‘You’ll be able to get six-pack abs while simultaneously getting a back massage’ shouts the marketing blurb for the MultiFlex, a sort of fitness rocking cradle. How you’re supposed to carve a six-pack – a goal traditionally achieved by doing resistance exercises and burning off belly flab – while getting a massage, we’re not too sure. Something to ponder when rocking back and forth on your new toy, perhaps.

Perfect for lazy gits. After rocking back and forth a few times you build up enough momentum to carry you through crunches without having to engage your core at all – and what’s the point of that? Abs cradles are normally pretty cheap, which means rickety, which means that after a few months they’re liable to collapse when you’re halfway through a crunch, pinning you like some kind of nasty gym-based bear trap. Avoid at all costs.

The makers of this blow-up fitness tool, which looks like a cheap inflatable chair, wanted to create something that could be used for both abs and full-body workouts. In reality, they’ve made a less versatile version of the gym ball. We’ve tried very hard but can’t think of a good reason why you’d use this instead of the original.

Jamming your feet under a sit up bar so you can perform crunches without your feet leaving the ground will work your hip flexors more than your abs. And anyway, doing endless crunches is pretty pointless: for one thing, you’ll burn hardly any calories, and for another, you need to keep your reps in the 8-12 range if you want to build muscle size.