Henrik Ingebrigtsen had no way of knowing that he was about to help shape the future of track-and-field fashion when, as a teenager in Norway nearly 20 years ago, he ordered a form-fitting one-piece speedsuit from Nike that was designed for 100- and 200-meter sprinters.

The twist was that Ingebrigtsen was not a sprinter. Instead, he specialized in the 1,500 meters, a middle-distance event that was the province of much more conservative attire.

Ingebrigtsen, though, had always enjoyed the stretchy apparel he had worn as a cross-country skier, and he thought the speedsuit would be a fun way for him to express himself on the track.

“Mostly because I thought it looked cool,” he said in a telephone interview.

At the 2024 Summer Olympics in Paris, Ingebrigtsen’s influence has been on full display. No longer satisfied with the drab garb of the profession — loosefitting singlets, side-split shorts — half of the runners in the men’s 1,500-meter final on Tuesday were clad in sleek thigh-length speedsuits made from materials like polyester and elastane.

Among them: Cole Hocker, the American who shocked a full stadium to become Olympic champion, and Josh Kerr of Britain, who placed second. Ingebrigtsen’s younger brother Jakob, who had hoped to defend his Olympic title and has seldom worn anything but speedsuits during competitions, finished fourth.