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.
[plop]
Even at the surface, the average person runs out of breath
after little more than a minute, but Alessia
is far from average.
[music playing]
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.
[cheering]
It's easy to forget how dangerous swimming under water
can be.
It can feel tranquil, almost womb like,
[thud]
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.
[splash]
Not so good on land, though.
All right, let's dive down where the mammalian dive reflex kicks
in, even at shallow depths.
[music playing]
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.