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  • And now, we briefly interrupt our critique of the "extra silly" to salute someone "extra special."

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

  • You'd probably say, no thanks.

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

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

  • 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.

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

  • 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.

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

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

  • 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.

  • Efficient monofin technique also helps.

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

  • OK, nearly ready to break some records?

  • It's time for a quick kit check.

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

  • Not so good on land, though.

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

  • Even at shallow depths.

  • Not exactly what I meant by mammalian dive reflex.

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

  • That's better.

  • 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.

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

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

And now, we briefly interrupt our critique of the "extra silly" to salute someone "extra special."

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B2 oxygen reflex dive propulsion breath blackout

The Dangers of Free Diving | Science of Stupid: Ridiculous Fails

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    林宜悉 posted on 2020/11/30
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