Sacha Waltz, Barbican, London<br></br>Sankai Juko, Sadler's Wells, London

For once you leave happy with your body

Toss the German word tanztheater into a roomful of radical theatre folk, sit back and see what happens. Very soon the mantra "Pina Bausch" will rise above the general hum. Announce you have a line on tickets and you'll find some new best friends. But tell them the artist is Sacha Waltz and draw a blank. Sacha who? Sacha Waltz - now a director of the legendary Schaubühne theatre in Berlin. Remember it, because the mantle of Pina Bausch is imminently hers.

The 40-year-old Berliner is not entirely new to London - her yearly visits to The Place have been quietly raising eyebrows for some time - but the spectacle that filled the Barbican Theatre last week is her first big splash. And it confirms what most of Europe already knows which is that Bausch does not have the monopoly on provocative, body-focussed theatre, a branch of choreography - to quote Bausch herself - "less interested in how people move than in what moves them".

To say that Waltz's show Körper is about the human body might seem like stating the obvious - isn't all contemporary dance concerned with that? But Waltz, like Bausch before her, has a knack for winkling mysteries from humdrum certainties and creating the world anew. Unlike Bausch, though, she doesn't take three hours to do it.

Take the way bodies work, purely mechanically. Falling bodies protect themselves, don't they? The Schaubühne dancers topple like skittles - ker-thud, ker-thud. Knees bend to cushion the impact of a jump, normally speaking. Here they land like steel rods. Ker-thud. A seated girl is flung through the air and remains thus, like a car advert mannequin, to land in the same position. Thud.

A sign outside the auditorium solemnly warns, "this show contains nudity and loud music". It should perhaps have read: "this show undoes your composure". The mild surprise of unclothed bodies pales next to the shock of seeing bodies do as bodies shouldn't.

The loud music never came. Hans Peter Kuhn's surround-sound track drives a forceful path through Waltz's disparate cabaret of ideas, but it's also wonderfully subtle. Nudity there is lots of, but of such an untitillating, unseductive kind, that you forget that bottoms and breasts were ever verboten.

Two men lift a woman and fling her to waiting arms across the room. Her nakedness is nothing compared to the horrifying fact of being picked up by fistfuls of her own flesh, front and back. Is that what subcutaneous fat is for - to facilitate handling so that a body can be thrown like a suitcase from the baggage-hold?

Happily, grisly alternates with comic fantasy. A man recites a long, involving story about a picnic with a girl he fancies. Each time the narrative mentions part of the body, he points to part of himself, but never a part that corresponds. What begins as comedy turns unsettling as you begin to doubt the true positioning of eye, ear or elbow. At which point I sensed the entire auditorium secretly, bizarrely, running through a checklist of their own body parts. How does it feel to meet a girl with four arms - three on the right side, one on the left, Waltz wants to know.

What happens when you match the top half of one body with the lower half of another? Answer: the feet point the wrong way, the knees bend inwards, and everybody laughs. Yet the laughter is part-relief: what we see doesn't threaten our sense of self.

Waltz is very clever in manipulating images and associations. Make a body suggest an inanimate thing, she's discovered, and humanity is erased at a stroke. Rows of crouching backs and buttocks resemble bulging sacks of grain. Stacked like a human sandwich, they cease to be people, just layers. Yet make them jiggle in rows as if along a factory conveyor belt, and their individuality - humanity - leaps out at you. Presented in all their imperfect glory, bodies are just too different from one another to be anything but personal.

Körper is, however, far from being intimate or cerebral. Waltz's ideas are theatrical and hungry for space. At one point she has the 10-metre high back wall of the set keel over (whump!) so she can use it as a runway. And the most resonant image of all takes place in an elaborately constructed glass tank. Make what you will of nine semi-naked bodies moving very very slowly, crawling over and around one another, some still and quiet at the bottom, some groping for the top. My companion saw foetuses. I saw gas chamber. It also underlined our bodies' distant relation to fish. Typically of Waltz, it was all these things and more. Rare is the evening with professional dancers that leaves you so happy with the body you've got.

I guess Ushio Amagatsu, director and leading performer of the Paris-based cult Japanese company Sankai Juku, was aiming for a similar level of resonance in Kagemi ("Beyond the Metaphors of Mirrors") the latest production to arrive at Sadler's Wells.

His slow-moving ceremonials based on the post-Hiroshima art of Butoh attract a devoted following around the world and many claim to find deep significance in the performers' pained, tortoise-paced movements. Death, birth, agony and ecstasy all roll together in this ghoulish mime-cum-dance form, all trappings of personality expunged by uniform shaved heads and white paint covering every inch of skin.

I am far from immune to the power of Butoh, yet for me the Sankai Juku experience is hollow. I can marvel at the control of the six practitioners (while itching to get away). And I can admire the glamorous stage settings (here, a field of giant lotus blossoms that suddenly float up to the ceiling like some poisonous cloud and hang around there for most of the show). But as for insights into the human condition, I find none.

jenny.gilbert@independent.co.uk