Dr. Craig Heller: Using Temperature for Performance, Brain & Body Health

00:00:00.000 | - Welcome to the Huberman Lab Podcast,

00:00:02.280 | where we discuss science and science-based tools

00:00:04.880 | for everyday life.

00:00:05.900 | I'm Andrew Huberman,

00:00:10.560 | and I'm a professor of neurobiology and ophthalmology

00:00:13.080 | at Stanford School of Medicine.

00:00:15.120 | Today, I have the pleasure of introducing Dr. Craig Heller

00:00:18.040 | as my guest on the Huberman Lab Podcast.

00:00:20.800 | Dr. Heller is a professor of biology and neurosciences

00:00:23.880 | at Stanford.

00:00:25.240 | His laboratory works on a range of topics,

00:00:27.480 | including thermoregulation, down syndrome,

00:00:30.400 | and circadian rhythms.

00:00:32.120 | Today, we talk about thermoregulation,

00:00:34.400 | how the body heats and cools itself

00:00:36.880 | and maintains what we call homeostasis,

00:00:39.660 | which is an equilibrium of processes

00:00:41.760 | that keeps our neurons healthy,

00:00:43.560 | our organs functioning well.

00:00:45.280 | And as Dr. Heller teaches us,

00:00:48.000 | thermoregulation can be leveraged

00:00:49.760 | in order to greatly increase our performance in athletics

00:00:53.380 | and mental performance as well.

00:00:55.700 | Learning to control your core body temperature

00:00:58.200 | is one of the most, if not the most powerful thing

00:01:01.320 | that you can do to optimize mental and physical performance,

00:01:04.560 | regardless of the environment that you're in.

00:01:06.820 | He also dispels many common myths

00:01:08.720 | about heating and cooling the body,

00:01:10.880 | including the idea that putting a cold pack

00:01:13.240 | on your head or neck is the optimal way

00:01:15.080 | to cool down quickly.

00:01:16.280 | And in fact, as Dr. Heller tells us,

00:01:18.880 | it actually can be counterproductive

00:01:20.460 | and lead to hyperthermia.

00:01:22.760 | It's a fascinating conversation

00:01:24.400 | from which I learned a tremendous amount of new information.

00:01:27.520 | And we didn't even get into the other

00:01:29.560 | incredibly interesting work that Dr. Heller does

00:01:31.700 | on Down syndrome and circadian rhythms and sleep.

00:01:34.680 | So we hope to have him back in the future

00:01:36.320 | to discuss those topics.

00:01:38.420 | As you'll soon see, Dr. Heller is a wealth of knowledge

00:01:41.460 | on all things human physiology, biology,

00:01:44.740 | and human performance.

00:01:46.400 | It's no surprise then that he's been

00:01:48.240 | chair of the biology department at Stanford for many years,

00:01:51.200 | as well as director of the human biology program.

00:01:54.260 | So if you're interested in human biology

00:01:55.920 | and how to improve your performance

00:01:57.860 | in any context or setting, athletic or otherwise,

00:02:01.320 | I think you'll very much enjoy today's conversation.

00:02:04.160 | Before we begin, I'd like to emphasize

00:02:05.880 | that this podcast is separate

00:02:07.280 | from my teaching and research roles at Stanford.

00:02:09.520 | It is, however, part of my desire and effort

00:02:11.600 | to bring zero cost to consumer information

00:02:13.520 | about science and science-related tools

00:02:15.800 | to the general public.

00:02:17.320 | In keeping with that theme,

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00:06:45.360 | And now for my discussion with Dr. Craig Heller.

00:06:48.780 | - Great to have you here.

00:06:49.720 | - It's good to be here.

00:06:50.560 | - Yeah, it's been a long time coming.

00:06:52.400 | I know that I and many people have a lot of questions

00:06:56.540 | about the use of cold.

00:06:58.860 | So one of the things that's happened in recent years

00:07:02.440 | is that for many reasons,

00:07:05.640 | people have become interested in things

00:07:08.220 | like taking cold showers and taking ice baths

00:07:11.680 | for many different purposes.

00:07:13.760 | Sometimes this is introduced as just a general health tonic,

00:07:18.240 | but other times people get specific

00:07:20.760 | about how it can improve resilience

00:07:22.840 | or it can improve one's metabolism.

00:07:25.660 | Could you just tell me a little bit about what happens

00:07:31.160 | when I get into a cold shower or an ice bath?

00:07:34.920 | What are some of the basic responses

00:07:36.920 | at the level of metabolism?

00:07:38.860 | Obviously, psychologically, we don't know exactly.

00:07:41.500 | It'll vary from person to person.

00:07:42.840 | But what happens when I submerge myself into an ice bath

00:07:46.180 | if I've never done it before?

00:07:48.220 | - Well, first of all, you get a tremendous shock.

00:07:52.180 | And what that's going to translate into

00:07:54.720 | is a bit of a shot of adrenaline.

00:07:57.300 | And I think this is really the so-called benefit,

00:08:01.260 | but I wouldn't call it a benefit of the cryochambers.

00:08:04.620 | You go into a cryochamber and it's a shock.

00:08:06.800 | So you get a shot of adrenaline.

00:08:08.220 | So sure, you're going to feel different when you come out.

00:08:11.080 | You've had a shot of adrenaline,

00:08:12.880 | but it doesn't necessarily translate into any benefit

00:08:16.840 | in terms of your physiology or performance and so forth.

00:08:21.040 | Now, if you take a cold bath or a cold shower,

00:08:25.400 | a couple of things are happening.

00:08:26.980 | One is you're going to stimulate vasoconstriction.

00:08:30.440 | So if anything, it's going to make it

00:08:32.040 | a little bit more difficult for your body

00:08:34.080 | to get rid of heat because you're shutting off

00:08:37.120 | your avenues of heat loss.

00:08:40.240 | If you're in a true cold bath,

00:08:43.520 | the overall surface area of your body is so great

00:08:47.440 | that it doesn't matter if you've vasoconstricted.

00:08:49.840 | You're still going to lose heat.

00:08:51.320 | - Okay, so vasoconstriction, the constriction of,

00:08:55.120 | is it capillaries, vessels, and arteries all constrict

00:08:58.780 | or just one or two?

00:09:01.680 | - Well, this is an area of controversy.

00:09:05.340 | In general, when people talk of vasoconstriction,

00:09:07.840 | they talk of the overall skin surface,

00:09:10.360 | and that is not true.

00:09:11.760 | The primary sites of heat loss,

00:09:15.140 | which we're going to get into,

00:09:17.080 | are the palms of your hands, the soles of your feet,

00:09:20.220 | and the upper part of your face.

00:09:22.280 | And the reason these are avenues for heat loss

00:09:25.760 | is they're underlain by special blood vessels.

00:09:28.840 | And these blood vessels are able to shunt the blood

00:09:32.760 | from the arteries, which are coming from the heart,

00:09:35.760 | directly to the veins, which are returning to the heart,

00:09:38.960 | and bypassing the capillaries,

00:09:40.880 | which are the nutritive vessels, but high resistance.

00:09:44.560 | So you can tell when you shake someone's hand

00:09:47.240 | what his or her thermal status is.

00:09:49.700 | The hand's hot or it's cold.

00:09:51.440 | - Do you think that's part of the reason

00:09:52.760 | why humans evolved this practice of shaking hands,

00:09:56.640 | assessing each other's level of anxiety?

00:09:58.520 | We all know that a limp handshake

00:10:00.040 | is pretty indicative of something,

00:10:02.360 | and a firm handshake is indicative of something,

00:10:04.480 | as is the crushing handshake, for that matter, right?

00:10:07.360 | - Yeah, I really don't know

00:10:08.360 | what the evolutionary origin of handshaking is,

00:10:10.880 | other than to get your hand away from your weapon, perhaps.

00:10:14.680 | - Right, a couple of questions

00:10:16.720 | before we get into these specialized vascular compartments

00:10:21.320 | on the soles, the palms, and the upper face.

00:10:24.840 | You mentioned whole body immersion, like into an ice bath

00:10:28.160 | or very cold water up to the neck, versus a cold shower.

00:10:31.880 | Is there something fundamentally different about those two,

00:10:34.560 | besides the fact that they both provide

00:10:36.280 | this release of adrenaline?

00:10:37.780 | Is there anything that's really important to understand

00:10:40.900 | about the difference in the physiological response

00:10:43.700 | evoked by cold shower versus immersion in cold?

00:10:48.480 | - Well, there are differences that are more physical

00:10:51.380 | than anything else.

00:10:52.400 | So if you are in a cold bath and you're still,

00:10:55.420 | you develop a boundary layer.

00:10:57.740 | If you're in a shower, you can't develop a boundary layer.

00:11:00.080 | - Could you explain what a boundary layer is?

00:11:01.800 | - Yes, it's best to explain it in terms of a hot bath,

00:11:06.080 | 'cause everybody's experienced that.

00:11:08.000 | You get into a hot bath and oh my God, it's really hot,

00:11:11.600 | almost painful, and then you sit down

00:11:14.640 | and eventually it doesn't feel so hot anymore,

00:11:17.760 | because the still water, which is close to your skin,

00:11:21.880 | is coming into equilibrium with your skin.

00:11:24.200 | So it's like having a blanket on you or an insulator on you.

00:11:28.360 | And then if you move around, you disturb that still water

00:11:32.560 | layer, you feel the hot temperature again.

00:11:35.880 | - I see, so if I were to get into a cold ice bath

00:11:38.760 | or a very cold body of water of some kind and stay still,

00:11:43.000 | I'd likely feel warmer, at least until I start-

00:11:45.840 | - You're not going to be losing as much heat.

00:11:47.700 | - I see.

00:11:48.540 | And then when I move it, I'll say-

00:11:49.360 | - If you flail around, if you flail around,

00:11:51.100 | then you're going to lose more heat.

00:11:52.440 | - Got it.

00:11:53.280 | - Yeah, but I think getting back to your original question

00:11:55.640 | about benefits, you have to keep in mind

00:11:58.800 | whether you're talking about aerobic activity

00:12:01.760 | or anaerobic activity, if you're referring to performance

00:12:05.440 | and exercise and so forth.

00:12:07.440 | So if you're doing aerobic activity that you can sustain

00:12:10.960 | for a long time, your production of heat is rising gradually

00:12:15.960 | and is being distributed throughout your body.

00:12:19.600 | So eventually your body temperature is going to come up

00:12:22.060 | to a level that's going to impair your performance.

00:12:25.240 | So the benefit of a cold bath or a cold shower

00:12:28.160 | before aerobic activity is that you increase the capacity

00:12:32.620 | of your body mass to absorb that excess heat.

00:12:35.960 | - I see.

00:12:36.800 | So could you say that in a rough sense that a protocol

00:12:41.220 | that one might use if they're going to head out

00:12:43.160 | for a long run, even on a reasonably warm day,

00:12:47.000 | not super hot, or maybe it is super hot,

00:12:49.680 | would be to take a cool shower before they go run?

00:12:52.980 | Would that be beneficial?

00:12:53.820 | - Sure, it'll take them longer to get to the sweat point

00:12:56.860 | and to heat up.

00:12:57.780 | - And what will that translate to

00:12:59.040 | in terms of a performance benefit?

00:13:01.700 | - Well, could increase your speed,

00:13:04.220 | or it depends on how you use that benefit.

00:13:06.860 | Some people are pacers.

00:13:08.620 | They will go at the same pace and then they will go farther.

00:13:12.040 | Or some people are, I want to say, pacers and regulators.

00:13:17.040 | And no, no, pacers or forcers, they will take that advantage

00:13:22.000 | and use it up as fast as they can.

00:13:23.860 | So they will go faster, but not necessarily farther.

00:13:27.420 | - I see.

00:13:28.260 | As far as I know, not many athletes,

00:13:30.400 | at least not the ones that I know,

00:13:31.740 | are getting into cool bodies of water,

00:13:33.580 | taking cold showers before they head out to train.

00:13:36.240 | But it sounds like there could be

00:13:37.260 | a real performance benefit there.

00:13:39.140 | - It could be a benefit.

00:13:40.620 | I know we're going to talk about our technology for cooling,

00:13:44.660 | but at one point, I don't know if they're using it now,

00:13:47.980 | but our cross-country team,

00:13:49.600 | when they would go to compete in a very hot place,

00:13:51.720 | they would do their warmup exercises, their stretching.

00:13:55.140 | Then they would extract heat

00:13:57.780 | before the beginning of the race.

00:13:59.740 | So I like to think of it as you have greater scope

00:14:03.220 | for heat absorption.

00:14:04.820 | - Interesting, about how long would one need

00:14:07.280 | to take one of these showers or cold immersions

00:14:09.960 | before heading out for a run?

00:14:11.180 | Roughly speaking, we don't have to get into details

00:14:13.360 | because everyone's performance level

00:14:15.620 | and regimen is going to be different,

00:14:17.040 | where they live is going to be different, et cetera.

00:14:18.740 | - Right, it's not as long as you think, it's minutes.

00:14:21.580 | - Couple minutes.

00:14:22.420 | - Yeah, because what's going to happen is

00:14:25.620 | as your core temperature goes down,

00:14:27.920 | you will eventually shut off your heat loss

00:14:30.920 | and that keeps it from going below normal.

00:14:35.220 | So if you've warmed up and your temperature has risen

00:14:39.580 | by half a degree, let's say,

00:14:41.740 | it doesn't take more than a few minutes

00:14:43.700 | to extract that heat if you're vasodilated.

00:14:46.440 | - Interesting, and what about for the anaerobic athlete,

00:14:49.920 | the strength athlete?

00:14:50.760 | - Right, for the anaerobic athlete,

00:14:53.000 | and let's say they're doing several sets

00:14:56.000 | and how many reps, whatever they're doing,

00:15:01.800 | their core temperature is not going to rise that fast

00:15:05.360 | because it's only certain muscles which are being used,

00:15:08.840 | but the temperature of those muscles will go up.

00:15:11.820 | - So it's a local effect.

00:15:13.080 | - It's a local effect, right.

00:15:14.720 | - So let's say, for sake of today

00:15:16.760 | and maybe for this discussion,

00:15:18.520 | if we assume that the basic workout,

00:15:21.200 | even though people do variation on this,

00:15:22.780 | is five sets of five or 10 sets of 10.

00:15:26.200 | So for those listening, it would be five sets of 10,

00:15:30.440 | of five rep repetitions or 10 sets of 10 repetitions,

00:15:34.080 | 10 by 10, five by five, yeah.

00:15:36.080 | So if somebody, let's say,

00:15:37.960 | is doing a large body compound movement

00:15:41.360 | like barbell squats,

00:15:42.720 | where there are a lot of large body movements,

00:15:45.040 | hip hinging and et cetera,

00:15:48.080 | but for instance, the biceps are not,

00:15:52.480 | they're involved, but more or less indirectly.

00:15:54.720 | - Right.

00:15:55.600 | - So the effect is going to be to heat up the quadriceps,

00:15:58.400 | heat up the hamstrings, heat up the glutes,

00:16:00.420 | this kind of thing.

00:16:01.260 | - Right. - I see.

00:16:02.600 | - And then during rest, that heat will leave the muscle,

00:16:06.720 | but it's not fast.

00:16:08.840 | And certainly the heat can't leave the muscle very fast

00:16:11.520 | while you're working out because when the muscle contracts,

00:16:14.480 | it squeezes the blood vessels.

00:16:16.440 | And the only way heat gets out of a muscle is in the blood.

00:16:20.440 | And your muscle metabolism can go up 50 or 60 fold

00:16:23.920 | during anaerobic activity.

00:16:25.860 | That means the heat production in the muscle

00:16:27.800 | goes up 50 or 60 fold.

00:16:30.000 | The blood flow to that muscle cannot go up 50 or 60 fold.

00:16:34.580 | So you literally have the capacity to cook your muscles.

00:16:39.080 | - So this is probably an appropriate time

00:16:41.720 | to just mention briefly

00:16:43.500 | what the underlying mechanism of this is.

00:16:45.340 | Could you just, we will return to the specifics

00:16:47.960 | of what one can do to mitigate this heating up,

00:16:51.320 | but could you just explain the relationship

00:16:54.260 | between energy production ATP and pyruvate kinase

00:16:58.080 | and the role of heat there?

00:17:00.040 | - Sure.

00:17:00.860 | We don't get something for nothing.

00:17:05.160 | So like a steam engine,

00:17:07.180 | most of the energy in our food is lost as heat.

00:17:11.980 | So we are roughly about 20% efficient.

