Why Katie Ledecky's Olympic world record last night is even more amazing than you think

Ian MacNicol/Getty Images

Katie Ledecky of United States poses with her Gold medal from the Women's 400m Freestyle.

Katie Ledecky didn't just win the women's 400 meter freestyle event in the Rio Summer Olympics.

She demolished her own world record time in the event by almost two seconds, finishing the race in 3:56.46, beating out silver medalist Jazz Carlin of Britain and bronze medalist Leah Smith of US by almost five seconds.

In swimming, five seconds is an insane amount of time.

The 19-year-old phenom was celebrating before her rivals even finished the race.

Many have described Ledecky as one of the greatest athletes in the world right now, and so it may not sound that surprising to hear that - yet again - she set a new world record.

But setting world records in the Olympics is even more amazing than it seems, according to Dr. Michael Joyner, a physician and Mayo Clinic researcher who is one of the world's top experts on fitness and human performance.

Record-setting at the Olympics

There are two main factors making this time particularly incredible.

First of all, the Olympics are a harder place to set a world record time than many other competitions.

"There are some spectacular performances," says Joyner, "but in the Olympics there aren't a lot of world records in general."

Al Bello/Getty Images

The competition is far behind.

The games aren't the ideal setting for a world record performance. Athletes are competing in multiple events, requiring a number of qualifying heats along with the final races, meaning that they can't devote all their energy to a world record performance in one event (the 400 was Ledecky's second event, she has two more to go).

Plus, at this point in time, many world records are set on courses that are designed for optimal race conditions and usually Olympic venues aren't equal to the very best venues in the world, according to Joyner. Pool technology has had a significant impact on race times throughout history, with some pools having especially smooth and fast water.

But Ledecky's performance isn't just impressive because of the venue. It's impressive that she has these records and is competing against herself in the first place, according to Joyner.

In the mid-2000s, long-standing swimming records were shattered by racers wearing expensive, high-tech, slippery swimsuits that many think helped swimmers propel themselves through the water faster than they'd normally be able to move.

Those high-tech swimsuits were banned in 2010. Yet competing against those times has clearly been no problem for Ledecky.

"It's like if you had runners going back to dirt tracks," says Joyner. "She's among the greatest endurance athletes ever, full stop."

So what might it take to beat her? She's still unbeaten in her solo major international events, so we'll have to see.

Ledecky still has the 200 and 800 meter freestyle events to go in Rio. And the Olympics don't even have a 1500 meter race for women, though that even is perhaps her top one so far.

"She is the real deal," says Joyner.