It's one of the hottest new exercise trends in the US, and the Gravity workout has just arrived in the UK, promising to work every muscle in the body without the need for heavy weights.
Based on the theory of using your own body as resistance to tone and strengthen, there's no faffing around with a string of machines – instead, there's a couple of pulleys attached to a bench, which can be tilted at an angle and which slides as you move. If you've done Pilates, it'll look familiar as it works as a reformer as well.
So far, so simple. And the equipment itself looks relatively innocent. But when Bodydoctor David Marshall starts talking about how it means you can move from a squat to a bicep curl in seconds, letting you work out harder in a shorter space of time, I realise just how intensive this fitness class is going to be.
As well as boosting your muscle strength and endurance, the class promises to increase agility and flexibility as well as a cardio workout – which involved me pushing off from the footplate so the bench slid up, as if I was jumping while lying down, and turned out to be surprisingly fun.
If you hate complicated classes, this is one for you. Each movement was ultra-simple and all very low impact, but at times there was no doubt how tough a workout I was getting! Using the pulleys to work my pecs was like trying to move through wet concrete, while the instability of the moving platform means your stomach muscles are working overtime to keep your body steady.
But if I was struggling with a move, the instructors were quick to adjust the bench – the incline lets you use anywhere between 5 and 59% of your weight so there's room for all abilities. And depending how hard I wanted to push yourself, I could choose various easier or harder options for some moves - although having cracked one move, I discovered the 'hard' version wasn't anywhere near as bad as I'd imagined.
And because you're only using one machine, apart from occasionally tweaking the set-up, it's very smooth moving from squats to crunches to pull ups as well the other string of other moves, so the time flies by – always a good thing! Despite what my muscles were telling me, because I was lying down, it felt oddly relaxing as well.
Burning up to 400 calories in 30 minutes, it's no surprise Coleen Rooney's a fan. Classes are available at selected Nuffield Health and Virgin Active clubs, as well as independent gyms. Visit www.gravityuk.net for the full list.