The Science & Use of Cold Exposure for Health & Performance

Cold exposure as a powerful nervous system stimulus

Temperature is one of the most powerful tools for shifting nervous system function, affecting every organ and system in the body.

"Temperature is a powerful stimulus on our nervous system and indeed on every organ and system of our body."

How cold should deliberate cold exposure be

The water should be uncomfortably cold — cold enough that you want to get out but can safely stay in. Cold showers are acceptable but immersion is more effective.

"If I don't say otherwise, then throughout this episode, if I say cold exposure, I mean deliberate cold exposure. And the reason I point that out is that as my colleague, David Spiegel in the Department of Psychiatry at Stanford says, it's not just about the state that we are in, it's about the state that we are in and whether or not we had anything to do with placing ourselves into that state and whether or not we did that on purpose or not. And what he really means by that statement is that there are important effects of what we call mindset. Mindset was a topic discussed in the guest episode with Ali Crumb some weeks ago. If you haven't seen that episode, I highly recommend it. And the science of mindset tells us that if we are doing something deliberately and we believe that it's going to be good for us, it actually can lead to a different set of physiological effects than if something is happening to us against our will or without our control. Now this is different than placebo effects. Placebo effects are distinct from mindset effects. If you want to learn more about the distinction, please see the episode with Ali Crumb. But again, when I talk about cold exposure in this episode, I'm talking about deliberate cold exposure, meaning that you are placing yourself into a cold environment on purpose in order to extract a particular set of benefits."

530% norepinephrine increase from cold water immersion

A landmark study showed cold water immersion produced a 530% increase in norepinephrine, with effects lasting well beyond the cold exposure session.

"So again, I do not think that you need to be super strict about these guidelines. It's most important when embracing a protocol, A, that you do it safely, but secondarily that you do it consistently. So find what you can do consistently and then vary the parameters that will allow you to continue to do deliberate cold exposure consistently, regardless of whether or not you have access to a shower or a cold immersion, et cetera. Okay, so we've been talking about mental effects and the use of deliberate cold exposure for sake of building resilience, which I do believe can be tremendously powerful. Look, it's no coincidence that the screening and the training for Navy SEALs involves a lot of exposure to cold water. One could argue that it is deliberate because they elect to go to BUDS, but when they get into the cold water at BUDS is dictated by the instructors. And the reason they use cold water exposure as the stressor is that it does offer considerable leeway in terms of duration and temperature in terms of how you can use it as a stressor. Whereas things like heat don't offer much variable space, as we say, there isn't a lot of room beyond which you start injuring or even killing people by using heat. So there are a lot of forms of stressors out there, but cold is one that we can titrate, that we can adjust in ways that can allow us to continually build up and or maintain mental toughness."

11 minutes per week of cold exposure for metabolic benefits

Research shows that approximately 11 minutes per week of cold water immersion, divided into multiple sessions, significantly increases brown fat and resting metabolism.

"So I want to emphasize this. I'm not suggesting that people do deliberate cold exposure. So I want to emphasize this. I'm not suggesting that people do deliberate cold exposure for an hour a day. And unfortunately, there are not many studies yet exploring how shorter, colder temperature environment exposure, say one minute or three minutes or six minutes at 55 degrees or at 50 degrees, whether or not that leads to similar, greater, or reduced levels of dopamine in the brain and body. And yet almost everybody who does deliberate cold exposure will say, yeah, it was stressful, I didn't enjoy it, or I eventually grew to like it, but that I always feel better afterwards. And then that feeling lasts a very long period of time. And I think it's almost certain that those experiences that people report relate to these increases in dopamine. And in concert with the increases in norepinephrine also explain the other effect that's commonly reported, which is an enhancement in mental acuity and the ability to focus. Now, here we can extrapolate to the study that I discussed at the early part of the episode where I was talking about the use of short 15 minute exercise, kind of moderate intensity exercise, and how that was shown to increase levels of energy and mental acuity in these working memory, visual attention tasks. And there again, we have to assume somewhat because they weren't doing neurochemical measurements, but we can reasonably assume that those improvements in cognitive performance were due at least in part to the increase in catecholamines known to accompany moderate intensity zone to cardio. So what you're starting to see here is a theme. The theme is that virtually any stimulus that delivers more norepinephrine, epinephrine, and dopamine to our system will sharpen our mental acuity and elevate our mood and will do so for some period of time."

The Soberg Principle: always end on cold to boost metabolism

To maximize metabolic benefits, end your protocol on cold rather than warm — forcing your body to reheat itself through shivering and brown fat thermogenesis.

"That increases the density and or efficacy of these receptors, which would allow that dopamine to have its greatest effect. And for those of you that want to get really, really fancy, I suppose you could do this fasted. So you get the further increase in norepinephrine and you get the dopamine increase from the cold exposure, the bonding, the dopamine. Although I do want to point out that at some point you start layering together enough protocols that you would be spending your entire day trying to get this dopamine pulse. And I would hope that you would have other activities that you would engage in. But if you're getting up in the morning and you're fasted because you haven't eaten all night and you have a cup of coffee, and then 60 minutes later, you take your cold shower, or two hours later, you do your cold immersion or your cold shower, you would be layering together these different mechanisms of dopamine receptors, epinephrine and so forth in a way that at least to me doesn't seem incompatible with having some other life, like going to school and having relationships, et cetera. And this increase in dopamine, particularly in the striatum is not a trivial one. I do want to point out as the authors do, that preclinical studies have shown that increases in striatal dopamine induced by things like modafinil, which is used to treat ADHD and treat narcolepsy, is necessary for their wake-promoting actions. What this really says is that just having elevated levels of dopamine from a drug or from an ice bath or what have you is not sufficient to get the effects of dopamine. You really need the receptors to be available and you need those receptors to be available in the appropriate density, and you need those receptors to be available in the appropriate density in and you need those receptors to be available in the appropriate density in the striatum in particular. So I think there are a number of reasons why, if it's compatible with the other aspects of your health, because of course, always you have to consider this on a background of cardiovascular health and blood pressure, et cetera, that ingesting a cup or two of coffee an hour before your ice bath, maybe fasted as well, could be quite beneficial for increasing dopamine over quite extended periods of time. A couple of key points that you'll want to pay attention to in thinking about deliberate cold exposure and metabolism."

Palmer cooling between sets dramatically increases training volume

Cooling glabrous skin (palms) between exercise sets restores muscle function by lowering core temperature, with studies showing doubling of pull-ups and tripling of dips.

"There's a particular paper that focuses on this and we will put a link to this as well. The title of this paper is Novel Application of Chemical Cold Packs for Treatment of Exercise-Induced Hyperthermia, a Randomized Control Trial. This is a pretty brutal study, brutal for the subjects that is. What the study involved was having subjects walk on a treadmill at a pretty significant incline, anywhere from nine to 17%, wearing a substantial amount of clothing that was not well ventilated. And the room was kept to 40 degrees Celsius, which is 104 degrees Fahrenheit. This is definitely not something to do at home. This study was designed to induce hyperthermia, which as I mentioned earlier, can be quite dangerous. And they compared two types of cooling. In the first form of cooling that they call traditional cooling, they had ice packs on their neck, in their armpits, and in their groin. And in the other group, there was the so-called glabrous skin cooling. So the palms, the soles of the feet, which were actually, so they were cooling inside the boots or inside of gloves and on the upper portion of the face."