Emma Bartley puts her scepticism aside, dons a secure swimsuit and reluctantly tries out Aqua Zumba...

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Are there two words in the exercise lexicon that sound lamer than “aqua” and “Zumba”? One is associated with pregnant women and old ladies; the other with church halls and Strictly wannabes. Put them together and, especially against the backdrop of various current exercise crazes – body attack, kickboxing, Sh’Bam – it sounds terribly sedate.

But Zumba isn’t just a craze. It’s a phenomenon. Fourteen million people attend the Latin dance-based classes in 150 countries around the world, many of them never having done regular exercise before. There are books, DVDs, games and variant classes: Zumba Sentao (with a chair), Zumba Toning (with maracas) and now Aqua Zumba.

I’ve also had a slight change of circumstances. Now 20 weeks pregnant, I’ve finally burst right out of my size 12 clothes and am embracing the elasticated waistband (what an invention). Pounding away on the treadmill has become a bit tougher, and more fraught with injury-risk.

So despite my scepticism, when I was invited to try an Aqua Zumba class with trainer Caroline Parsons on a press day at the newly refurbished Virgin Active gym in Kensington, I thought it was time to give it a try.

As befits my condition, I wore the most mumsy of all my mumsy swimsuits, in the hope that an underwire would stop anything falling out of anything during an enthusiastic arm-raise. Soon, I found myself standing in a line of five fitness journalists in Virgin Active’s nice new swimming pool facing Caroline, who was standing on the side, beaming.

She points out, by the way, that it’s a nice class to do if you’re body shy or uncoordinated (tick, tick), because the water means no one can see you. In fact, as this picture shows, the trainer can see you pretty well from her viewpoint, as can any photographers, PR reps and gym officials who happen to have come along to watch. But assuming you don’t have an audience, there’s no need to feel self-conscious.

Caroline put the Zumba music on and gave an impressively energetic demonstration of what we were meant to be doing under the water. There were big, theatrical steps to each side, hip thrusts, wiggling pirouettes and water-churning arm movements.

In the pool, we bobbed around in our line, trying to keep up with what she was doing without bumping into each other. The idea is that the water cushions the impact of the movements, making Aqua Zumba ideal for pregnancy, older people or anyone with an injury. In theory it also adds resistance for you to work against, but I really didn’t feel as if I was working very hard. Caroline, on the other hand, was making a superhuman effort, jumping up and down in the sauna-like air without the aid of water to buoy or cool her.

I found it particularly amazing how smiley she stayed – perhaps her training in musical theatre showing up. Then again, I was grinning even through my cloud of oestrogen – the class was very good fun, so much so in fact that an actual gym patron decided to join us midway through. What she thought the photographers were doing there I can’t imagine, but it’s further evidence that the pool removes any need to be shy.

“It’s very enjoyable and very social,” said Caroline afterwards. “You don’t get people looking at you like they hate you when you teach a Zumba class.”

The next day, however, I was surprised to wake up feeling quite stiff in my legs, particularly the upper thighs and bum. I decided that this “done a new workout” feeling must be down to the high leg raises to the front, sides and back that we were performing. In the pool, they were easy; on dry land, they left me feeling like an old lady. But at times like these, with the needle on the scales going up week by week, it’s good to feel you’ve at least engaged some muscles.

While I wouldn’t quite say I’d taken to it like a fish to water, I’m pleased to have discovered Aqua Zumba. It’s great if you’re feeling injured or tired, if you haven’t been active for a while or feel awkward in other group exercise classes. There are already plenty of classes around the country, and it’s rolling out across Virgin Active gyms throughout 2013. Give it a try – otherwise I just showed you a picture of myself in my swimsuit for nothing.