:56.580
through the glabrous skin surfaces.
link |
01:47:58.860
Now, if you want to understand all of the science
link |
01:48:01.500
behind this and all of the various applications,
link |
01:48:05.860
I invite you to please listen to the episode that I did
link |
01:48:08.260
with Dr. Craig Heller, again, in the biology department
link |
01:48:11.380
at Stanford.
link |
01:48:13.660
For sake of this episode, I'm just going to detail
link |
01:48:15.560
a couple of findings from his laboratory.
link |
01:48:18.360
The first one dealing with exercise-induced hyperthermia,
link |
01:48:21.380
because I think this is very interesting
link |
01:48:22.780
and it can even save lives
link |
01:48:24.580
if you understand the way this works.
link |
01:48:28.000
There's a particular paper that focuses on this
link |
01:48:30.420
and we will put a link to this as well.
link |
01:48:32.300
The title of this paper is novel application
link |
01:48:34.160
of chemical cold packs for treatment
link |
01:48:35.540
of exercise-induced hyperthermia,
link |
01:48:37.460
a randomized control trial.
link |
01:48:39.560
This is a pretty brutal study,
link |
01:48:42.160
brutal for the subjects, that is.
link |
01:48:44.820
What this study involved was having subjects
link |
01:48:47.940
walk on a treadmill at a pretty significant incline,
link |
01:48:50.960
anywhere from nine to 17%,
link |
01:48:53.660
wearing a substantial amount of clothing
link |
01:48:56.260
that was not well-ventilated,
link |
01:48:58.220
and the room was kept to 40 degrees Celsius,
link |
01:49:00.700
which is 104 degrees Fahrenheit.
link |
01:49:03.180
This is definitely not something to do at home.
link |
01:49:06.680
This study was designed to induce hyperthermia,
link |
01:49:09.180
which as I mentioned earlier, can be quite dangerous.
link |
01:49:11.580
And they compared two types of cooling.
link |
01:49:14.520
In the first form of cooling
link |
01:49:16.180
that they call traditional cooling,
link |
01:49:18.200
they had ice packs on their neck,
link |
01:49:21.500
in their armpits and in their groin.
link |
01:49:23.880
And in the other group,
link |
01:49:25.500
there was the so-called glabrous skin cooling.
link |
01:49:27.840
So the palms, the soles of the feet,
link |
01:49:29.580
which were actually,
link |
01:49:30.900
so they were cooling inside the boots or inside of gloves.
link |
01:49:35.440
And on the upper portion of the face.
link |
01:49:39.040
And the basic takeaway of this study
link |
01:49:41.220
is that by cooling the glabrous skin,
link |
01:49:44.240
the subjects were able to sustain this walking
link |
01:49:47.260
on these incline treadmills for much longer
link |
01:49:50.880
than were the people who received traditional cooling.
link |
01:49:54.180
And also the return to baseline temperature
link |
01:49:56.380
was much faster in the glabrous skin cooling group.
link |
01:49:59.820
So how this translates to the real world
link |
01:50:01.840
is that if ever you are hyperthermic
link |
01:50:04.040
or someone else is hyperthermic,
link |
01:50:06.780
one way to cool them down quickly
link |
01:50:08.880
is to cool these palmar glabrous,
link |
01:50:13.260
soles of the feet, glabrous,
link |
01:50:14.520
and upper portion of the face,
link |
01:50:16.400
glabrous portions of the body,
link |
01:50:18.040
using cool rags, using ice packs,
link |
01:50:21.080
or using any number of different cold objects
link |
01:50:24.680
or temperatures.
link |
01:50:26.440
One key thing if you're going to use glabrous skin cooling
link |
01:50:30.100
is that whatever you use to cool those surfaces
link |
01:50:33.160
cannot be so cold that it causes vasoconstriction.
link |
01:50:37.080
Because as I mentioned earlier,
link |
01:50:38.920
the arteriovenous osteomoses,
link |
01:50:41.660
these portals of arteries directly to veins
link |
01:50:43.920
that exist only in these glabrous skin surfaces,
link |
01:50:49.600
the way that they're able to cool the body
link |
01:50:51.580
and essentially pass cool into the body,
link |
01:50:53.920
although that's not really what they're doing,
link |
01:50:55.080
they're actually extracting heat from the body
link |
01:50:57.420
to be technical, they're extracting heat from the body.
link |
01:51:00.520
The only way they can do that
link |
01:51:02.520
is if those veins don't collapse,
link |
01:51:05.120
and veins will collapse if they are made very, very cold.
link |
01:51:08.800
So if you want to use glabrous skin cooling
link |
01:51:11.540
to offset hyperthermia,
link |
01:51:12.840
or for the other forms of performance,
link |
01:51:14.420
which we will talk about in a moment,
link |
01:51:16.200
you need to use a cool object or surface
link |
01:51:19.640
that is not so cold that it causes vasoconstriction.
link |
01:51:22.240
And this can be a little bit tough to dial in,
link |
01:51:24.720
meaning it can be tough to identify such an object.
