Supercritical Foam Explained
In brief: Supercritical foam is a midsole material made by infusing a polymer with nitrogen or CO2 in a supercritical state, neither gas, liquid nor solid. A rapid pressure release creates a uniform microporous structure that is lighter and more responsive than traditional chemically foamed midsoles. It underpins many modern super shoes from brands including Saucony and On Running.
What is supercritical foam?
Supercritical foam is a midsole material manufactured using a gas such as nitrogen or carbon dioxide held in a supercritical state, a condition where the substance is neither gas, liquid nor solid but blends properties of each. Instead of relying on chemical blowing agents to create bubbles, the process foams the polymer physically, which produces lighter and more responsive midsoles than traditional methods. This physical foaming is the technology behind much of the modern super shoe revolution, where cushioning that is both soft and springy has transformed how performance running shoes feel and perform. At OD's you will find it in premium running shoes from Saucony and On, where it delivers the lightweight, energetic ride that has redefined expectations at the front of the running market.
How is supercritical foam made?
The process begins by infusing a polymer with a supercritical fluid, the gas held under conditions where it behaves as both gas and liquid and penetrates the material thoroughly. A rapid release of pressure then causes the gas to expand, creating a uniform microporous structure throughout the foam. Because the bubbles are formed physically and evenly rather than through a chemical reaction, the result is consistent, fine-celled and remarkably light. This uniformity is key to the performance: an evenly structured foam returns energy more predictably and resists the dead, flat feeling of cheaper midsoles. The technique can be applied to several base polymers, which is why supercritical foams appear in so many different brand-specific midsole compounds across the market.
Why does it perform so well?
The headline benefits are low weight and high energy return. Supercritical foams can reach densities as low as around 0.09 grams per cubic centimetre with energy return exceeding 80 percent, an exceptional combination of light and lively. When the base polymer is PEBA, a supercritical midsole can be up to 50 percent lighter than EVA while improving running economy by roughly four to six percent, meaning you spend less energy to hold the same pace. That efficiency gain is the whole point of the super shoe, turning a softer, bouncier midsole into measurable performance. The microporous structure cushions impact while springing back quickly, so the foam feels protective on landing and propulsive on toe-off, a balance traditional foams struggle to match.
Which shoes and brands use it?
Supercritical foam now spans the industry, applied to several different base polymers. Adidas Boost uses supercritical TPU, Nike ZoomX uses PEBA, Saucony's PWRRUN HG is a PEBA-based supercritical foam, and Puma Nitro uses EVA or TPU formulations. Each brand tunes the polymer and process to its own ride character, so a Saucony midsole feels different from an On or a Nike one even though they share the underlying foaming science. The breadth of adoption shows how foundational the technology has become: from daily trainers to elite racers, supercritical foaming is now the default route to a light, responsive midsole. At OD's it features in premium running shoes from Saucony and On Running, the science behind the super shoe revolution.
Supercritical Foam at OD's Designer Clothing
At OD's we stock premium running shoes built on supercritical foam from Saucony and On Running, giving you the lightweight, energetic ride that defines the modern super shoe. Our team can explain how each brand's foam feels underfoot and help you match a midsole to the way you run, whether you want plush cushioning for daily miles or a snappy, propulsive platform for race day. Browse the running range online with next-day delivery and free click and collect, or visit our St Helens store to try pairs on and feel the difference supercritical foaming makes. It is some of the most advanced midsole science available, and it is genuinely transformed how a good running shoe feels.