A BALL of cast iron isn't the first thing that springs to mind when you imagine the latest celebrity fuelled fitness craze.

They usually opt for designer labelled yoga mats or beefed up personal trainers who'll carry their favourite pooch as they run. But when you've got a premiere and a divine dress to squeeze into there's only one option, and that's the ball of iron, or kettlebell as it's better known.

First invented 2,000 years ago, the exercise first originated in Russia and was used by Greek athletes and gladiators. More recently it's become a popular exercise choice in America and over the last year has been gaining momentum over here.

While at first it looks like a sure-fire route to gaining over the top muscles like a Miss Universe contestant, with celebrity fans like the super svelte Geri Halliwell, Jennifer Aniston, Penelope Cruz and Jennifer Lopez swearing by it, there must be more to the kettlebell than just beefing up.

Factor in the claim that it burns several hundred calories an hour, estimates vary from 600 to an amazing 1500 an hour, you can begin to understand its appeal to the fairer sex.

More than happy to jump onto any celebrity driven bandwagon, I decided it was time I gave this the once over. Enlisting the help of personal trainer Mark Newton I headed to Virgin Active, Thundersley, to be put through my paces.

I'd been told beforehand that 20 minutes of the exercises would be more than enough to turn my legs to jelly. So with the clock ticking we began.

The kettlebells looked far more intimidating than any equipment I'd experienced before. Usually they at least try and make these things look user-friendly by fooling us with bright colours or funky designs. There was none of that here. Just a stark black ball and weedy old me.

With the kettlebell radiating a menacing aura to the side of me, Mark began the warm up using a medicine ball. Here we did lots of twisting and stretching ready for the main event.

The balls come in various weights from the lightest 8kg, which I used, up to the terrifying 24kg. Women start with 8 or 12kg, and men are recommended to begin at 16kg.

The first thing I learnt was the basic move - the Swing, which once mastered provides the basis of most of the other exercises.

It's a basic squat where you use the power from your legs, hips and bum to swing the kettlebell like a pendulum from between your legs.

Whenever I've done it in aerobics classes before, the squat has always been a slow deliberate move, this was different.

This had to be fast. I felt like I was doing the timewarp at double speed and yes, the pelvic thrusts were indeed driving me insane.

As soon as I'd completed one, it was time for another and another. The faster the squats the higher the kettlebell reached.

With this completed to some level of competency, it was time to move on. Next it was the Clean. This would involve getting the 8kg ball from near ground level to behind my shoulder. Oh dear.

To do this, you swing the bell a couple of times to gain momentum and then on the third go you turn your wrist ready to swing the arm up and over to rest the bell on the shoulder. A bit like flicking your handbag onto your shoulder - albeit a very heavy one.

To my surprise I managed this without knocking Mark or myself out. I was certainly feeling the burn by this point. It wasn't going to stop there though. Next Mark introduced the Clean and Press. This was the same as the Clean but it ended with your arm in the air pointing to the ceiling like the heavyweight champion of the world.

This felt good. After that Mark showed me a few more exercises and then after an extremely thorough workout, we ended with the biggest challenge of all - me trying to walk down the stairs from the gym to the changing room.

As predicted, jelly had taken hold of my once fully functioning legs. Over the next few hours my arms, stomach, neck and shoulders went the same way.

A very thorough workout indeed - I loved it!

WHAT ARE KETTLEBELLS

"Kettlebells are like cannon balls with handles," explains Virgin Active personal trainer Mark Newton. "They have a number of benefits, including improved cardio vascular fitness, muscular strength, endurance and helps with balance and agility."

"But the big thing for a lot of people is that it burns lots of calories. There are some reports that you can lose one per cent of body fat a week. I don't know how true that is but I'd say it can probably burn between 600 and 800 calories an hour.

"It's that body fat burning potential that probably attracts women," says Mark. "Also because the power comes from the hips it brings about a lot of changes in the lower body, tightening the glutes and thigh muscles, which is what a lot of women want."