Watch the Guangdong Military Acrobatic Troupe perform

At the climax of the beguilingly bizarre Swan Lake performed by a troupe of Chinese acrobats, the woman playing the swan pirouettes on her prince’s shoulder, then on top of his head. She is on pointe, her body weight concentrated on one graceful tippy-tippy-toe. It’s breathtaking.

When I go backstage to meet the stars, I see what happens if someone stands on your shoulder on the toes of one foot, night after night. It’s not pretty. There’s a livid indentation in the prince’s left shoulder — a tight, deep circle surrounded by a bruise. And, as Wei Baohua and his wife, Wu Zhengdan, are the only people who can do this jaw-dropping stunt, they have no understudies and perform at every show. Ouch.

We’re in Basle. They’re performing in an immense sports hall that, though packed, saps atmosphere from the fantasy. When the troupe come to the red-and-gold Royal Opera House, the production will surely look more at home, however unconventional its take on Swan Lake.

The show, by the Guangdong Military Acrobatic Troupe, has wowed audiences both in China (where it has revived interest in unfashionable acrobatics) and on tour.

A familiar story unfolds through delicate classical ballet and exuberant tumbling.

The endearing result is somewhere between ballet, circus and bird impressions — quackrobatics, I suppose you might call it.

A tale about a woman-turned-bird lends itself to exploring diverse ways of becoming airborne. Dauntless aerialists leap from one human pyramid to another. There are virtuoso jugglers, tightrope walkers and trampolinists, not to mention a phalanx of swans on skates. The troupe’s currency is the impossible made to appear easy.

Perhaps surprisingly, the story retains its emotional clout. As the swan maiden, Wu arches her immensely flexible back in a helpless flurry. When she meets her prince, he cautiously clasps her foot and she flutters on pointe on his shoulder, a wild bird come to rest. It’s incredible, but surprisingly tender.

Backstage during the interval, a unicyclist circles as his colleagues warm up. Do people get injured, I ask the assistant director, Pan Hao. “All the time!” Most of the cast have trained since childhood, often coming from a gymnastics or sports background. Both leads started their careers early: Wu at six, Wei at 13. They trained at the prestigious Shenyang Sports School, in northeast China, which grooms athletes for international competitions. Wu was initially rejected (“The teacher said I was not very tall and a little fat,” she has said), but she eventually joined the relentlessly perfectionist establishment and was teamed with Wei for sports acrobatics events. In 1995, they became national and world junior champions.

After years of gruelling routine, they were hungry for change, so they joined the Guangdong Military Acrobatic Troupe, based in Guangzhou, southern China. When the choreographer Zhao Ming enhanced their routines with dance, the successful result gradually developed into this full-blown spectacular. It demanded some adjustment on the part of the performers. “We were both sportsmen, and our goal was competitions, to be judged,” Wei says. “Now we’re moving into a more dramatic aspect.” They admit that it took time to inhabit Tchaikovsky’s swooning score.

I meet Wu and Wei after the show in their grimly utilitarian dressing room, their kit spilling out of plastic bags and Tupperware. They must be knackered, but courteously discuss their craft through Pan Hao’s translation. The compact and muscular Wei, 37, is gracious; Wu, 10 years younger, sounds sparky and sardonic in her thick peacock eye shadow and long porcelain nails.

Wu tells me that, however daring her routines in Swan Lake, “I can’t neglect the character. It must all appear lovely to the audience, who can’t be allowed to think that I might be nervous”. But who wouldn’t be nervous at the show’s astonishing climax? Skulls may not be designed for load-bearing, but at least they present a tough carapace. Wei’s fleshy shoulder looks vulnerable, so how did they achieve that startling stunt? “It was difficult,” Wu says. “It took a lot of training. I always have to stand on exactly this point . Just a little variation means I’ll fall down — I’ve fallen before. When he’s sweating, it becomes difficult. We spent half a year learning to hit the precise spot, and now we do it almost 100% of the time.” Wei adds: “The first task is to keep your balance, the point of gravity — but I also try to look elegant.” He, too, remains vigilant: “Even a millimetre can cause a fall.”

As the ripening bruises make clear, perfection has its price. They never allow themselves to neglect their training. “We can’t ever be fully relaxed,” Wu says. “Even when we’re having a drink with relatives. We can never have a total vacation, otherwise it’s hard to pick up the energy we need.” After only 10 days without training, they have discovered, they can’t do the arduous lifts.

And my, they’re serious about their art. When the interview ends, they turn the tables on me. Is there anything I didn’t like? (I cautiously mention the extended comic sequences, but that doesn’t go down well.)

As a government-funded troupe, they have official duties: a sellout 2006 show in Shanghai was cancelled when they were called to Beijing to perform before President Bush. Dubya may have been easy, but their countrymen, they say, are hard to impress. Wu removes her false eyelashes and fingers them ruminatively. “They are picky, more detached,” she says. “People can be grudging in their applause.” As Wei’s bruise seems to change colour before my eyes, applause seems the least they deserve.

Royal Opera House, WC2, from August 5

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