It's been two months since Caleb Olson turned in one of the fastest times in Western States history, wearing what can only be described as a white fishnet running top, and now Nike has released details on what gives with its latest trail running technology.
With the planet turning hotter and long-distance trail races getting more popular, Nike identified a need for clothing that helps athletes stay cool. Nike Radical Airflow represents "a new era of breathable apparel," according to the brand, which is no surprise if you saw images of Olson, as his shirt appeared to have more space than substance.
“Wearing it is like stepping into a fridge," says Olsen, who ran the 100-mile race in 4 hours, 11 minutes, and 25 seconds despite battling temperatures in the 90s.
Couldn't he just take his shirt off, you might ask? Not according to Nike, which says fridge-effect isn't just about those gaping holes.
Nike Radical AirFlow technology
When your body starts to heat up while you're running on a warm day, your sweating mechanism works pretty much like an in-built air conditioning system, allowing heat to escape through moisture. But only if that sweat is allowed to evaporate off your skin, as we explain in our article on breathable fabrics.
According to Nike, Radical AriFlow doesn't just allow more sweat to escape through the giant holes in the mesh, thereby accelerating the body's natural cooling mechanism; it also speeds up airflow towards your skin while you run.
The holes, which Nike calls "airducts," expedite the flow of air while you're on the move, thanks to a "funnel-shaped" construction that goes from larger on the outside to smaller as they get closer to your body. In lab tests, engineers also discovered that placing dimples on the inside of the fabric (where it comes into contact with your skin) helps to improve the circulation of that air. And that's why the brand says it chose a long-sleeved top – to give athletes the maximum benefit possible.
Does it really work? According to Drew Holmen, who wore a prototype of the shirt for his win at the Lavaredo Ultra Trail 80 in Italy at the end of June, Olson's victory wasn't a mere fluke.
"I was shocked by the cool breeze I felt across my body," says Holmen.
Meanwhile, those large cut-outs under the arms offer mobility and also cut down on weight and chafing in high-friction and high-sweat areas, making it all the more interesting for ultra runners.
Nike says the technology has been tested over the last two years – one of the largest tests in Nike running history – in the field by Nike's All Conditions Racing Department, and in controlled research settings using thermal mannequins. Lab tests reveal that when compared to DriFit, Radical AirFlow prototypes absorb and retain 50 percent less sweat after prolonged running in hot conditions.
Athletes will continue to test the prototype throughout the 2025 elite season for release in 2026, so we'll be keeping our eyes peeled for more skin on display at this year's UTMB finals. No word yet on what your tan line will look like after a summer in the top.
