“How do we connect physics to a traditional piece of apparel?”: Nike Radical AirFlow could be the biggest rethink in performance apparel in years

When Nike’s Radical AirFlow top first appeared at Western States last year, it didn’t arrive with a lengthy explainer or a tidy innovation framework. It simply showed up in its perforated, slightly surreal, and impossible-to-ignorant way, worn by Caleb Olson en route to victory.

At a time when most performance apparel evolves in careful, incremental steps, this felt like something else entirely. It wasn’t anupdate or a refinement. Instead, Radical Airflow appears to be a disruption so big that it might reshape how we look at performance garment design in the future.

Dan Farron, VP, Apparel Innovation Product Design at Nike, whom I met in Milan at the Unlimited Air exhibition, doesn’t describe Radical AirFlow as a garment concept at all. He describes it as a physics problem and credits much of the breakthrough to Daniel Morgan, Lead Designer at Innovation Apparel, who originated the idea.

“[Daniel] is all about looking at the senses,” Farron explains, referring to Morgan. “He’s an engineer by trade – engineer, designer, scientist. He obsessed over, ‘How do I make this thing bring more air in and re-channel everything?’ It wasn’t a trail garment at first. It was just, let’s see how much air we can get into the material and speed it up.”

As Farron explained, Radical AirFlow didn’t begin as a brief for trail runners or a silhouette study for Nike ACG. Instead, it began as a material experiment, an attempt to accelerate airflow through fabric and across skin, and in doing so, amplify the body’s natural cooling response. Only later did that experiment evolve into something recognisably wearable.

“There was a sleeve that [Daniel] stitched up,” Farron says of Morgan. “And it’s moving. We’re like, ‘Well, this is… I think we’ve done it.’ From that moment onwards, we started to shape and tune it with the athlete. But before then, it’s just a thing that’s doing something we’re excited about.”

Running in a fridge

Cooling in endurance sport is as much psychological as it is physiological, and Farron is candid about that. “The first thing is perception of cooling is a big benefit,” he says. “For Caleb, when he finished Western States, the first thing he said in person was, ‘I felt like I was running in a fridge.’ He said, ‘I can feel it continuously.’”

In Nike’s Sports Research Lab, the garment was pushed through climate chamber testing to quantify what athletes were feeling in the wild. The team observed enhanced airflow across the skin and increased evaporative sweating, mechanisms that contribute to sustained cooling during long efforts in extreme heat.

“There’s a lot of cooling on the skin,” Farron says. “There’s a lot of evaporative sweat. For us, it’s about maintaining throughout that race that there’s a cooling effect going on. And then we continue to focus on how much we can accelerate that.”

But perhaps the more intriguing layer is how the top feels. Cooling sensation, particularly in ultra-distance racing, can influence pacing, decision-making and perceived exertion. In that sense, Radical AirFlow is operating at both ends of the spectrum: mechanical and mental.

Why it looks the way it does

The silhouette is unconventional, to say the least, and Farron admits it made even seasoned designers uneasy at first. “As a designer, you see a lot [of different concepts] over the years,” he says. “But Daniel pushed and pushed for this thing. There were times I wanted to cut a sleeve off. But he kept it to pure function.”

Crucially, the structure cannot be skin-tight. “If you make it skin-tight, it’s not going to work,” Farron explains. “You need the airflow inside. If you put it against the skin, it just hits your skin and doesn’t circulate.”

This space between fabric and body is what creates the garment’s distinctive profile. The form is a direct consequence of the function, which is perhaps why, when Caleb Olson lined up wearing it, reactions ranged from intrigue to memes. Farron laughs at the “Christmas sweater” nickname and the crocheted parodies that followed.

“What was really different for us is we didn’t talk about anything,” he says. “We just let the garment do its thing in the race. It was important for the teams to let the trail community work out what it is themselves first. It doesn’t come around very often that you get a really different silhouette like this.”

From trail to road and beyond

Radical AirFlow first landed in the trail world, but its potential reach extends far wider. Road running legend Eliud Kipchoge tested early versions, running long sessions in it and offering precise feedback on fit adjustments.

“We expect most of our runners to take it for 10 minutes,” Farron says. “I think he ran like 30 kilometres in it the first time.” Fit was tuned to balance airflow space with race-day security, including adjustments to hole sizes and placement, and length modifications without disturbing the core airflow system.

“The minute anyone does the arm swing in it, they’re like, ‘Wow, I can feel it,’” Farron says. “We know everyone’s going to want that cooling at some point. It’s just making sure it’s authentic and comes to life in the right way.”

He points to climate change as an unavoidable backdrop. As heat increasingly challenges athletes across disciplines, airflow-based cooling becomes relevant beyond ultras, extending to road marathons, club runs, and potentially other sports operating in extreme environments.

More surprisingly, Radical AirFlow has already begun to drift into everyday wear. “I didn’t expect it to be on people just wandering,” Farron admits. “But it’s happening.” Function, it seems, can accidentally become fashion.

More than layering

When asked whether Radical AirFlow could change Nike's approach to layering systems, Farron reframes the conversation. “I don’t think it’s just layering,” he says. “It challenges the whole ecosystem. Head to toe.”

The immediate question is how airflow interacts with other garments, such as sports bras, base layers, and outer shells. Can double layers of airflow be engineered? Can venting become conditional? Can airflow be amplified or directed differently depending on sport and climate?

“If we’re getting all that air inside, what do we want it to do?” Farron asks. “Can we amplify that? Sweat management is incredibly important to us, and that’s a part of it.” Rather than a standalone novelty, Radical AirFlow begins to look like the first step in a broader rethinking of how apparel manages heat, movement and environment.

A moment in time

Farron has worked in apparel innovation for two decades. He doesn’t overstate things lightly. “To have a material that gives you that instant perception, that doesn’t happen very often,” he says. “That’s like once every five to 10 years, maybe.”

After a brief pause, he adds: “[Radical AirFlow] is definitely up there as a pinnacle moment in my career, to see my team create this thing and bring it to life.”

In an industry often defined by micro-adjustments and seasonal refreshes, Radical AirFlow feels different. Not because it is louder (even though it is), but because it is structurally distinct. It asks a more fundamental question about what apparel can do when physics leads the design, rather than aesthetics or trends.

And if the future of performance gear is shaped increasingly by climate realities and athlete demand for tangible advantage, this experiment in airflow may prove less like an outlier and more like a starting point.

You can check out Nike's ACG range at the brand's website.