Dance: Spiegel, Sadler's Wells, London<br/>Jump, Peacock Theatre, London

Beware of falling dancers

At first you have to doubt what you're seeing. A man has just hurled a brick across the stage, a distance of some 20 metres, and if it doesn't actually decapitate someone then it's sure to make a hole in the floor. By some miracle it just misses a woman's head as she darts away and someone else dashes forward to catch it, only to send it flying back in a great arching trajectory whose end point looks certain to be where a man is obliviously putting on his jacket. A hundredth of a second before the thing fells him, he is shoved clear by another body which charges from the wings with the force of an InterCity train. Soon the air is thick with flying missiles, the floor a frenzy of ducking and sprinting and catching and chucking. Think what Andrew Flintoff could do with fielders such as these.

Physical risk is a fact of many dancers' lives, the difference between success and a broken neck a question of timing and trust. But don't we all enter that territory when we jaywalk on a busy street or cheat the closing doors on the tube? Wim Vandekeybus is fascinated by the fragility of human life, and its obverse, the body's resilience. Twenty years ago he was part of the Flemish New Wave that abandoned the formalities of modern dance for something more raw and instinctive. His latest piece, Spiegel, now on a UK tour, is a refashioning of key themes from two decades of work created with his company, Ultima Vez.

Its members don't resemble dancers so much as featherweight wrestlers. Three women in skimpy silk dresses and little boots hurl themselves with a fury across horizontal empty space, crash-landing on all fours and rolling away like a clutch of dropped pencils. Later, the same women appear as rigid objects, borne in the arms of men who handle them as if they were logs. As each man reaches the front of the stage, he drops his load, flump, on the floor. The further the women-objects have to fall, the more visible the impact, but still they don't flinch.

There is a great deal to make the spectator flinch in this show - you almost feel the bruises vicariously. At one point, men stamp about with work boots. narrowly missing bodies that lie on the floor. As if asleep, the bodies flip or twitch clear of injury at the last possible moment, only to position themselves unwittingly in the path of the next boot-fall. You're conscious of the softness of flesh, the brittleness of bone, the sheer wonder of the survival instinct.

But it's not all destructive violence. As if to remind us that yin will always have its yang, Vandekeybus also sets his cast gentler tasks - duetting with a wisp of smoke, say, or keeping an airborne feather aloft. Suddenly, after all that heavy falling, the women assume the power of vertical take-off, popping into the men's arms like Champagne corks before winding themselves, string-like, round their torsos. If proof were needed that almost any activity can be the stuff of theatre, then here is that proof, by turns terrifying and assuaging, visceral and meditative. And if Spiegel delivered powerfully in the big spaces of Sadler's Wells, how much more impressive will it be in smaller theatres.

There is more rough stuff across town at the Peacock Theatre, where the Korean Yegan Production Company has taken up residence with its martial arts show, Jump. They might equally have called it "Flip", "Kick", or "Running up Walls", because that's about all there is to it. It's essentially a showcase for the art of tae-kwon do, jollied up with some hoary vaudeville gags, a spoof of Crouching Tiger and a very silly plot.

Imagine British TV's My Family played out in suburban Seoul. Mum splits kitchen tiles with her karate chops. Daughter fends off unwelcome suitors with a volley of kicks to the head. Uncle is permanently drunk but does multiple back flips, and grandpa uses his walking stick for pole vaults.

Like any sitcom, Jump goes heavy on the comedy stereotypes. Mum is a sex maniac, and Dad never runs faster than when she's on the prowl. The boyfriend is a Clark Kent geek in glasses, but without them he's a snarling, sexed-up hunk. When a character gets knocked on the head, as happens with increasingly predictable frequency, the "bong" is followed by a tweeting of birds. Yet there's a kind of innocent charm in this crude cultural hybrid, and even if it doesn't make you laugh you can't dislike it. Things look up, plot-wise, in the second half with the arrival of a couple of bungling burglars, one of them far too fat, surely, to spring somersaults, but no. The finale is stupendous. They literally do run up the sitting-room walls. The injunction "Don't try this at home" was never more apt.

jenny.gilbert@independent.co.uk

'Spiegel', Nottingham Playhouse (0115 941 9419) Tue & Wed; Snape Maltings (01728 687110) Sat; touring. 'Jump', Peacock Theatre (0870 737 7737) to 14 April.