Sneaker Cushioning: What’s Best for You?
Odds are you know a little bit about the sneaker cushioning under your foot. At least, you know that Nike uses “Air” technology, or that Adidas’ uses Boost. However, do you know the difference between ZoomX and Zoom Air? What about e-TPU vs. TPEE?
No one foam will work for everyone, in every situation. Each has their own benefits, drawbacks and costs. This article is going to explain the differences between the various forms of cushioning, along with a few examples of sneakers you might have worn.
Pros and Cons of EVA Foam (ethylene-vinal-acetate)
Odds are pretty good that if you pick up a random sneaker off the shelf in a store, it’s probably made of EVA foam. First used by Brooks in 1975, though popularized by Nike a few years later, EVA is a staple in footwear. You can find it in sneakers, boots, dress shoes, and more.
The benefits of EVA are primarily it’s weight to squish ratio – especially for the cost. EVA is extremely light weight and incredibly flexible, while still providing excellent shock protection. For many years, all of the premier running shoes featured EVA soles. Further, since we’ve long since cracked the code on how to make it and shape it, affordable brands are able to create new and interesting designs without significant cost outlays.
The drawbacks of EVA are in its durability. Compared to just about any other type of foam out there, EVA will bottom out the fastest. In fact, for most EVA shoes, you’ll bottom out the cushion before you wear out any other part of the sneaker. This happens for the same reason EVA is light and squishy – the bubbles. Over time, the bubbles in EVA pop and lose the ability to rebound after a step.
EVA can be found just about every – the vast majority of sneakers out there use it. Nike’s React, Cushlon, and Grind, New Balance’s Fresh Foam, Adidas’ CloudFoam and Bounce are all examples of EVA foam.
Pros and Cons of Polyurethane Foam
The star of the 1980’s and 1990’s, Polyurethane, or PU, was primarily used in basketball sneakers. Or, sneakers that wanted to look like basketball sneakers. Polyurethane fell out of fashion in footwear around 2000, but the number of retro sneakers out there means you probably own a pair with it.
The biggest benefit of polyurethane is its durability. The rebound effect is the same as a memory foam mattress, another PU product, so you don’t get the harsh compression/decompression that causes the failures of other types of foam. If you were going to get something to play a lot of pick-up games in, you probably wanted this.
On the other side, there are two big drawbacks with polyurethane sneakers. The first is the weight – these things are bricks. Anyone who has switched from a modern basketball sneaker to something like a Jordan 5 will know this all too well. Further, there is the dreaded hydrolysis. Hydrolysis is the process where the foam absorbs water from the air and eventually falls to pieces. It’s why older Jordans in your closet fall apart.
There are ways to battle the hydrolysis – denser foams can absorb more water at the tradeoff of comfort, and wearing them helps – but the risk never goes away.
Pros and Cons of Boost (eTPU, or expanded thermoplastic polyurethane)
Boost foam – associated with Adidas but originally created for Puma – is a more modern take on the polyurethane foam used back in the 80’s and 90’s. Adidas’ exclusive agreement with BASF to make it has recently expired, so now just about every brand makes something like it.
There are a ton of benefits to eTPU. Everyone is aware of the comfort, but it also famously provides a bit more energy return than other options available when Boost debuted. There was a time period around 2015-2019 where everyone from real athletes to your fat uncle wore absolutely nothing but this due to the comfort. Another underappreciated benefit is the durability. Sure, it could bottom out and loose that amazing step in, but it still provided protection for hundreds of miles.
As for drawbacks, there are surprisingly few. For a long time, Boost was expensive, but now you can find it on sneakers at the outlets for under $40 dollars and even Sketchers has version of this foam. Others might not like the Styrofoam-like design. You can encapsulate this foam, but it loses a lot of the squish when doing so. Finally, it’s pretty heavy for a true performance sneaker.
Outside of Adidas Boost, you can find this in Sketchers HyburBurst Pro and Reebok FloatRide Energy.
Pros and Cons of Air
Nike Air is one of the most famous forms of sneaker technology out there. From the Air Force One to the Air Jordan One, you almost certainly have owned a number of pairs with this. Though, it’s worth noting, air is almost always tied to one of the other foams on this list.
