“Aren’t you freezing?”

The question was painfully obvious. But it was hard to avoid repeating it Saturday to runners young and old who huffed and puffed their way across the Roberto Clemente Bridge from Downtown Pittsburgh to the North Shore, wearing enthusiastic smiles, colorful skivvies and not much more in subfreezing temperatures.

The 300 or so participants in Cupid’s Undie Run 2024, an event that raises money to fight neurofibromatosis, had to brush off occasional snowflakes and temperatures near 30 degrees for their mile-or-so run that began on the North Shore next to PNC Park, crossed the Allegheny River and then returned.

Neurofibromatosis refers to three conditions involving the development of tumors that might affect the brain, spinal cord and the nerves that send signals between the brain and spinal cord and all other parts of the body, according to the National Institutes of Health. Most tumors are benign, although some can become cancerous.

Similar events are held in 30 other U.S. cities, organizers said.

Bright red bathrobes, boxer shorts sprinkled with hearts and superhero outfits gave a zany feel to the event held three days after Valentine’s Day.

But the seriousness behind the run also was clear.

Kevin Doane, 52, a truck driver from Dubois, lost his 10-year-old daughter, Paige, a few years ago.

“One of her tumors became cancerous,” he said.

He has taken part in similar events in other cities as well as in Pittsburgh. This year, he came dressed in a Buzz Lightyear vest.

Surrounding him and shivering in the cold were Amanda Cenci, 26, of Baldwin; Leah Cervenak, 28 of South Park; Logan Himich, 30, of Robinson; and Madeline Fanning, 23 of Philadelphia, four pediatric nurses from UPMC Children’s Hospital, some of whom cared for Paige during her medical stays.

They came out of respect for her memory.

‘’It doesn’t matter what the weather is like to us. The point is to be uncomfortable,” Himich said. “That’s the life she lived, and we want to do this to honor her.”

Returning from the bridge to the North Shore, another runner, Jason Hritz, 48, of Greensburg, didn’t deny going shirtless and in shorts in February was a challenge.

“It’s a little bit chilly, but it’s a good cause,” he said. Wearing pink, heart-shaped glasses, he called himself a member of “Tyler’s Army,” referring to a child in Windber, Somerset County, and family friend who has neurofibromatosis and has been 10 years chemo-free.

Before and after the run that began about 2 p.m., participants sought warmth and, in some cases imbibed, inside McFadden’s Restaurant and Saloon, a North Shore establishment near PNC Park. Buffet-style food helped warm up the runners.

Some kept up a brisk pace. Others walked at least part of the route. