The tone of Dancer, a documentary about ballet star Sergei Polunin, is set in the first scene. Filmed backstage just before a performance, Polunin boasts that he sometimes takes so many stimulants that he can’t remember being onstage. Then Black Sabbath’s Iron Man starts playing on the soundtrack, in case the film-makers weren’t clear enough about their angle: Polunin is the rock star of the dance world.

Superficially, this makes sense. The young Polunin has the mix of exuberance and arrogance, campness and virility, that found its first and most perfect expression in the 1960s' Mick Jagger. There are cheekbones, a wide white smile and luscious curls; there are Daily Mail headlines, tattoos and idolatrous fans. But Dancer constantly feels like it’s trying to justify Polunin’s bad boy reputation rather than looking beyond or behind it.

The story it actually tells is almost mournful, at odds with the blazing rise, epic fall narrative it subscribes to. Polunin was born in relatively humble circumstances in Ukraine, his talent clearing a path to bigger things. The most mesmerising parts of Dancer are the home videos of from his infancy: effortlessly shimmying himself up the jamb of an open door, his prodigious strength and co-ordination makes the young Polunin seem truly special, though as a picture-book superhero rather than a rock star.

Polunin wasn’t born with these powers, of course. There were hundreds of classes, hours of rigorous training. Of his mother, Polunin says: ‘I think she was angry with her parents for not having pushed her, so she made sure she pushed me.’ This story is the same for millions of children with ambitious parents, and it’s an entirely unremarkable one. The only thing that sets Polunin apart is the extent of his mother’s ambition, and the astonishing, mindless, unforgiving talent that resulted from it.

Dancer charts Polunin’s stint at the Royal Ballet (where he became its youngest ever principal), his move to Russia (where he appeared on humiliatingly tacky TV shows), and his redemptive collaboration with David LaChapelle on a dance choreographed to Hozier’s Take Me to Church, the video of which went viral.

Sergei Polunin in David LaChapelle's video for 'Take Me to Church'

Aside from the Take Me to Church footage, there’s not much in Dancer that demonstrates why Polunin is such an exciting dancer, and he’s not exciting enough off-stage to interest otherwise. Dancer’s examples of his ‘hard living’ aren’t shocking; they’re actually pretty endearing, especially the videos of Polunin and his adolescent contemporaries mugging for a smartphone camera, flaunting the cigarettes they’re audaciously smoking. Polunin’s consumptions and late bedtimes are only transgressive for those who have to treat their bodies like thoroughbreds. The effect of vodka shots on Polunin’s nervous system is predictable: he had a reputation for falling asleep at parties after ten minutes.

Dancer is most intriguing in its examination of the psychological toll of excellence. The existential trap of being drilled in a single discipline from toddlerhood is exacerbated by the physical trap of being a professional dancer at the highest level. As a top-tier ballet dancer, you are a ‘prisoner to your body’: your muscles seize up if you stop putting them under the relentless pressure of performance, a series of extreme tests that preclude most other activities due to the risk of injury. Polunin says that he always hoped he’d get injured, which is a desperately sad thing to admit to.

But there’s an obvious compensation, made most apparent in one of Dancer’s funnier moments: a crowd of female ballet students, watching Polunin practise, all have the same awed, hungry expression on their face. Mick Jagger might be jealous, especially these days.