link |
01:51:27.920
And for that reason, Dr. Heller and some of his colleagues
link |
01:51:30.340
have developed a commercial product called the CoolMitt.
link |
01:51:32.480
You can actually go to their website, coolmitt.com.
link |
01:51:34.560
I don't have any financial or other relationship to them.
link |
01:51:37.800
I know they've been developing this technology
link |
01:51:39.520
for some period of time.
link |
01:51:40.440
It involves a glove that you put your hand into.
link |
01:51:43.540
It circulates water of a given temperature,
link |
01:51:46.660
and it does so at a temperature
link |
01:51:49.320
that is sure to not cause vasoconstriction of the palm.
link |
01:51:53.120
And you may be asking,
link |
01:51:53.960
how can you just put your hand into one glove
link |
01:51:56.180
and have this work?
link |
01:51:57.020
Well, that's how powerful these glabrous skin surfaces are,
link |
01:51:59.760
even just by cooling one palm,
link |
01:52:02.800
the core body temperature drops radically.
link |
01:52:06.300
Now that's their commercial technology.
link |
01:52:08.920
I know that some people out there
link |
01:52:10.080
have started to experiment with a home version of this,
link |
01:52:13.060
which would be taking a package, for instance,
link |
01:52:15.580
of frozen blueberries or some other cold drink
link |
01:52:18.920
or cold metal object and actually bringing it into the gym
link |
01:52:21.760
or out on a run.
link |
01:52:23.380
There are even people who are now developing
link |
01:52:25.080
cooled bicycle handles for long rides.
link |
01:52:29.200
This might seem a little kooky or crazy to you,
link |
01:52:31.320
but as you'll soon hear in the study I'm about to describe,
link |
01:52:35.040
the increases in endurance
link |
01:52:37.300
and in the volume of strength training
link |
01:52:39.880
that people can conduct
link |
01:52:41.740
if they appropriately cool their body
link |
01:52:43.780
through these glabrous skin portals
link |
01:52:46.200
is actually quite significant.
link |
01:52:48.400
So again, as it relates to hyperthermia,
link |
01:52:50.520
if someone is overheating,
link |
01:52:52.260
by all means, try and get them out of that heat,
link |
01:52:54.240
get them to stop exercising.
link |
01:52:55.720
You can die from hyperthermia.
link |
01:52:57.640
Try and cool the bottoms of the feet,
link |
01:52:59.080
the palms of their hands
link |
01:53:01.300
and the upper portion of their face.
link |
01:53:03.200
That does not mean that it would be a bad idea
link |
01:53:06.440
to put cold water on the top of their head.
link |
01:53:08.160
That probably would also help and perhaps on their neck.
link |
01:53:10.640
What is probably not going to be a good idea
link |
01:53:13.400
is to do the more standard thing
link |
01:53:15.720
of draping someone in cold towels
link |
01:53:17.300
on the surface of their body
link |
01:53:18.360
because as I mentioned at the beginning of the episode,
link |
01:53:20.460
that thermostat in the hypothalamus,
link |
01:53:22.360
the medial preoptic area,
link |
01:53:23.860
will typically react to that
link |
01:53:25.660
by increasing core body temperature further.
link |
01:53:28.240
The effects of glabrous skin cooling
link |
01:53:30.400
on physical performance are truly remarkable
link |
01:53:32.800
provided the glabrous skin cooling is done correctly.
link |
01:53:36.360
And I want to point out that the main degree of effect
link |
01:53:39.960
is on volume or the ability to do more work.
link |
01:53:44.200
And I want to point this out
link |
01:53:45.400
because I think that many people,
link |
01:53:47.640
certainly in the exercise science community,
link |
01:53:49.320
but even in the general public,
link |
01:53:50.520
when they hear about some of these effects
link |
01:53:52.440
that are measured in the laboratory,
link |
01:53:54.600
they sort of look at those effects a bit askance
link |
01:53:59.080
and they think, well, that's not possible, right?
link |
01:54:01.040
Effects, for instance, that have been documented
link |
01:54:03.400
showing doubling or tripling of the number of dips
link |
01:54:05.860
that one can do in a relatively short amount of time,
link |
01:54:08.760
or doubling of the number of pull-ups one can do,
link |
01:54:11.760
or 14% increases in strength,
link |
01:54:13.920
or even comparable degrees in increase
link |
01:54:16.480
in weight training output
link |
01:54:18.280
to people who are on performance enhancing drugs,
link |
01:54:20.400
et cetera, et cetera.
link |
01:54:22.200
Part of the confusion is that the effects
link |
01:54:25.000
of proper Palmer cooling,
link |
01:54:27.380
because it almost always is done by Palmer cooling
link |
01:54:30.080
and less often in these experiments
link |
01:54:32.400
by cooling of the bottoms of the feet
link |
01:54:34.080
in the upper portion of the face,
link |
01:54:35.520
but those effects tend to be the ability
link |
01:54:39.840
to do more work over time.
