DUMBO is one of those New York City revival neighborhoods with acronymic names and nouveau hip reputations. Nestled literally in the twin shadows of the Manhattan and Brooklyn bridges, DUMBO (for Down Under the Manhattan Bridge Overpass) boasts gentrified galleries, cafes and artists’ lofts where factories formerly clustered along the Brooklyn waterfront.

St. Ann’s Warehouse is the area’s anchor arts center and one of the city’s hottest venues for alternative performance. It’s also one of the co-commissioners of End of the Road, the latest theatrical production by the Northampton-based Young@Heart Chorus, and where the show is playing through this weekend. (No Valley performances are scheduled.)

St. Ann’s attracts a younger crowd than most theaters, and certainly younger than this show’s cast, which averages over 80 years old. So when I visited last weekend, I was curious to see not only the new show but how this urbane audience would respond to the geriatric Young-sters.

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5 p.m. The cast of 28 is gathered on stage, fine tuning the blocking of one of their numbers with the director, Roy Faudree of No Theater. End of the Road is the third show the theater has created with the chorus, including The Road to Heaven in 1997 and The Road to Nowhere in 2004. No’s playfully out-of-kilter experimental style makes a fittingly quirky match with the rock ‘n’ roll on Geritol formula that has made Young@Heart an international sensation.

Faudree is keenly aware that much of the group’s appeal lies in the novelty of senior citizens belting out Talking Heads and James Brown numbers. He also recognizes that the fame bestowed by the award-winning 2008 documentary Young@Heart can be seductive and lead to complacency. So before they break for dinner, he gives his cast what he calls a “soap box speech.”

“You’re absolutely adorable, and that’s wonderful,” he says. “You are reaping the fruits of an enormous amount of work over many years. But it’s very dangerous to think these audiences are here to serve you. You are here to serve them, and that means giving as much as you can.” The joy and magic of live theater, he continues, is that “when folks like you are performing in a room with other live people, you can take them to a place where they can’t go on their own. You lift their spirits. You don’t do it because it’s some sort of sugar-coated cutesie thing, you do it because you know how important it is to be alive. That’s what keeps the show from being a novelty and makes it something that really has the power to change lives.”

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6 p.m. A buffet has been set up in St. Ann’s cavernous lobby and the cast digs in. I’m standing in the serving line with 87-year-old Dora Morrow, who has been with the group for 10 years. She remarks sweetly, “The play is very nice. Roy did a really nice job with it. Roy is a really good stage person, and everything has to be really right, which I don’t blame him. If it’s not right, he’s going to keep after you until you get it right. If you get up there and make a mistake, you can’t say Roy didn’t warn you. It’s not his fault.”

It’s company policy to leave the performers alone during mealtimes, so I join Faudree and his partner Sheena See, costume designer Jill St. Coeur, musical director Ken Maiuri and the group’s co-founder and guiding spirit, Bob Cilman. We laughingly realize that this is “the kids’ table,” even though most of us also have gray and/or thinning hair.

Cilman started the chorus in 1982 and soon afterward began introducing rock and punk into the repertoire—a process that still, with each new unfamiliar song, challenges the members’ taste and tolerance. He explains that the challenge is part of the point. “What is so great about these people is they sing this material differently from what we’ve heard in the past. They go someplace quite different with it.”

Cilman acknowledges that the film has changed things. For half its existence the group has been better-known overseas than in the U.S.—with the obvious exception of its sizeable home-town following. There have been 16 European tours since 1997, as well as trips to Australia and Japan. Now, buoyed by the film’s success, “we’re touring all the time in the U.S.”

Over half the company is new since the movie was shot in 2006. People have died or become too brittle to travel, and the group’s new celebrity has attracted more members, many of them with more formal musical backgrounds. But Cilman says the chorus retains its ensemble character. “Very rarely do we get people who say, ‘Make me a star. I’m here to show you what I can do.’ And when we do, they stay for about two days.”

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8 p.m. Showtime. A multigenerational crowd jams the lobby, including more than a few friends and fans from the Valley. A concession stand is doing a brisk business in Young@Heart T-shirts printed with the slogan “Putting the zen in senior citizen.”

In the auditorium, almost every seat is filled. The chrome and neon set suggests an ultra-modern hotel lobby or airport bar where strangers anonymously mingle and pass on. The cast is costumed in an odd assortment of getups, from formal evening dress to funky chic to uniforms (policewoman, nurse) and a self-described “biker chick.”

The show opens with Louise Canady, walking with a cane but resplendent in a beplumed gold gown, crooning a jazz standard of the ’30s. The poignant atmosphere soon gives way to the company’s trademark let-‘er-rip style, supported by a seven-piece band. The show’s 42 songs span 75 years, from Duke Ellington to Dean Martin to Dylan to Blondie to Nirvana and beyond. Show-stoppers include Steve Martin tearing it up with “Only the Strong Survive” and a delightfully bizarre pairing of Brock Lynch (age 86) and the Pixies’ “Monkey Gone to Heaven.”

Halfway through the show, urged by Dora Morrow to “Get up and dance to the funky music!”, the whole audience is on its feet, clapping, swaying and stomping. From that high-energy crescendo, the evening moves through songs that reflect ironically on the aging process itself and into tender elegies, like Springsteen’s “You’re Missing,” that invoke memories of lost loved ones and fellow chorus members.

After the show, the lobby is filled with hugs and congratulations as the cast comes out to greet old friends and new fans. One spectator says, “I could feel the love up there—I could feel it.” Another is overheard saying, “I loved it. It’s the anti-American Idol.”

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10 p.m. I join the company on the yellow school bus that shuttles them back to their hotel. Half the cast heads straight for the bar, where I squeeze into a booth with three octogenarians, all of them longtime chorus members.

Diminutive Jeanne Hatch, who wore the biker outfit in the show, recalls that Roy Faudree recruited her in 1998 to join the tour of the first Road show. She had to choose between the chorus and continuing her career on the faculty of Holyoke Community College. “I had taught for 30 years and didn’t intend to retire. I had to make a decision. I’ve never been sorry.”

Ebullient, outspoken Steve Martin acknowledges that being in the chorus is “a lot of hard friggin’ work.” End of the Road was in rehearsal for 14 months. “And frankly, it became boring and annoying. We were getting tired. I felt I was being tuned so much, my sparkplugs couldn’t spark anymore. But once we start doing a show, then all that is off and you begin feeling a lot better.”

He also gives voice to many members’ initial reluctance to embrace some of the new material. “We think, ‘It’s asinine,’ the words and all, and then we hear the rhythm and we go, ‘Oh my God!’ But Bob has great patience with us. Bob is like a patient sculptor, he’s been molding and chiseling away at us for 28 years.”

“All I’ve known all my life was singing,” says Louise Canady, who grew up singing in church. “In the show, I become somebody else, I’m out of me, and I don’t feel my knee and my hip no more. People ask, ‘My God, aren’t you tired?’ And we say, ‘Yeah, I’m tired, but I’m going on.’ I think we’re spreading good cheer and saying to the audience, ‘You can do it too.'”

Martin tells of an audience member who said after a performance, “I gave up music years ago. I’m 73. But I’m going back and I’m going to start singing again.” He observes that “music helps the aging process. Louise can barely move on stage, Jeanne was run over by a truck, for Christ’s sake, and look at her arthritic hands. But to see her on stage, it’s a love fest. The audience falls in love with her. And that’s what makes me so proud of being a member of this chorus.”

End of the Road: Through May 1 at St. Ann’s Warehouse, 38 Water St., Brooklyn, NY, (718) 254-8779, stannswarehouse.org.