Every two and a half hour performance requires serious athleticism!

Especially in the form of stamina.

To better understand the endurance necessary to perform in the award winning musical, we enlisted cast member, India Bolds.

Amazingly, during the show, she portrays nine different characters.

Including a lioness, hyena, gazelle and even the grass of the pride lands.

So you have to be a tremendous athlete to pull all that off, especially with your endurance.

Absolutely.

It's one of those roles where you have to really pace yourself.

I think I'm certainly moving throughout the entire show.

I get maybe a minute or two to rest and sit down and take a breather.

Before India dons her first costume, we wire her up with a high tech bioharness.

This wireless sensor will measure her breathing, heart rate and movements to help us analyze her athleticism during the show.

Now when they're performing, cast members are always in motion.

And India might be busier off stage, as she changes costumes 14 times!

Into another costume!

This virtually non-stop pace is reflected in data recorded by the bioharness.

India's heart rate averages 125 beats per minute and peaks at 192!

And with a breathing rate that peaks at up to 40 breaths per minute, India demonstrates why dancers have an aerobic capacity on par with elite soccer players.

When you're out on the stage, you obviously are exercising quite a bit.

When you come back here the energy is so crazy, you don't have any time to rest.

Not enough time, no, because as much as I'm on stage performing, I'm off stage performing as well.

Surprisingly, another factor contributing to India's stamina is that The Lion King is a musical.

And music has been shown to improve almost all aspects of physical performance.

For example, studies have shown that when vigorous activity is performed in time to music, endurance can increase by 15%.

- You're pretty winded right now. - Oh, yeah.

Yeah, I was doing a lot of running.

How's your endurance feeling?

I'm feeling pretty good, you know, I'm lifted, I'm energized.

Because her entrances come from both sides of the stage, India covers a lot of ground by making numerous trips down and up stairs to get from one side of the stage to the other.

In fact, all told, during the course of the show, India travels almost 2.7 miles!

That's farther than NBA MVP Point Guard, Steph Curry averages during an NBA game.

What do you have to tell people who might look at a show and think "Well, I might be able to just step in and do that"?

It is not easy!

It's fun, it's amazing, it's extraordinary but it is hard work.

For ESPN Sports Science, backstage on Broadway,

I'm John Brenkus.