link |
01:54:42.880
And just to illustrate some of the major effects
link |
01:54:45.160
that the Heller lab has seen
link |
01:54:46.320
and that are documented in this manuscript
link |
01:54:48.080
that I'll share with you in a moment,
link |
01:54:49.920
the typical protocol is to have people come in
link |
01:54:53.320
and do some endurance training,
link |
01:54:54.720
so running on a treadmill,
link |
01:54:56.200
and to have a condition where one group
link |
01:54:59.440
is actually doing Palmer cooling
link |
01:55:00.960
while they are on a bike or on a treadmill.
link |
01:55:03.600
And inevitably the outcome is that they can do more work.
link |
01:55:06.960
They can pedal further at a given speed,
link |
01:55:09.920
or they can run longer at a given speed
link |
01:55:12.780
than people who are not doing Palmer cooling
link |
01:55:14.800
or who are receiving cooling by way of, you know,
link |
01:55:18.040
cold compress to the back of the neck
link |
01:55:19.600
or ice pack to the armpits, et cetera.
link |
01:55:22.760
So the effects of Palmer cooling are very clear
link |
01:55:25.040
and very robust.
link |
01:55:26.720
And in the context of endurance exercise,
link |
01:55:29.560
almost always allow people to do more work,
link |
01:55:31.920
to go longer with less perceived effort
link |
01:55:34.080
and to quit later, so to speak.
link |
01:55:37.120
In terms of strength training,
link |
01:55:38.780
they've looked at the capacity to perform sets of dips.
link |
01:55:42.540
So one of the more famous examples of this
link |
01:55:44.760
that Dr. Heller shares in the episode that we did earlier
link |
01:55:48.760
and that you can find at Hubermanlab.com
link |
01:55:50.940
involves someone coming in and doing sets of dips,
link |
01:55:54.080
maybe 40 dips,
link |
01:55:55.900
this person actually could do 40 dips on their first set,
link |
01:55:58.320
then resting for a period of two to three minutes
link |
01:56:00.600
and then doing 35
link |
01:56:02.420
and then resting for a period of two or three minutes
link |
01:56:04.480
and then doing progressively fewer and fewer and fewer
link |
01:56:06.840
to the point where over a period of time,
link |
01:56:09.400
they add up the total number of dips that they can do,
link |
01:56:11.800
and then they have them come back
link |
01:56:14.220
after a period of recovery.
link |
01:56:15.620
So not immediately after, but take a couple of days,
link |
01:56:18.700
come back and do effectively the same protocol,
link |
01:56:21.520
but during their rest periods,
link |
01:56:22.900
they're doing two minutes of Palmer cooling,
link |
01:56:25.880
which essentially allows heat to move out of the body,
link |
01:56:29.320
lowering core body temperature, in other words.
link |
01:56:31.520
And what they find is that they see enormous increases
link |
01:56:35.320
in the total number of dips that people can do,
link |
01:56:37.280
but that doesn't mean that the person goes
link |
01:56:38.600
from being able to do 40 dips
link |
01:56:39.880
to being able to do 50 dips or 60 dips on that first set.
link |
01:56:43.080
What it means is they are able to do 40 on the first set,
link |
01:56:46.020
then 40 on the second, then 38 on the third
link |
01:56:48.880
and so on and so forth,
link |
01:56:50.040
so that the total duration of the workout is extended
link |
01:56:52.800
and yet they're doing much more work,
link |
01:56:55.480
even though it takes more time.
link |
01:56:57.300
So that's an important point.
link |
01:56:59.400
And I think a point that perhaps wasn't as clear
link |
01:57:02.840
or as clearly made by me in the previous episodes
link |
01:57:05.400
that discussed this topic.
link |
01:57:07.420
For those of you that are interested
link |
01:57:08.700
in exploring Palmer cooling,
link |
01:57:10.920
first of all, I recommend taking a brief glance
link |
01:57:13.780
or even a deep dive into this study,
link |
01:57:17.040
which is entitled work volume
link |
01:57:18.560
and strength training responses to resistive exercise
link |
01:57:21.180
improve with periodic heat extraction from the palm.
link |
01:57:25.360
In this study, they describe big increases in anaerobic,
link |
01:57:30.840
meaning strength training output,
link |
01:57:32.600
things like improvement in dips, improvement in bench press,
link |
01:57:36.960
improvement in pull-ups, et cetera, in human subjects.
link |
01:57:40.720
And it's a really nice study
link |
01:57:42.360
and points to some of the protocols
link |
01:57:43.920
that you might be able to adapt in your own setup.
link |
01:57:46.760
For instance, over six weeks of pull-up training,
link |
01:57:48.880
palm cooling in between sets, improved volume by 144%.
link |
01:57:54.560
And this was in experienced subjects.
link |
01:57:56.440
So that's interesting because a lot of studies
link |
01:57:58.840
of strength training and improvements in hypertrophy
link |
01:58:01.320
and strength are done in inexperienced untrained athletes,
link |
01:58:04.560
which changes the picture somewhat
link |
01:58:07.340
compared to experienced athletes.
link |
01:58:10.640
They found that strength, meaning the one repetition maximum
link |
01:58:13.440
increased 22% over 10 weeks in bench press training.
