Trainers are tricky things.
Yes, all they do is protect your feet, I admit that. However they're complicated beasts to make. Let's break it down for a second:
First of all there's the outsole, which is a complex shape and usually moulded out of several different materials. This is the hard "base" of the shoe that protects your foot from sharp objects, and helps you grip the surface you're walking or running on.
Then you have the midsole, the spongy middle layer which is great for shock absorption.
Next you have the inner sole, this provides further shock absorption and foot protection, and is usually replaceable for when it gets worn down.
Lastly you have the rest of the shoe: the collar, foxing, heel counter, heel tab, lace guard, padding and the sock liner. Essentially all of the bits on top of the sole which wrap up and around your foot (I didn't know what these part were called before I looked it up either).
Typically these parts are all different materials, sometimes different colours, and are attached to each other in different ways, be it stitching, plastic welds, or various types of glue.
What does this mean? Why am I telling you this?
Because all of these components that make up a trainer ultimately mean that you can't recycle it. They're designed to be worn until the sole has worn down, then the whole thing ends up in landfill. There are two many materials joined in too many ways to be separated for recycling. At best they might be shredded up and maybe made into playground flooring or have parts melted into one of those brown plastic park benches you sometimes see... but probably not.
So you can see what I mean when I say trainers are tricky things.
Everyone needs foot protection though, and everybody wears through shoes. 300 million pairs of running shoes are thrown away each year in the UK alone! So what do we do?
Adidas have had enough of this waste and have created a new type of trainer that's made out of one material.
More specifically, one TPU (thermo plastic urethane rubber) material that has been formed into outer sole, midsole, inner sole, padding, laces, collar, lace guard... you name it! All of the parts are laser welded (melted) together so no glue is needed either.
This means that once the shoe is worn out, it can be returned to Adidas, who then ship it to a factory with others where it is washed and shredded before being turned back into TPU pellets to make new trainers, and this can happen over and over and over and over...
This great mini-documentary explains all.