00:17:15.100 | So of the energy that we take in in our food,

00:17:17.840 | about 20% of that can go into doing work

00:17:20.440 | and the rest of it is lost as heat.

00:17:22.880 | Now we're mammals.

00:17:24.520 | We use that heat to keep our body temperature

00:17:27.000 | considerably above the environment.

00:17:29.500 | But if you raise body temperature a few degrees higher,

00:17:34.160 | you're in trouble.

00:17:35.640 | That's hyperthermia.

00:17:37.820 | So individual muscles can reach hyperthermic limits

00:17:41.720 | before you might experience it in the whole body.

00:17:45.520 | So to keep you from damaging your muscle by hyperthermia,

00:17:50.520 | we have fail-safe mechanisms.

00:17:52.580 | And one of those fail-safe mechanisms is an enzyme

00:17:56.340 | which is critical for getting fuel.

00:17:59.560 | In other words, the results of metabolism of glucose,

00:18:04.400 | getting that fuel into the mitochondria,

00:18:06.840 | which is making our major coinage of energy exchange ATP.

00:18:11.800 | So that particular enzyme is temperature sensitive.

00:18:16.840 | So when the muscle temperature gets above 39 or 39.5,

00:18:20.660 | it shuts off.

00:18:22.120 | And that essentially shuts off the fuel supply

00:18:25.300 | to the mitochondria.

00:18:26.400 | That's when you cannot do one more rep.

00:18:28.920 | - So failure, could we say that one component

00:18:32.320 | of muscular failure is overheating of the muscle locally?

00:18:35.920 | - Right. - There are probably

00:18:36.760 | other things too.

00:18:37.960 | - Well, yeah, if you lack oxygen,

00:18:40.560 | but our oxygen delivery is pretty good to the muscle.

00:18:45.040 | If you run out of glucose, yeah, that's going to impair you.

00:18:48.220 | But the most immediate impairment of muscle activity,

00:18:53.220 | muscle fatigue, in other words,

00:18:55.600 | is the rise in temperature of the muscle.

00:18:57.680 | - Interesting.

00:18:58.520 | I want to talk about how that muscle fails locally,

00:19:02.280 | but I have this burning question in my mind

00:19:04.460 | that I cannot seem to answer for myself.

00:19:07.980 | I'm hoping you can answer it for me.

00:19:09.420 | So let's say I'm doing five sets of five with squats.

00:19:13.040 | I hit muscular failure at a given weight.

00:19:17.320 | And according to what I now know,

00:19:21.400 | it's my quadriceps and the muscles associated

00:19:24.480 | with the squat that have failed

00:19:26.060 | because of this mechanism triggered by heat

00:19:29.860 | that shuts off the muscle.

00:19:31.660 | But my biceps are nice and cool.

00:19:33.840 | You're telling me.

00:19:34.680 | They're not doing too much work.

00:19:36.080 | It's only indirect work.

00:19:37.500 | So why is it that I can't set the bar down

00:19:40.920 | in the squat rack, walk over and do barbell curls

00:19:45.000 | with the same intensity that I could

00:19:47.640 | if I were to do those barbell curls fresh,

00:19:51.040 | not having done anything prior?

00:19:52.980 | - Well, you will still have a fatigue curve

00:19:55.440 | with your upper body, okay?

00:19:58.540 | And that will be influenced by any rise in temperature

00:20:02.340 | that has been generated by your lower body exercise.

00:20:06.100 | - So temperature in both cases is the limiting factor.

00:20:09.900 | - It's one limiting factor.

00:20:12.060 | It's one limiting factor.

00:20:13.280 | - I find that amazing.

00:20:14.660 | I find that amazing because I always thought naively

00:20:18.700 | that the reason muscles fail is because we, quote,

00:20:20.700 | "Don't have the strength to do another repetition."

00:20:24.180 | You lack glycogen or some ability to access that glycogen.

00:20:28.560 | But of course we still have glycogen.

00:20:30.980 | It's naive for me to think that

00:20:32.180 | because if I wait three minutes and go back,

00:20:34.500 | I can do those repetitions again.

00:20:35.920 | So the glycogen wasn't restored in that three minutes.

00:20:38.560 | Obviously it was there.

00:20:40.180 | So I realized there might be other mechanisms involved.

00:20:42.980 | Sounds like heat is if not the dominant mechanism

00:20:46.940 | that prevents more work.

00:20:49.220 | It's one of them.

00:20:50.520 | - It's one of them.

00:20:51.360 | And it's a quick one.

00:20:53.100 | It's a fast one.

00:20:54.220 | So it can happen with,

00:20:57.420 | let's say you are a really experienced weightlifter, okay?

00:21:01.820 | You may be doing very, very high weights

00:21:04.380 | with sets of five or six.

00:21:07.540 | - Yeah, to be clear for the audience,

00:21:08.740 | I'm not doing very high weights for sets of five.

00:21:11.540 | Not particularly strong.

00:21:12.860 | I'm not super weak, but I'm not particularly strong.

00:21:15.700 | But Craig's referring in the general sense to you.

00:21:19.020 | So why is it that if I finish a set of squats,

00:21:24.020 | I can't simply cool off my quadriceps

00:21:27.800 | by throwing a nice cool towel on my quadriceps?

00:21:31.360 | Why is that not the best way to go about it?

00:21:34.500 | - Because your body surface is a very good insulator, okay?

00:21:39.100 | We think we don't have fur

00:21:40.860 | and therefore we're not insulated.

00:21:42.640 | But the skin, the fascia, the muscles underneath,

00:21:47.640 | they're all very good insulators.

00:21:50.940 | And that's why I said earlier

00:21:52.560 | that the way the heat gets out of the muscle is in the blood.

00:21:56.580 | - So I want to step through a couple other portals

00:21:59.480 | by which one might think that heating and cooling

00:22:02.660 | would be ideal and then get back to these

00:22:06.220 | specialized surfaces on the hands, the feet, and the face.

00:22:09.740 | So if throwing a cold towel or even ice cold towel

00:22:12.860 | on my quadriceps isn't going to work

00:22:14.320 | or standing in front of the fan

00:22:15.460 | because I'm insulated from that cool,

00:22:17.180 | I can't cool off my blood fast enough,

00:22:19.320 | what about drinking 16 ounces of ice water?

00:22:22.700 | - Sure, you can do that,

00:22:23.540 | but you can calculate how much heat that can absorb.

00:22:27.580 | And you can't continue drinking liters of ice water.

00:22:31.020 | You're going to dilute your blood and have other problems.

00:22:34.480 | But yes, it'll help.

00:22:35.760 | Sure, it will help.

00:22:36.960 | But it doesn't have the full capacity you will need.

00:22:41.960 | - What about an ice pack to the back of my neck

00:22:44.520 | or to my head or squeezing the cold sponge over the head?

00:22:47.620 | I'm deliberately moving through these options

00:22:50.240 | because these are the ones that we see most often.

00:22:52.440 | We were actually just watching

00:22:53.540 | the Olympic track and field trials last night

00:22:55.620 | up in Oregon, I'm a huge track and field fan.

00:22:57.820 | And there were a lot of sponges on the backs of necks

00:23:02.820 | before and between and after events.

00:23:05.340 | And how good is that or how poor is that as a strategy?

00:23:10.340 | Since now we know that being overheated locally

00:23:13.760 | and systemically throughout the body

00:23:15.400 | is a serious limiting factor on performance.

00:23:18.300 | - Well, you have to understand something

00:23:20.060 | about our thermoregulatory system.

00:23:22.900 | We have a thermostat just like you have a thermostat

00:23:26.140 | in your house and that thermostat is in the brain, okay?

00:23:30.140 | - Do we know the specific site?

00:23:31.660 | - Yes. - Yes.

00:23:32.500 | - It's called the preoptic anterior hypothalamus.

00:23:35.580 | It does many things in terms of physiological regulation,

00:23:39.320 | but it serves as a thermostat.

00:23:41.760 | Now that thermostat has to have information.

00:23:44.060 | It has to have input.

00:23:45.700 | Where does that input come from?

00:23:47.400 | It comes from our overall body surface

00:23:49.500 | where we sense temperature, okay?

00:23:52.040 | So one of the things that can happen when you're overheated

00:23:55.740 | is that you can send in a cold stimulus to your thermostat.

00:23:59.980 | And that's sort of like wanting to cool your house

00:24:02.760 | by putting a wet washcloth over your thermostat.

00:24:06.020 | You know, it's doing the wrong thing.

00:24:08.860 | So we've actually had experiences

00:24:10.720 | where we've had people exercising, getting overheated

00:24:14.020 | and then cooling the body surface.

00:24:16.020 | And they say, "It feels great, this is fantastic."

00:24:19.220 | And their core temperature is going up.

00:24:21.020 | - Well, I think this is such an important point.

00:24:22.920 | First of all, I was weaned in a laboratory

00:24:26.000 | where there were always battles

00:24:27.460 | over the temperature in the lab.

00:24:29.640 | So people were always putting ice packs on thermostats

00:24:33.040 | or putting fans towards thermostats

00:24:35.140 | and trying to play this game.

00:24:36.540 | Good to know we were all being foolish

00:24:38.560 | even though we were neurobiologists.

00:24:40.360 | Putting a cold towel over my torso

00:24:45.320 | or putting ice on the back of my upper back,

00:24:47.940 | you're saying could actually heat up my core.

00:24:51.840 | - It'll at least decrease your heat loss,

00:24:55.120 | your rate of heat loss.

00:24:56.960 | You're going to raise the issue a little later, I know,

00:25:00.860 | and that is our natural portals for heat loss.

00:25:04.120 | So you can think of the natural portals for heat loss

00:25:07.300 | as our air conditioners, okay?

00:25:09.500 | The thermostats in the brain

00:25:11.140 | and the information to the thermostat

00:25:13.700 | is coming from the overall body surface.

00:25:16.420 | So what can happen if you, let's say,

00:25:18.740 | cool the torso with an ice vest,

00:25:21.380 | you can actually cause vasoconstriction of your portals,

00:25:25.640 | your heat loss portals.

00:25:27.160 | So that's what impairs the rate at which you're losing heat.

00:25:30.580 | It feels good.

00:25:31.820 | Now back to the head.

00:25:34.220 | That's really interesting.

00:25:35.980 | The major blood flow to the brain

00:25:38.060 | comes up four arteries through the neck.

00:25:41.460 | There's the carotid arteries

00:25:43.060 | and there's the vertebral arteries.

00:25:45.220 | So when you put a cold towel around the neck,

00:25:48.060 | you're going to be putting a cold stimulus into the brain.

00:25:53.060 | Well, that's great for protecting the brain.

00:25:55.340 | You want to protect the brain,

00:25:57.100 | but it's also going to make you feel cooler than you are.

00:26:01.460 | So you will think you're ready to go again quickly

00:26:04.620 | when you've just essentially cooled the thermostat.

00:26:09.200 | - This is an important point

00:26:10.500 | and there's a lot of interest nowadays

00:26:13.340 | in people doing marathons

00:26:14.640 | and there are even some people do these ultras,

00:26:16.460 | ultra running, which I guess is everything longer

00:26:18.240 | than a marathon and last man standing,

00:26:21.820 | last man, last woman standing kind of things.

00:26:24.580 | So you're saying that if somebody is hyperthermic,

00:26:27.480 | they could trick themselves into subjectively thinking

00:26:31.420 | that they are cooling off by putting the cold towel

00:26:33.860 | and that they can go further, but their brain could cook.

00:26:36.380 | - Well, if they stop the cooling,

00:26:38.020 | then that hot blood from the body core

00:26:39.900 | is going to go to the brain.

00:26:41.380 | - Interesting.

00:26:42.260 | Well, many, it's a bit of a tangent,

00:26:44.860 | but many people report after long bouts of exercise

00:26:48.920 | or even just very intense bouts of exercise,

00:26:51.740 | feeling a kind of brain fog or mental fatigue.

00:26:54.720 | I assumed that that was due

00:26:58.160 | to lowered brain oxygenation post-exercise,

00:27:01.880 | but is it possible that there are some post-exercise effects

00:27:05.080 | on heating and cooling of the brain

00:27:06.840 | that might impact cognition

00:27:09.060 | or I should say negatively impact cognition?

00:27:11.560 | - It's certainly possible because we know

00:27:14.120 | that a rise in temperature decreases cognitive capacity.

00:27:19.120 | I mean, you can experience that yourself.

00:27:22.000 | You can get on a treadmill and follow your temperature

00:27:25.400 | and then just do a simple activity

00:27:27.400 | like adding and subtracting.

00:27:29.340 | You get to about 39 degrees, you can't do that anymore.

00:27:33.320 | You can't just calculate how long

00:27:35.560 | you've been on the treadmill.

00:27:36.700 | - So the phrase cool, calm, and collected is-

00:27:39.200 | - Cool, calm, and collected.

00:27:40.040 | That's the goal in all pursuits.

00:27:42.200 | - That's right.

00:27:43.600 | - So I want to talk about these portals

00:27:47.060 | because you've mentioned them a few times.

00:27:49.160 | Before I ask about what the portals are exactly

00:27:53.260 | and how they work

00:27:54.100 | and how they can be leveraged for performance,

00:27:56.280 | there's a question that my neurobiologist self

00:27:59.440 | can't resist but ask.

00:28:01.340 | We have this thermostat in the preoptic area

00:28:05.080 | of the hypothalamus, which is interesting to me.

00:28:07.920 | The medial preoptic area is also one that's known

00:28:10.500 | to be sexually dimorphic,

00:28:12.640 | dependent on testosterone exposure early in life, et cetera.

00:28:16.400 | Although people should just note

00:28:18.840 | that it's not actually testosterone

00:28:20.600 | that creates these sexual dimorphisms, these differences.

00:28:23.200 | It's actually testosterone converted into estrogen.

00:28:26.040 | It's actually estrogen is the effector,

00:28:28.000 | which is fascinating.

00:28:29.480 | Nonetheless, we've got this area that acts as a thermostat.

00:28:33.400 | And you said it's collecting information

00:28:35.920 | from the whole body.

00:28:37.840 | Does that mean that there are pathways

00:28:40.160 | as the neuroscientists like you and I refer to them

00:28:43.500 | as these afferent or input pathways

00:28:46.080 | from the body to the preoptic area?

00:28:48.600 | Is there a map of our body in the preoptic area?

00:28:51.640 | 'Cause I have to imagine that you can't have

00:28:55.000 | the information just coming from the left shoulder,

00:28:57.360 | just from the right toe.

00:28:58.560 | It sounds like you need probably a pretty crude map

00:29:02.480 | but that you need a complete map of the body surface there.

00:29:05.160 | Well, you don't need a complete map in the hypothalamus.

00:29:08.680 | I mean, that thermal afferent information that you mentioned,

00:29:11.600 | it also goes to the somatosensory cortex.

00:29:14.780 | So you know if an ice cube has touched you on the back,

00:29:18.940 | but that doesn't necessarily translate into a change in,

00:29:24.000 | let's say you're shivering or sweating.

00:29:27.360 | So the information that's going to the hypothalamus

00:29:31.600 | is more integrated, representation of body temperature.

00:29:36.360 | - So it's sort of an average of what's happening

00:29:38.080 | across the body. - It's an average.

00:29:39.560 | - So if I were to, let's say I get hot on a hot day

00:29:42.580 | and popsicles when we were in summer camp,

00:29:44.560 | I went to a sports camp near here actually

00:29:46.440 | and we'd run around like crazy

00:29:47.900 | and then we'd get into the shade if we could,

00:29:49.320 | but we were popsicles.

00:29:50.880 | - Brain freeze. - It was all about popsicles.

00:29:51.900 | Or the kids were putting ice cubes down each other's shirts

00:29:55.260 | or something.

00:29:56.100 | But that's an average

00:29:58.120 | because other parts of the body aren't exposed.

00:30:00.600 | The mouth is exposed to the ice in the popsicle case

00:30:03.000 | or the cold cubes or in the hands.

00:30:05.640 | As you said, it feels really good.

00:30:07.480 | - It feels good, yeah.

00:30:08.320 | - But it sounds like it feels deceptively good

00:30:11.640 | because in reality, it could still be quite warm internally.

00:30:16.600 | - Absolutely, yeah.

00:30:18.240 | - Interesting.

00:30:19.060 | - Yeah, you can feel great

00:30:20.920 | and have a dangerously hyperthermic temperature.

00:30:24.440 | But I should say that when you get into the danger zone,

00:30:28.220 | things get bad fast.