Even though it is easy to say that Nike’s marketing did the heavy lifting, there are real benefits to the air technology. Especially when it came out in 1979. The most obvious is weight – the air inside the pouch weighs nothing. Hard to get lighter than zero. The other is response – where every other foam needs to take a bit of time to expand for the next landing, air expands immediately.
As for drawbacks, the biggest drawback is that it’s just not the best for actually cushioning the impact of your foot (a problem Nike solved with ZoomAir). A small bag of air isn’t really going to compress, just deform. And a large pouch of air – think Air Max 720 – will deform a whole lot. The other concern is popping. If you get a hole in one of those pouches for any reason, the whole sneaker is toast. If you can keep it together, this is a pretty durable option.
Nike Zoom Air
Zoom Air was Nike’s attempt to solve some of the issues that Nike Air had 20 years after launch. While still using a pouch full of air, the big change is the inclusion of a number of small elastic fibers that help keep the pouch in specific shape during compression and expansion.
For the most part, Zoom Air has the same benefits as Nike Air, with significantly fewer drawbacks. However, it does add one – cost. Zoom Air is hard to build, especially in larger pouches, so it comes with a much higher price tag than regular air shoes.
Pros and Cons of Rubber
While it might sound crazy to those who look to sneakers to provide a plush ride, a surprisingly large number of sneakers are made where rubber is the only thing in the mid or outsole. Most commonly seen in cup sole designs, this is one of the oldest forms of cushioning available due to its simplicity in design.
The pros of using rubber as your “foam” are the durability and how that can impact looks. Rubber is going to be, by far, the most durable option for a solid midsole in a sneaker. The outsole can basically run all the way to the insole (though, you might have void added for a bit of compression). This durability also means you can make shapes that are much thinner than other types of sneakers – giving a minimalist design impossible to replicate.
The cons of using rubber are due to the comfort. Or, rather, the lack there of. Rubber simply doesn’t compress in the way that the other types of sneaker padding does. I don’t think anyone picks this style as their first pick for comfort.
These foams are (for the most part) still the exclusive realm of super high-end running sneakers. However, that was true of all of the foams above at one point. I would except to see this tech trickle down to every day sneakers within the next few years.
Pros and Cons of Pebax (Polyether Block Amide)
One of the newest types of foam out there, Pebax caught headlines when it was used on sneakers that absolutely smashed the marathon record. One of the most complicated forms of foams out there, different manufacturing methods create different shaped blocks within the structure of the foam itself. This allows manufacturing to super-fine-tune the feedback of the foam itself.
You may have heard this referred to as Pebax, which is the name brand. The generic name is PEBA – though some claim Pebax to be superior to the point of putting it in a different category.
The pros of Pebax are the absolutely amazing comfort and energy return. This material is truly game changing – to the point where even an out-of-shape guy like myself looks for reasons to go on a run. It feels like little mini-trampolines on your feet. It’s also very light weight, allowing for thicker stacks and even more comfort.
As for cons, Pebax sneakers have quite a few. First is cost. Almost every sneaker with this tech in it starts around $200, and the Nike/Adidas ones are higher than that. Next, they don’t work well visually for casual wear. This foam creases immediately, and can look pretty bad quickly. Finally, the durability will pretty much be at the bottom of this list. Wearing these casually, you might completely bottom out in a couple of months. This is especially true if used in very cold or very warm weather.
The most famous sneaker branding that uses this technology is Nike’s ZoomX, but ASIC’s FlyteFoam, Saucony’s PWRRUN+, and Reebok’s Floatride are all the same tech.
Pros and Cons of TPEE (Thermoplastic Polyester Elastomer)
Designed to try and offer an alternative to PEBA, TPEE is currently really only used in Adidas’ Lightstrike Pro. It was first used as a way to try and augment EVA foamed sneakers with a bit of extra spring, but is now available in full mid-sole make ups.
The pros of TPEE over PEBA is its durability and temperature range. Able to be used in cold and warm weather, TPEE already offers significantly better usability than its competitor in real-world usage. Even better, the foam should last longer before losing its spring. To be clear, it is sill less durable than others on this list, but getting closer to usable in a casual sneaker.
As for drawbacks, TPEE isn’t quite at the same level of comfort and energy return as the PEBA. Amazing, for sure, but not quite as good.