Demystifying Running Shoe Foams: The Runner's Guide to PEBA, TPU and EVA

Shoe shopping can feel like swimming through a bowl of alphabet soup: acronyms galore, with each brand having proprietary names for their foam, plates, midsole curve (looking at you, Saucony Speedroll) and even lacing system (Nike really tried to make "Flywire" a thing). While it's hard to distinguish the science from the marketing jargon, choosing the right midsole foam is one of the keys to picking the right shoe for you. 

The midsole foam used in a running shoe is the leading player in determining performance, durablity and comfort. In this article, we dive into the world of running shoe foams and explore three popular options: PEBA, TPU, and EVA. We'll compare the merits and drawbacks of each and provide top picks in each category.

PEBA Foam: Super Shoe Speed

First introduced to the running world by Nike in 2017, PEBA (polyether block amide) is a lightweight and highly resilient material that's known as "super foam" due to its high performance properties. Known for its energy return and responsiveness, PEBA foam offers a bouncy feel during each stride. This foam excels in providing a snappy toe-off, making it ideal for runners seeking an extra boost in their performance. PEBA foam also maintains its properties in a wide range of temperatures, ensuring consistent performance on hot summer runs or chilly winter outings. 

Keep in mind that shoes with PEBA foam may have a higher price tag due to its premium characteristics. However, the stuff certainly lives up to its "super" moniker: it's the foam in most marathon-racing super shoes on the market (which also use carbon fiber plates, a topic for another article), like the Nike Alphafly used by Eliud Kipchoge to break the 2 hour marathon barrier. Due to its popularity in higher end racing shoes, PEBA is also starting to trickle down to some daily trainers, which we've listed below. 

PEBA Cheatsheet

• Main use case: Race day shoes
• Key qualities: High energy return, light weight, temperature resistance
• Drawbacks: High price and low durability compared to other options
• Typical shoe price: $200+
• Brand names: Pebax, Nike ZoomX, Saucony PWRRUN PB, Saucony PWRRUN HG
• Popular race day shoes using PEBA: Nike Vaporfly, Nike Alphafly, Hoka Rocket X 2, Saucony Endorphin Pro 3, Saucony Sinister, Saucony Endorphin Elite, Mizuno Wave Rebellion Pro
• Popular daily trainer shoes using PEBA: Nike Invincible Run 3, Saucony Endorphin Speed 3, Tracksmith Eliot Runner, Topo Athletic Cyclone 2, Saucony Tempus

Note: this foam is commonly referred to as Pebax, which is trademarked by the producer of that foam variant, Arkema. Some shoe brands source their PEBA from Arkema, so they're using real Pebax, while others buy it from generic producers. So while it may be correct to call it Pebax depending on which shoe you're talking about (e.g., Nike uses real Pebax), you may also be calling a store brand tissue a Kleenex.

TPU Foam: Comfort for Cruising

Next up, we have TPU (thermoplastic polyurethane) foam—a versatile foam popularized by Adidas in the Ultraboost line of shoes. TPU foam strikes a balance between responsiveness and cushioning, making it a reliable choice for daily trainer shoes where you'll be packing on the miles. Both Adidas and Saucony use an expanded-bead version of TPU that is soft underfoot while also being resilient. This foam offers excellent durability, providing long-lasting support during your everyday training runs; I got 700+ miles from my first pair of Adidas Ultraboost shoes. TPU foam also offers good energy return and stability, helping to minimize excessive foot movement and reduce the risk of injury. The main downside with TPU is that it tends to be heavier than competitor foams. 

Over the last few years, TPU has been getting phased out in favor of lighter weight PEBA and more advanced EVA. However, it's hard to beat in terms on on-foot comfort, especially in the Sacouny Triumph series. So if you're seeking a well-rounded shoe that combines comfort, responsiveness, and durability, TPU foam might be your go-to option.