00:30:29.680 | What are some of the symptoms

00:30:30.720 | that people could be on the lookout for, for hyperthermia?

00:30:34.240 | - Essentially, it's almost ironic

00:30:36.800 | that if individuals are transitioning into heat stroke,

00:30:41.800 | they actually vasoconstrict and they stop sweating.

00:30:46.560 | And that's a pathological situation.

00:30:50.280 | I couldn't begin to explain it.

00:30:53.080 | But essentially, you are just feeling exhausted.

00:30:57.940 | You're feeling miserable.

00:31:01.280 | The heart rate is very high.

00:31:06.080 | Your heart rate goes up as your core temperature goes up,

00:31:09.320 | called cardiac drift.

00:31:11.860 | So you just feel rotten.

00:31:15.900 | But that's why, since it's not a danger signal

00:31:21.540 | that you can translate immediately into,

00:31:23.880 | nope, I'm going into heat stroke,

00:31:25.900 | that's why people can overcome their bad feeling

00:31:29.120 | with motivation to continue going, to work harder.

00:31:32.560 | So there have been a number of high-profile athletic deaths

00:31:37.560 | due to heat stroke that were during practice,

00:31:42.120 | not in competition when people are really trying to do it,

00:31:45.360 | but in practice,

00:31:46.880 | which shows they were just motivated to push.

00:31:50.480 | - So let's talk about these magnificent portals

00:31:53.880 | that not just humans, but other animals,

00:31:56.900 | mammals are equipped with.

00:31:58.780 | So if putting cold on the neck or on the head

00:32:02.340 | or on the torso is not optimal, what is optimal?

00:32:06.440 | And maybe walk us through a theory

00:32:10.820 | as to why we would have these portals located

00:32:13.380 | where they are, and then we can talk about

00:32:15.500 | how one might leverage them for performance.

00:32:18.140 | - Okay, where the portals are, are in the glabrous skin,

00:32:23.660 | big word, okay?

00:32:25.380 | Glabrous just means no hair.

00:32:28.080 | So it's the hairless skin.

00:32:29.600 | You say, well, most of my body is without hair.

00:32:32.980 | No, most of your body has hair follicles.

00:32:36.880 | We are mammals.

00:32:38.240 | Mammals have fur.

00:32:39.860 | We've lost the fur, but we still have those,

00:32:43.240 | that hairy skin phenotype all over our body, except,

00:32:47.560 | except for those skin surfaces

00:32:50.100 | where our mammal relatives didn't have fur.

00:32:53.880 | So the pads of the feet.

00:32:55.980 | And for the primates, upper part of the face.

00:32:58.940 | For rabbits, no portions of the ears,

00:33:02.240 | the inner surface of the ears.

00:33:03.080 | - No, I never thought about that.

00:33:04.180 | - For bears, the tongue.

00:33:06.820 | Bears have big tongues, huge tongues.

00:33:09.120 | - I didn't know that either.

00:33:11.860 | I'm in that close to a bear yet.

00:33:13.460 | - Yeah, I've had a licking match with a bear.

00:33:15.960 | - Not yet, no.

00:33:17.500 | So anyway, our mammalian relatives can't lose heat

00:33:22.500 | over their overall body surface.

00:33:26.480 | So probably very early on in mammalian evolution,

00:33:30.180 | they evolved these special blood vessels

00:33:32.600 | in the limited surface areas that don't have fur.

00:33:36.180 | And as I said, what these blood vessels are,

00:33:38.840 | are shunts between the arteries and the veins.

00:33:42.140 | Arteries and veins are both low resistance vessels.

00:33:45.540 | So you can have high flow rate.

00:33:47.460 | Capillaries, which normally are between arteries and veins,

00:33:50.860 | are high resistance because they're very tiny, okay?

00:33:54.220 | - Is it fair to say that what I was taught

00:33:57.400 | is that blood flows from arteries, then to capillaries,

00:34:01.620 | and then to veins, and then back to the heart.

00:34:03.740 | So it's sort of like from the heart through arteries,

00:34:05.940 | then through these little capillaries,

00:34:07.780 | which are like little estuaries and streams,

00:34:09.660 | and then to the veins, back to the heart.

00:34:11.420 | Is that generally true?

00:34:12.780 | - Yeah, absolutely.

00:34:13.780 | - So what I learned in basic physiology is still,

00:34:16.060 | - I wouldn't get an F in your class.

00:34:18.700 | - No.

00:34:19.620 | - Maybe a D or a C, but not an F.

00:34:22.580 | - So that's excellent.

00:34:23.420 | - Okay, and so you're saying that in this glabrous,

00:34:26.540 | or beneath the glabrous skin.

00:34:28.300 | - There are these shunts.

00:34:30.900 | - And those go directly from arteries to veins.

00:34:33.860 | So you skip the capillaries. - Capillaries, yeah.

00:34:37.140 | - And is it actually, as long as I say that in the skin,

00:34:41.460 | you know, when I feel the pads in my hands,

00:34:45.680 | how deep to the surface do these vessels reside?

00:34:49.180 | - They're below the, obviously, the epidermis.

00:34:54.180 | So if you are warm and you look at the palms of your hands,

00:35:00.120 | they are fairly red.

00:35:02.320 | The backs of your hands aren't.

00:35:04.340 | You don't have these vessels in the backs of your hands.

00:35:06.780 | Now, if you take a glass, like a water tumbler, right,

00:35:12.000 | and you grab it, you can see if you squeeze a little bit,

00:35:16.660 | the hand goes white.

00:35:18.940 | That's because you've shut off that blood flow.

00:35:21.540 | - Oh, interesting.

00:35:22.400 | I'm going to do that little home experiment.

00:35:23.900 | - So if you're bicycling on a hot day,

00:35:26.240 | you don't want to be grabbing your handlebars all the time.

00:35:28.860 | You want to periodically.

00:35:30.740 | - Well, this is important.

00:35:31.580 | I know you're privy to some really amazing results

00:35:35.300 | that we're going to talk about,

00:35:36.140 | but I actually heard you say this during this lecture

00:35:38.780 | recently that Stanford held about human performance

00:35:41.660 | that we were both part of.

00:35:43.260 | And you mentioned this, that if you're cycling

00:35:46.420 | and you're working hard and you want to be able

00:35:48.580 | to do more work, we now know why you want to remain cool

00:35:52.500 | in order to continue to do work.

00:35:54.660 | And if you get too warm, that's bad.

00:35:56.760 | That gripping the handlebars too tightly

00:35:59.180 | will actually limit your performance.

00:36:01.360 | And that's probably also true on the Peloton

00:36:03.240 | or any other kind of device or the skier

00:36:05.260 | or anything like that.

00:36:06.860 | So loosen the grip, or if you safely can,

00:36:09.460 | you want to actually expose your hands to the world.

00:36:12.440 | Now, what about for people wearing gloves?

00:36:14.220 | What about the, to me, that just seems crazy

00:36:16.980 | based on everything you're telling me.

00:36:18.580 | - Well, gloves definitely impede heat loss from the hands,

00:36:23.380 | just as socks impede heat loss from the feet, okay?

00:36:27.020 | So if you want to maximize your heat loss,

00:36:29.460 | you want to have as thin a protectors as possible

00:36:32.460 | on your hands.

00:36:33.740 | And of course the feet are more problematical

00:36:36.440 | because you have to be using them in certain ways.

00:36:38.820 | - Some people run barefoot.

00:36:40.580 | - Well, yeah.

00:36:41.420 | - Yeah, that's become somewhat popular.

00:36:43.700 | It seems like it kind of came and went.

00:36:44.980 | They had those toe shoes things,

00:36:46.800 | but they looked so ridiculous that I think most people

00:36:49.140 | just were willing to take the performance hindrance

00:36:51.740 | of regular shoes.

00:36:52.700 | - Actually, we had a track coach here at Stanford

00:36:54.820 | who for a while was famous for introducing training

00:36:59.340 | without shoes running. - Interesting.

00:37:01.260 | - And he thought it was because it changed the posture

00:37:03.740 | of the runner.

00:37:04.860 | And I think it was just due to the fact

00:37:06.780 | that he was increasing the capacity of his runners

00:37:09.780 | to lose heat.

00:37:10.620 | - Interesting.

00:37:11.540 | Yeah, so heating up at the level of the hands

00:37:14.980 | obviously is going to hinder performance.

00:37:16.340 | So if I can, how about with running?

00:37:18.820 | I noticed I ran across the country briefly in high school

00:37:22.020 | and not particularly well at that,

00:37:24.040 | but that we were told to run as if we were holding,

00:37:26.420 | you know, crackers in our fingers or something,

00:37:28.800 | like very lightly and to keep hands kind of loose.

00:37:30.960 | So running like this would actually be

00:37:32.900 | more beneficial performance than,

00:37:35.100 | - Or gripping a phone, which is probably

00:37:37.420 | what most people are doing nowadays, right?

00:37:39.680 | - Right. - Interesting.

00:37:40.580 | And once, I'll tell you the experience I had once.

00:37:43.980 | I was in Alaska in the winter and I went out running

00:37:47.580 | and I absentmindedly forgot gloves.

00:37:51.380 | And I realized this after a short period running

00:37:54.520 | because the backs of my hands were aching from the cold.

00:37:58.740 | The palms of my hands were sweating and were hot.

00:38:01.340 | - Oh, amazing, amazing.

00:38:02.900 | So these compartments are a real thing.

00:38:04.740 | And you mentioned the upper half of the face.

00:38:06.900 | - That's where our primate ancestors don't have fur.

00:38:10.340 | - And the bottoms of our feet.

00:38:11.580 | So let's just take a moment and talk about

00:38:14.900 | some of the more amazing results that have been associated

00:38:18.820 | with proper cooling of these glabrous skin surfaces.

00:38:23.620 | - Let me introduce one more thing.

00:38:25.100 | - Sure. - Because you asked earlier

00:38:27.240 | about the pouring of water on the head, okay?

00:38:31.100 | One of the things which is not appreciated fully

00:38:34.400 | is that the blood which is perfusing

00:38:38.920 | these special blood vessels in the face above the beard line,

00:38:42.700 | that's the non-hairy skin,

00:38:44.280 | that blood then returns in the venous supply to the heart,

00:38:50.220 | but it actually does it in a very strange way.

00:38:54.180 | It actually goes through what are called,

00:38:57.900 | I'm blocking on the name now.

00:38:59.240 | - Take your time.

00:39:00.080 | - These are blood vessels that go through the skull, okay?

00:39:03.500 | And that's why the scalp bleeds a lot if you cut the scalp.

00:39:07.540 | And these blood vessels, which are called,

00:39:09.760 | I wanna say emergent, but it's not emergent,

00:39:11.880 | it's a word that means leaving.

00:39:14.420 | And these blood vessels were primarily thought to be ways

00:39:18.300 | that blood is leaving the brain.

00:39:21.280 | But when you're overheated, the direction of flow

00:39:25.240 | in those blood vessels reverses.

00:39:28.200 | So the cool blood that's coming from your facial region

00:39:33.300 | goes into that circulation

00:39:35.140 | and actually is a cooling source for the brain.

00:39:38.260 | So you can cool the brain,

00:39:41.080 | you can have a cooling effect on the brain

00:39:42.900 | by pouring water on your head.

00:39:45.900 | - Interesting, so that practice, which we,

00:39:48.380 | at least for me, I most commonly associate

00:39:50.520 | with combat sports, where someone,

00:39:53.060 | the fighter goes to their corner,

00:39:54.500 | they usually sit down on a stool

00:39:56.940 | unless they're trying to do some mental warfare

00:40:01.260 | from the corner, in which case they don't even take a seat,

00:40:04.300 | and their corner crew will squeeze a glove,

00:40:09.300 | excuse me, a sponge full of cold water over them.

00:40:12.580 | That you're saying is somewhat effective

00:40:16.420 | in cooling the brain.

00:40:17.540 | - Yeah, it's one of the natural mechanisms

00:40:19.740 | for cooling the brain.

00:40:21.380 | - I want to return to this at some point as well,

00:40:23.680 | but is there any known benefit to cooling the brain

00:40:27.500 | in terms of offsetting physical damage,

00:40:30.020 | offsetting the negative effects of concussion?

00:40:32.460 | Because one of the reasons why fighters

00:40:35.620 | will often get a cold on the back,

00:40:38.460 | cold item on the back of the neck or on the head,

00:40:41.020 | is not just to cool them down,

00:40:43.120 | but the theory is that it might offset

00:40:46.240 | some of the damage of neurons.

00:40:48.480 | - I just can't comment on that.

00:40:51.760 | I'm aware of those ideas, but they're controversial.

00:40:55.820 | One of the things that you want to do

00:40:57.740 | for injury to the brain is to decrease swelling.

00:41:01.900 | And one of the ways that you decrease swelling

00:41:05.180 | in many parts of the body is to cool.

00:41:07.820 | It decreases inflammation, it decreases the blood flow.

00:41:14.060 | So, you know, I think it's a really interesting topic,

00:41:18.560 | and it's something that should be investigated.

00:41:21.780 | It's kind of hard to investigate.

00:41:23.380 | - Yeah, interesting.

00:41:26.260 | Okay, so I hear these stories and I've seen the data,

00:41:31.260 | so I believe the stories.

00:41:33.520 | Maybe tell us a story about an observation

00:41:36.900 | that your group has made with respect to anaerobic exercise

00:41:41.740 | and proper cooling of these glabrous surfaces.

00:41:46.740 | And we can talk about the technology.

00:41:48.780 | Maybe give us the dips example first.

00:41:52.820 | Of course, I think most people are familiar with dips.

00:41:55.240 | You're supposed to, I guess, get down.

00:41:56.600 | - Raise and lower your body mass.

00:41:57.640 | - Yeah, raise and lower your body mass,

00:42:00.120 | usually with your legs dangling down.

00:42:01.540 | Sometimes people are strong enough

00:42:03.080 | to attach a weight there and they'll do,

00:42:06.320 | it's essentially a compound upper body exercise.

00:42:08.560 | - Right.

00:42:09.400 | - One dip would not be particularly impressive

00:42:12.580 | for most people.

00:42:13.660 | 100 would be very impressive.

00:42:16.300 | 20 would be impressive for some, et cetera.

00:42:19.240 | What happens when a skilled athlete comes in

00:42:23.040 | and does dips for multiple sets

00:42:25.180 | and then what happens when they cool properly

00:42:27.420 | using the glabrous skin surfaces?

00:42:30.580 | - This was a story that occurred early on

00:42:33.580 | in our investigations when we first made the discoveries

00:42:37.060 | that cooling has a benefit to increase your work volume,

00:42:41.620 | your capacity to do more reps, okay?

00:42:45.020 | So the word got over, I think, to the 49ers camp

00:42:48.860 | and one of their players, Greg Clark,

00:42:52.660 | who was a tight end at the time,

00:42:54.080 | he had been tight end at Stanford,

00:42:56.280 | he decided, or I don't know if he was asked or what,

00:43:01.580 | to come over and check it out.

00:43:03.980 | So Greg came over and we said,

00:43:06.380 | "Greg, what are you good at?

00:43:07.580 | What activity do you like to do?"

00:43:09.860 | He said, "Dips, I can do a lot of dips.

00:43:12.420 | I can do 40 dips in a first set

00:43:15.260 | and I can probably do five sets.

00:43:16.940 | That's a usual workout for me."

00:43:19.140 | And we said, "Okay."

00:43:20.420 | So he came over to the gym one day

00:43:22.820 | and that's exactly what he did.

00:43:24.440 | He did 40 dips the first set and then maybe 25 and 15

00:43:29.440 | and down from there.

00:43:31.760 | - Do you recall roughly what kind of rest periods

00:43:34.020 | he was taking between sets?

00:43:35.000 | - Yeah, we standardized the rest period to three minutes

00:43:40.000 | because that's what we had set on for cooling

00:43:43.880 | as the intervals.

00:43:44.720 | - That's a good long rest period.

00:43:46.040 | - Yeah, it is.

00:43:46.880 | - Still a lot of dips, I got it.

00:43:48.160 | - Yeah, it's actually a longer rest period

00:43:50.200 | than many people would prefer during workouts.

00:43:54.040 | They want to make the most time.

00:43:54.880 | - Not me, I prefer to take as much rest as I possibly can.

00:43:58.740 | - So several days later, he came back

00:44:00.600 | and his first set he did, I think maybe 42,

00:44:04.880 | a little bit better,

00:44:06.060 | but now people were standing around watching.

