Dance is "one of the only pure languages", if the late Patrick Swayze was to be believed. On stage – "without the luxury or hindrance of words" – the level of communication that could take place was an amazing, intense, nuanced thing, he said, and dancers were "the most organic actors".

Their bodies, their beings and their whole universe were “all made of up rhythms”, he said. “And when you key into those rhythms, something magical happens.”

In Dirty Dancing, that rhythm goes a bit like "g'gung . . . g'gung . . .", and if, at this point, you can picture dance instructor Johnny Castle (Swayze) taking the hand of ingénue Frances "Baby" Houseman (Jennifer Grey) and drumming it against his chest to teach her that dance is "a feeling, a heartbeat", chances are that you are fan.

You will remember, although perhaps not as well as you think, the main beats of the 1987 coming-of-age film, set in the Catskills at the Kellerman's resort, in the summer of 1963 – as told in a near-perfect script by Eleanor Bergstein.

The film has found a new rhythm in a hit stage show, and for Gareth Bailey and Claire Rogers dancing isn't just a feeling, but their living. The pair play Johnny and his professional dancing partner Penny in Dirty Dancing: The Classic Story on Stage, the hit show currently touring Ireland and the UK. The parallels may not be as extreme for this cast as they were for Swayze, who grew up amid a Texan "redneck mentality" and had to fight his way up "just like Johnny", but as performers they share an empathy with their characters – dancing is a precarious profession.

“We are so lucky to be successful,” says Bailey, speaking in the bar of Sheffield’s Lyceum Theatre as he prepares to rejoin the tour after a seven-week recovery from a sprained ankle.

He "came down on it", painfully, while practising the Time of My Life final sequence – "it was just before the lift, actually" – and no amount of physiotherapy, strapping and icing could stop it swelling up. "There isn't a dancer who hasn't had an injury," he says.

Even though the show “looks like fun”, it has “a real serious side for us as professionals”, says Rogers, who gets to do all of Penny’s thrilling leg extensions. Establishing a rapport with fellow cast members, including any understudies pressed into action, is part of the job.

“The dancing is quite structured, even though it looks quite free, so we do spend a lot of time together with our partners, learning each other’s bodies. We become very close.”

Dirty Dancing: The Classic Story on Stage premiered in Australia, in 2004, and raked in more than £42 million (about €52 million) on its last UK and Ireland tour. It tends to cast the central role of idealistic, virginal teenager Baby from an acting rather than a dancing background, with the effect that the actor's professional "journey" in the rehearsal room echoes Baby's physical education.

"We did one dance class a week at Lamda [the drama school] so, comparatively, I haven't danced," says 24-year-old Roseanna Frascona, who plays Baby in the current production.

The whole show, Frascona says, is about that thing Johnny goes through when he says: “The reason people treat me like I’m nothing is because I’m nothing.”

Eventually, of course, Baby persuades him to stand up for himself and others, no matter the cost. This, the cast agree, is an inspirational message for today’s limber youth.

“Nobody who is young and excited should feel ‘I shouldn’t go for this audition, because I’m never going to get it’,” says Frascona. “The whole film says, ‘Of course you can – go and have a go’. ”

But it would be wrong to characterise Dirty Dancing as an individualistic, hedonistic story of self-actualisation. It is true that if Grey and Swayze had not generated such astonishing heat, the film might never have broken through, racked up so much VHS custom or spawned the musical, the 2004 prequel and all that hot-pink merchandise. But there is more to Dirty Dancing than a marketable whoopfest of chemistry, biology and quotable bits.

Bergstein’s tale is overtly framed by a backdrop of class struggle and narrow gender preconceptions, as well as hints of the civil rights movement and generational divide that was to come.

As Baby’s succinct opening monologue tells us, its events take place “before President Kennedy was shot, before the Beatles came, when I couldn’t wait to join the Peace Corps and I thought I’d never find a guy as great as my Dad”.

Away from the stultifying main house of the Kellerman’s resort, the workers escape their hand-to-mouth existence through close-contact choreography picked up from “the basements back home”. The scene where Baby follows Johnny’s cousin, Billy, into the staff quarters and covets the cool sexiness of the (apparently all-heterosexual) crowd – before telling Johnny she “carried a watermelon” – was the critical moment in the film for Swayze.

During an interval at the Sheffield Lyceum, I put it to Karl Sydow, the stage show producer, that the film is misremembered as Baby simply having a crush on Johnny, when in fact what she initially craves is to belong to his scene. She wants to be Penny as much as she wants to be with Johnny.

“She wants to be grown up, to be independent,” Sydow says. “It’s there in that first speech Baby makes. She doesn’t know anyone who will live up to her father, but she is making that transition.”

When I went to see Dirty Dancing during its first Dublin run, in 2012, an odd silence temporarily fell on the otherwise raucous crowd when they saw why it is that Baby ends up filling Penny's dancing shoes. Plenty of Hollywood tales feature a plucky novice dancer who must step up for a big occasion, but few fill in because the professional has an appointment for an economically essential backstreet abortion.

In 1963, the US was still a decade away from the landmark Roe v Wade decision, and Bergstein's script depicts the reality: an abortionist with "a dirty knife and a folding table", the threat of police action and the privileged man (a Yale-bound, womanising Robbie, clutching a copy of The Fountainhead) who won't accept responsibility.

This plot point inevitably plays differently to Irish audiences – still – than it does in pro-choice Britain, in ways that those behind the production may not fully understand.

Back in its VHS heyday, Dirty Dancing was talked about in Ireland in semi-hushed tones not just because of its teasing title – dancing is only "dirty" if you believe moral chaos can be unleashed by a roll of the hip – but because Baby borrows money off her father to pay for Penny's abortion, and this is portrayed largely as an example of her "Miss Fix-it" helpfulness.

Like all the best musical productions, however, the Dirty Dancing stage show segues through tonal shifts with as much panache as it can muster.

“I think you just play it for the truth as much as possible,” Frascona says. The plot is so conflict-packed and issue-laden that the climactic lift, when muscle-honed Bailey “bench-presses me up, and I have to make it look nice”, is not empty showiness, but hard-won triumph. “It literally feels like I’m flying,” says Frascona, but it doesn’t scare her, as it reportedly did Grey.

All the giggles, groin thrusts, confrontations and disappointments lead up to this moment when Baby trusts Johnny to hold her aloft. “You kind of know it’s got to happen, don’t you? It can’t not happen. And the audience is so with you, and it comes at the end of a number where you are just so in it. I am so in it as Baby.”

It is hard to keep a straight face as it unfolds, and the producers do everything in their power to make sure you don’t. Dublin audiences contribute “a nice amount of heckling”, according to Bailey.

The stage show’s commercial success, swelled by repeat attendees, is because “crappy things” happen at Kellerman’s, just as they do in life, Frascona says, and the defiant conclusion that “you can still have a song and a dance” translates wherever Johnny hangs his leather jacket.

“On the one hand, it’s just a bit of fluff,” says Sydow. “On the other hand, it’s not fluffy at all. That’s why it works.”

Dirty Dancing is at the Bord Gáis Energy Theatre in Dublin from July 8th to 26th. It then moves to Belfast's Grand Opera House from July 29th to August 16th