link |
01:58:17.120
And they point to the particularly strong effects
link |
01:58:20.000
of using Palmer cooling when people reach plateaus
link |
01:58:23.360
in endurance and strength training.
link |
01:58:25.080
And there, I think it's an important point.
link |
01:58:26.660
I think that if you're going to explore Palmer cooling,
link |
01:58:30.240
it's probably not the sort of thing that you're going to do
link |
01:58:32.560
in every run or in every bout of cycling
link |
01:58:36.000
or in every strength training session,
link |
01:58:38.600
but that it might be used to vastly increase your volume
link |
01:58:42.480
or vastly increase your endurance in a given session
link |
01:58:45.720
or a set of sessions in order to push through plateaus.
link |
01:58:49.060
A particularly interesting point in light of that
link |
01:58:51.640
is Dr. Heller has observed again and again
link |
01:58:54.680
that Palmer cooling reduces delayed onset muscle soreness
link |
01:58:57.620
or can eliminate it entirely.
link |
01:58:59.440
And that's very interesting because it also points
link |
01:59:01.560
to the fact that reducing core body temperature
link |
01:59:03.920
may somehow be involved in short circuiting
link |
01:59:06.160
the normal mechanisms of delayed onset muscle soreness.
link |
01:59:09.620
And you might say, well, how would temperature
link |
01:59:11.920
be involved in delayed onset muscle soreness?
link |
01:59:14.320
Well, I want to refer you back to the meta analysis
link |
01:59:17.560
that we talked about earlier where the short duration,
link |
01:59:20.360
very cold temperature exposure after training
link |
01:59:23.040
did indeed reduce delayed onset muscle soreness
link |
01:59:25.480
in part through reduction, excuse me, in creatine kinase.
link |
01:59:28.960
So it's not inconceivable that temperature
link |
01:59:32.280
and delayed onset muscle soreness are related.
link |
01:59:34.960
And that raises perhaps the most important point,
link |
01:59:37.160
which is the way that Palmer cooling can improve performance
link |
01:59:42.520
by way of reducing core body temperature is known.
link |
01:59:46.080
And that is because when one engages in exercise
link |
01:59:50.360
or muscular output of any kind,
link |
01:59:52.080
strength or endurance exercise,
link |
01:59:54.880
the range of temperatures under which a muscle can perform
link |
01:59:58.360
is actually very narrow.
link |
02:00:00.560
There's an enzyme called pyruvate kinase,
link |
02:00:02.760
which is critical to muscle contractions
link |
02:00:05.600
and pyruvate kinase can only function
link |
02:00:07.900
in a very narrow range of temperatures.
link |
02:00:09.780
If that temperature gets too hot,
link |
02:00:11.500
meaning if the muscle heats up locally,
link |
02:00:13.880
whether or not by running or cycling or swimming
link |
02:00:16.240
or weightlifting, the ability for that muscle
link |
02:00:19.240
to continue to contract is reduced
link |
02:00:21.500
and eventually is short-circuited completely.
link |
02:00:23.880
And I think this is a much under explored
link |
02:00:26.760
or at least a much under discussed aspect
link |
02:00:29.400
of so-called muscular failure
link |
02:00:31.000
or the failure of one to continue to endure in running.
link |
02:00:35.280
So for instance, when you run
link |
02:00:36.680
as compared to a bench press or something,
link |
02:00:38.720
you don't stop running
link |
02:00:39.920
because you can't actually contract the muscles further,
link |
02:00:42.400
but somehow signals about the heating up
link |
02:00:46.000
of muscular tissue are conveyed to the brain.
link |
02:00:48.700
There's a crosstalk there.
link |
02:00:49.720
It's probably bi-directional and people stop, they quit.
link |
02:00:53.340
This is the quitting reflex.
link |
02:00:56.080
In strength training,
link |
02:00:58.140
one can no longer perform a repetition
link |
02:01:00.160
or set of repetitions in part
link |
02:01:01.720
because of heating up of the muscle locally.
link |
02:01:03.460
There are other mechanisms as well, of course,
link |
02:01:05.540
and I realize that.
link |
02:01:06.980
But what's very clear from the palmar cooling work
link |
02:01:09.620
is that by simply holding onto a cool object,
link |
02:01:13.220
remember not an object so cold
link |
02:01:14.880
that it constricts the vessels of the palms
link |
02:01:17.080
or constricts the vessels on the bottoms of the feet,
link |
02:01:20.040
but by holding onto a relatively cool object
link |
02:01:22.760
in one or both hands in between sets for two minutes or so,
link |
02:01:26.080
you can very efficiently reduce your core body temperature.
link |
02:01:29.780
And in doing so,
link |
02:01:31.160
reduce the temperature of the muscles
link |
02:01:32.880
that are doing the work,
link |
02:01:35.040
increase the capacity for pyruvate kinase
link |
02:01:37.880
to continue to allow your muscles to contract
link |
02:01:40.760
and thereby allow you to do more volume of endurance
link |
02:01:43.980
and strength training.
