Your Body vs. Extreme Heat

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[Sean] Nice train.

Keep going, keep going, keep going.

Alright, you’re good.

Nice.

Woo!

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I’m excited for the day.

Excited to see how training in a heat chamber

differs from regular training at the gym.

Yeah, I’m curious to see

how my body responds to it.

This past July was the hottest month

in human history, as far as we know.

No matter who you are,

heat is gonna be a greater part of our lives.

And so I think understanding the physiology

of what heat does to us and what humidity does to us

is increasingly important.

Any other questions?

Questioning that egg sandwich I had this morning.

So this is called a VO2-max test

and the basic idea is to run as fast as you can

to understand your cardiovascular fitness.

[Sean] Keep going, keep going, keep going.

Alright, good.

Nice.

Your VO2 max is about 53 milliliters per kilogram

of your weight per minute.

In the 95th percentile for your age.

[Dhruv] I’ll take that, I’ll take that.

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[Sean] Look down.

This is one of the labs that actually

is able to simulate direct sunlight.

So it’s not just the ambient temperature,

it’s not just the humidity,

but it’s also mimicking what it’s like to be out in the sun.

I’m gonna be walking basically on this treadmill

for the next two hours in 140 degree heat with 40% humidity.

They’re gonna be tracking all sorts of different metrics

to try to understand my tolerance to extreme heat.

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It reminds me of being in a New York City subway

underground during the month of July.

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I have maybe a slight headache.

I just feel extremely puffy everywhere.

You’d have to cut my finger off

to get my wedding ring off right now.

We’ve given up on the subway

and just somehow ended up inside a sauna.

A lot of your ability to regulate your heat

has to do with where the blood goes in your body.

And so when it gets really hot,

your blood goes to the periphery, to your skin

so that you can excrete that heat

usually in the form of evaporation from sweating.

The issue is when you’re working outside

and when you’re moving like I am,

your skeletal muscles also need blood to keep moving.

And so there starts to become this kind

of competition between cooling your body,

between feeding your skeletal muscles,

and feeding your internal organs, including your brain.

And so that’s where things get a little dicey

if you’ve been out in the heat for a long time

and you’re having trouble regulating your temperature.

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Well, you are done.

So we can go ahead and stop.

So if you want to go ahead

and hold onto the treadmill and press stop.

All right, great.

And then I’m gonna go ahead and unhook you here.

If you want a final sip of water, go ahead and take.

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And then remember we’re I pour…

You doing okay?

Where I pour?

You’re gonna go ahead and rub with your hand

kind of like you’re scrubbing in the shower, okay?

So the first thing we’re gonna do is your hair.

So go ahead and start rubbing.

We took two gowns of distilled water

and we went through every body part.

And the idea is we wanted to get all of the electrolytes,

the sodium, magnesium, the chloride,

everything off of his skin and into the water.

And that’s why we have all this clothes in here as well.

So now what I’m gonna do is I’m gonna go ahead

and mix everything up.

I’m gonna ring out the clothes so we can get the water

and the sweat out of the clothes

so that we can go ahead and put that into our analyzer.

In total, he sweat about a little over one liter

over the course of the two hours.

So about 2.2 pounds.

I can’t think very clearly.

Yeah, so I just finished up 90 minutes of activity

in kind of an extreme heat chamber.

One of the things that you really feel palpably

is how it affects the body.

I mean, some of the things are obvious

when you’re looking at your heart rate,

your core body temperature, but some of ’em are more subtle.

I felt a headache.

I felt like I wasn’t thinking as clearly.

I wasn’t able to pay attention to things.

So all these things after just two hours

of being inside the heat chamber,

really give a view into what it’s like

and what it’s going to be like

to be living in a hotter world.

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