極限憋氣的秘密
發佈於: 5年前
Hi, this is David from MinuteEarth.
When I try to hold my breath for as long as possible, I can only last for about a minute before I need to gasp for air.
That's because humans need oxygen to survive, so our bodies have several systems designed to make sure we get new supplies at regular intervals. But the best breath holders in the world have figured out how to hack three of these survival systems, and as a result, they can hold their breath for an astonishing amount of time.
Hi. Sorry to interrupt, but some of this next stuff is really, really dangerous, and you definitely shouldn't try it at home. Actually, don't try it anywhere.
The first survival system that gets hacked is our fight-or-flight response. Our brain understandably feels threatened when we start to use up our oxygen. But this panic over running out of air causes our heart to beat faster, which ironically causes us to expend more oxygen than we would have if we hadn't panicked in the first place. However, the best breath holders can avoid this vicious cycle; through intensive training, they're able to remain calm and keep their heartbeat steady even as oxygen runs low, allowing them to double their breath-holding time.
The second survival system they hack is the mammalian dive reflex. It turns out that all mammals – and thus all humans – have developed an anti-drowning mechanism for when they unexpectedly find themselves underwater. When we get dunked, a branch of one of our cranial nerves senses the temperature and pressure change and alerts our brain to begin rationing oxygen. Our brain tells our heart to slow way down, which slows down the rate at which we use oxygen. Then the blood vessels on our skin and in our limbs constrict, directing more of the blood flow – which contains oxygen – toward our brain and other vital organs.
Finally, our spleen – which serves as a blood reservoir – contracts, sending out a bunch of backup oxygen-rich red blood cells into our bloodstream. Since this only happens when your face is underwater, the best breath holders take advantage of this adaptation by...well...putting their heads in the water, which allows them to hold their breath up to 50% longer than they can on dry land.
The third survival system they hack is the diaphragm spasm. When your oxygen level falls below a certain point, it causes your diaphragm to start spasming, which painfully jerks on your lungs, basically yelling at them to get more oxygen as soon as possible. But elite breath holders have figured out that at that point there's still some oxygen left. So they repeatedly ignore those spasms, which allows them to hold their breath for several more minutes. In fact, some of them have trained themselves to let their oxygen levels fall to just before it causes them to blackout – before they finally gasp for air.
The world's best breath holder can withstand more than 75 of these distress spasms, which, helps him hold his breath for more than 11 minutes; that's long enough to watch this video 4 times in a row.