link |
02:01:45.000
So a simple protocol that Dr. Heller passed to me
link |
02:01:48.180
is find a relatively cool object.
link |
02:01:51.560
So you could, for instance, fill two bottles with cold water,
link |
02:01:54.360
maybe put a few ice cubes in there, right?
link |
02:01:56.440
This is not exact because we're not talking
link |
02:01:58.400
about the commercial cool mint product here,
link |
02:02:00.020
we're talking about an at-home version,
link |
02:02:01.800
or use a pack of frozen blueberries or broccoli,
link |
02:02:05.280
the sort of pack of those as what he described,
link |
02:02:07.800
and then in between sets to put your hands,
link |
02:02:10.380
and ideally you'd put the bottoms of your feet,
link |
02:02:12.080
but that's not always feasible in most gyms
link |
02:02:13.880
where they won't let you take off your shoes and so forth,
link |
02:02:16.180
but to put the palms of your hands on that cool surface
link |
02:02:19.120
for a minute or two minutes between sets
link |
02:02:22.520
and then returning to your sets of work.
link |
02:02:24.880
Now, if you are heating up through other mechanisms,
link |
02:02:28.600
like you're wearing a stocking cap
link |
02:02:29.900
and you're in a very warm environment,
link |
02:02:31.500
this might not have as potent an effect
link |
02:02:33.400
as if you were to do this cooling
link |
02:02:35.080
in a more moderate environment
link |
02:02:36.740
wearing lighter clothing, et cetera.
link |
02:02:38.640
So by all means, warm up to do your exercise,
link |
02:02:41.480
lubricate your joints and get into a place
link |
02:02:43.240
where you're not going to injure yourself
link |
02:02:44.340
doing whatever form of exercise you do,
link |
02:02:46.400
but then if you'd like to explore Palmer cooling,
link |
02:02:48.920
I know a number of people who've written to me saying
link |
02:02:51.120
they heard about Palmer cooling
link |
02:02:52.220
on the episode with Dr. Heller,
link |
02:02:53.460
they've tried this and they see quite excellent results.
link |
02:02:56.600
It does take some discipline, right?
link |
02:02:58.200
It's one thing to just kind of hang out in the gym
link |
02:02:59.920
and play on your phone in between sets.
link |
02:03:01.240
It's another to do deliberate cooling with your palms
link |
02:03:04.120
or the bottoms of your feet
link |
02:03:04.960
or the upper portion of your face.
link |
02:03:06.520
You might get some weird looks,
link |
02:03:07.880
but of course you'll be the one
link |
02:03:09.060
doing significantly more volume,
link |
02:03:11.040
not experiencing delayed onset muscle soreness
link |
02:03:13.500
and achieving better endurance and strength gains
link |
02:03:16.000
were you to do this properly.
link |
02:03:17.500
Now, as a final topic related to the use
link |
02:03:19.920
of deliberate cold exposure
link |
02:03:21.400
for improving health and performance,
link |
02:03:23.760
I'd like to touch on this theme that exists online
link |
02:03:27.520
on social media, on YouTube,
link |
02:03:29.000
and in various fitness communities
link |
02:03:31.760
of using deliberate cold exposure to the groin,
link |
02:03:34.280
in particular to the testicles,
link |
02:03:36.300
in order to try and increase testosterone.
link |
02:03:39.280
And while this might sound really kooky,
link |
02:03:42.480
indeed this practice exists.
link |
02:03:44.360
Indeed, if you were to go on the Amazon,
link |
02:03:47.120
there are actually ice pack underwear
link |
02:03:50.360
that are being marketed
link |
02:03:52.560
for sake of increasing testosterone.
link |
02:03:54.800
Now, I am not aware of any specific well-controlled studies
link |
02:03:57.800
that show that this indeed works.
link |
02:04:00.400
I can imagine based on what I know about the nervous system,
link |
02:04:03.720
testosterone and cold, et cetera,
link |
02:04:06.000
that there are a couple of mechanisms
link |
02:04:07.340
by which one might experience increases in testosterone
link |
02:04:11.000
as a consequence of deliberate cold exposure.
link |
02:04:13.120
First off, let me say there is no reason
link |
02:04:14.840
why you would have to apply these ice packs
link |
02:04:17.960
in the way that I just described.
link |
02:04:20.360
One could, of course, take a cold shower.
link |
02:04:22.200
One could, of course, use cold immersion of various kinds,
link |
02:04:26.280
and you're still going to get that exposure
link |
02:04:28.660
of the groin and the testicles to cold.
link |
02:04:31.380
Now, I should point out that people do report,
link |
02:04:34.680
at least anecdotally, increases in testosterone
link |
02:04:38.460
as a consequence of this practice.
link |
02:04:40.000
And I have to imagine
link |
02:04:41.160
that they are measuring their serum testosterone,
link |
02:04:43.040
that they're not just guessing
link |
02:04:44.040
that their testosterone went up.
