If British sport is looking to encourage young athletes, it should probably ban this documentary. Shot over four years, it follows four London sprinters aiming for a place at the 2012 Olympics, and it's clearly very hard work. We get few personal details; it's mostly about the gruelling physical preparation, its toll on the body, the pocket and the mind. It's a life of punishing discipline, all of which could be undone by random injury. But it's also a life of bludgeoning repetitiveness, which somewhat diminishes this film's power. There are only so many super slo-mo shots of bodies in motion you can take, and the athletes' observations drift into cliche ("Once the gun goes, there's no turning back," etc). And until the Olympics happen, the final chapters to these athletes' stories is missing. So we get the pain, but little of the gain.