While Amy Purdy was doing the cha-cha during the premiere of "Dancing With the Stars," viewers were shaking their heads in amazement as just how the she was able to move so well on two prosthetic legs.
Purdy, 34, is a bronze medalist paralympian snowboarder. She lost both her lower legs to bacterial meningitis when she was just 19.
"Good Morning America" correspondent Cameron Mathison caught up with Purdy while she rehearsed for her appearance on the dance reality TV competition's 18 th season, where she competes for the championship and the mirror ball trophy alongside actors and actresses, two Olympic gold medalists, an endurance swimmer and a former pro hockey player, among other cast members.
Purdy explained that she has different prosthetic legs for various activities.
"I have different legs for snowboarding, and I've got walking legs - and my walking legs right now are my dancing legs," she said.
She makes walking and dancing look effortless, but her prosthetics do come with limitations.
"The thing with prosthetic feet is you can't have all this crazy motion or you'd be all over the place - because it's mechanical and it's outside your body," she said.
Purdy may have been an underdog going into the competition, but she earned 24 out of a possible 30 points last week, putting her near the top of the pack. No one considers her an underdog now.
Asked whether there was any choreography that wasn't possible because of the prosthetics' limitations, Derek Hough, Purdy's pro dance partner and multi-time mirror ball pro champion, replied: "There are going to be certain dances that we are going to hit a few little barriers, but I kind of thrive on that kind of stuff. We've been talking about, like, what we could do differently, almost like looking at it as what advantage do we have, not a disadvantage … what can we do that nobody else can do because of that?"
All that challenging footwork comes with some risks for Purdy, who has bottle caps duct taped to her feet for a specific, unusual reason.
The locking mechanism on each of her prothetics is activated at the touch of a button. Since her legs hit each other during many of her dance moves, she had to do something avoid the mechanisms' accidental activation.
"It's as easy, I guess, as a push of a button to take my legs on and off, and with dancing, obviously I want to make sure that nothing is going to happen, so we put these bottle caps over the buttons so even if I smack my legs together, they are not actually touching the buttons," she said.
Some thought also has to go into Purdy's costume. Last week, she wore long fringe pants.
"For me costumes are a really, really important part of the show, not just for looks, but also for movement," Hough said.
No one knows just what she'll wear tonight - it's a secret - but they're going to do a swing dance, so expect to see some lifts.
"If you want something bad enough and you work hard enough, anything's possible," Purdy said.