link |
02:04:46.420
If you know of a study exploring this directly,
link |
02:04:48.480
please let me know,
link |
02:04:49.720
put it in the comment section on YouTube,
link |
02:04:51.520
or even just email me.
link |
02:04:53.160
We have a email that you can find at hubermanlab.com.
link |
02:04:57.400
Please email me the reference.
link |
02:04:58.880
I wasn't able to find a reference.
link |
02:05:00.600
But I can imagine two reasonably plausible mechanisms
link |
02:05:04.220
by which deliberate cold exposure to the groin
link |
02:05:07.540
and particularly the testicles would increase testosterone.
link |
02:05:10.720
The first is somewhat direct,
link |
02:05:13.240
which is that anytime you cool a body surface,
link |
02:05:17.080
that if it's cold enough,
link |
02:05:18.480
you're going to get vasoconstriction.
link |
02:05:20.200
And then subsequently,
link |
02:05:21.280
you're going to get a rebound increase in vasodilation,
link |
02:05:24.680
meaning you're going to constrict the blood vessels
link |
02:05:26.620
in that area.
link |
02:05:27.460
And then after the cold is removed,
link |
02:05:29.520
there's going to be more blood flow to that area.
link |
02:05:31.400
And of course, blood flow relates
link |
02:05:33.520
to organ health and tissue health generally,
link |
02:05:35.800
so perfusion of that region and the gonads, to be specific.
link |
02:05:40.800
With additional blood,
link |
02:05:42.860
you could imagine in some ways increasing testosterone.
link |
02:05:46.200
That's reasonably plausible.
link |
02:05:48.300
The other probably more likely mechanism relates
link |
02:05:51.580
to the dopamine increases caused by cold exposure
link |
02:05:54.900
that we talked about earlier.
link |
02:05:56.300
Again, anytime you have a somewhat stressful stimulus,
link |
02:05:59.640
but in particular with cold exposure,
link |
02:06:01.440
it seems that the catecholamines norepinephrine, epinephrine
link |
02:06:04.500
and dopamine all increase.
link |
02:06:07.320
And dopamine is known to be in the pathway
link |
02:06:10.800
that can stimulate testosterone.
link |
02:06:13.060
And so while there isn't a direct relationship
link |
02:06:15.100
between dopamine stimulating testosterone,
link |
02:06:17.260
there is an interesting pathway whereby dopamine increases
link |
02:06:20.220
can trigger increases in things like luteinizing hormone,
link |
02:06:23.300
which can trigger increases in testosterone,
link |
02:06:26.060
as well as estrogen for that matter.
link |
02:06:28.140
So I know that there are a lot of people out there
link |
02:06:30.180
that are interested in the use of cold exposure
link |
02:06:31.960
for increasing testosterone.
link |
02:06:33.380
And some of those people in communities
link |
02:06:35.360
are indeed using cold exposure directly on the gonads,
link |
02:06:40.240
on the testes in order to do this.
link |
02:06:42.420
I'm not certain that that direct contact is necessary.
link |
02:06:46.340
And in some cases it might actually be quite dangerous
link |
02:06:51.040
or you at least should be careful
link |
02:06:52.380
in terms of the tissues there and avoiding damage.
link |
02:06:55.760
But nonetheless, I think that a dopamine impact
link |
02:06:59.880
on testosterone is very likely given the 250% increases
link |
02:07:04.020
in dopamine that have been observed
link |
02:07:05.280
with cold water immersion.
link |
02:07:06.380
And all of that points to the fact
link |
02:07:07.660
that cold water immersion very likely increases testosterone,
link |
02:07:13.320
but as a downstream consequence
link |
02:07:15.260
of the cold water immersion effects
link |
02:07:17.380
on dopamine and luteinizing hormone.
link |
02:07:19.500
And again, there's no reason to think
link |
02:07:21.080
that the increases in luteinizing hormone
link |
02:07:23.200
would also increase estrogen,
link |
02:07:25.260
probably not too dangerous or levels
link |
02:07:29.300
that one would want to avoid.
link |
02:07:31.560
But I don't think that there's anything
link |
02:07:33.140
particularly specific about cold for inducing testosterone
link |
02:07:36.860
and not other hormones.
link |
02:07:38.140
I think it's very likely to increase
link |
02:07:39.300
as a number of different hormones.
link |
02:07:41.540
I do hope that there will be a systematic study on this
link |
02:07:44.280
in the not too distant future.
link |
02:07:45.820
I also hope to not be a subject
link |
02:07:47.720
in the cooling of the gonads experiment.
link |
02:07:50.360
Now, I promise you the last topic was the last topic,
link |
02:07:52.540
but there's one other really important point
link |
02:07:54.580
that I think everyone should be aware of
link |
02:07:56.400
if you're going to use deliberate cold exposure.
link |
02:07:59.020
And that brings us back to the very first thing
link |
02:08:01.940
that we discussed today
link |
02:08:03.460
along the lines of deliberate cold exposure,
link |
02:08:05.180
which is that your baseline temperature
link |
02:08:07.140
is going to be lowest about two hours before you wake up.
link |
02:08:11.440
It's going to increase in the morning and as you wake up,
link |
02:08:15.040
and increase throughout the day and afternoon,
link |
02:08:17.260
and then start to drop in the evening
link |
02:08:19.200
and come down at night as you head to sleep.
link |
02:08:22.980
I also want you to remember
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02:08:24.520
that if you are to cool the external portion of your body,
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02:08:27.980
in particular your torso,
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02:08:30.340
the net effect of that
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02:08:31.940
is going to be an increase in body temperature.
