Cyberjam, Queen's Theatre, London

Americans used to be scornful of performers in English musicals who could sing but not dance - or vice versa - and whose acting was not much better than that of the old-time opera singer whose technique was "emotion: raise one eyebrow; extreme emotion: raise two". Matters have greatly improved since those not-so-distant days, so perhaps it's only natural for Americans to up the ante. There is no acting or singing in Cyberjam, but nearly everyone in the 36-member cast plays an instrument and dances or does gymnastics - at the same time.

If this show strikes terror into the hearts of musicians whose most strenuous activity is hoisting a drinks tray, it must stupefy those who look like musicians. The youthful troupe, black and white, are not only fit but pretty, and flash brilliant American teeth when not engaged in playing flute, trombone or sax. Bouncing on little trampolines or atop rubber balls fitted with little platforms, they blow their little hearts out. The drummers have less scope to move, but they jig about like an energetic Gene Krupa, juggling their sticks and incorporating a kick at the skins into a tap routine.

Though Cyberjam is billed as a bold leap into the future, neither its music nor its dance has reached the present. The 15 numbers are by such futuristic composers as Louis Prima, Chuck Mangione and Dave Brubeck, and the newly "requisitioned" number by Violaine Corradi borrows from that cutting-edge composer Ravel. "Bohemian Rhapsody" has been updated with a few bars from the Edwardian parlour piece "Glow-Worm", to go with the miners' helmets that send beams of light across a dark stage. All has been processed into a jazzy-Latiny sound that, while pleasant, is in no danger of inflaming any passions.

The choreographers - Jim Moore, George Pinney, and Jonathan Vanderkolff - take their dance vocabulary not only from TV variety shows but from American football. This show loves batons - twirled, tossed and illuminated (the last spun round in the dark, of course). Laundry day was also an inspiration - pairs of dancers grasp a sheet at each short side and flap it up and down.

The costumes (black or silver sleeveless top and trousers) and set (coloured lights and simple shapes outlined in neon) are functional rather than magical, and the whole enterprise - directed by Vanderkolff, Pinney and James Mason - a less-than-human affair. Yet, unlike some of my colleagues, who appeared to think it as reprehensible as the invasion of Iraq, I cannot find it in my heart to damn Cyberjam. Even when its musicians resort to such infantile stunts as emitting a vibrato when a man scratches himself, the tone is good-natured, the mechanical perfection impressive. More than two hours of wordless musical numbers, with hardly any variety in the music and dance, is far too much of a merely pleasant thing. But if your taste runs to wholesome displays of energy, you and a friend could do worse than to share one ticket. Half a show each is not, in this case, meanness but a more judicious measure of Cyberjam's attention-holding capacity than has been served up by its creators.

To 25 October (0870 890 1110)