Cloud Gate Dance Theatre, Sadler's Wells, London <br></br>Kirov Ballet, Royal Opera House, London

Were medical researchers to have taken the blood pressure and pulse rate of Sadler's Wells patrons at the door last week, and again on exit, they would have noted a dramatic change. Something happens to a body in the presence of Taiwan's Cloud Gate Dance Theatre – something calming, balancing, almost tranquillising. And it's safer than Valium and a lot more fun than a flotation tank.

Cloud Gate, Taiwan's first contemporary dance company, has developed a unique performance language based on meditation and t'ai chi, the slow-moving Chinese exercise regime. This gives its stage presentations an almost tangible rhythm of breathing that spectators find themselves falling in step with. Either that, or one gets so twitchy one has to leave. The fidgety gent who pushed past my knees mid-performance I fear could be heading for a coronary.

In Moon Water, choreographer Lin Hwai-Min's latest extraordinary offering, a big black empty stage is swirled with white brush strokes to resemble a pool which, halfway through the evening, and without your noticing at first, becomes slowly flooded with water. Angled sheet-steel mirrors above and behind throw back hazy, rippled reflections, so that at one point the 15 white-silk saronged bodies on stage become 30, or 60, by dint of optical effects.

Awesome control, suppleness and strength lie behind the serene gestures and balances, which now and then snap you awake with spasms of sharp martial-art attack. In line with t'ai chi philosophy, every movement begins in the centre of the torso and flows out to the extremities. So at the start there's a lot of splay-legged undulating, which in the context looks elemental rather than sexy. There is something plant-like in the movements generally, like sea anemones following the current. The climax of the 75 minutes, and the show's most remarkable moment, arrives at a point of complete stillness, wet dancers sprawled about as if deeply asleep, the only sound the burble of water tipping over the rim of the stage. You feel – in some obscure, quasi-spiritual way – that you have arrived.

My only gripe with Moon Water is the music – selections from Bach's solo cello suites – which might be played live but aren't (what, no cellist prepared to get his spike wet?). Yet the effortless meshing of Bach with eastern modes of thought and action in itself is rather wonderful. Bach too knew how to arrive at a state of grace.

Over at the Opera House, fans of the Kirov – which we now really ought to be calling the Mariinsky, in line with Russia and the rest of the world – were treated to two gala evenings of opera and classical dance. Seeing that the company would not otherwise be setting foot in the UK this year, it was a bright move of the British Friends of the Kirov to bring them over for a "Celebration of 300 years of St Petersburg", albeit six months ahead of the actual tercentenary.

The programmes were meant to represent a spread of Petersburg achievement, and the operatic items included several unfamiliar gems – a sweetly understated aria from Rimsky-Korsakov's The Tsar's Bride, an equally unflamboyant baritone extract from Rubinstein's Demon. But the ballet's contributions, whether out of condescension or habit, were predominantly lollipops. The pas de deux from Don Q wants a 10-year moratorium, unless it sports the most exciting talents. Diana Vishneva delivered the goods perkily enough but her Basilio, Andrei Merkuriev, fluffed a lift early on and never quite recovered. More assured, but horribly in want of a context, was the Bluebird divertissement from Sleeping Beauty. The era is past when a man clad in turquoise feathers can expect ovations for a few flashy leaps apropos of nothing. Perhaps audiences have grown up a little.

The company looked best in the one full-length item, Balanchine's Serenade, whose mysterious synchronised swimming and pony frolickings are now a perfect fit on the Russians. That this work happens to be the cornerstone of American ballet marks a rapprochement indeed.

j.gilbert@independent.co.uk