Essentials: Increase Strength & Endurance with Cooling Protocols | Dr. Craig Heller

**Andrew Huberman** (0:00)
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, I have the pleasure of introducing Dr. Craig Heller as my guest on the Huberman Lab Podcast. And now for my discussion with Dr. Craig Heller. Great to have you here.

**Craig Heller** (0:27)
It's good to be here.

**Andrew Huberman** (0:28)
Yeah, I know that I and many people have a lot of questions about the use of cold. So one of the things that's happened in recent years is that for many reasons, people have become interested in things like taking cold showers and taking ice baths for many different purposes. Could you just tell me a little bit about what happens when I get into a cold shower or an ice bath?

**Craig Heller** (0:57)
Well, first of all, you get a tremendous shock. And what that's going to translate into is a bit of a shot of adrenaline. And I think this is really the so-called benefit, but it doesn't necessarily translate into any benefit in terms of your physiology or performance and so forth. Now, if you take a cold bath or a cold shower, a couple of things are happening. One is you're going to stimulate vasoconstriction.
So, if anything, it's going to make it a little bit more difficult for your body to get rid of heat because you're shutting off your avenues of heat loss. If you're in a true cold bath, the overall surface area of your body is so great that it doesn't matter if you have vasoconstricted, you're still going to lose heat. The primary sites of heat loss, which we're going to get into, are the palms of your hands, the soles of your feet, and the upper part of your face. And the reason these are avenues for heat loss is they're underlain by special blood vessels. And these blood vessels are able to shunt the blood from the arteries, which are coming from the heart, directly to the veins, which are returning to the heart, and bypassing the capillaries, which are the nutritive vessels, but high resistance. So you can tell when you shake someone's hand, what his or her thermal status is. The hand's hot or it's cold.

**Andrew Huberman** (2:25)
A couple of questions before we get into these specialized vascular compartments on the soles, the palms, and the upper face. Is there anything that's really important to understand about the difference in the physiological response evoked by cold shower versus immersion in cold?

**Craig Heller** (2:44)
Well, there are differences that are more physical than anything else. So if you are in a cold bath and you're still, you develop a boundary layer. It's best to explain it in terms of a hot bath because everybody's experienced that. You get into a hot bath and, oh my God, it's really hot, almost painful. And then you sit down and eventually it doesn't feel so hot anymore because the still water, which is close to your skin, is coming into equilibrium with your skin. So it's like having a blanket on you or an insulator on you. And then if you move around, you disturb that still water layer, you feel the hot temperature again.

**Andrew Huberman** (3:25)
Got it.

**Craig Heller** (3:25)
Yeah. But I think getting back to your original question about benefits, you have to keep in mind, whether you're talking about aerobic activity or anaerobic activity, if you're referring to performance and exercise and so forth. So if you're doing aerobic activity that you can sustain for a long time, your production of heat is rising gradually and is being distributed throughout your body. So eventually your body temperature is going to come up to a level that's going to impair your performance. So the benefit of a cold bath or a cold shower before aerobic activity is that you increase the capacity of your body mass to absorb that excess heat.

**Andrew Huberman** (4:08)
I see. So could you say that in a rough sense that a protocol that one might use if they're gonna head out for a long run, even on a reasonably warm day, not super hot, or maybe it is super hot, would be to take a cool shower before they go run. Would that be beneficial?

**Craig Heller** (4:26)
Sure. It'll take them longer to get to the sweat point and to heat up.

**Andrew Huberman** (4:30)
And what will that translate to in terms of a performance benefit?

**Craig Heller** (4:34)
Well, it could increase your speed, or it depends on how you use that benefit. Some people are pacers. They will go at the same pace, and then they will go farther. Or some people are forcers. They will take that advantage and use it up as fast as they can. So they will go faster, but not necessarily farther.