00:44:07.980 | So there was a little impetus there to show off.

00:44:11.000 | So then his second set was, I don't remember the numbers,

00:44:15.820 | but very much above the second set on the control day.

00:44:19.680 | This was after we cooled his-

00:44:21.720 | - Okay, so when is he doing the cooling?

00:44:24.520 | - He's sitting down and putting his hands

00:44:27.280 | in the devices that we had built,

00:44:28.840 | which were cooling the palms of his hands.

00:44:31.760 | - For how long does that cooling take?

00:44:33.440 | Can he do it inside of a three-minute rest period?

00:44:35.400 | - Yeah, that's what we were doing.

00:44:36.640 | We standardized the interval for resting or cooling

00:44:40.880 | to three minutes.

00:44:42.200 | Okay, but the point is he got to his fifth set

00:44:45.840 | and all of the sets were above

00:44:48.160 | what he had done on the previous day.

00:44:50.560 | And he said, "You know, I'm not tired, I can do another set.

00:44:53.900 | And then I can do another set.

00:44:56.320 | I can do another set.

00:44:57.780 | I can do another set."

00:44:58.620 | So from one day to two or three days later with cooling,

00:45:03.480 | he doubled the total work volume.

00:45:06.480 | He doubled the total number of dips.

00:45:08.680 | - By adding more sets and more repetitions to each set.

00:45:12.160 | - Right.

00:45:13.200 | So then he kept coming back for four more weeks,

00:45:17.760 | twice a week.

00:45:18.900 | And by the end of that month, he was doing 300 dips.

00:45:23.900 | - Wow, so what percent?

00:45:25.660 | - So he tripled.

00:45:26.500 | - He tripled. - He essentially tripled.

00:45:28.240 | And so here's a professional athlete

00:45:30.440 | at peak physical conditioning

00:45:32.240 | and he triples what he can do.

00:45:34.840 | - Amazing.

00:45:35.840 | And in terms of his ability to recover,

00:45:38.060 | was that explored or discussed at all?

00:45:42.080 | Because my understanding is that

00:45:43.940 | if we cause enough stress to a muscle

00:45:47.740 | during anaerobic training,

00:45:49.640 | we provide the stimulus for compensatory regrowth, et cetera.

00:45:54.100 | But if we do more work,

00:45:56.820 | we essentially scale up the amount of recovery that's needed

00:45:59.740 | or the recovery time.

00:46:00.700 | I'm very curious about whether or not he needed longer

00:46:03.120 | to recover between these super performing workouts.

00:46:05.940 | - That's very interesting.

00:46:07.500 | That was a major discovery,

00:46:09.720 | which we didn't realize we were making at the time.

00:46:13.460 | There is this phenomenon you're referring to

00:46:15.540 | as delayed onset muscle soreness, DOMS.

00:46:19.020 | And this is due to those little micro tears and so forth

00:46:22.340 | that are happening as we extend our workout capacity, volume.

00:46:27.340 | So we've had this experience so many times

00:46:32.940 | that an athlete or anyone will come in to the lab

00:46:36.740 | and they will exceed what their previous goals were,

00:46:40.220 | their previous expectations.

00:46:42.140 | And I can always see the words coming out of their mouth.

00:46:44.900 | I'm going to be so sore tomorrow.

00:46:47.660 | They never are.

00:46:49.300 | - Interesting.

00:46:50.140 | - And we've actually demonstrated that with a naive group.

00:46:53.360 | We had a class, a physical conditioning class,

00:46:58.120 | and we had half of them.

00:47:01.620 | The first days of the class,

00:47:02.980 | we had to establish their true capacity,

00:47:05.580 | what they could do.

00:47:07.140 | So these were pretty heavy workouts for these new recruits.

00:47:11.260 | And we gave half of them the benefit of cooling

00:47:14.700 | and the other half not.

00:47:16.140 | And then we had them record their subjective levels

00:47:19.300 | of delayed onset muscle soreness.

00:47:21.180 | And those that were cooled

00:47:23.420 | didn't have significant muscle soreness.

00:47:25.900 | - Amazing.

00:47:26.740 | And I know there are also published results

00:47:28.340 | and we will provide links to some of these papers

00:47:30.740 | for people seeing similar effects,

00:47:33.980 | I should say similar performance enhancing effects

00:47:36.780 | using bench presses, bench press,

00:47:40.300 | or pushups or other sorts of things.

00:47:42.700 | Maybe you could give us an example

00:47:44.360 | from the realm of endurance work or aerobic work,

00:47:48.860 | running, cycling, things of that sort.

00:47:51.660 | - Well, one of the problems for us

00:47:55.360 | is that our equipment now is not really portable.

00:47:59.720 | I mean, it's portable in the sense

00:48:01.020 | you can carry it to the gym or to the football field.

00:48:03.980 | - But you're not going to run with it.

00:48:04.820 | - But you're not going to run with it, right.

00:48:06.580 | - Or equip a bicycle with it.

00:48:07.780 | Although when are the cooling handles on bicycles coming?

00:48:10.420 | - Yeah, that would be good.

00:48:11.840 | But one itinerant activity is golfing

00:48:15.740 | and people have put it on their golf carts

00:48:17.740 | and they're out.

00:48:18.580 | - Do people really heat up that much in golf?

00:48:20.900 | - They do.

00:48:21.740 | - Not to be disparaging of the golfers,

00:48:23.100 | but the way I conceptualize golf,

00:48:25.260 | it's like a swing and then a walk

00:48:26.740 | and then a cart ride and then a meal.

00:48:29.500 | I probably just offended all the golfers out there.

00:48:31.740 | - Well, one time we were doing work

00:48:35.280 | for the Department of Defense

00:48:38.980 | and they wanted to check it out

00:48:40.580 | whether or not what we were doing was really worthwhile.

00:48:43.720 | So they sent out a team of special ops soldiers

00:48:48.720 | to be our subjects and test it out.

00:48:51.500 | They were here for a week.

00:48:53.220 | So that was a fun week.

00:48:56.060 | - Yeah, I do some work with those guys.

00:48:57.880 | They're hard driving guys.

00:49:00.100 | They also know how to have fun.

00:49:01.420 | But yeah, they definitely have,

00:49:04.900 | if they have an off or a quit switch,

00:49:07.700 | it's buried deep within their nervous system.

00:49:11.400 | They don't like to hit that quit switch.

00:49:13.640 | - So the guy who wrote the final report,

00:49:16.280 | he gave an addendum to the report and he said,

00:49:19.360 | "Well, I'll tell you this, after I've gotten home,

00:49:22.680 | it's added that technology."

00:49:24.240 | They took the technology with them.

00:49:25.660 | They wanted to keep it.

00:49:26.500 | - Oh yeah, that sounds about right.

00:49:29.260 | - And using it, it has added 20 yards

00:49:31.640 | to every club in my bag, and that's no effing small deal.

00:49:35.920 | - So it's allowing people to hit further,

00:49:38.160 | hit the golf ball further.

00:49:39.700 | - Right.

00:49:40.540 | - Interesting.

00:49:41.360 | All right, so for the golf players out there,

00:49:46.640 | then that's the reward you get back from Craig

00:49:52.440 | for all my little knocks on golf.

00:49:54.040 | I actually, I don't have any knock on golf.

00:49:56.080 | I just don't think about it as a sport

00:49:58.280 | where heating up is a limiting factor.

00:50:00.980 | So since they're getting more out of their drive,

00:50:04.560 | what do you think is going on there?

00:50:06.300 | - Well, they can be heating up.

00:50:08.480 | - And they're wearing gloves, right?

00:50:09.320 | - They're wearing gloves on a hot day and so forth.

00:50:11.880 | But let me just tell you one more serious story

00:50:14.660 | about golfers, and that is individuals

00:50:17.360 | with multiple sclerosis

00:50:19.400 | are exceedingly temperature sensitive.

00:50:21.680 | - I didn't know that.

00:50:22.520 | - So they may still be mobile,

00:50:24.780 | but they have to stay in cool locations

00:50:27.040 | and not increase their exercise to any great extent.

00:50:31.220 | But we've had subjects that have,

00:50:34.300 | with multiple sclerosis who have just essentially

00:50:36.840 | put the device on their golf cart

00:50:38.340 | and they're back out playing golf

00:50:39.540 | in the middle of the summer.

00:50:40.540 | - Oh, that's great.

00:50:41.380 | - Yeah. - That's great.

00:50:42.880 | Anything that allows people to have normal levels

00:50:45.760 | of livelihood and recreation is great.

00:50:50.640 | We always think about performance

00:50:52.480 | at these kind of like peak and elite levels

00:50:54.460 | and pushing harder.

00:50:56.280 | But yeah, anything that allows people

00:50:58.040 | to be mobile and functional is great.

00:51:00.440 | So what's your favorite example of endurance?

00:51:04.860 | And feel free to give us the extreme one

00:51:06.780 | and then we'll talk about averages

00:51:09.000 | to make sure we're thorough

00:51:10.540 | about averages versus exceptions.

00:51:12.880 | - Right, we haven't done a lot in the field.

00:51:16.720 | I mean, outdoors.

00:51:18.660 | Most of our endurance has been in a hot room

00:51:22.280 | with treadmill work and so forth.

00:51:24.060 | So the very first experiment we had,

00:51:26.380 | I think maybe 18 subjects just off the street.

00:51:29.300 | I mean, we just recruited people in the hallways,

00:51:32.100 | come on in and do this.

00:51:33.480 | And what we found is we could, for this group,

00:51:37.700 | with one trial with and without cooling,

00:51:39.900 | we could double their endurance walking on the treadmill,

00:51:43.600 | walking uphill on the treadmill in the heat,

00:51:45.960 | like maybe 40 degrees ambient temperature,

00:51:48.380 | 40 degrees centigrade.

00:51:49.540 | - So what does that experiment look like?

00:51:50.960 | You're having people walk on an incline,

00:51:52.720 | it's really warm.

00:51:54.080 | Some people are just going to hit the quit button

00:51:56.320 | and say, "I've had enough," and get off the treadmill.

00:51:58.720 | - Right. - With proper cooling,

00:52:00.520 | when are they doing the cooling?

00:52:01.960 | - They're doing it continuously.

00:52:04.200 | - I see. - Because in the laboratory,

00:52:06.540 | we can suspend devices from the ceiling, for example.

00:52:10.460 | Now we do have prototype wearable devices.

00:52:13.240 | We did them in response to emails from Ebola workers

00:52:18.240 | a number of years ago in Sierra Leone.

00:52:21.960 | They said, "We've read about your work with athletes.

00:52:24.120 | Can't you do something for us?

00:52:25.480 | I mean, we're in the personal protective gear

00:52:27.600 | and we can't be in the hot zone

00:52:28.940 | for more than 15 or 20 minutes."

00:52:31.500 | So that started us on the challenge

00:52:34.760 | of developing wearable systems that could go under the PPE.

00:52:39.160 | We've published that work now.

00:52:40.780 | - That's great.

00:52:41.620 | And I'm guessing the military special operators

00:52:43.560 | that are out in the desert and other locations

00:52:45.440 | are probably excited about this technology.

00:52:47.960 | - Well, once they get it.

00:52:49.280 | - Once they get it, it's coming, it's coming.

00:52:52.020 | - Yeah, you know, I think some people might wonder,

00:52:55.380 | you know, if there are all these studies

00:52:56.760 | and there are these incredible results over the years,

00:52:59.180 | why haven't we heard more about it?

00:53:00.660 | And I will ask your opinion on that as well,

00:53:02.920 | but I'll just editorialize a little bit,

00:53:04.860 | is that the best laboratory work

00:53:09.460 | and its practical applications

00:53:11.060 | oftentimes requires many studies.

00:53:13.860 | And oftentimes there isn't a portal, so to speak,

00:53:19.420 | to get that information out into the technology sector.

00:53:22.140 | So there is a company that's developing this technology

00:53:25.740 | for people to use, to purchase and use.

00:53:30.260 | We might as well just tell us now,

00:53:31.420 | what is the name of that company?

00:53:32.980 | And do they have a website?

00:53:34.820 | People are going to want to know

00:53:36.560 | where can they get this magical technology?

00:53:39.140 | And is there a poor man's version of it as well?

00:53:42.000 | - Well, the company is Arturia, A-R-T-E-R-I-A.

00:53:46.220 | And the website is www.coolmit.com.

00:53:51.220 | So coolmit is just C-O-O-L-M-I-T-T, coolmit.com.

00:53:56.940 | - It's a great website.

00:53:58.260 | When I went there, it says that right now

00:54:00.120 | the technology is only available

00:54:01.660 | to professional sports teams and military.

00:54:04.020 | Is that true?

00:54:04.860 | - Well, where we stand now is the new version

00:54:07.660 | of the technology is sort of in beta test versions.

00:54:10.620 | We got it into the hands of people

00:54:12.520 | who had used the technology before.

00:54:14.520 | So there's NFL teams that are using,

00:54:17.960 | there's college teams, there's Olympics,

00:54:22.040 | there's the Navy Seals, Major League Baseball,

00:54:26.360 | the NBA, the National Tennis Association.

00:54:29.440 | They have locations where now they are trying this out

00:54:33.860 | and reporting back, how's it working?

00:54:35.560 | How could you change it?

00:54:36.520 | How could you improve it?

00:54:37.600 | - Great. - And so forth.

00:54:38.860 | So that's where we are.

00:54:40.620 | But on the website, you can actually sign up

00:54:44.440 | for being one who will be able to get one

00:54:47.720 | when they are finally manufactured.

00:54:50.500 | They're now being made in fairly small lots

00:54:52.920 | because you want to change things

00:54:54.640 | as you realize how it can be improved.

00:54:57.020 | - Yeah, this is Stanford after all.

00:54:58.420 | You want to get the technology right.

00:55:00.440 | I like to joke that one of the reasons

00:55:02.800 | I like being at Stanford so much

00:55:04.080 | is that not only are my colleagues amazing

00:55:06.240 | and they're so forward thinking,

00:55:07.640 | but they're all perfectionists.

00:55:09.280 | And so the perfectionist mindset has to be perfect

00:55:12.880 | before it can go live, so to speak.

00:55:15.920 | Well, I think there will be a lot of interest.

00:55:18.400 | Let's talk about the technology

00:55:20.680 | in a little more detail for a moment.

00:55:22.200 | And then let's talk about whether or not

00:55:24.460 | cruder forms of that technology exist

00:55:26.480 | either for sake of safety and/or performance.

00:55:29.140 | So what is, the cool mitt, as I understand,

00:55:33.800 | is it's a mitt, it's a glove.

00:55:35.640 | You put your hand into, you hold on to a surface

00:55:39.360 | and that surface cools your hand

00:55:42.280 | and thereby through this specialized portal,

00:55:46.120 | cools your core body temperature

00:55:47.800 | and all the muscles of the body.

00:55:50.040 | Subjectively, if I were to do this right now,

00:55:53.200 | would I think that it was ice cold

00:55:55.240 | or would I think it was just cool?

00:55:58.260 | - Just cool. - I see.

00:55:59.520 | - Ice cold is too cold.

00:56:01.580 | So people always ask, "Well, why can't you just

00:56:03.660 | "stick your hand in a bucket of ice water?"

00:56:05.800 | It's too cold.

00:56:07.120 | What that does is that causes reflex vasoconstriction

00:56:10.680 | of the very portals that you're trying

00:56:13.840 | to maximize the heat loss from.

00:56:16.580 | So you stick your hand in cold water

00:56:18.840 | and when it comes out, it's cold.

00:56:20.280 | - You just sealed up all the heat in your body.

00:56:22.280 | - Yeah, right.

00:56:23.960 | So what I sort of recommended to someone at one point,

00:56:27.800 | they said, "Well, when I'm running,

00:56:29.220 | "can't I just carry a frozen juice can

00:56:31.840 | "and it will gradually melt?"

00:56:33.360 | And I said, "Well, no, because that's going to decrease

00:56:36.260 | "the heat loss from that hand."

00:56:37.720 | But if every couple minutes you switched hands,

00:56:41.040 | it might work.

00:56:41.880 | - Well, I have a feeling that there are people

00:56:43.760 | now doing that as well as trying this.

00:56:46.760 | So how long in the cool mitt at the proper temperature,

00:56:51.560 | how long are people putting their hands into the mitt?

00:56:55.400 | - We once again had just standardized on three minutes.

00:56:59.320 | And part of the reason for that is that the rate of heat

00:57:03.560 | loss is an exponentially declining curve, okay?

