What are they? Special insoles that are moulded to the exact shape of your feet.

How much do they cost? You can spend hundreds of pounds on high-spec custom orthotic insoles, but I tried some Sole thin sport footbeds, which are £38.

What do they promise? Having insoles that fit the contours of your feet can improve support, increase comfort and reduce pain. They’re also reportedly quite good for bunions, backache, flat feet and overpronation.

What are they actually like? I’ve run in custom insoles sporadically throughout my life – usually because I’ve been too much of a flake to tell the shop assistant that I don’t want them – and, anecdotally at least, it’s been hard to tell how much good they do. If you have very flat feet, or feet that roll outwards, they should help correct your posture.

The main difference with the Sole footbeds is that you mould them at home – either by wearing them for a few days until they wrap around your feet, or by heating them up in the oven. But once they were in, I couldn’t really see much of a difference from the off-the-shelf insoles. They didn’t cripple me, but at the same time I wasn’t suddenly able to run faster or harder, and the bit of my foot that blisters when I run still blistered.

Best and worst bit The best bit was putting the footbed in the oven, mainly because it felt as if I was doing actual science. But I’m still not convinced by custom insoles: it just feels as if there’s something alien in my shoe.

Are they worth it? If you really think you need them, sure.