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02:08:35.460
So for many people, not all, but for many people,
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02:08:38.900
if you are going to do deliberate cold exposure,
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02:08:41.980
you are going to increase your core body temperature.
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02:08:45.180
And that makes sense if you think about
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02:08:46.660
how deliberate cold exposure can increase metabolism
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02:08:50.180
by increasing thermogenesis.
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02:08:52.400
What that all means is
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02:08:54.700
that if you are doing your deliberate cold exposure
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02:08:57.340
early in the day,
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02:08:58.700
you are going to get yet a further increase
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02:09:01.500
in core body temperature
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02:09:03.020
that would be associated with wakefulness,
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02:09:05.620
your ability to be alert that morning
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02:09:07.460
or throughout the day, and so on.
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02:09:10.260
It also means that if you do your deliberate cold exposure
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02:09:13.880
very late in the evening or at night,
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02:09:16.280
so 6 p.m., 7 p.m., 9 p.m., and so on,
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02:09:21.300
you are going to increase your core body temperature.
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02:09:23.700
And if you recall,
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02:09:25.780
a decrease in core body temperature of one to three degrees
link |
02:09:29.500
is not just beneficial,
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02:09:31.300
but is necessary in order to get into deep sleep
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02:09:34.340
and remain in deep sleep.
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02:09:36.380
So the takeaway from this is
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02:09:38.380
deliberate cold exposure done properly
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02:09:40.480
will increase your core body temperature
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02:09:42.240
and make you feel more alert.
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02:09:44.220
So if you're doing it early in the day,
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02:09:46.200
that's probably terrific,
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02:09:48.180
given that most of us want to be alert during the day.
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02:09:50.940
However, if you do it too late in the day,
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02:09:53.220
evening or night, it can disrupt sleep
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02:09:55.880
by way of disrupting your core body temperature.
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02:09:58.780
Now, the caveat to that is I myself
link |
02:10:02.320
tend to do my deliberate cold exposure early in the day,
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02:10:05.140
maybe not first thing in the morning, but mid-morning,
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02:10:07.560
maybe as late as three or four in the afternoon
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02:10:09.580
in some cases.
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02:10:10.420
In the longer days of summer, I might do it even later,
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02:10:12.760
5 or 6 p.m., and have no trouble sleeping.
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02:10:15.600
I have done deliberate cold exposure very late at night,
link |
02:10:18.940
10 p.m., 11 p.m., and so on,
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02:10:21.740
as part of a 30-day challenge of doing
link |
02:10:23.540
deliberate cold exposure every day for 30 days,
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02:10:25.940
and I got sloppy with my timing,
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02:10:27.540
and then in order to not miss a day,
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02:10:29.300
I would do it at 11 o'clock at night.
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02:10:30.940
And I must say, I found that I could still fall asleep
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02:10:34.300
very easily, even doing deliberate cold exposure
link |
02:10:36.940
very late at night.
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02:10:38.060
However, on those particular days, I was particularly busy,
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02:10:42.280
and so I was particularly exhausted
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02:10:44.580
when I arrived at the deliberate cold exposure,
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02:10:46.860
and I had no trouble falling asleep
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02:10:49.100
after doing deliberate cold exposure
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02:10:50.540
and then taking a nice warm shower and then going to sleep.
link |
02:10:53.020
But I could imagine that because of the increases
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02:10:56.020
in core body temperature caused by deliberate cold exposure,
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02:10:59.340
that were one to do that too late in the day,
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02:11:02.060
evening or night, that it could indeed disrupt your sleep.
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02:11:04.860
So my recommendation would be for most people,
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02:11:07.680
only do deliberate cold exposure
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02:11:09.220
if you are prepared to be fairly alert
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02:11:11.560
for the next one to four or maybe even six hours
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02:11:14.820
following that deliberate cold exposure.
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02:11:17.000
So for today's episode, as is the case
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02:11:18.860
with most episodes of the Huberman Lab Podcast,
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02:11:21.720
I covered a lot of material.
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02:11:23.180
We talked about mechanisms of catecholamines and stress
link |
02:11:25.940
and pulsatile release of epinephrine,
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02:11:28.580
metabolism, mental effects, performance,
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02:11:31.140
glabrous skin cooling, and on and on and on.
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02:11:33.880
And while the goal of course is to make sure
link |
02:11:36.100
that everyone arrives at specific, very clear,
link |
02:11:39.460
mechanistic and actionable protocols,
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02:11:41.740
I do realize that it is an immense amount of information.