00:57:07.600 | And three minutes sort of gets the best part of the curve.

00:57:11.600 | So you can go longer and get more benefit,

00:57:14.240 | but the biggest bang for the buck

00:57:15.840 | is in the first two, three minutes.

00:57:18.400 | - Okay, you mentioned a number of impressive organizations,

00:57:22.160 | sports teams and military that are using this.

00:57:24.520 | This is not something that I typically see

00:57:26.320 | on the sidelines of games, although to be honest,

00:57:29.440 | I haven't looked very carefully.

00:57:31.700 | I'm guessing that they are probably keeping the technology

00:57:35.080 | somewhat under wraps.

00:57:36.700 | Where and how are they doing this?

00:57:38.600 | Are they running back to the locker room?

00:57:40.180 | I mean, the military special operators

00:57:41.740 | are doing their thing, but in terms of the athletes,

00:57:44.360 | is it possible, hypothetically,

00:57:46.420 | the athletes are doing this somewhat incognito?

00:57:51.020 | - It's possible, but I really don't know.

00:57:53.860 | People have mentioned here at Stanford,

00:57:56.380 | they don't see the football team using it.

00:57:59.000 | Well, the football team here at Stanford

00:58:01.000 | is mostly playing in cold weather, cool weather.

00:58:04.740 | Night games are cool, even date games

00:58:07.560 | are not very hot frequently here,

00:58:09.400 | but when they go to a hot place like Arizona or Utah,

00:58:13.600 | at least our coach, Shaw, says that they take it with them

00:58:17.880 | and that's when they find the benefit,

00:58:20.160 | that's when they use it.

00:58:21.220 | - Interesting.

00:58:22.720 | So is there a poor man or woman's version of this?

00:58:27.720 | You mentioned the juice can passing back and forth.

00:58:31.680 | You mentioned cooling the hands.

00:58:34.480 | A number of people said to me after learning a little bit

00:58:37.720 | about this science and technology,

00:58:39.760 | that they've experienced some big effects,

00:58:43.240 | positive effects of cooling by,

00:58:46.360 | and I confess I've done this,

00:58:47.400 | taking a package of frozen blueberries

00:58:50.380 | and just kind of passing it back and forth between my hands.

00:58:52.240 | Now, talking to you,

00:58:53.440 | I realize I probably didn't do it long enough.

00:58:55.700 | I probably was, I was only doing maybe 30 seconds,

00:58:58.840 | passing it back and forth between my hands

00:59:00.640 | and then going back into sets.

00:59:02.400 | I did see a performance enhancing effect, absolutely,

00:59:06.320 | but I realized I probably wasn't optimizing the protocol.

00:59:10.900 | If you were going to give a crude protocol for,

00:59:14.540 | let's just say for the gym,

00:59:15.720 | because with running, it's a little bit tricky,

00:59:17.520 | but what would that look like

00:59:19.660 | if people wanted to just play with this

00:59:21.520 | in some sort of fashion?

00:59:23.920 | - Well, you know, it would be experimental.

00:59:28.780 | - Sure, yeah, none of that is very controlled.

00:59:31.360 | - Your idea of frozen peas is a good idea,

00:59:34.520 | and I think since there's been no actual study of that,

00:59:38.240 | you would have to be you working out

00:59:40.840 | what is the best for you.

00:59:42.880 | But one way to figure it out is that if,

00:59:46.080 | after you hold the cold peas in one hand

00:59:50.400 | and you switch it to the other hand,

00:59:52.360 | if someone then comes and feels your hand,

00:59:55.160 | is it warm or cold?

00:59:56.880 | If it's cold, it means you've as a constricted.

00:59:59.960 | If it's warm, it means the hot blood is still going there.

01:00:04.400 | Okay, so we do that in the lab.

01:00:06.340 | - And the key is for it to not vasoconstrict.

01:00:08.720 | - Right. - Okay.

01:00:09.560 | So there's a test out there, folks.

01:00:11.220 | If you're going to try this in kind of crude fashion,

01:00:13.420 | at least until the cool mitt is available more broadly

01:00:17.320 | to the general public, you could assess,

01:00:21.480 | you want to assess whether or not your palms

01:00:23.940 | actually feel cool to the touch by somebody else.

01:00:27.680 | And if it does, that means you've essentially shut down

01:00:30.080 | the porter, you're sealing in more heat, which is bad.

01:00:32.640 | What about putting this cold pack

01:00:36.160 | of some sort on the face or-

01:00:39.320 | - Or the feet. - More of the feet.

01:00:40.420 | I work out at home, I don't often work out barefooted,

01:00:43.120 | but I suppose I could, like they did in the '70s,

01:00:45.440 | you know, when those guys were walking around

01:00:47.360 | without shoes and squatting without any shoes or socks on.

01:00:51.360 | Could I put my feet on them?

01:00:53.720 | - You could.

01:00:56.520 | If you had simply had a water-perfused pad

01:00:59.040 | and you were circulating cool water through it,

01:01:01.700 | you could just put your feet on it, okay?

01:01:04.180 | Part of the problem is that you don't want,

01:01:11.760 | let's say you have just a cold pack of something.

01:01:16.640 | The problem is back to boundary layers again.

01:01:19.680 | If you don't have a convective stream of the cooling medium,

01:01:24.160 | the heat sink is not as effective because there'll be

01:01:27.040 | a boundary layer developed between the heat sink material

01:01:30.880 | and your skin, so that decreases its efficacy.

01:01:35.320 | - I see.

01:01:36.160 | Maybe we should just for a moment talk about convection,

01:01:39.160 | radiation and convection, and just make that clear.

01:01:41.360 | Like if I put my hands, let's say it's a cold night

01:01:44.680 | and I'm at a campfire and I take my hands

01:01:46.660 | and I put them out to the fire.

01:01:48.000 | - You're getting radiation.

01:01:49.160 | - You're getting radiation.

01:01:50.400 | - Right, right. - Okay.

01:01:51.860 | - And then if it's a windy, warm night,

01:01:55.060 | no, I don't know if that's the best example.

01:01:56.560 | Give us a good example of convection.

01:01:58.940 | - Convection, sure, is in a cool breeze.

01:02:01.300 | You know, with the wind chill factor,

01:02:03.060 | that's due to convection, okay?

01:02:05.320 | But in terms of heat transfer between two objects,

01:02:10.180 | if you have convection of the medium,

01:02:13.180 | whether it's blood on the inside and water on the outside,

01:02:17.780 | you increase the heat exchange if you have convection

01:02:22.280 | on both sides.

01:02:23.120 | - Right, so this is why just planting my feet

01:02:25.540 | on two packages of, my bare feet on two packages

01:02:29.000 | of frozen peas, there's really no opportunity

01:02:31.160 | for circulation and therefore heat transfer.

01:02:34.840 | So it's not really optimal, which is, and I-

01:02:38.120 | - But once again, it depends on the surface area

01:02:40.440 | to get any benefit at all.

01:02:42.020 | We have a study that we published

01:02:45.240 | which was investigating the standard treatment

01:02:49.200 | for hyperthermia in the field.

01:02:51.400 | And the standard treatment that's recommended

01:02:55.920 | by medical organizations is you take cold packs

01:03:00.080 | and you put them in the axilla, the groin.

01:03:03.180 | - The axilla or the armpits?

01:03:05.240 | - The armpits, yeah, the groin, which is-

01:03:08.100 | - Thin skin, lots of vasculature.

01:03:11.600 | - Right, and the neck.

01:03:14.440 | So what we did is we did studies

01:03:16.720 | in which we made people hyperthermic

01:03:18.700 | and then we measured the rate at which we could cool them

01:03:21.800 | by putting those positions in those heat exchange bags

01:03:27.520 | in the recommended location versus on the glabrous skin,

01:03:30.760 | versus palms, soles, and face.

01:03:33.560 | The cooling rate was double.

01:03:36.480 | - Wow.

01:03:37.320 | - So we put the same ice packs, the same cold packs

01:03:41.720 | on the heat portals rather than the axilla,

01:03:46.400 | the groin and the face.

01:03:47.880 | - Wow.

01:03:48.720 | - Or the neck.

01:03:49.840 | - Wow, so face, hands, and bottoms of feet

01:03:53.280 | will cool you twice as fast

01:03:55.120 | as putting cold packs into your armpits,

01:03:59.940 | your groin, or back of neck.

01:04:01.940 | - So I like to give the analogy

01:04:03.640 | of if your car is overheating, okay,

01:04:06.160 | and you have a hose, a garden hose,

01:04:09.040 | where should you spray your cooling system?

01:04:12.060 | Should you spray the radiator

01:04:13.960 | or should you spray the tubes

01:04:15.640 | going in and out of the radiator?

01:04:17.680 | Well, the rationale with putting these cold packs

01:04:20.200 | in the axilla, the groin, and the neck

01:04:22.120 | is that you're getting close to the major arteries.

01:04:25.400 | Sure, that's going to be effective,

01:04:27.360 | but it's much more effective

01:04:28.880 | if you actually increase the heat loss capacity

01:04:32.000 | of the radiating surface, the radiators.

01:04:34.440 | - So you cool the hot stuff heading toward the core.

01:04:38.660 | That's essentially what the standard operating procedure is,

01:04:43.660 | that you hit the arteries.

01:04:46.560 | - Amazing.

01:04:47.400 | - And the veins, the arteries and veins.

01:04:48.920 | - I'm going to just tell a brief story

01:04:50.420 | that illustrates how almost everybody gets this stuff wrong,

01:04:55.420 | and then I'm going to use that as an opportunity

01:04:57.560 | to ask you about heating, deliberate heating,

01:05:00.260 | as opposed to deliberate cooling.

01:05:02.080 | So about four months ago, a friend of mine, incidentally,

01:05:06.840 | a guy who did nine years on the SEAL team

01:05:08.800 | is really skilled cold water swimmer.

01:05:10.840 | We went out for a swim in the morning.

01:05:13.160 | I'm not nearly even close to being in the same universe

01:05:17.400 | of his output potential.

01:05:19.740 | We do these swims, I'm familiar with them.

01:05:21.820 | I got enough blubber on me that I stay warm enough

01:05:24.500 | in the cold Pacific, no wetsuits.

01:05:26.080 | We do the morning cold swim for about a mile or so,

01:05:28.960 | and we brought with us a young kid that I know real well

01:05:32.900 | that hangs out with us sometimes and trains with us,

01:05:35.380 | who's got very little body fat.

01:05:37.720 | He's just exceptionally lean,

01:05:39.980 | despite eating everything inside, right?

01:05:42.480 | Teenager, great athlete, great kid, great swimmer.

01:05:47.480 | So we're out there swimming, and at some point,

01:05:50.680 | we're talking to him and it's clear

01:05:52.080 | that he's gone hypothermic.

01:05:54.000 | He's slurring his words, he's not doing well.

01:05:56.960 | So we get him onto the beach, his teeth are turning yellow,

01:05:59.800 | he's quaking, he's not, he's got, you know,

01:06:03.240 | his saliva is taking on that consistency that's clear,

01:06:06.200 | like he's hypothermic.

01:06:07.900 | We go to the lifeguard station.

01:06:10.140 | Lifeguard says, "Okay, let's get his vitals,

01:06:12.420 | "let's do all this."

01:06:13.260 | Meanwhile, trying stand next to him, you know,

01:06:17.340 | and heat him up by heating up his torso.

01:06:19.660 | So there we are, like pressing against this guy, our friend,

01:06:23.980 | trying to heat him up.

01:06:24.940 | They get a blanket on him.

01:06:27.000 | He's, I'm realizing he was barefoot, his face was exposed,

01:06:30.900 | although we did cover his head with the blanket,

01:06:32.740 | and he eventually came back.

01:06:33.720 | We got some warm liquids into him and he was okay,

01:06:36.680 | he was fine.

01:06:37.700 | I don't know that his mother is ever going to let him swim

01:06:39.640 | with us again.

01:06:41.220 | If I ever disappear and go missing,

01:06:43.760 | it's because of that incident.

01:06:46.500 | Anyway, he did great, he recovered,

01:06:49.540 | he's back in the water and doing well.

01:06:51.740 | But I realized that pretty much everything from the point

01:06:55.940 | where we got back on the beach until he was back to normal

01:06:59.860 | was we did incorrectly.

01:07:01.380 | We heated his torso, we left his extremities exposed,

01:07:06.380 | and we assumed we were doing the right thing.

01:07:09.180 | And the lifeguard is a skilled lifeguard

01:07:11.060 | at a major public beach.

01:07:13.260 | So I guess the simple question is,

01:07:15.460 | did we get everything wrong?

01:07:16.940 | Did we get anything right?

01:07:18.820 | And what would have been the better option

01:07:21.040 | to heat up a hypothermic person in that

01:07:24.920 | or a similar situation?

01:07:26.780 | - Well, it's interesting you asked that

01:07:28.400 | because that is the way we got into this area

01:07:33.040 | of investigation.

01:07:34.340 | I worked on how the hypothalamus regulates body temperature

01:07:39.180 | neurophysiology.

01:07:40.920 | And one day we were having a discussion with a colleague

01:07:45.640 | in the Department of Anesthesia.

01:07:48.020 | And he jokingly said to my colleague, he said,

01:07:51.640 | "Yeah, you guys think you know so much about temperature.

01:07:54.560 | I bet you couldn't solve a problem we have

01:07:56.700 | in the recovery room."

01:07:58.640 | What's that?

01:07:59.860 | Well, the patients come out of surgery,

01:08:01.660 | they're hypothermic and it takes us hours

01:08:03.880 | to get them to stop shivering.

01:08:06.340 | What do they do in the recovery room?

01:08:08.020 | Exactly what you suggested.

01:08:09.780 | They put in warm blankets, they put on heat lamps,

01:08:13.820 | and it takes them an hour or two hours

01:08:16.880 | to get these patients to stop shivering

01:08:18.940 | to bring them back up.

01:08:20.580 | So we say, ah, it's a trivial problem.

01:08:22.740 | No, it's a hard problem.

01:08:24.920 | It's a hard problem because when you're under anesthesia,

01:08:28.380 | you're vasodilated.

01:08:29.840 | When you come out of anesthesia, you're hypothermic

01:08:32.600 | and you vasoconstrict.

01:08:34.420 | That makes it very difficult to get heat into the body.

01:08:38.200 | So we got the idea that, well,

01:08:40.400 | if we could just take one appendage, like an arm,

01:08:43.800 | and we put it in a environment wrapped in a heating pad

01:08:47.940 | and a negative pressure, you know, suction,

01:08:51.260 | that would pull more blood into that limb,

01:08:53.660 | that blood would get heated,

01:08:55.020 | and it would warm the body up faster.

01:08:57.360 | So my colleague built a prototype device.

01:09:02.000 | You couldn't get such a device into the hospital these days.

01:09:04.860 | But we were with our anesthesiologist friend.

01:09:09.620 | We took it into the recovery room,

01:09:11.720 | and first thing the patient said, "No way.

01:09:15.380 | "You're not gonna put that on my patient."

01:09:17.620 | But he prevailed, and first patient didn't shiver at all.

01:09:22.980 | First patient was back to normal temperature,

01:09:25.340 | core temperature, in I think it was eight minutes,

01:09:28.300 | eight or nine minutes.

01:09:29.260 | - Is this now standard practice in hospitals?

01:09:31.540 | - No, no, no.

01:09:32.380 | - So this is another example where I don't get upset about,

01:09:36.240 | although it's upsetting to know that it's not,

01:09:38.960 | but I think that it's yet another case

01:09:41.460 | where a fundamental problem exists.

01:09:44.780 | There's a science-based solution

01:09:49.780 | that makes sense at the level of physiology,

01:09:52.300 | engineering, and practice, and yet it's not being done.

01:09:55.900 | - Right.

01:09:56.820 | - And I mean, that's a whole other discussion

01:09:59.060 | as to what the limitations are.

01:10:00.680 | Well, perhaps, I know a number of our listeners

01:10:03.300 | are in the healthcare and medical profession

01:10:05.220 | as well as military athletes,

01:10:06.380 | and just also standard other types of jobs,

01:10:08.820 | civilians doing other types of work.

01:10:11.400 | It would be wonderful if people understood this.

01:10:14.020 | So once again, is there a homegrown technology

01:10:19.020 | that people could use?

01:10:20.020 | If somebody is hypothermic, what is going to be the best way

01:10:24.100 | for them to warm up?

