Tonight, Jay Sullivan doesn't just have to transform into a boy who will never grow up in the Alley Theatre's production of J.M. Barrrie's classic Peter Pan, he has to fly, too.

Risk-taking often comes with the gig. Performers are used to great physical demands in addition to what's already on their plate. This weekend and next , several outstanding artists have some difficult circumstances thrust upon them and are succeeding with extraordinary flare, while giving audiences that extra dose of awe and wonder.

Sullivan looks so comfortable in the airspace, one wonders if he's been there before. He hasn't. This is Houston run of Peter Pan marks his debut as the perennial adolescent. Although the actor found flying quite intuitive, he still had to attend flight school.

"Our flying director Brian Owens (ZFX) started us off observing where our center of gravity had shifted and how to manipulate our bodies on the lines," Sullivan says. "We experimented with choreography for each flight, discussed the story each flight was telling physically and we established a movement vocabulary that fit with how Peter moved on the ground."

"Did you ever have a moment when you thought, hey I'm upside down near the ceiling of the Alley Theatre?" I asked the spiky-haired actor.

"That's exactly what I thought the first time we did the bomb run (Peter Pan's Hurt Locker moment)," Sullivan says.

I'm not surprised. That's one amazing stunt when Peter swoops in to defend Wendy and the lost boys from Captain Hook and his gang.

"That flight is trickier for the two operators than it is for me," Sullivan says. "They are watching a monitor to make sure I'm in position to reach the bomb, and my job is to balance in a plank position and break it to turn over at the right moment. If we are all on our marks, the bomb slips right into my hands. It's the last flight in a fast-paced action sequence, so there's some adrenaline helping me fly straight."

Sullivan isn't the only actor in the show with a difficult job. Patrick Damien Earl spends the entire play in a giant furry Nana suit as the Darling's faithful canine nanny, while Luis Gonzalez slithers about in a huge crocodile suit. Both Earl and Gonzalez have their share of adorable scene-stealing moments, too.

Tonight and Friday, a handful of Momix dancers are entrusted to serve as a Centaur's hind legs in Botanica, Moses Pendleton's spectacle of kinetic illusion, presented by the Society for the Performing Arts (SPA) at Jones Hall.

"Someone has to be the ass," Momix's founder, Pendleton, jokes. "The performers have to run with their backs bent over at a right angle at break neck speed with their heads jammed against their fellow dancers' behinds."

Pendleton finds the role a great way to break in newbies.

"After two years of being an ass, they have paid their dues," he quips. "Some of the dancers are decked out in foam as gigantic rocks. That's not too comfortable either."

The half-man/half-horse stunt is just one of numerous visual eye candies in the show, many of which require dancers who can take on extra body parts, suspend from each other's bodies and run on all fours like antelopes. Fearful movers need not apply.

Next week, we can see David F.M. Vaughn perform on his knees as Lord Farquaad in Shrek, running Oct. 19-31 at the Hobby Center for the Performing Arts as part of Broadway Across America. Vaughn shrinks down his 6-foot-1-inch frame to four feet to play the height-challenged Farquaad. To achieve this illusion, Vaughn spends the entire show in "The Rig," which gives him the freedom to move about the stage with a pair of hilarious fake legs.

"The choreography is hard work, but the audience loves it," says Vaughn, who performed in the original Broadway production of Shrek. "Really, the physical requirements don't get in my way. It's like having a whole new body."

Vaughn finds the task expanding. "Farquaad suffers from short man's disease, so the costume informs the character," the actor says. "I have to use my arms more and find other ways to express my physicality."

Contrary to what you may think, the role is harder on the actor's back than his knees. Stretching, physical therapy and strength training keep him in tip-top shape to manage the demands of role, which comes with one silly perk.

"I get to stare at a lot of butts on stage," Vaughn adds.

Bobby Haworth and Karen Schlag know a thing or two about performing on their knees, having spent the entire one hour and fifteen minutes of the Mildred's Umbrella production of Giuseppe Manfridi's Cuckoos locked in the sex act.

"It's a good thing I had dance training so I could manage the physics of it," Schlag remembers about the role. "In a way, it was freeing not to worry about moving."

Haworth found the limitation frustrating at first, especially to not even be able to see Schlag's face.

"I always go for challenges as a performer; it makes me grow as an actor," says Haworth, who credits hours of ab work for his survival.

Justin Doran may be best known for the the time he spent hanging upside down during the torture scene of the Alley production of Martin McDonagh's The Lieutenant of Inishmore

"Of course, the visual of a half-naked man covered in blood hanging by his heels having his nipples cut off does tend to stick in the mind," insists Doran, who also did a stint in the daredevil dance troupe Diavolo. (SPA presents Diavolo on Nov. 5.) "I had spent weeks preparing by doing headstands. Although my spirit agreed to go up and down multiple times during the day, my stomach did not."

Despite the gruesome situation, Doran nailed the scene.

Whether it's up in the air or on their knees, performers do what it takes to deliver the magic. If you happened to be at last Thursday's performance of Peter Pan, that was me gasping with delight. Sullivan wouldn't want it any other way.

"The physical life of a character is such fun and fertile territory to explore," he says. "As flying and joy are intertwined, my job in those moments is to enjoy flying. Yes, it's a unique physical challenge, but in a lot of ways it acts itself.

"The experience of flight tells me as much about Peter as the words on the page."

Watch Jay Sullivan as Peter Pan save Wendy with one incredible swoop:

Enjoy a sneak peek Momix in Botanica: