As a bunch they're hard to classify, and their much-lauded female star even more so. Thin as a whippet but wirily pugilistic, Louise Lecavalier has always defeated the critics. "A human projectile", "a flame on legs": the metaphors work overtime, but they still don't nail the essence of her violent, high-velocity performances. It comes as no surprise to discover that this shy, tenacious creature has done a stint of boxing for real: taking time off to nurse a hip injury, she got a job playing a bodyguard in Kathryn Bigelow's feminist-thug movie Strange Days, and trained for it by sparring in a gym.
According to Lock, the company evolved "in darkness and obscurity" at a time when conservative Quebec paid no attention to its home-grown radicals; this gave them unusual freedom to experiment. His first ambition had been to write, but he was drawn to choreography because of its subtler expressive possibilities. Lecavalier was propelled into his orbit by the limitations of conventional modern dance: she meant to collaborate for a year, but has now been his muse for nearly 20.
"Neither of us knows what's going on in the other's head when we meet in the studio," she says. "He sees who I am that day, how I am dressed, what my energy is, and my mood, and then he will suggest things. Try this jump, try that, with the arms down, with the arms up, flip your wrists less extreme - more extreme - and the dance emerges little by little, a detail at a time. If something is simple, I add another layer. If something is easy for me, he makes it harder. I try to make all my movements" - she fishes for words - "huge, atomique." Her models are not so much other dancers as actors and singers - Prince, Michael Jackson, Bjork; Sylvie Guillem she admires for her combination of cleverness and animality. "We're all animals, and it's nice when someone recognises the fact."
Lock describes his work in terms of games with perception. "I can't describe the back of my hand, but I could recognise it in a thousand. Why can we recognise things that we can't describe? What I like about speed - as when you wave your hand in front of your eyes - is how a solid thing becomes transparent, a blur. You impose the memory of your hand on what you are seeing. In the same way, if somebody is moving very precisely and at speed across the stage, you lose any sense of their shape, and start to see pure flux." Pure flux, in their current season at the Peacock Theatre, means a 90-minute show "about youth and death", enigmatically titled 2n
La La La Human Steps perform '2' at the Peacock Theatre, London WC2, until Friday. Booking: 0171-314 8800