01:10:24.940 | Is it going to be holding a nice warm mug of cocoa

01:10:28.000 | or something like that, but not too hot, I guess,

01:10:30.780 | is again the idea? - Yeah, sure, yeah.

01:10:33.360 | Well, actually, you can go hotter on the glabrous skin.

01:10:37.860 | - Oh, because it'll dilate.

01:10:39.180 | - Because it takes the heat away faster, okay?

01:10:42.500 | But back to the anesthesia,

01:10:44.260 | what you can do is you can use warm pads.

01:10:47.700 | They have them in all hospitals.

01:10:49.800 | They have circulating water-perfused pads.

01:10:52.780 | - Hot water bottle type stuff. - Put them on the feet.

01:10:54.660 | Put them on the feet. - So typically,

01:10:55.500 | they'll slide them under your lower back

01:10:57.320 | or something like that. - Yeah, put them on the feet.

01:11:00.180 | Okay, sure, that will do it.

01:11:02.620 | But it turns out that we discovered through this work

01:11:07.360 | that it had nothing to do with the whole arm.

01:11:09.600 | It was only the hand.

01:11:11.400 | And that's when we came to the realization

01:11:13.540 | of these special blood vessels.

01:11:15.400 | We didn't discover the blood vessels.

01:11:17.160 | They're described in Grey's Anatomy,

01:11:19.180 | but nobody knew what they were for.

01:11:21.120 | - And you mentioned bears earlier and other hairy animals.

01:11:24.880 | Do they have these AVAs as well?

01:11:29.360 | And I suppose we haven't defined AVAs.

01:11:31.000 | We've been pretty good about the no acronyms rule.

01:11:32.880 | AVAs is?

01:11:33.840 | - Arteria venous anastomoses.

01:11:35.900 | So a connection between the arteries and the veins, yeah.

01:11:40.440 | - I actually use this technology.

01:11:41.820 | I have a bulldog, bulldog mastiff.

01:11:43.480 | He has a very high propensity for overheating

01:11:47.840 | 'cause they're terrible at dumping heat

01:11:49.720 | and bulldogs are great at pushing themselves

01:11:53.040 | to the point of exhaustion or death, it happens.

01:11:56.120 | And so now we do what we call palmer cooling.

01:11:59.540 | Sorry, I couldn't help myself.

01:12:00.960 | Where I'll take Costello and lower him

01:12:02.880 | into a cool body of water, just the bottoms of his paws.

01:12:06.800 | Although I think animals instinctually know to do this

01:12:10.760 | and will go and stand in bodies of water.

01:12:13.680 | They don't often lie down all the way, some do.

01:12:17.120 | But they seem to know that's a great way

01:12:20.020 | to cool themselves off.

01:12:21.160 | - Yeah, oh, absolutely, yeah.

01:12:23.680 | - And they get the advantage that their palms

01:12:25.880 | and their feet are essentially the same thing.

01:12:27.520 | - So we actually built devices for dogs.

01:12:29.960 | - Did you really?

01:12:30.800 | - And tried them on, I did a rod sled dogs

01:12:33.160 | and it worked beautifully.

01:12:34.780 | They had little backpacks with the equipment

01:12:38.120 | and pads on all their feet and it worked beautifully.

01:12:42.560 | - Amazing, amazing.

01:12:43.920 | Along the lines of heating, deliberate heating,

01:12:47.200 | wearing a knit cap is something that,

01:12:51.840 | you see more of that on the East Coast.

01:12:53.860 | People run around Boston and New England with a knit cap.

01:12:58.160 | I've always done that at the start of my runs

01:13:00.240 | to try and warm up more quickly and then I take it off.

01:13:02.880 | I shed layers as I go.

01:13:04.560 | Is that a rational practice the way I just described it?

01:13:09.160 | Yeah, because warming up is important too.

01:13:11.960 | There's a certain amount of quote unquote warming up

01:13:14.800 | that's required to lubricate joints

01:13:17.040 | or at least to get the sense that joints are lubricated

01:13:19.380 | and to be able to move more easily.

01:13:21.520 | Do you still recommend that people warm up?

01:13:24.400 | - Yeah, but I think we're misled by the term warm up

01:13:28.800 | as if the major purpose is to raise temperature.

01:13:33.120 | I'm not aware of any data on this,

01:13:36.960 | but I do think that the major contribution

01:13:39.600 | is increasing flexibility.

01:13:41.700 | So you're going to avoid having damage of joints

01:13:45.480 | and tendons and ligaments and so forth.

01:13:48.240 | But also the ability of the mitochondria to produce energy

01:13:55.140 | can be impaired at lower temperatures.

01:14:00.400 | And you have to keep in mind

01:14:01.960 | that we say our body temperature is 37 degrees,

01:14:04.960 | but that's not true.

01:14:06.540 | - Yeah, it varies across the day.

01:14:08.240 | - Well, it varies in parts of your body.

01:14:10.880 | I mean, my hands and arms are not at 37 degrees right now.

01:14:14.500 | They're much lower.

01:14:15.500 | - So that raises an interesting question.

01:14:18.440 | What is the best way to measure core body temperature?

01:14:22.480 | - Well, the best core temperature is that,

01:14:25.620 | what we use is esophageal.

01:14:28.020 | So we put a thermocouple up the nose

01:14:30.820 | about two feet down the esophagus

01:14:32.860 | so that it's about the level of your heart.

01:14:34.840 | - Not gym or home practical, although I don't know.

01:14:37.860 | Some of those COVID swab tests go pretty far.

01:14:40.240 | - I can't even imagine it going any further.

01:14:42.120 | I felt like my brain was getting tickled.

01:14:44.220 | And it was really unpleasant.

01:14:46.840 | - Timpaniq is a pretty good-

01:14:48.220 | - So the ear.

01:14:49.060 | - The ear, it's not foolproof

01:14:51.560 | because you have to actually have it aimed properly

01:14:54.840 | at the tympanum.

01:14:56.160 | And frequently what you're getting

01:14:57.760 | is you're getting sort of a mixture of tympanic

01:14:59.920 | plus ear canal temperature.

01:15:02.320 | - And for those listening and for those watching,

01:15:04.560 | the tympanic is not going to be the pinna

01:15:06.920 | that this part of the ear, the outer part of the ear,

01:15:08.760 | the tympanic is going to be near the tympanic,

01:15:10.420 | headed towards the tympanic membrane.

01:15:11.840 | And yes, I'm sticking my finger in my ear

01:15:13.680 | because that's where the laser would actually have to go

01:15:17.160 | to measure your temperature.

01:15:18.680 | So when we were walking into restaurants

01:15:20.200 | and other places nowadays

01:15:21.280 | and they're shining the laser at our forehead,

01:15:22.960 | that's probably giving a pretty crude readout

01:15:25.040 | of temperature.

01:15:25.880 | - It is, but there's much less insulation

01:15:28.440 | between your brain and your forehead skin

01:15:31.000 | than there is between your biceps and your arm skin.

01:15:34.480 | So if you're going to measure a surface temperature,

01:15:37.900 | that's where you would do it.

01:15:39.040 | And we do temperatures in the infrared.

01:15:42.440 | We take infrared videos of athletes and our subjects.

01:15:46.860 | And of course the face lights up.

01:15:49.540 | - Okay, so if we're not,

01:15:51.300 | I imagine there's going to be a technology coming soon

01:15:53.400 | where you can point your smartwatch

01:15:56.140 | or your smartphone at yourself

01:15:57.200 | and you're going to get a heat map.

01:15:58.700 | - Right, right.

01:15:59.540 | - That's got it.

01:16:00.360 | If somebody out there hasn't already invented this

01:16:02.480 | for the typical folks outside military,

01:16:04.800 | somebody please invent that

01:16:06.080 | because I think there's growing interest in temperature

01:16:10.180 | based on the work that you're doing

01:16:11.600 | and also for sake of something I do want to touch on,

01:16:14.440 | which is sleep and metabolism.

01:16:16.500 | Although we don't want to open up those portals all the way

01:16:19.400 | because we'd need several days to cover it.

01:16:21.540 | Okay, so putting on the cap,

01:16:25.320 | what about some of the helmets and gloves

01:16:28.940 | that are used in typical sports?

01:16:30.640 | Do you think that those can be improved

01:16:32.240 | in order to improve performance

01:16:34.420 | in terms of their ventilation ability

01:16:36.180 | or keeping Palmer surfaces open, for instance?

01:16:40.100 | - Well, you mentioned about the knit cap

01:16:42.760 | in cold weather especially,

01:16:44.520 | and that is significant

01:16:46.260 | because you do lose a lot of heat from your head,

01:16:50.220 | but it's a constant heat loss.

01:16:53.260 | It's not variable like your glibrous skin.

01:16:56.540 | So if you decrease that heat loss,

01:16:59.740 | you're going to be warmer.

01:17:02.700 | So sure, that has an impact.

01:17:06.420 | Now, in terms of helmets, they should be ventilated.

01:17:10.540 | I mean, they should have enough space in them

01:17:13.580 | and holes in them so that air can circulate.

01:17:17.180 | You don't want to thermally insulate your scalp.

01:17:22.180 | That's going to decrease heat loss quite considerably.

01:17:25.420 | Just for a resting individual,

01:17:27.180 | the brain is about 20% of your metabolism.

01:17:30.200 | So that's a lot of heat production.

01:17:32.180 | - Yeah, absolutely.

01:17:33.220 | I realized there was a question that I failed to ask earlier

01:17:38.520 | that is burning in my mind now,

01:17:41.740 | and I think is likely burning in the minds

01:17:43.740 | of some of the listeners, which is,

01:17:45.740 | so if you do this cooling in between sets in the gym,

01:17:49.860 | you get this performance enhancing effect.

01:17:52.660 | You don't get the delayed onset muscle soreness,

01:17:55.060 | which is great.

01:17:56.540 | So presumably, the body is adapting.

01:17:59.080 | You're getting better as a consequence

01:18:00.780 | of being able to do more work per unit time

01:18:03.180 | or to go harder in some way, of course.

01:18:06.140 | You get that adaptation.

01:18:09.040 | Does that mean that you see a performance enhancing effect

01:18:12.620 | even when you don't cool

01:18:14.820 | if you've previously done the cooling workouts?

01:18:17.320 | So for instance, let's say I can do 10 sets of 10 dips,

01:18:19.740 | which I like to think I can.

01:18:21.660 | Maybe I need to go try.

01:18:22.540 | I don't know if I've done that recently.

01:18:24.020 | I do the cooling.

01:18:24.940 | I cool for three minutes between sets.

01:18:27.380 | And let's say I get to the point where I can do 20

01:18:32.220 | for 10 sets, 10 sets of 20 repetitions,

01:18:35.700 | and then I don't cool.

01:18:37.360 | Will I be able to match or approximate

01:18:40.780 | my new better performance?

01:18:42.620 | - You keep your gains.

01:18:44.220 | It's a true conditioning effect.

01:18:46.260 | You respond to the increased work volume

01:18:49.820 | by all of those mechanisms you mentioned.

01:18:52.460 | - Amazing.

01:18:53.300 | - You increase the number of contractile elements

01:18:55.140 | in your muscles, muscles get bigger.

01:18:57.620 | - Amazing.

01:18:58.460 | - We had an experiment that involved

01:19:00.300 | some of our female students, not athletes,

01:19:05.300 | but just regular, they were freshmen actually.

01:19:08.300 | And the experiment was 10 sets of pushups

01:19:12.460 | to muscle failure with or without cooling.

01:19:15.220 | - Same regimen, three minutes of cooling

01:19:17.300 | in between sets of pushups.

01:19:18.580 | - Right.

01:19:19.580 | Some of those young ladies reached over 800 pushups

01:19:25.320 | - Now the total duration of the workout

01:19:26.860 | could be getting much longer as a consequence

01:19:28.620 | of doing more work.

01:19:29.620 | - No, it doesn't take you longer.

01:19:31.300 | Well, minor, I mean, a pushup is pretty fast.

01:19:34.580 | - Yeah, it's pretty fast.

01:19:35.500 | - So you do 10 sets, the maximum 45 minutes total.

01:19:40.080 | - That's a lot of pushups.

01:19:41.880 | - That's a lot of pushups.

01:19:43.620 | So the interesting thing is they came in one day

01:19:45.660 | and they said, "Dr. Heller, you cost us a lot of money."

01:19:48.820 | Why?

01:19:49.660 | Well, we had a formal dance this weekend.

01:19:51.220 | We all had to buy new sleeveless dresses.

01:19:53.340 | - Nice, it's a good problem to have.

01:19:56.260 | Good problem to have.

01:19:57.360 | Let's talk about steroids, anabolic steroids.

01:20:01.840 | We're heading into an Olympics.

01:20:05.060 | Every time the Olympics rolls around,

01:20:07.220 | you hear about these cases of people getting popped

01:20:10.100 | as they call it, or caught for anabolic steroids.

01:20:12.980 | There are some accusations out there now

01:20:14.700 | there'll be more, this will get handled in the press

01:20:19.700 | and then the various organizations.

01:20:21.980 | Clearly athletes and non-athletes use anabolic steroids.

01:20:26.140 | And typically anabolic steroids

01:20:27.820 | are of the testosterone variety.

01:20:30.220 | There are derivatives, et cetera.

01:20:32.740 | And those derivatives do different things

01:20:34.980 | in the anabolic versus androgenic, et cetera.

01:20:36.940 | But typically the idea is, at least as I understand it,

01:20:41.460 | in talking to some of these individuals,

01:20:43.460 | is that they allow people to train more

01:20:47.540 | because they recover faster.

01:20:50.560 | They are able to synthesize more protein

01:20:53.120 | because they're basically getting a second puberty.

01:20:55.680 | Because as we all know, during puberty,

01:20:57.340 | there's a lot of growth of the body.

01:20:59.140 | And of course there are a lot of negative effects

01:21:02.680 | of abuse of these things.

01:21:04.060 | And they are banned from various sports organizations.

01:21:07.820 | Especially I should mention in combat sports,

01:21:10.140 | it's especially concerning because in combat sports,

01:21:13.760 | a performance enhancement means that you can harm somebody

01:21:16.780 | more than you would be able to otherwise,

01:21:20.020 | as opposed to in other sorts of sports,

01:21:21.940 | just to conceptualize it.

01:21:23.600 | And I'm not taking a moral stance on any of this.

01:21:25.860 | I just want to ask you,

01:21:28.060 | when you compare Palmer cooling to anabolic steroids,

01:21:32.960 | in terms of gym performance, what do you see?

01:21:37.960 | - Well, we do not do research on steroids,

01:21:41.640 | but there is a lot of research in the literature.

01:21:46.780 | A lot of that research in the strength conditioning

01:21:51.180 | magazines is not very scientific.

01:21:55.300 | - No. - Okay?

01:21:56.420 | - Or it might not even be scientific at all.

01:21:58.300 | - Right. - Right.

01:21:59.140 | - But we did do an analysis of reputable papers.

01:22:02.780 | And we did find, I think it was probably eight or nine,

01:22:06.940 | 10 studies on bench press,

01:22:10.700 | increase in bench press performance on steroids or not.

01:22:15.180 | Okay?

01:22:16.160 | The bottom-- - These were males or females?

01:22:17.980 | - Well, these were all males,

01:22:20.620 | but I'll get back to the females.

01:22:22.220 | Okay.

01:22:23.500 | The bottom line is that in all of these independent studies,

01:22:28.400 | their rate of improvement was approximately 1% per week.

01:22:33.400 | - Okay. - Okay.

01:22:35.340 | Now I've just told you about studies

01:22:38.340 | in which we've had 300% increase in a month.

01:22:44.920 | So. [laughs]

01:22:46.940 | - It's an enormous, enormous difference.

01:22:49.540 | - So why would you endanger your health

01:22:51.940 | as well as your legal ability to compete

01:22:55.380 | with such an ineffective tool?

01:22:58.280 | - Yeah.

01:22:59.120 | No, I think the notion of performance enhancement

01:23:03.460 | is a really interesting one

01:23:04.900 | because people clearly pay attention to nutrition.

01:23:07.860 | Sleep is now something that I think everybody,

01:23:10.820 | but especially athletes are paying attention to.

01:23:12.860 | - Right.

01:23:14.220 | - And I predict that temperature

01:23:16.660 | will be one of the more powerful parameters

01:23:21.460 | that people are going to be focusing on.

01:23:23.180 | - Yeah, that's true.

01:23:24.220 | - Because of the magnitude of the effects

01:23:25.820 | that you're describing.

