Claudia is enthusiastic but not encouraging. “That’s a rope burn (pointing to a snaking abrasion on her ankle) and I’ve fallen off a couple of times. But I’m hooked. It’s only after the calluses on your hands and the black bruises behind your knees that you begin to feel the benefit.” She has been coming to static trapeze classes twice a week for a year, Cambridge finals notwithstanding.

The trapezes hang under a pitched glass roof at Circus Space in Hackney, East London, and above us a peal of thunder rolls ominously. Somewhat older and a lot less fit than Claudia, I try to look nonchalant. Clare Midgley arrives to teach the class. Neat in black tights, she takes them - only three today, it being August - through their paces while I watch. My turn will come later.

Claudia is hanging upside down. (Why haven’t I chosen something easy like parachuting?) Jacky Chapman arrives to take the photographs, takes one look and asks: “Exactly how compulsory is this?” Claudia is suspended by her armpits, arms out like an aeroplane. I contemplate popping out to swig some Ventolin but there is no time: “Your warm-up will have started,” says Clare.

Oh help. I know I can’t cope without a bit of a limber up. But first I have to find the class. It being Sunday, there’s only one and most of the others on rubber mats are tumblers with rubber limbs. Twelve-year-old tumblers, by the look of them. I copy - stretching, bending, doing the splits (nearly). Then, suddenly, everyone else is inside out - feet and hands on the floor, backs arched, tummies to the ceiling. I couldn’t even do that at school. I think we called it “frog” then. More of a breathless slug, I try to look inconspicuous.

Back upstairs, the beginners’ class is ready. Josie, Tamara and Ken are already attacking the trapezes. Clare gives me her attention: “Have you climbed a rope lately?” “Er . . . not very recently”.

It’s the first lesson for every would-be circus acrobat. You sandwich the rope between your feet, lean into it and pull yourself up by your legs, not your arms. Clare says I passed on the way up, but failed on the way down. I like to think gravity won.

At last, time for the real thing. I approach one of the lower-swinging trapezes and, under instruction, achieve Pike. Arms above your head, you grab the bar, jump, tucking knees to chest, then point your toes at the wall behind your head, aiming for a graceful jack-knife effect. It’s quite comfortable when you find the point of balance and it illustrates what static trapeze is all about: keeping the bar as still as possible while you move yourself around it, exploiting the points of balance to do so. Swinging is frowned upon - that’s for the daring young people on the flying variety.

From Pike, swing the legs over the bar and hang down, hooked by the knees. Hocks we call that. I’m beginning to feel one of the gang. Clare leaves me to practise while she turns to the rest of the class. Right. Pike again. Easy peasy. Whoops, I’ve gone right over, doing a kind of head-over-heels while still holding the bar. It’s called Skinning the Cat, apparently - but you’re not supposed to do it by accident.

Next I have to haul myself into a sitting position and, bending each leg in turn, stand. The bar must be gripped by the toes to prevent swinging. The moves are hard work, muscles stretched and hands burned by the rough rope. This must be what Clare means when she says static trapeze causes “a lot of surface damage”. But every bit of progress is an achievement and there is something immensely liberating about the physical discipline - especially as there is some hope of an “artistic” pay-off.

Clare is firm but encouraging. She is taking me through quite a lot for one 90-minute session. Later she tells me that it took her five lessons to see the point of it all; the effort seemed to outweigh the rewards. And it is a ridiculously hard way to keep fit. (In fact, she says, if you don’t use your muscles correctly, you can end up with “a nice firm little pot belly”.) Then, suddenly, she saw that all the moves could be put together to make a kind of aerial dance sequence. That was four and a half years ago. She has been teaching for two, and she performs in the Circus Space cabarets.

I finish off with what Clare calls “something pretty”: two positions called Mermaid and Half Angel. I’m working on the higher trapezes now, feeling like a (slightly creaky) trouper. For Mermaid I hold on to the rope by one hand, both feet together just above the bar. For Half Angel I hang from the bar with one hand, one foot flexed in the rope opposite, body turned over. Elegant or what! Actually I’m beginning to feel a bit queasy - pure exhaustion, I suspect.

Afterwards Clare says I’ve done pretty well and I glow with pride and pain as she recommends sugar in my tea, the classic treatment for physical shock, and warns that I’ll be sore the next day and will feel worse the day after. She’s right. I feel as if I’ve been put through a coffee grinder. But it was worth it and, I’m thinking about signing up for more. I wonder how long it takes to get into the cabaret . . .

Would-be trapeze artists may be able to watch a lesson at Circus Space. Four weekly sessions cost Pounds 26. For information on trapeze and other courses (for adults and children) and cabaret evenings, tel: 0171 613 4141