During rehearsals and previews of A Chorus Line at its first stop on a national tour, there were oxygen tanks offstage. Yes, the singing and dancing in the Tony Award-and Pulitzer Prize-winning musical are demanding, but the thin air in the Mile-High City was the real reason for the backup supply.

“The elevation here has been sort of a challenge,” said Nikki Snelson, who plays Cassie, during a recent phone conversation from Denver, Colo. “I passed out on the line in rehearsal one day. It’s a whole different climate than we’re used to and we get out of breath and lightheaded.

“It’s a good thing we’re starting here because L.A. will seem like a breeze after that,” she added with a laugh.

The national touring production of the 33-year-old show’s revival comes to Downtown Los Angeles for a seven-week run at the Ahmanson Theatre beginning May 22.

Snelson had an unlikely path to Cassie. She auditioned for the 2006 Broadway revival, but didn’t get cast and ended up playing an aerobics instructor in another production, Legally Blonde. She was thrilled to get a call to play Cassie in the touring show.

“It’s very exciting to go from not getting it and having the dream squashed to getting to play a really exciting role of a lifetime,” Snelson said. “Cassie is sort of the quintessential female dance role of our time. It’s one of those roles that any little girl dancer growing up and wanting to pursue this as a career is dying to do. There’s 12 minutes on stage alone singing and dancing with nobody in sight.”

In A Chorus Line, Cassie auditions for her ex-lover and mentor Zach’s big Broadway show. She was on the verge of becoming a Broadway star under Zach’s direction years earlier, but when Zach proved to be consumed by his work, she broke off their affair and left for Hollywood. Now, desperate for a job and content to be in the chorus rather than in the spotlight, she comes back into Zach’s life like a storm.

“Of course, it’s completely unresolved. There was no closure to it when she left. So there’s all of that sort of subterranean angst on top of trying to cast this show,” said Michael Gruber, who plays Zach. “Cassie sort of disrupts his concentration as he’s trying to hire these four male and four female dancers.”

Original Touches

A Chorus Line remains the longest-running of any American musical, with 6,137 performances from 1975-1990. In 1976, the original Broadway production received 12 Tony nominations and won nine, including awards for Best Musical, Best Musical Book (by James Kirkwood and Nicholas Dante) and Best Score for music by Marvin Hamlisch and lyrics by Edward Kleban.

Gruber comes from that original production, where he played Mike, the tough Italian from New Jersey. That role was his first on Broadway. In the revival, he initially picked up the part of Gregory, the sophisticated Upper East Side Jew. “I desperately wanted to do it again because I hadn’t done it since 1990 when the show closed,” Gruber recalled.

Now as the driven director and choreographer Zach, his only regret is that he couldn’t play more roles. “That’s only three of the 10 male characters on the line,” he said from his hotel room in Denver. “I’m kind of sad that some of them have passed me by, you know? That I’m too old to play them.”

Gruber’s not the only one who brings authenticity to the production. Bob Avian, the original Tony Award-winning co-choreographer (with director Michael Bennett), directs; and Baayork Lee, who played Connie in the original show, re-stages the choreography. “So we have not even one degree of separation,” Gruber said.

Even in Broadway terms, the show is exceptionally enduring. Maybe the fact that the stories in A Chorus Line are real helps explain the musical’s long-lasting appeal. As Gruber pointed out, Bennett interviewed dancers in a workshop to create the show, so the 17 dancers’ tales mean there is “something that everyone can relate to.”

”A Chorus Line is the story of a whole group of people coming from different walks of life and different backgrounds to pursue their lifelong dreams - and that transcends dance,” Snelson added.

Snelson identifies strongly with Cassie, seeing parallels with her own life in theater. “I was very lucky to get to play my first Broadway role when I was like 20 years old,” she said, recalling her part in Annie Get Your Gun with Bernadette Peters. “I got really excited and carried away with the concept that I was going to get to play parts for the rest of my life. I moved out to L.A. and tried to do the TV thing and that didn’t work out and came back and had to go back in the chorus. Now I’m lucky to be back playing parts again.”

This part in particular has been a challenge, in more ways than one. Snelson said playing Cassie has required more athleticism than her role as aerobics queen Brooke Wyndam in Legally Blonde. The emotional demands are also high, she said. “It’s really intense. There’s a lot of tears shed. It’s a really beautiful, cathartic piece.”

Gruber praised her talents in the highest way possible, by comparing her to the woman who won a Tony for the role. “Donna McKechnie was really a unique talent in 1975, a woman who could sing as well as she could dance and be an incredibly vulnerable and expressive actress. To find those three gifts is always a challenge. And Nikki really has them all.

“She’s a very spontaneous actress, and she’s also very skilled at bringing in the vulnerability of Cassie as well as the strength. When she’s on the stage, you can’t take your eyes off her, especially when she’s dancing. And her voice is extraordinary, which is rare because a lot of Cassies are hired as dancers and they may not really be able to sing,” Gruber said, adding, “I’m a big fan.”