They work by moving an electrically-powered belt around quickly in the opposite direction to your walking or running, allowing you to exercise your muscles without actually moving. The effect is like going for a long walk, only without having to brave the elements, hurt your feet or worry about where to go.

At its most basic, a treadmill is little more than the belt, a handle and an ‘on’ switch, but treadmills can potentially have many more features than that. The best treadmills know can be programmed to time you as you run or measure how much distance you would have covered, and alert you when you have done a certain number of minutes or miles. Some models are also capable of counting the exact number of steps you have done, the number of calories you have burned, and many other things besides.

If you’re thinking of buying a treadmill, there are two things you absolutely must do. Firstly, you must measure the space where you’re planning to put it and take the measurements with you to the shop, as treadmills that look quite small there will suddenly seem a lot bigger once you get them home, and might not even fit through your door (measure that too, by the way!).

The second thing you need to do is to make sure to try out the treadmill in the showroom before you buy it, no matter how silly you might feel doing it – treadmills are expensive, and not every one is suitable for every person. As the shop probably won’t take it back once you’ve used it, you need to make sure that it’s right for you before it ever comes through your door.