挑战极限：屏息背后的生理与心理奥秘

Inside the tank is Brandon Birchak, and he is going to attempt to hold his breath for this entire video.

Brandon is one of the world's foremost experts in breath work, so please don't try this at home.

I'll put his info in the description if you want to learn more.

I'm going to keep this shot going continuously on the right side of the video, and while he's holding his breath, we will figure out how he does it.

And I'm even going to learn how to hold my breath way longer than I ever have before.

I failed the very first level of swimming 'cause I refused to put my head underwater.

This is somewhat terrifying.

All the cells of the human body need oxygen in order to survive, oxygen to react with glucose and produce ATP, the molecule that delivers energy wherever it's needed in a cell.

Breathing is so important, it happens without conscious thought.

It's under the control of the autonomic nervous system.

When resting, we breathe about 12 times per minute.

But that rate automatically increases when exercising.

The brain knows how often we need to breathe using chemical sensors called chemoreceptors.

There are chemoreceptors for CO2 in the carotid arteries and in the brainstem.

Increasing CO2 in the blood makes it more acidic, and it's thought that this CO2 acidity is the main feedback mechanism that regulates breathing.

CO2 is created at the same rate oxygen is used up, so acidic blood tells the body we're building up too much CO2, and therefore, running out of oxygen, so we better breathe.

The only known chemoreceptors for low blood oxygen are in the carotid arteries, but these are thought to play a smaller role in regulating breathing.

And this is why hyperventilating before going underwater is a really bad idea, because hyperventilating expels a lot of CO2, making the blood more alkaline.

But it doesn't actually increase the amount of oxygen in the blood, which is limited by the concentration of oxygen in the air and the number of red blood cells.

So, with the blood starting out alkaline, more CO2 must be produced before the CO2 chemoreceptors give you the urge to breathe, which means more oxygen will be used up, sometimes to the point where the brain runs out of oxygen to stay conscious, so you can black out underwater before even getting the urge to breathe.

If you want to maximize the time you can hold your breath for, you have to optimize two sides of an equation.

First, you need to maximize the amount of oxygen in your body before you start, and minimize CO2.

And second, you have to reduce the rate at which oxygen is used up during the breath hold.

So, when we work with an athlete, one of the first things we do is we check their BOLT score.

Just tell them, "All right, hold your breath." (inhales) And then they hold their breath 30, 40 seconds or something.

They breathe, that's your new BOLT score.

Where BOLT stands for Body Oxygen Level Test.

If you want, you can try to hold your breath along with me.

Whenever you're ready, give a really nice exhale and then a really big inhale.

(Brandon inhaling)

The BOLT score just measures the number of seconds you can hold your breath before you feel the first urge to breathe.

Your first inkling to breathe is when most people choose to breathe.

Yeah, that's, (both laughing) That is exactly when I'm going to want to breathe.

Some people are naturally better at holding their breath.

The bigger your lungs, for example, the more air, and hence, oxygen, you can hold.

Most people have a lung capacity between four and six liters, but some people have a 10-liter capacity.

(exhales) I dunno, how was that?

40 seconds.

There you go, 40 seconds!

Stretching can help expand what you've got.

I'll do degrees this way, 90, 90, and then also on my chest.

And then I'll do it again at about half the volume of a lung pack, so I (exhales) and then I'll do it again.

The ideal physique for breath holding is someone tall and skinny with plenty of lung capacity, but not too much tissue to use up oxygen.

Aleix Segura, excellent breath holder.

He's also built for it, too.

He's six feet tall, weighs less than me.

I mean, he's like a lung with a brain.

Another technique that can increase the amount of air stored in the lungs is called lung packing.

After taking a full, deep breath, you continue to take little sips of air, packing it in on top.

I'll hold my breath (exhales) and then I'll do about 20 packs.

(inhales rhythmically)

The other side of the equation involves reducing the rate oxygen is used.

And since muscles use oxygen to contract, it's very important to be relaxed.

Go through the whole body and we're going to do a muscle check.

We're going to go all the way down and then all the way up.

So, once I hold my breath, (inhales) now I'm just going to check to make sure that nothing is engaged.

Brandon sometimes does performances where he's active during the breath hold, but since he's moving around, he uses up oxygen faster, and so doesn't hold his breath for as long.

People actually have a secret weapon when it comes to reducing oxygen consumption by virtue of our evolution.

It's called the mammalian dive reflex.

