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Sports shoe technology, in plain terms

What follows is what each technology in a shoe actually does, grouped by the part it belongs to: insole, midsole, outsole. Waterproofing sits alongside them as a property rather than a part, because on this side of the Channel it decides rather a lot. Tick the box next to any technology and the table further down narrows to the models that carry it.

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Brand

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Insole

An open-cell foam insole that OrthoLite makes and sells on to dozens of brands, which is why the same name turns up in shoes that have nothing else in common. It breathes better than the standard EVA insole and flattens more slowly, so the shoe keeps its feel for longer. It is a comfort layer, not a speed one — and it is the first thing to come out if you wear your own orthotics.

Salomon - Speedcross 6 GORE-TEX

Midsole

Two different Adidas foams under one heading. Boost is made of fused TPU capsules: it returns more energy than almost anything else and, unusually, does not go stiff in the cold — which is worth something between November and March. It is also heavy. Lightstrike is EVA-based, lighter and firmer, meant for quicker work. Long easy miles and cold mornings favour Boost; sessions and race day favour Lightstrike.

Adidas - Ultraboost 5

React is the foam; Air is the pressurised gas unit. React cushions along the whole length of the sole and holds up well without packing down. Air cushions at one point, usually under the heel. In the running models what you feel is the React; on the lifestyle models the visible window is doing more for the look than for your stride.

Nike - Pegasus 41

Foams with nitrogen forced into them under pressure — lighter and springier than plain EVA at the same volume. The difference shows up when you push off hard, which means when you run fast. At an easy pace the advantage over a good EVA is small, and the shoes that carry it cost noticeably more.

Geometry rather than material: the sole is curved like a rocking chair and rolls the foot forward for you. It saves the ankle and the calf a good deal of work over long hours on your feet, which is why it gets recommended while coming back from injury. The cost is stability — at walking pace and on uneven ground it feels tippy, and it is no use at all for side-to-side work in the gym.

Hoka - Clifton 9

A soft, high-volume New Balance foam: it takes the impact rather than handing it back. That makes long easy miles kinder on the knees, and it suits a heavier runner particularly well. For tempo work and racing there are more responsive foams — several of them in New Balance’s own range.

A light Asics foam with an obvious bounce, and the reason the Novablast has the following it does. It makes easy miles genuinely enjoyable. The stack is tall, though, so on a rutted path or through a sharp change of direction the shoe rolls under you.

Asics - Novablast 4

Brooks foam with nitrogen blown into it. Soft underfoot without the dead, sunken feeling that plain soft EVA gives after a few miles, which is why it carries the Glycerin and the Ghost Max. Softness is not speed: a foam this compliant absorbs more than it returns, and like every soft foam it packs down sooner than a firm one.

Not a foam at all. Two raised walls sit either side of the heel and do nothing until the heel rolls further than it should, at which point they stop it. Brooks call it holistic support because it works on the movement rather than on the arch. Worth knowing what it is not: it is not arch support, and on a gait that never over-rolls it simply never engages.

Saucony use the name for a family, not one material. Plain PWRRUN is an EVA and TPU blend, PWRRUN+ is lighter and springier, and PWRRUN PB is the PEBA in the race shoes and feels like a different shoe altogether. The name on the box therefore tells you less than it looks: check which of the three is actually in the model.

Saucony - Endorphin Pro 4

The hollow pods under an On. They collapse on landing and lock as you push off, which gives the brand its distinctive feel underfoot — people tend to either take to it immediately or not at all. The pods are open to the ground, so on gravel and trails they pick up stones, and the newer models close them off for exactly that reason.

On - Cloudmonster

The compound the pods are moulded from. On claim it holds its rebound across temperatures, which matters more in a British winter than the marketing suggests — most foams stiffen in the cold. Helion is a family name too, covering several versions, so it says which house the foam belongs to rather than what it does in a given shoe.

On - Cloudmonster

A stiff carbon-fibre sheet set inside the foam. It creates no energy — it changes where yours goes, resisting the toe joint as it bends so less of the push-off is spent folding the foot. Shoes built around one measure roughly 4% better running economy in the lab, but that figure belongs to the whole shoe, foam included, not to the plate. The cost is stiffness, which loads the calf and the Achilles differently: ease into them. World Athletics allows one plate and a 40 mm stack, which is why every race shoe stops at exactly 40.

Saucony - Endorphin Pro 4 Nike - Vaporfly 3

Outsole

A rubber compound licensed from the tyre company. The difference shows on wet tarmac, exactly where an ordinary outsole starts to let go — which, in this country, is most of the year. On dry ground the advantage is slight, and the rubber adds both grams and pounds to the price.

Adidas - Ultraboost 5

A hard Asics rubber placed where the sole wears fastest: the outer edge of the heel and the forefoot. It adds real miles to the life of the shoe. It also weighs more than foam, which is why it appears in patches rather than across the whole sole.

Asics - Novablast 4

Nike’s original waffle pattern: square lugs that hold on tarmac and on a packed path alike. It is a genuine all-rounder, with the usual catch — in mud the squares clog, and on wet rock they slide.

Nike - Pegasus 41

A thin rubber laid in patches over Hoka’s foam sole, only where the wear actually happens. It keeps the weight down and leaves the shoe soft. It also wears through faster than a full rubber outsole, particularly on road miles with a heel strike on the outer edge.

Hoka - Clifton 9

Puma’s rubber, standard across the NITRO range. One of the few places where the difference is immediate: it holds on wet tarmac and on painted surfaces — underpasses, multi-storey car parks, the tiled bit outside a supermarket. The trade is a firmer feel underfoot.

Not one rubber but a family of compounds and patterns, combined according to the ground the shoe is built for. On soft, churned-up trail the deep lugs dig in and hold. The same lugs on tarmac and rock wear down quickly and you feel every one of them through the sole.

Salomon - Speedcross 6 GORE-TEX

Waterproofing

A membrane between the lining and the upper: it stops water getting in and lets vapour out, though more slowly than plain mesh does. It earns its place in rain, slush and snow — and it is worth saying plainly that a waterproof shoe which does fill up, over the collar, then stays full.

Salomon - Speedcross 6 GORE-TEX

Models

The result. The bar here narrows it further by activity, material and price.