01:23:27.180 | And also because so much of the variability

01:23:30.980 | around performance, as you mentioned,

01:23:32.460 | has to do with when you go to a new environment.

01:23:35.820 | Everyone has their home environment worked out pretty well.

01:23:39.380 | Sleep well in your own bed at home.

01:23:40.860 | When you can control everything,

01:23:42.620 | your performance is always great.

01:23:43.820 | This is why I think military special operators

01:23:45.740 | are a particularly interesting group

01:23:48.020 | because their whole world is centered

01:23:51.020 | around elite and high performance

01:23:54.060 | with very high risk, high consequence

01:23:56.180 | under variable conditions.

01:23:58.220 | The essence of their work

01:23:59.400 | is variable, unpredictable conditions.

01:24:01.900 | So you mentioned female athletes and steroids.

01:24:05.260 | I'm curious about this.

01:24:06.580 | - Yeah, because everybody has always said to us,

01:24:08.720 | "Well, you only use male subjects."

01:24:11.300 | And obviously they have this testosterone background.

01:24:14.460 | They have higher levels of testosterone.

01:24:16.300 | That's why you get these results.

01:24:18.200 | So we did a comparative study on females.

01:24:20.780 | We get the same results.

01:24:22.780 | - Impressive.

01:24:23.620 | And these are our Stanford athletes or also-

01:24:25.900 | - No, these were not Stanford athletes.

01:24:27.260 | They were Stanford students, but not athletes.

01:24:31.100 | Well, we have done, of course, work on some athletes,

01:24:34.020 | but in general, we don't do research on our teams,

01:24:37.420 | our varsity teams, so they have their own protocols.

01:24:40.580 | They have their own training programs.

01:24:42.460 | - Yeah, they don't like us to get too close to them.

01:24:44.500 | No, I work with some of these folks and the coaches

01:24:46.660 | and they're very skeptical with good reason also.

01:24:49.860 | And the reason I ask is that when you see these Pac-10

01:24:54.300 | or division one college athletes

01:24:56.320 | and then you see their peers,

01:24:58.100 | there's clearly a difference, right?

01:25:01.280 | I mean, they are pedigreed throughout, right?

01:25:05.000 | And more typical folks also have different goals.

01:25:10.340 | They may not want to get infinitely stronger

01:25:13.180 | or perform more endurance work.

01:25:14.840 | So I want to ask you a couple of things

01:25:18.200 | about shivering and metabolism,

01:25:20.900 | because I think they're very interesting

01:25:22.980 | and sufficiently related.

01:25:25.180 | So my understanding is that shiver is an adaptation

01:25:29.940 | that's designed to heat us up.

01:25:31.580 | - Yes.

01:25:32.700 | - That we have brown fat

01:25:35.980 | that's in compartments around our body

01:25:37.660 | that are activated by shiver or coactivated by shiver,

01:25:41.900 | and that shivering is useful for increasing metabolism.

01:25:46.600 | Is that true?

01:25:48.100 | And does it require that cold be the stimulus?

01:25:50.760 | So two scenarios, I'll give you an experiment.

01:25:53.260 | I put someone into cold water of some sort,

01:25:56.060 | and then I make them get out or I have them stand near it,

01:25:58.540 | and then they start shivering.

01:25:59.840 | My understanding is that their metabolism will increase.

01:26:03.740 | What if I take someone and I just have them shiver,

01:26:06.900 | but they're not exposed by cold?

01:26:08.140 | It's kind of a deliberate shivering.

01:26:09.940 | Will that also create a substantial increase in metabolism?

01:26:14.740 | - Sure.

01:26:15.620 | So deliberate shivering without cold

01:26:19.180 | is essentially what happens when you get a fever.

01:26:21.660 | Your set point goes up and you're hypothalamus,

01:26:25.400 | and you actually, even though you're normal body temperature,

01:26:28.760 | your thermostat is telling you you're too cold.

01:26:31.060 | Increase your metabolism, so shiver, right?

01:26:34.540 | So sure, shivering is a good way of increasing metabolism,

01:26:39.140 | but it only can take metabolism up

01:26:41.060 | maybe three or four times resting.

01:26:43.700 | - Okay.

01:26:44.540 | - Whereas exercise can take you up 10 times.

01:26:48.140 | - Got it.

01:26:48.980 | All right, I'm going to ask a couple

01:26:49.800 | of more random questions, and seemingly random.

01:26:53.700 | Do bears actually hibernate?

01:26:55.380 | - Oh yeah.

01:26:56.300 | - The true hibernation?

01:26:58.180 | - Well, it depends on how you define true.

01:27:00.540 | A bear, actually, we've done a lot of work on bears.

01:27:04.700 | - Do you also put the nose thermocouple

01:27:08.260 | down in the esophagus?

01:27:09.380 | - Oh, we implant them surgically.

01:27:10.980 | - Okay, they're anesthetized when you implant them.

01:27:12.800 | - Yes.

01:27:13.640 | - What kind of bears are these?

01:27:14.460 | - Black bears.

01:27:15.300 | - Okay.

01:27:16.140 | - And did this with colleagues at University of Alaska,

01:27:18.220 | and we're analyzing the data now.

01:27:19.920 | But what we've done is we've had now a total of 18 bears,

01:27:24.460 | and we implant them with EEG, EKG temperature sensors.

01:27:29.280 | And sometimes we actually measure their oxygen consumption.

01:27:31.840 | - These are bears in the wild.

01:27:32.900 | - These are bears in the wild,

01:27:34.100 | but they're brought in to University of Alaska,

01:27:36.820 | where we keep them in an outdoor enclosure.

01:27:38.940 | So they're hibernating in an S-box, in an enclosure.

01:27:42.580 | And we're recording this electrophysiological data

01:27:45.340 | continuously for six months.

01:27:47.220 | - Amazing.

01:27:48.060 | How do I get on this protocol?

01:27:49.580 | Craig and I are doing some work together going forward,

01:27:53.540 | and maybe you can slide me onto this protocol too.

01:27:56.260 | That sounds amazing.

01:27:57.300 | Right now, it's a matter of just analyzing the gigabytes,

01:28:00.660 | terabytes of data that have been collected.

01:28:03.840 | But anyway, you asked about hibernation.

01:28:05.880 | So bears only go down to about 33, 34 degrees centigrade

01:28:10.880 | in the core temperature.

01:28:12.680 | And that's been argued that, well, they can't go lower

01:28:16.400 | because they have so much insulation.

01:28:18.240 | They're so big, their surface volume ratio and so forth.

01:28:21.060 | And that's not true.

01:28:22.600 | They shiver.

01:28:23.640 | So if we have a day like minus 40,

01:28:27.320 | which you get up in Alaska,

01:28:30.480 | they will go through periods of shivering

01:28:32.760 | and maintain a core temperature on 33, 34.

01:28:35.920 | Now the ground squirrels and the marmots,

01:28:38.660 | which are smaller animals,

01:28:41.120 | they will drop down to a body temperature,

01:28:44.400 | maybe within a degree of the environment.

01:28:47.620 | So they can go down to one or two degrees centigrade,

01:28:50.600 | just above freezing during bouts of hibernation.

01:28:54.320 | So they'll stay in hibernation for seven or eight days

01:28:56.720 | and they'll come back up to normal body temperature

01:28:58.680 | for a day, then they'll go back down and do another-

01:29:00.520 | - What do they do during that day

01:29:01.360 | when they're warming up again?

01:29:02.720 | Do they go around?

01:29:03.560 | - They rearrange their nests, eat, if they've stored food.

01:29:07.200 | Some species store lots of food,

01:29:09.120 | others just depend on their fat.

01:29:10.880 | - A former mentor of mine, my master's degree mentor,

01:29:14.760 | and a colleague and friend of yours,

01:29:17.820 | Irving Zucker at UC Berkeley, told me a story once,

01:29:21.340 | told me a lot of stories, tells great stories, as you know.

01:29:24.020 | He told me that when an animal comes out of hibernation,

01:29:27.260 | periodically, that it's a very dramatic thing to observe.

01:29:31.460 | That it's not like they wake up and yawn and look around,

01:29:34.340 | but it's like a complete epileptic seizure.

01:29:37.660 | - Right.

01:29:38.820 | - What's going on there? - Shivering.

01:29:40.200 | - It's just a very dramatic shiver.

01:29:42.020 | - So at the low temperatures, they cannot shiver

01:29:45.620 | because the effect of temperature on the conduction

01:29:48.660 | of the nerves and the muscle factors-

01:29:50.860 | - So they're shut down, basically.

01:29:52.100 | - They're shut down.

01:29:52.940 | So there, they use brown fat.

01:29:54.300 | So activate brown fat, and then when they get up

01:29:56.760 | to a temperature of maybe 15, 16 degrees centigrade,

01:29:59.820 | then the shivering starts and it gets very, very violent,

01:30:02.620 | but they're still asleep.

01:30:05.340 | - Do we shiver in our sleep?

01:30:08.100 | - I would imagine we do, but it probably wakes us up.

01:30:12.380 | - Interesting.

01:30:13.220 | So the brown fat is kind of like kindling.

01:30:16.140 | - The brown fat is a tissue which has lots of stored energy,

01:30:21.140 | 'cause it's fat, but unlike our white fat, our regular fat,

01:30:26.900 | it also has lots of these little powerhouses, mitochondria,

01:30:30.980 | and lots of blood supply.

01:30:32.740 | So essentially, it is a tissue just to produce heat.

01:30:36.880 | That's what it's there for.

01:30:38.260 | Now, in these hibernators, there are big patches

01:30:41.700 | of brown fat at certain locations that are critical,

01:30:44.180 | like around the heart, for example.

01:30:46.800 | For us, the brown fat is sort of distributed.

01:30:49.780 | So for many, many years,

01:30:51.740 | it was thought humans don't have brown fat,

01:30:54.100 | but indeed we do.

01:30:55.560 | It's just not localized into discrete fat pads

01:30:59.020 | like it is in ground squirrels, marmots.

01:31:02.980 | - I don't know why the phrase fat pads

01:31:04.860 | is so satisfying to say, but it is fat pads.

01:31:08.460 | Speaking of fat pads, I was taught that we have,

01:31:12.760 | by the internet, I should say,

01:31:15.020 | I was taught by the internet that we have brown fat

01:31:18.100 | between our scapulae and our upper neck.

01:31:20.240 | Is that truly a source of brown enrichment for brown fat?

01:31:24.420 | - If you're a ground squirrel.

01:31:26.500 | - So it's complete, this is all the drawings out there.

01:31:29.040 | Okay, so what I'm hearing you say is that brown fat

01:31:32.180 | is actually distributed in patches.

01:31:33.700 | - In humans, it's distributed along with other fat tissue.

01:31:38.420 | It's not as discrete.

01:31:41.060 | - So the reason I'm kind of shocked and amused

01:31:44.640 | and troubled by this is because there is

01:31:49.380 | a somewhat standard protocol in the performance,

01:31:53.960 | wellness, whatever, world, whatever you want to call it,

01:31:56.760 | of putting ice packs on the upper back

01:31:59.860 | as a way to stimulate brown fat thermogenesis.

01:32:04.460 | I'm hearing some inhales of concern from the physiologist.

01:32:09.060 | So tell me why, it sounds like that's probably not

01:32:12.100 | the best way to stimulate brown fat activation.

01:32:14.880 | - Well, let's put it this way.

01:32:17.140 | - You're not attacking anyone specifically

01:32:18.760 | because the whole world believes this.

01:32:20.460 | So it doesn't-

01:32:21.420 | - But it may not be totally facetious or false.

01:32:26.140 | Think of what that's doing.

01:32:27.540 | If you put ice right there where your spinal cord

01:32:31.100 | is close to the surface,

01:32:32.800 | that's where you're going to hit the vertebral arteries.

01:32:35.400 | So you're essentially putting a cold source

01:32:38.060 | into the brain, to the hypothalamus.

01:32:40.340 | The hypothalamus says you're too cold,

01:32:43.340 | so it is going to turn on shivering and brown fat.

01:32:47.180 | - Would there be a better site

01:32:50.660 | for sake of activating brown fat?

01:32:56.200 | Polymer cooling?

01:32:58.040 | - You know, I can't say,

01:33:01.620 | because the activation of brown fat

01:33:03.700 | is a sympathetic nervous system response.

01:33:07.620 | So any lowering of core temperature

01:33:10.700 | that will let the thermostat say you're too cold

01:33:15.220 | is going to turn on sympathetic.

01:33:16.960 | Now, people will have perhaps different amounts of brown fat.

01:33:21.960 | So newborn have more brown fat than adults.

01:33:25.740 | - 'Cause newborns can't shiver, correct?

01:33:27.700 | - I don't know.

01:33:28.540 | - Okay, that's what I read.

01:33:29.860 | I don't know if it's true.

01:33:31.180 | I read that in what I believe to be credible sources.

01:33:34.700 | - Yeah, it could be, I just don't know.

01:33:37.180 | It depends on if it's really newborn.

01:33:40.140 | I can agree because you don't have

01:33:42.300 | all of the motor pathways connected up yet.

01:33:46.320 | That's something that occurs in early days of life

01:33:49.820 | and is probably one of the functions of REM sleep,

01:33:54.120 | which infants have a lot of, okay?

01:33:57.160 | But how to activate brown fat?

01:33:59.560 | If you are consistently exposed to cold,

01:34:02.880 | so if you live in the Arctic

01:34:05.380 | and you go out jogging in the winter,

01:34:08.080 | maybe that will increase the amount of brown fat you have.

01:34:11.040 | If you live in the tropics, maybe you have less brown fat.

01:34:13.920 | I don't know.

01:34:14.760 | I don't know of any studies which have looked into that.

01:34:17.720 | - Okay, ice headache.

01:34:20.420 | Sometimes I'll drink a cold beverage

01:34:22.040 | after all, eat ice cream and my head will-

01:34:25.900 | - Brain freeze. - Slitting, brain freeze.

01:34:27.700 | And speaking of special forces, I was talking to,

01:34:30.740 | we all see the images, the SEAL training/screening

01:34:35.560 | in Coronado where they're going in and out of the Pacific,

01:34:37.680 | which is very cold.

01:34:38.920 | But I know they also spend some time

01:34:41.800 | in the very cold waters of Kodiak, Alaska.

01:34:44.720 | You mentioned Alaska.

01:34:46.680 | Brain freeze, so-called ice headache,

01:34:49.240 | is a common occurrence there in those situations.

01:34:54.240 | But we all have experienced this.

01:34:56.220 | We eat ice cream, we get that brain freeze.

01:34:58.560 | I can feel it right now a little bit subjectively.

01:35:00.940 | I can induce it.

01:35:02.860 | What's going on there?

01:35:04.000 | And I would always just rub my tongue

01:35:06.200 | on the roof of my mouth.

01:35:07.220 | Is there something that I'm doing that's functional there

01:35:09.760 | just to try and alleviate it?

01:35:11.320 | - Good question.

01:35:12.160 | The thing is that the roof of your mouth

01:35:14.320 | is very close to your hypothalamus.

01:35:16.780 | So if indeed it's a popsicle

01:35:20.020 | that's giving you the brain freeze,

01:35:21.600 | it may be a direct cooling effect

01:35:24.720 | from the roof of your mouth.

01:35:25.800 | You put your tongue there,

01:35:26.860 | you're insulating the roof of your mouth.

01:35:28.860 | I don't know, I'm guessing.

01:35:30.540 | - But what's the source of the brain freeze?

01:35:32.740 | Is it a vasoconstriction?

01:35:34.220 | - It's a vasomotor change.

01:35:36.820 | Whether it's constriction,

01:35:37.980 | I think it's more likely a vaso,

01:35:39.960 | an increase in blood pressure,

01:35:41.820 | which will essentially cause an expansion of the arteries

01:35:45.600 | and activate pain receptors.

01:35:48.200 | We don't have pain receptors in the neural tissue,

01:35:50.860 | in the brain.

01:35:51.700 | We have them in the meninges

01:35:53.280 | and predominantly associated with the blood vessels,

01:35:56.320 | the walls of the blood vessels.

01:35:57.900 | So if you have something which will dramatically

01:36:00.880 | increase your blood pressure going to the brain,

01:36:05.840 | you're likely to get a...

01:36:07.240 | We've had some preliminary data.

01:36:11.040 | I even hate to mention this

01:36:12.420 | because we have not been able to pursue it

01:36:15.440 | systematically, but we've had some experience

01:36:19.980 | with people with migraine that say,

01:36:22.780 | if they use one of our devices to heat,

01:36:26.980 | that the migraine goes away.