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02:11:44.780
And for that reason, I've created a list
link |
02:11:47.140
of deliberate cold exposure protocols
link |
02:11:49.940
aimed at improving mental toughness and resilience,
link |
02:11:53.660
mood, performance, metabolism,
link |
02:11:57.000
reducing inflammation, and so on and so forth.
link |
02:11:59.440
All of those have been condensed into succinct form
link |
02:12:02.700
and can be found
link |
02:12:04.180
at the Huberman Lab Neural Network Newsletter.
link |
02:12:06.860
This is a monthly or semi-monthly newsletter
link |
02:12:09.380
that we release that includes takeaways
link |
02:12:11.540
from the podcast and protocols.
link |
02:12:13.660
You can access those protocols, zero cost,
link |
02:12:16.480
by simply going to HubermanLab.com,
link |
02:12:19.060
signing up for the Neural Network Newsletter.
link |
02:12:20.900
It's very easy to do.
link |
02:12:21.840
You just supply your email and you will receive
link |
02:12:23.980
the newsletter.
link |
02:12:24.940
We do not share your email with anybody else.
link |
02:12:27.780
In fact, we have our privacy policy laid out
link |
02:12:30.740
on the HubermanLab.com website,
link |
02:12:33.100
so you can find that there.
link |
02:12:34.660
And the protocols that I've designed
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02:12:36.740
should make it very straightforward for you to create
link |
02:12:40.380
a set of protocols that you could use with cold showers,
link |
02:12:42.800
with cold immersion, with or without ice,
link |
02:12:44.820
in combination with exercise, specifically for one goal
link |
02:12:47.500
or another, or to accomplish multiple goals simultaneously.
link |
02:12:50.580
If you're learning from and are enjoying this podcast,
link |
02:12:52.780
please subscribe to our YouTube channel.
link |
02:12:54.560
That's a terrific zero cost way to support us.
link |
02:12:57.260
In addition, please subscribe to the podcast
link |
02:12:59.620
on Spotify and or Apple.
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02:13:01.260
And on Apple, you have the opportunity to leave us
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02:13:03.500
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02:13:05.200
You can also now leave reviews on Spotify,
link |
02:13:07.940
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02:13:10.020
If you have suggestions for future guests
link |
02:13:12.140
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link |
02:13:14.020
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link |
02:13:16.780
please put that in the comment section on YouTube.
link |
02:13:19.620
Please also check out the sponsors mentioned
link |
02:13:21.440
at the beginning of today's episode.
link |
02:13:23.320
That is the best way to support this podcast.
link |
02:13:25.860
In addition, we have a Patreon.
link |
02:13:27.620
It's patreon.com slash Andrew Huberman,
link |
02:13:30.380
and there you can support the podcast
link |
02:13:32.220
at any level that you like.
link |
02:13:33.740
On many previous episodes of the Huberman Lab Podcast,
link |
02:13:36.360
we talk about supplements.
link |
02:13:37.820
While supplements aren't necessary for everybody,
link |
02:13:39.940
many people derive tremendous benefit from them
link |
02:13:42.180
for things like sleep and focus and other aspects
link |
02:13:44.880
of health and performance.
link |
02:13:46.460
One issue with the supplement industry
link |
02:13:47.960
that's very serious, however,
link |
02:13:49.580
is that many supplement companies simply do not use
link |
02:13:52.620
high quality ingredients or the amounts of the ingredients
link |
02:13:55.600
they list on the packaging does not match
link |
02:13:57.940
what's actually contained in their products.
link |
02:13:59.800
For that reason, we partner with Thorne, T-H-O-R-N-E,
link |
02:14:03.540
because Thorne supplements are known to be
link |
02:14:05.520
of the very highest quality ingredients
link |
02:14:07.340
and the very highest degree of specificity
link |
02:14:10.100
in terms of the amounts of the ingredients
link |
02:14:12.140
that are listed on the packaging
link |
02:14:13.700
accurately match what's contained in their products.
link |
02:14:16.640
If you'd like to see the Thorne products that I take,
link |
02:14:18.560
you can go to Thorne, that's T-H-O-R-N-E dot com
link |
02:14:21.940
slash the letter U slash Huberman,
link |
02:14:24.140
and there you can see the Thorne products that I take
link |
02:14:26.160
and get 20% off any of those products.
link |
02:14:28.580
In addition, if you navigate deeper into the Thorne site
link |
02:14:31.060
through that portal, Thorne,
link |
02:14:32.380
T-H-O-R-N-E dot com slash the letter U slash Huberman,
link |
02:14:36.380
you can also get 20% off any of the other products
link |
02:14:38.800
that Thorne makes.
link |
02:14:40.020
If you're not already subscribed to Huberman Lab
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02:14:42.180
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link |
02:14:44.440
There I cover science and science-related tools
link |
02:14:46.880
that sometimes overlap with the content of the podcast,
link |
02:14:49.600
but oftentimes is distinct from the information
link |
02:14:51.900
covered on this podcast.
link |
02:14:53.580
So thank you once again for joining me in the discussion
link |
02:14:56.420
about the use of deliberate cold exposure
link |
02:14:58.600
for health