The Technology Behind the Running Sneakers That Make You Feel Like You're Not Wearing AnyS

Ever since Christopher McDougall explained and espoused minimal running in his 2009 book Born to Run shoemakers have responded by trying to find the space between futuristic design and a return to nature with innovations like zero drop shoes (which don't elevate the heel), lighter footwear, sneakers that look like gloves — you get the idea. New Balance in particular has made it a mission to find the perfect balance between comfort and protection and actually feeling the ground underfoot. Their Minimus HI-REZ sneakers are engineered to give runners a high-definition running experience, using the language of pixels and resolution to get at the heart of what minimal runners want in their sneakers.

I recently spoke to Katherine Petrecca, New Balance's Innovation Studio Manager, about what it took to design their sneaker of the future.

Why develop the Minimus HI-REZ now?
We actually wanted to introduce this product two years ago. We had the idea for it several years ago as we were gearing up to build our first Minimus shoes. This was one of the original concepts; to have a sole that [had] completely articulated, independent areas of cushioning. But we didn't know how to do it! We did a little trial and error, but we weren't able to figure it out. So we put it on the back burner and continued on with the more traditional product, [the one that used] more processes that we knew, while we figured it out.

What does it mean for a shoe to have a "high resolution" experience?
The difference between this midsole and the traditional midsole is that when you look at most athletic shoes, the midsole is just one continuous piece of foam — think of that as one pixel. Our HI-REZ product has 42 individual midsoles, or "pixels," so the opportunity to receive more direct and specific feedback and sensation is enhanced.

Does it really matter that a runner feels the ground beneath his or her feet?
We designed this shoe with the experienced, dedicated minimal shoe runner in mind. What they're looking for is to allow their natural biomechanics to take over as much as possible — to have the protection to get through and across terrain, but with as barefoot an experience as possible.

You spoke to a number of barefoot runners in the process of developing this shoe. What was that process like?
We talked to a lot of minimal runners over the past few years, and what we found is that, for minimalists, they own an awful lot of shoes. They're looking to use different types of shoes for different types of workouts. (We're seeing this more than ever in the entire running population.) Some of them are doing some of their running barefoot.

How much time and testing went into developing it?
Much longer than our typical process. We started with 6 or 7 concepts, and then went through several rounds of trying to narrow them down to one. It was new for us, and very new for our factories. It required different equipment than we normally use. So it took quite a while, but we're happy to finally have the process understood so that we can utilize it in different types of products.

Were there any major pitfalls in the design process?
[Laughs] There were so many! How to attach the pods. We didn't want to use glue; we didn't want to cement 42 individual pods onto the bottom of the shoe. So we needed to find a way to inject the foam directly onto a piece of fabric that would be the base of the shoe. We tried several different ways, and even the chosen way took many months to figure out how to do that reliably. And then the next biggest challenge was we had a piece of fabric with 42 lugs on it. We had to get that onto an upper. Normally it would be cemented, but you couldn't do that with the fabric. So we actually stitched the upper and sole together, which was a new process. We continued to unearth new obstacles [chuckles] but it was interesting to invent new ways to solve old problems.

Can you describe the materials you used and how they were ideal for the HI-REZ?
[We had] to figure out which type of foam to use for the lugs. We needed one that could stand up to ground contact, but that could also adhere to the fabric when it's injected. We needed to find a base fabric that was flexible and also porous enough to allow for the mechanical bonds with the foam, but at the same time be tough and resistant enough to be exposed to the elements. So, again, there was a lot of trial and error.

For what kinds of terrain or situations is the HI-REZ ideal — or not ideal?
We recommend that people use it as much as possible on clean, level surfaces: roads, sidewalks, grass, sand, track. We understand that it has limitations. You'd have to have a really seasoned, hardened foot to run on trails with these. So we do not recommend them for use on gravel or trails where you're going to be hitting objects or hazards.

How might a seasoned runner compare the HI-REZ to your average running shoe?
This is a zero drop shoe versus the traditional 12-mm [heel-to-toe differential]. It [weighs] 4 oz. versus the traditional 12 oz. So this isn't something we'd recommend for somebody who has no experience running in a minimal shoe. But we would recommend it for people who prefer minimal shoes to use in workouts [geared toward] working on their form.

Would you say that the Minimus HI-REZ improves running performance?
I would say so! I think it's certainly next-level in terms of allowing the foot to move as independently as possible within a shoe.

How do you expect shoes to look in the future?
A few years back there was more of an arms race in terms of how much people could put into shoes. You saw a lot of molded, plastic components and stability devices, and a sort of one-upmanship in terms of the components being put into a shoe for correction. Now, there is more of an emphasis in neutral cushion shoes, and people pay more attention to their running form and its effects versus their shoes. So I think you'll see people continue to design around that, to design for more simplicity using the geometry of the foam, and design to deliver benefits versus adding weight and gear.

Thanks to Katherine for taking the time to explain "hi-res" running shoes. Learn more about New Balance's entire line of Minimus footwear here.

Kwame Opam is a tech writer and content producer for Studio@Gawker.