TPU Cheatsheet

• Main use case: Comfort-oriented daily trainers
• Key qualities: Comfort, cushioning and bounce
• Drawbacks: Heavier weight
• Typical price: $130 to $160
• Brand names: Adidas Boost, Saucony PWRRUN+, Skechers Hyper Burst Pro
• Popular shoes using TPU: Saucony Triumph, Adidas Ultraboost, Adidas Solarglide, Adidas Supernova, Skechers GOrun Razor

EVA Foam: Durable for the Daily

Last but not least, we have the tried-and-true EVA (ethylene-vinyl acetate) foam—the staple of running shoe midsoles. EVA foam is known for its extreme durability mixed with its cushioning properties, providing a plush and comfortable ride. It absorbs shock effectively, reducing the impact on your joints and muscles during those aerobic base-building runs.

EVA foam shoes are often more affordable compared to those with PEBA or TPU foam, making them accessible to a wider range of runners. It's certainly not the sexiest option on the market, but it's what powers most of the workhouse trainers you reach for to pile on those daily miles.

• Main use case: Daily trainers
• Key qualities: Durable, responsive and versatile
• Drawbacks: Not as light or bouncy as PEBA; not as inherently comfortable as TPU
• Typical shoe price: $100 to $180
• Brand names: Saucony PWWRUN, On Helion, Asics FF Blast, New Balance Fresh Foam
• Popular shoes using EVA: Hoka Clifton, Hoka Bondi, On Cloudmonster, Saucony Kinvara, Saucony Ride, Brooks Ghost, Brooks Glycerin, New Balance Fresh Foam X 1080, New Balance Fresh Foam X 880, New Balance Fresh Foam More

Supercritical Foams

Supercritical foam isn't a compound itself, but rather a process used to infuse gas into one of the three foam compounds we've outlined above (or other less common foam types not listed here). Supercritical foams generally add bounciness and reduce weight without harming a shoe's durability. Below, we've listed some of the common supercritical foams and shoes on the market today.

Supercritical PEBA

These shoes are geared toward race day, providing bounciness and high response for your fastest efforts. Most of the shoes below have a carbon fiber plate (Sacuony) or carbon-infused rods (Adidas) for increased race day performance.

• Brand name supercritcal PEBA: Saucony PWRRUN HG, Adidas Lightstrike Pro
• Shoes with supercritical PEBA: Saucony Endorphin Elite, Adidas Adizero Adios Pro, Adidas Adizero Takumi Sen, Tracksmith Eliot Runner (sockliner only; midsole is standard Pebax)

Supercritical EVA

These shoes are designed mainly for fast training days or more exciting daily miles, with the gas-infused EVA providing a poppier ride than its non-supercritical counterpart.

• Brand name supercritical EVA: New Balance FuelCell, Brooks DNA Loft, Brooks DNA Flash, Skechers Hyper Burst, Altra EGO PRO
• Daily trainers with supercritical EVA: New Balance FuelCell SuperComp Elite, Skechers Max Road, Altra Vanish Tempo
• Race day shoes with supercritical EVA: New Balance FuelCell SC Trainer, Altra Vanish Carbon

Choosing the Right Foam: Three Considerations

Now that we've covered the basics, how do you choose the perfect foam for your next running shoe? Consider these factors:

Running Style

Think about your running preferences and goals. If you're a speed demon seeking maximum responsiveness and performance for your next race, a shoe with PEBA foam (and a carbon plate) might be your best bet. If you prioritize comfort and bounce for long-distance runs, TPU foam could be your winner. And if you're after a durable weekday warrior you can reach for again and again, a show with EVA foam will likely fit the bill.

Foot Type and Biomechanics

Pay attention to your foot shape, arch type, and any specific biomechanical needs. Some foams may offer better support or stability for overpronators or runners with higher arches. If you have any concerns or specific requirements, it's worth checking with a knowledgeable running shoe specialist (support your local small-owned businesses!).

Budget

Consider your budget and how much you're willing to invest in your running shoes. PEBA foam shoes tend to be higher-priced, while EVA foam options are usually cheaper. If you plan on running multiple days a week, it also could be worth it to build a running shoe rotation with a shoe from each category.

Final Thoughts

When it comes to choosing your next pair of running shoes, understanding the differences between foams is key to finding the perfect fit for your needs. PEBA foam delivers responsiveness and energy return at a light weight; EVA offers stability and reliable cushioning in a heavier package; TPU is the king of comfort. 

Cheers and thanks for reading. Email us at yowana@supwell.io with any questions or suggestions.