What is it? Weightlifting, but focusing on the downward motion. A negative chest press, for example, involves slowly lowering a weight towards you, rather than quickly pushing it away.

How much does it cost? Free on regular gym machines, though you’ll probably need a partner to help you. Instead, I used specialist X-Force resistance machines at All About You, which costs £35-£55 a session.

What does it promise? Negative training means you do all the work on the muscle-lengthening portion of the movement, while using heavier weights, so you’ll tear more muscle fibres. This is what makes you stronger.

What’s it actually like? Oh God. There are between 10 and 16 X-Force machines in a circuit, each roughly performing the same role as traditional resistance machines. However, these are 40% heavier on the negative movement, and each movement takes an agonisingly slow five seconds to complete. Resisting this huge weight as it returns to its starting point takes massive effort, which is why you perform only one set of movements (as many as you can do, until you can’t do any more), supervised by a trainer. You get on a machine, you exhaust yourself within seconds, then you move on. Focusing on the part of the exercise you normally ignore will take time at first, but it’s pleasingly intense when you get it right.

Best and worst bit You can get a full body workout on the X-Force machines in half an hour, and you need to do it only once a week. However, your muscles will work so hard that you’ll be sore for three days afterwards.

Is it worth it? Yes.