01:36:28.340 | And I don't know.

01:36:31.940 | - Yeah, it's very interesting.

01:36:32.940 | A lot of people suffer from migraine.

01:36:34.340 | I know there are a lot of different types of migraine.

01:36:36.780 | - Right.

01:36:37.620 | - I've been reading a lot about this lately

01:36:38.640 | because I get so many questions about migraine, but-

01:36:42.620 | - I hate to say anything.

01:36:43.660 | - Sure, and we'll just underscore this is preliminary.

01:36:46.140 | And people have been great about understanding

01:36:49.420 | that when we say preliminary,

01:36:50.720 | we mean it has not passed through the required filters

01:36:54.660 | to call it a hard fact yet.

01:36:57.960 | - We don't even have a decent data set.

01:36:59.900 | - Right.

01:37:00.740 | - It's just these are anecdotal reports.

01:37:02.420 | - Anecdota as people like to know,

01:37:03.980 | but I don't even like to call it that

01:37:05.440 | because then we don't want to give it more weight

01:37:07.540 | than it deserves, but that's interesting.

01:37:09.900 | The ice headache and the increase in blood pressure

01:37:12.540 | is interesting because the only thing that I've heard

01:37:15.380 | is similar to it is something that comes from,

01:37:19.340 | they have these competitions where people eat

01:37:21.060 | these very hot chili peppers.

01:37:23.100 | It's kind of an ego thing, I guess,

01:37:26.380 | for reasons that escape me, that eating really hot peppers.

01:37:29.840 | And every once in a while, someone will eat one of these

01:37:31.940 | and get what's called thunderclap headache,

01:37:33.920 | where a headache comes on extremely quickly

01:37:36.940 | and so quickly that it's caused,

01:37:39.540 | so severe, rather, that it's been known to cause stroke

01:37:43.140 | and brain damage.

01:37:44.520 | So these very, very hot peppers,

01:37:46.700 | if you're not acclimated to them,

01:37:48.380 | and maybe even if you are, have been shown to cause,

01:37:51.120 | actually cause brain damage.

01:37:52.260 | Yeah, some good evidence for this.

01:37:54.220 | I do want to talk about something

01:37:58.360 | that we have not touched on yet, which is NEAT,

01:38:02.900 | non-exercise induced thermogenesis, right?

01:38:08.300 | So non-activity associated thermogenesis

01:38:11.280 | and the fidgeters, right?

01:38:12.940 | So the classic work of like Rothwell and Stock

01:38:15.900 | and the idea that some people who overeat

01:38:19.820 | are burning off that energy by way of shaking their knee

01:38:23.740 | or moving around a lot.

01:38:24.860 | These are the kind of nerve, they quote,

01:38:26.860 | quote, unquote, nervous types.

01:38:28.020 | But they quoted in those studies a huge degree

01:38:33.020 | of caloric burn, you know, 800, 2,500 calories per day

01:38:36.960 | burned above those who sit rather still.

01:38:39.960 | Does that seem far-fetched?

01:38:42.140 | Those are older data, but any comment on NEAT

01:38:45.260 | or non-exercise induced thermogenesis?

01:38:48.420 | - Well, I do think it's pretty straightforward

01:38:50.640 | that if you increase muscle activity of any kind,

01:38:53.220 | you're increasing your energy consumption

01:38:55.720 | and your heat production.

01:38:57.460 | And no, the really extreme example

01:38:59.760 | is hyper and hypothyroidism.

01:39:02.820 | People that are hyperthyroid are fidgety

01:39:05.680 | and they have a high metabolic rate and they're hot.

01:39:09.360 | And people that are hypothermic are cool.

01:39:12.260 | They don't move very much.

01:39:15.200 | So any kind of muscle activity increases.

01:39:17.780 | And when you say it's not much activity,

01:39:20.540 | but remember it's only 20% effective.

01:39:23.440 | 80% of the energy is going to heat.

01:39:26.900 | So it may not exert much energy to tap your foot,

01:39:32.220 | but four times the amount of energy

01:39:35.700 | that is going into the movement is being lost as heat.

01:39:39.360 | - That's very interesting.

01:39:41.860 | A couple more quick questions.

01:39:44.080 | There's a lot of excitement these days,

01:39:46.300 | or at least usage these days of so-called energy drinks

01:39:48.940 | or pre-workout drinks.

01:39:50.620 | Many of these contain thermogenic compounds.

01:39:53.340 | So caffeine, things,

01:39:55.540 | there's a culture now of taking arginine,

01:40:00.540 | things that support arginine, so beet juice

01:40:03.700 | and L-citrulline, things to dilate the blood vessels.

01:40:08.020 | Sometimes this is for sake of increasing blood flow

01:40:10.540 | to the muscles during resistance exercise.

01:40:12.200 | But a lot of these are thermogenic.

01:40:14.180 | It's to increase body temperature.

01:40:16.320 | And is it possible that some of these energy drinks

01:40:19.140 | are actually, or similar,

01:40:21.660 | six espresso or whatever it is,

01:40:23.600 | are acting to prevent optimal performance

01:40:27.560 | or reduce performance?

01:40:29.340 | - I don't think that the temperature rise is that.

01:40:33.660 | I really don't know.

01:40:35.660 | But what it does is it makes you more jittery

01:40:38.800 | and you're going to increase that neat

01:40:40.900 | that you were talking about.

01:40:42.340 | Or it's another thing,

01:40:44.340 | and that is that when you are exercising your muscle

01:40:48.720 | and it becomes slightly hypoxic,

01:40:52.300 | I mean, the oxygen supply is not enough,

01:40:56.780 | the muscle releases adenosine.

01:40:59.760 | And what adenosine does in the muscle

01:41:01.880 | is cause the blood vessels to open up, to dilate.

01:41:05.660 | So it's a way of increasing the blood flow to the muscle

01:41:09.220 | and therefore the oxygen supply to the muscle.

01:41:11.620 | - And caffeine is essentially an adenosine antagonist.

01:41:14.780 | - An adenosine antagonist, right.

01:41:16.780 | - So under the strict logic, ingesting caffeine

01:41:21.500 | will reduce adenosine release

01:41:23.460 | and will reduce oxygen utilization at the muscle.

01:41:27.480 | So that would lead me to believe

01:41:29.520 | that motivational support aside,

01:41:33.340 | that caffeine will hinder muscular performance.

01:41:37.020 | - I would think so,

01:41:38.120 | but I can't give you an authoritative answer on that.

01:41:43.120 | - Okay, we're just going through the logic

01:41:46.340 | and the gymnastics around that.

01:41:48.060 | I think it's a fascinating area that deserves attention

01:41:52.480 | because the question of what one can ingest

01:41:56.400 | in order to perform better,

01:41:57.980 | to say nothing of hormone augmentation,

01:42:00.900 | but has often leads back to stimulants.

01:42:05.900 | And if those stimulants,

01:42:08.060 | most of which include caffeine of some sort,

01:42:10.760 | are inhibiting the adenosine system

01:42:13.080 | and the adenosine system

01:42:14.000 | is supporting the oxygenation of muscle,

01:42:16.000 | then I would imagine that avoiding them

01:42:19.960 | might be the better option.

01:42:21.860 | - Yeah, I just am not aware of data that would...

01:42:26.860 | So this is a general phenomenon of adenosine

01:42:30.400 | and blood flow.

01:42:31.880 | It has, of course, a different effect in the brain.

01:42:34.360 | Adenosine causes sleep, so caffeine keeps you awake.

01:42:38.620 | And if you stay awake,

01:42:40.280 | you're going to have a higher metabolic rate

01:42:42.000 | than if you go to sleep.

01:42:45.140 | So, and the thing is you say energy drinks,

01:42:48.940 | the question is, what really is in them?

01:42:52.240 | - It's usually a cocktail of things.

01:42:54.320 | I don't take these, I don't like them at all,

01:42:56.020 | but they're usually a combination of vasodilators,

01:42:59.280 | stimulant, caffeine, some sort of stimulant.

01:43:01.280 | - And a source of glucose.

01:43:02.760 | - Sometimes a source of glucose and sometimes not.

01:43:05.000 | And oftentimes there are vasodilators

01:43:10.000 | and there are compounds

01:43:14.160 | that are thought to be so-called nootropics, smart drugs,

01:43:16.760 | that basically increase acetylcholine

01:43:18.840 | or norepinephrine transmission.

01:43:21.080 | You know, in the '80s and '90s,

01:43:25.280 | the beta-3 agonists like clambuterol were very popular,

01:43:28.680 | but they were all banned.

01:43:30.100 | So those are all banned from,

01:43:32.300 | although people use them recreationally,

01:43:33.920 | which I do not recommend.

01:43:35.560 | There were actually a number of deaths

01:43:36.880 | due to dehydration, overheating,

01:43:39.560 | as well as cardiac effects.

01:43:41.660 | Before we wrap up,

01:43:44.060 | I know you've done a ton of work on sleep.

01:43:46.780 | I think we're going to have to do another episode

01:43:48.700 | about your work on sleep

01:43:50.200 | because the amount of data that you produce there is vast.

01:43:53.440 | Actually, that's how I first got to know you and your work

01:43:56.240 | related to sleep and temperature.

01:43:59.400 | We all hear nowadays that it's good to keep the room

01:44:02.960 | that you sleep in cool, keep it dark.

01:44:05.480 | I've talked a number of times on podcast episodes

01:44:08.480 | about the role of light and shifting in circadian rhythms.

01:44:11.780 | I have two questions related to sleep.

01:44:15.140 | One is, are there any things that may

01:44:19.440 | or may not relate to temperature,

01:44:21.420 | but that you think are very useful for getting better sleep

01:44:26.000 | that you don't hear that much about,

01:44:29.020 | that people might want to consider or try,

01:44:33.120 | realizing that there are a lot of reasons

01:44:34.480 | why people don't sleep great,

01:44:36.460 | but what are some things that you don't hear

01:44:39.280 | that much about these days that you wish people knew?

01:44:43.080 | - Well, the sleep medicine community

01:44:45.640 | now puts a lot more emphasis

01:44:48.140 | on cognitive behavioral therapy than on pharmacology.

01:44:53.140 | So what cognitive behavioral therapy does

01:44:55.920 | is it essentially increases your sleep hygiene.

01:44:59.720 | So there are certain just general rules.

01:45:02.700 | So have a regular bedtime and a regular arousal time.

01:45:06.200 | Don't be skipping back and forth all the time.

01:45:08.860 | - Arousal, you mean wake up time.

01:45:10.180 | - Wake up time, yeah.

01:45:11.200 | - Spoken like a true physiologist.

01:45:12.560 | [both laughing]

01:45:15.220 | - Another thing is don't use screens

01:45:20.760 | within a couple hours of bedtime

01:45:22.480 | because screens are predominantly rich in blue light.

01:45:26.820 | And what that does is you mentioned the circadian system.

01:45:29.540 | That affects your circadian system.

01:45:31.540 | That pushes off your circadian stimulus for sleep, okay?

01:45:36.540 | Another thing is of course, relax.

01:45:40.480 | I mean, don't work right up till the time

01:45:42.560 | you're going to bed.

01:45:44.240 | Take some time to do something relaxing.

01:45:46.600 | And then temperature, you've mentioned that.

01:45:50.160 | And for many people, a warm bath

01:45:53.320 | is really conducive to good sleep.

01:45:57.000 | And people are now swearing

01:45:59.240 | by a cooler environment for sleep.

01:46:02.640 | And that makes sense in terms of the circadian effect

01:46:06.080 | on body temperature.

01:46:07.680 | So our circadian clock is affecting our thermostat.

01:46:12.680 | So at the time we go to bed,

01:46:14.880 | our thermostat is on its way down to a lower set point.

01:46:19.720 | So what happens?

01:46:20.560 | You go to bed and you're feeling a little bit cool.

01:46:24.040 | So you pile on lots of blankets.

01:46:26.880 | And then what happens is you wake up a little bit later

01:46:29.880 | and you're hot, so you throw them off.

01:46:31.300 | It's because your thermostat has set downward.

01:46:35.160 | Now, why is it better to have a cool environment?

01:46:37.720 | It's better to have a cool environment

01:46:39.340 | because it's easier to thermoregulate.

01:46:42.280 | So you can go to Europe in the summertime

01:46:44.680 | and the hotel rooms still have these big comforters,

01:46:47.920 | these down comforters.

01:46:50.000 | So how do you deal with that?

01:46:51.760 | You stick out your hands and your legs, okay?

01:46:54.960 | - I've always slept with,

01:46:56.000 | I have one leg that just kind of hangs out of the, yeah.

01:46:59.960 | - But that's, they're your heat loss surfaces, right?

01:47:03.360 | So if you're in a cool environment,

01:47:04.840 | you can take advantage of that.

01:47:06.600 | You can take advantage by passively

01:47:09.340 | regulating your body temperature.

01:47:10.960 | You don't have to get up and wake up and say,

01:47:13.840 | "Oh my God, I've got to change the covers or blankets,"

01:47:16.640 | or what have you.

01:47:17.680 | If you're in a warm environment, what can you do?

01:47:20.800 | - You need to sleep with one hand in the cool mitt, right?

01:47:23.600 | And right now that's not available yet.

01:47:25.480 | - Right, it's not available.

01:47:26.960 | - I've never heard about it that way.

01:47:28.760 | I've always heard you want to sleep in a cool room

01:47:31.140 | or keep the room cold.

01:47:33.100 | But I never realized why that's useful,

01:47:35.740 | which is, as you're saying,

01:47:37.300 | that then you can move these glabrous surfaces in and out.

01:47:41.620 | You could even also sometimes even wake up

01:47:43.220 | under the blanket completely.

01:47:45.300 | Very, very interesting.

01:47:47.140 | That finally a rational science grounded explanation

01:47:51.940 | for why we need to sleep in a cool room.

01:47:53.620 | 'Cause I always thought,

01:47:54.460 | well, if your temperature is going down anyway,

01:47:56.100 | why do you have to sleep in a cool room?

01:47:57.620 | What about wearing socks while you sleep?

01:47:59.380 | That was big a few years ago where they said,

01:48:01.020 | you know, you should put socks on.

01:48:02.820 | Now I would think that's probably the wrong advice.

01:48:05.300 | You probably just-

01:48:06.140 | - Well, I don't know if it's wrong advice.

01:48:08.260 | There's an old, old study that was supported by,

01:48:12.220 | I think, Eddie Bauer, the sleeping bag company.

01:48:17.220 | And what the study showed,

01:48:19.000 | what the study was asking is,

01:48:21.380 | what are the most temperature sensitive spots in the body?

01:48:24.340 | Where do you feel cold?

01:48:26.020 | And what that showed was it was the toes.

01:48:28.900 | So- - Makes sense.

01:48:29.900 | So when you sample water with your toe,

01:48:31.720 | you always see that-

01:48:33.560 | - So the socks essentially are promoting thermal comfort

01:48:37.600 | by insulating that area that's quite sensitive.

01:48:40.900 | Now, of course, if it's too warm,

01:48:42.120 | you're not going to put socks on.

01:48:43.420 | - Right.

01:48:44.460 | Well, Craig, thank you so much.

01:48:47.000 | You gave so much information

01:48:49.800 | that's actionable and interesting.

01:48:51.760 | I know a lot of people are going to be really interested

01:48:55.060 | in the Palmer Cooling Technology from Coolmit.

01:48:58.540 | We will be sure to provide resources to the website

01:49:01.020 | so that people can register interest.

01:49:03.020 | I do encourage people to play around with, so to speak,

01:49:08.020 | the Palmer Cooling Technology that we all have,

01:49:12.600 | which are these glabrous surfaces.

01:49:15.040 | And I also just want to thank you

01:49:16.760 | for taking time out of your busy schedule

01:49:18.760 | to share this information. - Sure, you're welcome.

01:49:20.380 | It was fun, it was lots of fun.

01:49:22.800 | - I certainly learned a lot,

01:49:24.000 | and I know a lot of people are going to learn a lot

01:49:26.560 | that's useful to them.

01:49:27.700 | - Good questions.

01:49:28.700 | - Well, fabulous answers, thank you.

01:49:30.920 | - Thank you.

01:49:31.760 | - Thank you for joining for my discussion

01:49:33.220 | with Dr. Craig Heller.

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01:51:30.020 | [upbeat music]

01:51:32.600 | (upbeat music)

Dr. Craig Heller: Using Temperature for Performance, Brain & Body Health | Huberman Lab Podcast #40

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