All mammals have this physiological adaptation that helps us survive when we're submerged in water.

The trigeminal nerve in our face detects the coolness of the water and triggers a series of responses.

The heart beats slower, decreasing the rate at which blood, and hence, oxygen, are circulated around the body.

Our blood vessels in our extremities constrict, confining blood to our vital organs and brain, ensuring we have enough oxygen to stay conscious.

If you take a free diving class, you can see your fingers, your hand, very sort of like a pale color.

If I do a 10-minute breath hold, this will read at 50 or 60.

And then it'll just turn off, 'cause I'll have no blood in my hands by the end of that long breath hold.

It's all from here to here.

And the spleen releases extra pre-oxygenated red blood cells into the bloodstream, increasing the available supply of oxygen.

The brain also uses a disproportionate amount of oxygen.

Mental activity, neuronal activity also uses oxygen, so you're trying to preserve as much as you can.

When your body's not moving, your brain is using 80% of the oxygen that your body is utilizing.

80%, it's a biblical amount.

So, you want to turn that off a little bit.

You want to give yourself some sort of mantra that you can just keep cycling back and forth.

You want to stop thinking, but you do need to pass the time somehow and you have to fight against this urge to breathe.

So, give yourself something short, something that you can remember.

And then, you get through the mantra enough times that you'll pass another maybe 20, 30 seconds toward the end of the breath hold, particularly when it's really hard and the CO2 is high and you're dealing with a really bad about of acidotic response.

Once you do your body check, I want you to go through the alphabet and I want you to have a gratitude for each letter.

The more you practice this, the better you'll get at just the sensation of compassion or gratitude.

And then, that in itself will be very, very relaxing.

When I do a really big breath hold, I'm not thinking about anything.

I'm on cloud nine.

I'm just, between five and 15 minutes, I feel like I'm just on a rocket ship at 1,000 miles an hour.

I'm just like, I'm not thinking or feeling anything.

I just have a sensation and a color.

But that's because of the whole experience.

It's a little bit psychedelic.

After a half hour of practicing with Brandon in the pool, this is the longest breath hold I was able to achieve.

Nice, nice and relaxed.

Immediately relaxing.

I'll leave it running in the bottom of frame, here.

Just know that that urge to breathe is just your body lying to you.

You do not need to breathe.

You have plenty more time.

So, when you get that urge to breathe, relax.

It's just your body taking a real-time pH readout, sending a signal, telling you to expel CO2.

But you're totally fine.

You've got maybe four or five minutes until you drown, so you're totally, totally good.

So, when you get that urge to breathe, around a minute, relax, appreciate it for what it is.

And then I want you to try to count to 10 as slowly as you can.

Just give yourself 10 extra seconds after the urge to breathe, okay?

Okay.

All right.

I practiced breathing at a set rhythm.

And I want you to breathe about five seconds in, five seconds out, just through your stomach and through your nose.

And again, as much as you can, but without engaging any muscles.

So, one, two, three, four, five in, and then one, two, three, four, five out.

Followed by holding my breath for increasing durations.

I feel like, psychologically, I was like, "I'm not comfortable not breathing for this long."

Well, you made it about a minute.

Nice, you made 1:30.

Oh, wow.

Yeah, crushed it!

Easy, and we're we're just starting!

Amazing, amazing, amazing!

For real, what was that?

We made about 1:45, I think, close to 1:50.

I modified the strategies Brandon suggested to keep my mind calm.

I think what I was doing that time was going through the alphabet, and just, I couldn't do gratitudes.

(Brandon laughing)

They were too hard.

But I was just doing animals.

Yeah, great, great.

Good way to gently distract the mind.

I was singing nursery rhymes because it's something do for my kids.

(laughs) I love that!

I was like, "I'm just going to sing some of the songs I sing for them."

I was skeptical that my heart rate would drop significantly, but my watch showed that the mammalian dive reflex really did kick in.

My average heart rate was 72-

48, you got down to, nice!

Look at that.

That's wild.

I don't even get down to 48 when I sleep.

That is, that's low.

That's low for me.

That's awesome.

It's that thing of, when have I not breathed for a minute?

Maybe never in my whole life.

How'd you go?

2:36.

2:36, look at that!

Yeah, baby!

I think I can guarantee that I've never held my breath for 2 1/2 minutes.

The psychological side is the hardest.

How do you distract your mind for a few minutes?

