Now, if I suggested a sport that literally drained your body of life sustaining oxygen, edging you to the very brink of existence.

現在，如果我建議一種會讓你身體維持生命的氧氣耗盡的運動，並讓你體會到生命的極限。

You'd probably say, no thanks.

你可能會說：不用了，謝謝。

But then you're not Alessia Zecchini, aiming to dive deeper on one breath than any female freediver has before in her category.

但你又不是 Alessia Zecchini，立志達成一口氣下潛比以往所有在此領域的女性自由潛水者更深的目標。

Even at the surface, the average person runs out of breath after little more than a minute, but Alessia is far from average.

即使在水面上，一般人閉氣超過一分鐘就會沒氣了，但 Alessia 卻遠高及平均值。

And down at 351 feet, almost the length of a football field, she breaks the record, surfacing after a single breath hold of 3 and 1/2 minutes.

在海深 351 英尺處，幾乎是一個足球場的深度，一口氣憋了三分半鐘浮出水面後，她打破記錄了。

It's easy to forget how dangerous swimming under water can be.

人們很容易忘記在水中游泳有多麼危險。

It can feel tranquil, almost womb like, until you hit a problem, which in free diving can result in oxygen starvation, nitrogen narcosis, decompression sickness, blackout, all the bad stuff.

它能讓人感到寧靜，幾乎像在子宮裡一樣，直到你發生狀況為止，在自由潛水可導致缺氧、缺氮、減壓症、短暫昏迷等等所有糟糕的症狀。

But while I wouldn't advise trying to beat Alessia's record, I would recommend learning the science behind the feat.

但我不會建議你去打破 Alessia 的記錄，我建議學習此功績背後的科學。

As our freediver dives, his body consumes its oxygen supply, which can lead to a potentially lethal blackout.

當自由潛水員下潛時，他的身體會消耗氧氣供應，這可能導致潛在的致命性短暫昏迷。

In his favor is an evolutionary response called "the mammalian dive reflex," which diverts oxygen-rich blood to the vital organs and reduces the heart rate, lowering oxygen consumption.

下潛時，「哺乳動物潛水反射」的進化反應對他相當有利，此反應是將富氧的血液轉移到重要器官，並降低心率、減少耗氧。

Efficient monofin technique also helps.

高效的單蹼技巧也有所幫助。

Its large surface area displaces a lot of water, propelling him forwards with minimal effort, thereby conserving oxygen.

它的大表面積可排出大量的水，以最小的力氣推動著它前進，從而節省了氧氣。

OK, nearly ready to break some records?

好了，差不多準備好打破一些記錄了嗎？

It's time for a quick kit check.

是時候快速檢查一下裝備了。

Flippers work on the same principle as monofins, displacing water to generate propulsion.

蛙鞋的運用原理和單蹼是一樣的，排出水以產生推進力。

Not so good on land, though.

不過在陸地上就不太好行走。

All right, let's dive down where the mammalian dive reflex kicks in!

好吧，讓我們在哺乳動物潛水反射開始發揮作用時潛下去吧！

Even at shallow depths.

即使只是在很淺的深度。

Not exactly what I meant by mammalian dive reflex.

我剛說的哺乳動物潛水反射不是這個意思。

And while they'll still be experiencing the reflex, they're rather wasting its oxygen-conserving effects.

儘管他們仍然會體驗到反射，但他們卻在浪費它保留氧氣的效果。

That's better.

這樣還差不多。

Making the most of the propulsion generated by his flippers with gentle rhythmic kicks, conserving precious oxygen for the swim back up, or for riding a bike.

充分利用蛙鞋的推進力，用平緩的節奏踢腿，節省寶貴的氧氣，以便保留給回程，或騎單車用。

OK, let's head up, but calmly and oxygen efficiently so as to avoid that thing all free divers fear.

好了，讓我們抬起頭來，但要冷靜且有效地吸氧氣，以避免發生所有自由潛水者都害怕的事情。

I was actually thinking of --- blacking out, but on that evidence, I think we should leave Alessia's record well alone.

那件事情就是— 昏厥，但根據這些證據，我認為我們就好好保留 Alessia 的記錄就好。