What is it?

TechnoGym's Wellness Ball. Active Sitting is designed to turn sitting into exercise, by helping improve posture and give muscles a workout while you're sitting down, writes Abi Jackson. It consists of an inner ball which you inflate, and a cover made of non-slip, washable fabric.

What's it like?

Not the easiest of things to assemble. It took me about half an hour with help. But once properly inflated and zipped up in its cover, it was worth the effort.

Sitting on a ball forces you to sit up straight and engage your core (abdominal and lower back) muscles, improving posture, strength and balance. I use it at my work desk and, though it feels odd at first and gets some getting used to, I can feel it working and I am sitting up in a far healthier position. The cover's very effective so there's minimal slipping and rolling around.

When you're done sitting down, it doubles up as a regular exercise ball - a great way of fitting a quick workout into your lunch break.

A leaflet illustrates how to sit and use it correctly.

l Wellness Ball - Active Sitting, £230, available from technogym.com