Gymnastics and theater call upon some obviously similar physical skills. But the difference between them, says Cathy Rigby, who has been a champion in both, is that "gymnastics is about not thinking or feeling, but acting is all about playing in the moment."

She's had a lot of those moments in her signature role as Peter Pan, the boy who won't grow up, in the musical adaptation of the James Barrie classic with a score by Mark Charlap, Carolyn Leigh and others. Sitting in the Pittsburgh CLO office at the start of a whirlwind eight-day rehearsal period leading up to tonight's opening, Rigby can look back at some 2,800 performances as Pan, right back to a 1973 arena version for "Disney on Parade."

That's an astonishing 35 years since she first began spinning through the air, dueling with Captain Hook and crowing with feisty joy; 2,800 performances are the equivalent of seven full-time years at eight shows per week. Rigby joins a century-long history of other actresses who have made Pan their own, such as Maude Adams, Eva Le Gallienne, Mary Martin and Sandy Duncan.

Yet performing is just her second career, because by the time she was 20 she had already been a medal-winning Olympics gymnast. Now 55, the compact Rigby ("I'm five feet and a quarter inch," she insists, disputing reports that she's just four feet, 11  3/4) is as cute as ever and still able to soar.

Normally it's intrusive and beside the point to ask a performer her age, since what she creates is an illusion that would be compromised by the pedantic fact of actual age. But her age puts Rigby in the ranks of such American actors famed for life-long runs as Yul Brynner in the King of Siam, Joseph Jefferson as Rip Van Winkle, Carol Channing as Dolly Levi, William Gillette as Sherlock Holmes and James O'Neill (Eugene's father) as the Count of Monte Cristo.

Some of those legends performed in a pre-celluloid, pre-electronic age on endless cross-country tours where they would always seem new. But Rigby has prospered under the closer scrutiny of a later, up-close and personal, media-intrusive age, performing on TV as well as on stage.

"It's forced me to stay in shape," she says, as though playing Pan were a lifelong fitness plan, which in a way it is. As she talked over a salad lunch in the CLO office, she was on break from the first day of rehearsal, where that morning she had already been doing the role's hand springs and jumps.

"You don't have to be 20 to do this," she insists, while admitting that her determination is to do it as well as a 20 year-old. She also admits that after so many years she is sometimes surprised to catch sight of herself in a mirror -- an experience anyone in mid-life knows well, even without the magnifying glass of public performance.

The key, Rigby says, is whether "your body and soul" are both still able to play the role. And she laughs at herself with the story of a young fan, gushing over her performance and then peering at her, saying, "but as I get up close, I see you have wrinkles!"

Not many. Playing Pan has been an elixir of youth, she says.

"There's no greater joy than reliving your childhood -- playing in the backyard with your kids, getting down on the floor to play with your grandchildren, being in the moment." Or doing all that in front of 2,800 people.

Rigby points out that a long run has advantages. "You get to a point when you can be alive in the moment, no white-knuckling it. You know where to rest and breathe. You can become the role on stage -- especially Peter, who's so mischievous." She claims she's still finding new things. "As you get older, you stop worrying about what anyone thinks. It frees you up. Trying to be perfect stifles you."

But playing Pan is not just an illusion. "The sword fighting is intense. They're real swords -- not sharp, but real." She recalls a couple of serious accidents along the way, blood flowing even as the performance continued, with stitches to follow.

"That's part of being Peter Pan, to throw caution to the winds and be daring. I really trust the two guys who fly me" -- both at the ends of long ropes, one controlling her vertical movement, one her lateral.

She's not performing alone, of course. As her comic nemesis, the CLO welcomes back Broadway veteran Tom Hewitt. Elisa Sagardia plays Wendy; Barbara McCulloh is Mrs. Darling; and John and Michael Darling are played by young Pittsburghers Brian Brazon and Joseph Serafini, both students at the CLO Academy.

Directing is CLO and Broadway veteran Glenn Casale, Tony Award-nominated for reviving "Peter Pan" with Rigby on Broadway. The musical director is another CLO veteran, Craig Barna, and the choreographer is Dana Solimando, a former Tiger Lilly and also Rigby's daughter-in-law.

After retiring from competitive gymnastics at the ripe age of 19, Rigby prepared for her new career with years of training as an actor and singer. Her first stage role was as Dorothy in "The Wizard of Oz," which she calls "the scariest thing since the Olympics." But she soon fell in love with performing.

On Broadway, she has also starred as the Cat-In-The-Hat in "Seussical the Musical." Other stage musicals around the country have included "Annie Get Your Gun," "Meet Me in St. Louis," "South Pacific," "Paint Your Wagon" and "The Unsinkable Molly Brown."

Now, many years later, she is a full show-biz professional, joining with Tom McCoy, her husband of 27 years, to lead the McCoy Rigby Entertainment Series at the La Mirada Theatre for the Performing Arts in California, as well as a production company that packages national tours and a 600-student dance and theater school.

"I want to have my grandchildren around," she says, "but not all the time." She's a self-confessed animal addict, with a cockatoo, three dogs and a big African turtle: "I'm a little bit nuts that way. I'd have a zoo if I could." In fact, she just played the title role of the dog in the comedy "Sylvia."

Explaining why she's back playing Pan a couple of years after what was billed as her farewell tour, she says, "I'm at that stage in my life when I don't have to prove anything, but I also want to keep active."

That's what you call an understatement.