What is it? A small lump of ergonomically shaped plastic with handles on each side. It looks a bit like a Cyberman’s face, but if you hold the AB-MXR behind your head when you do sit-ups, theoretically you’ll get a six-pack.

How much does it cost? Varies, depending on weight. I have one that weighs 3kg, which Amazon sells for £68.

What does it promise? “A gym within a product,” goes the marketing spiel. It’s shaped to help maintain your posture during sit-ups, and to isolate your abdominal muscles for a more effective workout. In addition, you can use it as a weight alternative during other exercises.

What’s it actually like? I showed my AB-MXR to a trainer at my gym. He turned his nose up at it, and declared that it wouldn’t be much cop. Nevertheless, I went home to run through the accompanying DVD, and ended up doing quite a tough workout, including lunges and planks, as well as sit-ups. I’ve been using the AB-MXR at home for a while now, and I noticeably don’t have much of a six-pack. Is this the fault of the AB-MXR, or is it because I eat about 12 doughnuts a day? Who can really say?

Best and worst bit In my experience, bicycle sit-ups with the AB-MXR work your core incredibly well. Then again, mine was a freebie – I’d probably run a mile if I had to spend that much of my own money on it.

Is it worth it? If you’re unsure of correct sit-up technique, or you’re easing yourself back into training after an injury, yes. If not, probably just lay off the doughnuts.