If you're in the market for a new pair of shoes, whether that be a new daily trainer or for race day, you can often find yourself stumbling down the rabbit hole of what foams different models of shoes use. Whether that be to reduce the weight, give you more bounce, or more cushion, then this can get a little confusing- especially when brands often use a mix of multiple compounds.
As this is often the case, we have created a list of the most popular foams used by brands on the market, why they are used, and what type of shoe they are used in.
Compression Moulded EVA
EVA- Ethylene Vinyl Acetate
This is the most traditional, classic running shoe foam on the market, and has been the market standard for decades. During manufacture, EVA is compressed by layers to create the foam underfoot. Given its age and popularity, it is relatively inexpensive to produce, so this is why it is found in a wide range of daily trainers. This doesn't mean it is bad, but it is found in a wide range of models.
As this type of foam is firmer and less manipulated than other foams on this list, shoes that utilise this type of foam are more stable, meaning that the midsole doesn't collapse or ‘wobble’ as much when running. By virtue of the fact that it is firmer, this will also mean that the shoe will be firmer.
For daily running, this will be durable enough to cover you; however, over long-term use, this will lose its return and bounce, as it compresses more, the durability will decrease.
Any Compression Moulded EVA (CMEVA) will have an initial energy return around 60%
Examples of these shoes include the Hoka Bondi 8 and Arahi 6. In Brooks, this foam was used in the old Adrenaline GTS 20 and older Saucony Guide models.
Super Critical EVA
Although at its core it is still traditional EVA, it is more manipulated during manufacture so that it has a higher energy return and is significantly lighter.
Rather than just compressing the foam by layers, the ‘super critical’ element is introduced when nitrogen or CO2 is injected into the foam under high pressure. By doing so, the gas expands, creating bubbles (cells) in the cushioning, which in turn results in an overall lighter foam- leaving an impression of a sort of aerated sponge style.
For everyday use, this essentially means that the cushioning is more durable as it doesn't pack down as quickly, and it also means there is better rebound as the bubbles give a sort of trampoline effect underfoot, giving an energy return of around 70%.
Models which use this supercritical foam include:
Hoka Mach x2, Clifton Pro (ProGlide +), Brooks Hyperion Max 2 (DNA Flash) and Saucony Triumph and Endorphin SpeedPWRRUN
TPEE
Thermoplastic polyester elastomer.
Colloquially being called the foam of the future, TPEE acts differently as unlike the previous two iterations of EVA, this is different by the fact that its compounds are essentially a mix of rubber and plastic instead of a traditional foam.
By mixing plastic and rubber, this retains the two best elements together: the flexibility of the rubber alongside the tough structure of plastic, fundamentally making it a durable cushioned material. This also means that it is more popular for those long-distance running shoes but also those race day shoes, as it gives valuable energy return as well as spring and bounce, which a runner wants to get for valuable energy return and longer-term wear. As a side benefit, it also becomes more temperature resistant, behaving better in both colder and warmer weather.
Models that use this foam are usually race-day shoes, as this foam can give up to 80% energy return.
Models include: Hoka Cielo x1 2.0, Saucony Endorphin Elite 3, Brooks Hyperion Elite 4
PEBA
Polyether Block Amide 90% return
This is the foam which has been the driving force behind most of the ‘super shoes' that you see on the market now. Similar to TPEE, it keeps the flexibility of rubber and the durability of plastic in a more enhanced way.
It was originally used in winter sports equipment like ski boots, as once again it can withstand a wide range of temperatures without breaking down.
It is extremely lightweight as it has a low density, meaning that the midsole weight drops by around 20-30%, hence why many race day shoes can have extremely high stacks without sacrificing on the weight.
Due to the high rebound the energy return it can have up to a energy return of up to 90%.
Models that use this newer foam include-
Nike AlphaFly, Hyperion Elite 5 (DNA Gold), Hoka Rocket x2, Saucony Endorphin Pro 5
PEBA- Based
With pure PEBA, it can often get quite expensive, so many brands tend to lean towards using a blend of PEBA and a mix of other polymers. To bring down the price for the consumer, it is often mixed with EVA, TPU, or other elastomers to keep the majority of what you get from pure PEBA.
Another benefit of this mixed foam is that when it is mixed with more dense foams, you re-introduce some stability; oftentimes when foams are too soft they can lead to greater rotational issues; with any plated race-day shoe this is expected, but this can be increased. In addition, this then extends the lifespan of the shoes slightly as well, as the midsole will have greater rigidity; this will also mean you will get more miles than some of the all-out race-day shoes.
Models include: Hoka Skyward x2, Saucony Endorphin Azura, Brooks Hyperion Elite 5.
TLDR:
- PEBA (highest rebound, lightest)
- PEBA-Based (close to pure PEBA but less expensive)
- TPEE (high rebound, often a little firmer but more stable)
- Supercritical EVA (less aggressive than TPEE but more energetic than EVA)
- Compression Moulded EVA (CMEVA) most durable and stable but least lively.
It is also worth noting that although these foams play a large role in the shoes, other elements like plates and rocker geometry all help to make your running more efficient and (somewhat) easier.
Hopefully this has helped to give an understanding of the foams now on the market and what you should look out for. But if you need any more advice or would like to make sure you're getting the right pair before you start a new training plan or the right race day shoe, book a gait analysis here.