Flashdance The Musical, Shaftesbury Theatre

They keep on coming, these screen-to-stage musical adaptations, noisy, bombastic, as unsubtle as juggernauts. The best of them offer up their uncomplicated entertainment with some pizazz; but Flashdance is a particularly vacuous example of the genre. You probably had to be female, and teetering on the edge of your teens, to enjoy Adrian Lyne’s critically derided film back in 1983 (I freely admit that I was, and I did): Tom Hedley and Joe Eszterhas’s screenplay is both shapeless and pointless. This new version, written by Hedley and Robert Cary and directed by Nikolai Foster, does nothing to improve upon it.

What ramped up the appeal of the movie in its day was a thumping soundtrack assembled by electro-innovator Giorgio Moroder, a string of eye-popping, high-energy dance sequences and a sassy, sexy lead performance from Jennifer Beals as Alex, the blue-collar Pittsburgh girl who works as a welder by day and a bar dancer by night, and dreams of studying at a snooty ballet school. Key moments have become iconic: Beals whisking off her welder’s helmet to shake free her long, dark curls; Beals onstage, draped over a chair and drenched in water; and perhaps most famously, Beals in red shoes and ripped grey sweatshirt, insouciantly divesting herself of her bra before the besotted eyes of her boyfriend, the steel-mill boss’s son.

All of these are slavishly recreated in Foster’s production, in line, no doubt, with audience expectations. But the reworked storyline is sentimental and silly; and while a clutch of numbers from the film are included, Cary and Robbie Roth’s new songs are tedious.

Victoria Hamilton-Barritt is Alex, styled to resemble Beals as closely as possible. In a performance that rarely sees her step offstage, she shows considerable stamina, and if her mouthy little miss is strictly one-dimensional, that’s scarcely her fault, given the material. Her voice is strong, and she’s clearly a competent dancer, too; but when the show purportedly hinges on terpsichorean ecstasy, it’s strange that it should be impossible to tell if she’s much more than that.

Arlene Phillips’s choreography is stuffed full of knowing Eighties references: there’s body-popping, breaking and robotics, as well as ballet and bump and grind. But the staging of the dance numbers ranges from dull to laughable. Desultory street performers in tracksuits wander in between scenes to bust a few moves; the sequences at the club, curiously, are performed on a tiny platform that permits only restricted movement. "Manhunt" – one of the best-known tracks from the movie – sees a Latina character inexplicably got up as a matador, casting a proprietorial eye over two ludicrous writhing barechested boys. Even Alex’s climactic audition at the ballet school, danced to the familiar title track, looks peculiarly cramped and underpowered.

The smallest speck of grit that enlivened the movie is here wiped away by mawkishness and melodrama. Cary and Hedley give Alex a long-suffering mum who runs a drycleaner’s and gets gunned down for the contents of her till, as well as a girlfriend addicted to drugs and alcohol, who makes a miraculous recovery after a hug and a few words of feminine wisdom. Bubblegum pop and electro add a nostalgic patina to the score, but there are far too many turgid power ballads; and Morgan Large’s sets look cut-price, an impression reinforced by some ugly video projections by Ian William Galloway.

It all feels decidedly half-hearted – and, disastrously for a show about dance, more than a little lame. Only die-hard fans of the film could find it reason enough to dig out the leg-warmers.

• Flashdance The Musical is booking at the Shaftesbury Theatre, London WC2 until 26 February, 2011
• Find Flashdance on Amazon

Jennifer Beals dances to "What a Feeling" in Flashdance the movie: