“Use what your mamas gave you,” urges Michael Burgess, our teacher for Carnival Slam, an exercise class at LA Fitness health club based on carnival-style dancing. I take this to mean that we are to shake our collective booty, and when it comes to carnival-influenced dance moves, the bigger the booty, the more you have to shake. Don't you love it already - an exercise class that celebrates the softer, ample female form as much as, if not more than, the sinewy hard body?

This African and Caribbean dance-based exercise is a celebration of the female body. Hips (you know, those things you try to whittle away in other classes) sway sexily from side to side; thighs, large or lithe, become things of strength and agility; breasts are to be thrust out; and bottoms take on a life of their own. There's nothing proper about this class.

We are in a lovely, air-conditioned mirrored studio in Central London, but with a bit of imagination and much encouragement from Burgess, we are at carnival, without the crowds, obnoxious whistles, deafening sound systems and fear of getting lost. For me, the best thing about the Notting Hill Carnival is watching the dancing. Flamboyant, sexy, liberating and sometimes downright dirty, the dances always inspire a wistful “I wish I could do that” feeling in me. So I was whooping with delight when I found that LA Fitness was running classes that incorporate some of the moves I watch with envy.

The music was so much better than the thump-thumpa techno electrobeat clubby drone you get in so many aerobics classes. It was just pure drumming. When Burgess shouted: “Listen to the drums, they are talking to you,” it was almost a spiritual experience. Suddenly, this 47- year-old housefrau was Beyoncé on the beach, thrusting out chest, behind, and shaking, and grinning ear to ear.

More fun than squats at the gym

If you are aerobicphobic, dance-based exercise classes are the way to go because they never feel like exercise. However, like many high-energy aerobics classes, you get a good all-over workout, and with having to think about posture and your posterior muscle group, it's great for core stability. Many of the moves involve starting from or getting into a position that is like a deep squat, so your thighs work hard - much more fun than doing squats at the gym.

Burgess, originally from Belize, knows how to tap into the psyche of those with a passion for dance, but who think they can't dance. He trained as a dancer at the Alvin Ailey Dance centre in New York, focusing on African contemporary, flamenco and other ethnic fusions. At the Harlem School of Arts, he developed an interest in West African dance styles from Ghana, Mali, Guinea and Senegal. He has also danced in the London production of The Lion King. “People are attracted to dance class because it helps them to feel more self-confident,” he says, adding that it is certainly true for any type of class that involves hip-thrusting and butt-shaking.

He talks me through some of the moves based on traditional dances. “A lot of the dancing you see at carnival originates from West African countries, but the basic squat position is more Senegalese. You are working your bum; it is very earthy, grounded, rooted.”

Burgess tells me about the punta, a Carib Indian dance which works the pelvis in a hula style. I have some videos of punta dancing, and it just looks kind of down and dirty - I love it. But it is very difficult for me to do. I start banging on about being a middle-aged white lady who is a bit hung-up about the whole vibrating booty thing. He is not having any of it. “Don't do that white girl thing with me! Culturally dance is all mixed up now.” On the outside, I am an ordinary mum of two, slowly running to seed. But for 45 minutes, under his guidance, I am a Caribbean queen, all grace, elegance and sensuality.

Ros Saunderson, the national group fitness manager of LA Fitness, says that in terms of motivation, the personality of the instructor is important. “The teacher has to be motivated to get the class motivated.” This is so true. There are exercise teachers who are more intimidating than motivating, but Burgess's class is so motivational I can't stop thinking about it. I start grinding my hips while doing the washing up. When I have to bend to pick up something I've dropped, I do so in a dancer-like, deep squat. I am accused of “taking things too far” by my nearest and dearest.

The main thing about moving your body in ways you normally wouldn't, unless deeply intoxicated, is that you don't want to feel that you don't fit in. Carnival dancing doesn't feel like something you do to make your body the right shape or weight. If you go to enough classes, that will happen anyway, but this just feels like going out dancing with the gals. It might eventually lift my bottom, but for now, I am very, very happy for it to lift my spirits.

For information on Carnival Slam classes, contact LA Fitness at www.lafitness.co.uk

More good vibrations

Ceroc

A fusion of jive and salsa from France, which gives an aerobic workout, tones legs and gives you leaner muscles. Burns up to 800 calories an hour.

Salsa

A sexually charged dance from Latin America, the Caribbean and North America, salsa benefits co-ordination, balance and strength. Can burn between 400 and 800 calories an hour.

Belly dancing

A hip-shimmying, bottom-wiggling dance from the Middle East. Very good for core strength. It also tones the thighs, stomach and bottom, burning 300 calories an hour.

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