Pensioners singing rock numbers is more than just a cute idea. The Young@Heart group is a world-touring sensation, singing mind-altering, floor-shaking versions of Rolling Stones, Radiohead and Outkast songs. Belinda McKeonsaw them rehearse for their Irish gig

IT looks like every community centre in the world. On the corner of two busy roads out of Florence, a suburb of a suburb of Springfield, Massachusetts, it sits with its windows and doors open to the neighbourhood - and most of the neighbourhood speeding past it. It looks worthy and worthwhile, but also a little bit dull with mommy-and-me groups, decoupage sales and old people shuffling around, doing old people things.

In fact, today there are some old-seeming people sitting in groups inside the windows, standing beside an upright piano, looking like they're getting across a good volley of grumbles in between whatever gentle numbers they're croaking their way through.

And then a roaring blast into David Byrne's Road to Nowhere breaks onto the humid morning air, a blast of energy so loud and so potent that it's utterly startling and not a little unsettling, and all notions of the fusty and the innocuous are vanquished. These folks sure aren't playing bridge. Charged and visceral and forceful, Byrne will segue into the Stones, into the Ramones, into Radiohead and Sonic Youth and Outkast. The floors will thud. The walls will shake. The innards of that old piano will take a licking they'll never forget.

The Young@Heart Chorus is warming up. By the time they get to Ireland next month for their performances at the O'Reilly Theatre in Dublin (as part of the Ulster Bank Dublin Theatre Festival) and at Glór in Ennis, they should be truly on fire.

"My kids say, Mom, you're not doing that song!" says Jéan Florio, 85. "They say, get out of here, you can't be doing The Clash. And we say, oh yes we are."

"In the old days we would have just turned these songs off the radio," says Jack Schnepp, 77. "We would have just turned down the noise. Now we know the words. We know there's always a good beat in them. Now we enjoy them; they're all good songs."

"Well, the only thing I won't listen to is hip-hop," says Jéan. "I don't care for that."

"Or hard rock," adds Jack.

"No, no, some hard rock is pretty good."

Pensioners singing pop and rock numbers - that's a cute idea, but in itself it won't carry far beyond the initial dose of cuteness. The Young@Heart Chorus has been going strong since the early 1980s and has grown to become one of the biggest deals in international theatre, touring the world and filling venues, winning delighted, astonished ovations wherever they go. Young@Heart shows go far beyond a set-list, even though the performances of the songs are mind-altering, riveting and moving.

The concerts are theatrical visions, black-edged, intelligent and deep; complex in their choreography and provocative in their worldviews, demanding of the ensemble members that they brilliantly act as well as memorably sing, demanding from them a whole-body, whole-spirit, whole-life performance that is as uplifting as it is powerfully unsettling, as intoxicatingly funny and enlivening as it is poignant, beautiful, and profound.

The quiet desperation of Fake Plastic Trees, the jagged mania of Schizophrenia, the voltage of Springsteen, the insolent lunacy of Hey Ya . . . to watch all of this woven into a meditation - physical and musical and visual and emotional - on aging and existence and identity.

"What a drag it is getting old," the chorus hollers on the Rolling Stones' Mother's Little Helper. "I can't control my fingers, I can't control my brain," they moan (Offspring's I Wanna Be Sedated). "We're one, but we're not the same," intones Louise in a version of the U2 song that would put Bono to shame. "They're coming to take me away, hahahehegigagigagigagigagigagigagiga," jabbers 87-year-old Len, in a reprisal of the controversial Napoleon XIV hit from 1966.

Never a dull moment. All those oh-my-aching-back gestures, you quickly come to realise, are strictly for effect. This place is as about as stiff and creaking as a mosh pit.

Young@Heart had modest - indeed, potentially dead-end - beginnings; in 1983, a young council employee named Bob Cilman was charged with responsibility for the local senior citizens' music group. All he had in mind at the time, he says now (he remains the company director) was "a way to kill the time". He gained, early on, an interesting sidekick in the form of Roy Faudree, an actor and director who has long had a close association with the Wooster Group; Faudree's own group, No Theatre, was local to Massachusetts, established with Sheena See in 1974. When they got together to pool their ideas, something unique - and decidedly avant-garde - was formed.

The first staged show came in 1984, a collaboration with local breakdancers, and when an elderly singer performed a version of Manfred Mann's Do Wah Diddy at an Aids benefit a couple of years later, Cilman recalls, "the whole thing went crazy". Soon afterwards, Faudree arranged for the chorus to perform at a festival in Rotterdam, and a world touring sensation was born.

The group's first major show was called Road to Heaven, a glimmer-in-the-eye celebration of the riches of old age; the new show, Road to Nowhere, does more than just celebrate. It questions, it criticises, it reveals.

"With the last show," says Roy Faudree, "it came right down the middle, where suddenly the audience was sort of caught off guard and there no longer was any clowning. This one flip-flops back and forth, from complaints about the problems of being old and the working situations of being old, to reflections on where you get your power and your energy and your love for life. And it keeps zipping back and forth on that."

"I think it's interesting in that it gives the group a chance to be angry," says sheena See. "You don't get to see, I mean, old people are always so sweet, aren't they nice, aren't they cute, and here you get them seeing people who have problems and complaints that they get to voice with energy and with anger."

The emphasis is not on vaudeville, on "gotta-make-'em-laugh". "Even just hearing them singing about love lost, in a real serious way," says See, "really has a different resonance than hearing some 20-year-old complain about his lost girlfriend. I think that really resonates."

"In terms of a theme, with this show, we were thinking about older people who just never get to stop working," says Bob Cilman. "And it's a real phenomenon here; there are just old people who never get to retire. You see them work in places like McDonald's and those places, so that was the idea, of people who are sort of stuck in what they have to do all the time."

It's something the cast understands; although they're all retired now, they worked long careers in jobs that must have sometimes seemed as though they would never end.

"None of us were showbiz people," says Brock Lynch, 83, who has been to more than a dozen countries with the chorus. He even met the king and queen of Norway on one trip. "We may have been connected with the theatre, but we never made a living at it. So the argument of amateur versus professional is moot; we had to become professionals."

The show will be performed by the cast in various workplace uniforms, on a set which will be an exact reproduction of the community centre where they rehearse. This is mostly to convey the "playfulness", the "theatricality" of the rehearsal room, says Faudree, where, according to Cilman, all the most exciting things happen. It's also partly, however, intended to offset the physical risks and inconveniences posed by an unfamiliar set to a mostly septuagenarian and octogenarian cast.

The minimum age of entry to the chorus is 73. (Pat Cady, a retired police officer who is the youngest of the group at 72, says she lied about her age to get in, and you're not entirely sure that she's joking). Its make-up changes regularly as new members join - and depart. Some of the voices that, on previous tours, made numbers like Ruby Tuesday and One magnificently their own are now silent forever, and these losses have to be accepted and integrated; the show does goes on.

"It's all like one family," says Jack Schnepp, and the other cast members around him murmur in agreement. "You lose somebody, they're still there."

"The spirit of the group," says See, "is about always moving and continuing on." And about shaking things up as it goes.

Young@Heart play the Ulster Bank Dublin Theatre Festival on October 10th and Glór, Ennis, Co Clare on October 16th and 17th