How do you stay calm when you feel like, "This is not something I'm used to?"

Calming my mind while holding my breath was honestly the most challenging part.

But it really helped to have a knowledgeable, experienced guide there in Brandon to help me through it.

And I think that sort of assistance can be helpful in everyday life, too, which is why this part of the video was sponsored by BetterHelp.

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There's a link in the description.

It is betterhelp.com/veritasium.

Clicking that link both helps support this channel and it also gets you 10% off your first month of BetterHelp, so you can try it out and see if it helps you.

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To give BetterHelp a try, visit betterhelp.com/veritasium or click that link in the description.

And now, back to breath holding.

I managed to hold my breath for two minutes and 36 seconds, but that is nowhere near the record.

In 2014, Branko Petrovic held his breath for an astonishing 11 minutes and 54 seconds.

He did this after breathing just regular air.

But there are additional ways to extend breath hold duration.

One way is to spend time at high altitude or in low oxygen chambers.

Right now it's set to 5,000 meters.

In the chamber, there's not a lot of O2 in there?

Right, very little.

This triggers your body to create more red blood cells, increasing your oxygen carrying capacity.

But if you really want to extend your time, you could breathe pure oxygen beforehand.

Brandon's record for a non-oxygenated breath hold is 10 minutes.

But with oxygen, he has held his breath for 23 minutes.

Breathing pure oxygen is dangerous if you don't know what you're doing, especially dangerous for free divers.

The theory says if you do that and you pass six meters, or five or six meters, your risk of oxygen toxicity is much higher.

But if done correctly, breathing pure oxygen before a hold can extend it dramatically.

The current record is held by Budimir Sobat, who held his breath for 24 minutes and 37 seconds after breathing pure oxygen.

For this video, Brandon went through a lengthy breathe-up process, and the last part involved breathing pure oxygen.

Here he is packing in the last few gulps.

15 minutes, 15 minutes!

But even with oxygen, remaining submerged for all this time isn't easy.

With his wife, Brandon has pioneered the first active underwater performance that lasts 10 minutes.

It's one thing to choreograph a piece and direct it and put it together when you are able to communicate normally, when you're not dealing with different elements.

But when you have a man underwater and you're trying to set something to music and you're trying to give direction and you're trying to piece this together with an aerial dance, we've done some really big projects in our careers, but this was unlike (Brandon laughing) any other challenging piece of theater that we've had to put together, that's for sure.

This has never been done before, so we're literally writing the book as we go and we're trying to make sure that, we have to take risks to make something that's this crazy.

But it's that limit, right?

How far do you go, how far do you push?

I think we're dancing on that line.

You have the urge to breathe, and it starts kind of like maybe a little bit in the chest or the lower diaphragm.

But then, eventually, you'll start to really have these convulsions.

CO2 has a slight narcotic effect as well.

You get it high enough, you lose sense of time, and that's one of the ways that you know that your breath hold is over.

What do you mean, you lose a sense of time?

Time is slow or time is fast or you have no idea how fast time is passing?

No idea.

You're totally, you're screwed.

Your urge to breathe increases, increases, increases, increases, increases.

Then, the urge to breathe just plummets.

16:45.

And you're like, "Oh, I'm fine."

but your body's not fine. (laughs maniacally)

17 minutes.

So, that's when you got to pull the plug. (laughs maniacally)

And if you want to learn how to hold your breath for up to five minutes, check out Brandon's information in the description.

What was going on in your head?

In the first few minutes, I'm just focused on retaining that really heavy pack and not letting my epiglottis come open or losing any air.

Making sure that while I'm engaging that, I'm not also engaging other muscles, like my traps or my back or my intercostals.

So, just focusing on that one tiny muscle group that I need to engage, making sure that everything else is calm.

And then, after about five minutes, my lung volume goes down enough that I can really relax.

So, then, typically between five and 15 minutes, I'm super relaxed.

I have this sense of falling, I feel super euphoric.

And then, typically, after 15, then the CO2 starts to encroach on me.

And as it goes up, I have to focus more and more on fighting the mechanisms of the urge to breathe, like my diaphragm, like my intercostals, like my epiglottis fluttering, stuff like that.

Can you feel a difference in your blood when you're getting really acidic?

Yeah, yeah, absolutely.

What does that feel like?

Acidic.

(both laughing)

Feels like the urge to breathe.

If you do it enough times, you get used to it.