There are moments in design when a product looks so strange that you can’t stop staring at it, and then you find out how it works and it suddenly makes perfect sense. That’s exactly what happened when trail runner Caleb Olson crossed the finish line at the 2025 Western States Endurance Run in the second fastest time in the race’s history. People clapped. Then they immediately started asking: what is he wearing?
The shirt is the Nike ACG Radical AirFlow, and calling it a “shirt” feels generous. It looks more like a sweater that had an encounter with a drill press. Cone-shaped holes punctuate the fabric in deliberate patterns, creating what Nike calls airducts. They’re not just decorative (though they definitely are that, too). They’re functional in a very specific, physics-driven way. The design harnesses the Bernoulli principle and the Venturi effect, two concepts most of us haven’t thought about since a physics class we may or may not have paid attention to. The short version: as air moves through a narrowed opening, it speeds up and pressure drops. Nike essentially engineered that phenomenon into a fabric layer sitting on your body while you run.
Designer: Nike
The result, according to Nike’s own testing, is a top that absorbs and retains 50% less sweat than DriFit, the brand’s long-trusted performance fabric. It’s also 25% less resistant to the evaporation of sweat. For those of us not running ultramarathons in the California mountains, those numbers might sound abstract, but the principle holds whether you’re hiking a trail in August or doing anything remotely active in heat. The body cools itself through sweat, and anything that helps that process happen faster is worth paying attention to.
What makes this interesting beyond the performance specs is how it got here. The Radical AirFlow came out of Nike’s All Conditions Gear line, a sub-brand with a very specific purpose: designing for the outdoors, not the gym. ACG lives by the motto “Designed, Tested, and Made on Planet Earth,” which sounds like a marketing line until you realize the top was debuted mid-race at one of trail running’s most grueling events. The testing wasn’t a controlled brand activation. It was a competitive ultra-marathon.
The design itself doesn’t pretend to be subtle. It’s a cropped silhouette, worn long-sleeved, with large cutouts under the arms and at the elbows for mobility. The airducts are visible and intentional. It reads more like a prototype from a materials science lab than a rack piece at your local athletic retailer. And I think that’s the point. Nike ACG has always occupied that niche space between gear and fashion, performance and provocation. The Radical AirFlow leans all the way into that tension.
It also went viral in a way that athletic apparel rarely does, because the response was split. Some people immediately understood it. Others were convinced it was a joke. Trail runner Drew Holmen, an ACG athlete who tested the garment, said it plainly: “When I first saw the product, it was like nothing I had ever seen before.” That reaction, repeated by thousands of people online, is actually a good sign in design. If no one’s confused, nothing is new.
The broader conversation Radical AirFlow opens up is one about where performance apparel is headed. For a long time, innovation in this space meant better synthetic blends, tighter weaves, smarter seam placement. The Radical AirFlow goes in the opposite direction. It removes material entirely, then structures the absence of it. The holes aren’t a compromise or a cost-cutting measure. They’re the technology.
Whether you’d actually wear it outside of a race context is a fair question, and a cap version built on the same technology is already on the way, which might make the concept more accessible. But the full racing top is a genuine design statement, one that prioritizes function in a way that can’t be hidden. You can see it working. That kind of transparency, in design, is rarer than it should be.
