Meet Yurri Mial, the Designer of Under Armour’s Slingflex, SpeedForm Fortis, Fat Tire Mid, and More

One of the most surprising shoes of 2017 has been the Under Armour Threadborne Slingflex. With the debut of Threadborne on the Curry 3, we were introduced to a supportive, stiffer-than-normal woven material that wouldn’t seem to make a comfortable, flexible runner. Well, it did, and the Slingflex is a shoe worth checking out for the versatility in performance and design (performance review here).

But who was behind the design of that runner? It was a question the good people at Under Armour solved for us and gave us access to. I present the brilliant Yurri Mial.

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[Bryan Hinkle for]: For the record, what is your name and where are you located?

Yurri Mial, Senior Designer, Footwear – Run at Under Armour.

Being young, and fairly new, how many shoes have you worked on already, either lead designer or on the team? Is it only running, or lifestyle, basketball, training? Which ones were they?

I’ve been in the industry for about eight years now and in that time I’ve designed nearly 50 styles of footwear. Since coming to Under Armour in 2013, I’ve designed around 20 styles that you’ve seen at market. I’ve primarily worked on running and lifestyle footwear silhouettes, including UAS (Under Armour Sportswear). There honestly have been too many to pick just one favorite, but a few in particular that stand out are the Fortis, Hightlight Delta, UAS Club Mid, and Fat Tire Mid.

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What is your favorite design you have done, besides the Slingflex?

That’s a tough question because every season that answer changes for me. Since we design into the future, I have some styles releasing soon that I’m really excited about. If I had to choose, I’d say the SpeedForm Fortis holds a special place in my heart because of the lessons for me that came along with the design process.

Where would you put the Slingflex in the UA lineup: running, lifestyle, crossover to both? Personally, I wear them for everything — relax and chill, running short distances, and weight training. 

I would put it in both, but it was born from performance like all of our products. You see the striking color block on the lateral of the Slingflex upper? That is actually a knit engineering process that provides the wearer with more stability for quick lateral movements or sprints. Threadborne is not just another knit for the sake of a trend, each style has true functionality.

The Threadborne on the Slingflex and the Threadborne on the Curry 3 feels completely different — the Curry is stiff and solid while the Slingflex is soft and sock-like. Is this an evolution of the materials or a design/category specific material change? Can the material be adjusted for each sport/activity or is the softer feel the ultimate aim?

Threadborne is an umbrella of techniques and processes that allow you to tune and design at the thread level. Where appropriate, the yarns and structures may be more dense for stability in one style, or softer and stretchy for zonal compression in another style. It all depends on the wearer and what they want out of their footwear.

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With the use of Dyneema, is that more of a structural material or durability? To me, during the review, it seemed structural, with the direction of the threads and the flexpoints around the toe. 

Exactly! It’s a very strong material that provides structure and also has natural cooling properties. Its application makes the most sense in the forefoot because, naturally, a tremendous amount of force is applied in that area while the wearer is running. Additionally, it’s a smart place to keep the foot cool.

The outsole being segmented and cut out provided a great feel underfoot, especially coupled with the soft upper. For sprint work and short distances this felt great, but are there plans to add any structural elements, like a stiffer midfoot shank or medial post?

We feel great about where the style of the Slingflex landed. We have some additional styles coming up that address the needs of someone looking for more stability in their run. We’re excited for you to check those out too.

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The cushioning of the Slingflex is Charged, and we see the layers in the midsole, and honestly, it feels fantastic. Are there any plans to adapt this Charged to the basketball line? Maybe not the Curry line, because I know he is very specific in what he wants on-court, but the Drive line? Or maybe a shoe you can’t talk about yet?

What you’re experiencing is the Charged Cushioning & Micro G dual layering in the Slingflex. The combination of both works well for running. I can’t really speak to the basketball line, but I know they are constantly innovating on underfoot platforms that deliver the right amount of cushioning and support needed for the court.

Lastly, and this may be too far, but I talked to Dave Dombrow last year about some upcoming developments, and he mentioned a crossing over — taking elements from U.S. football and using in running, or basketball and using in training. How has that happened in the year since that interview, or have you seen it at all?

I’ll say this, 2018 is going to be crazy!

yurri mial UA designer

If you enjoyed our talk with Yurri Mial, let us know in the comments below. Have you worn some of his designs?



  1. Cool interview.

    Seems like a very down-to-earth, simple kind of guy and if the Under Armour Threadborne Slingflex (sounds like a ballistic material for a futuristic weapon in the army) is any indication, is a helluva designer too.

  2. This is the type of stuff that makes weartesters a great website. It’s not just posts about hype shoes, you guys go behind the design of the shoes. I love it.

  3. Yurri is such a great guy, and definitely inspirational! I had the chance to intern in apparel design at UA last summer, and he was always crazy hard at work and always answered my footwear questions when I had them. So proud of this guy and can’t wait to see what he accomplishes!

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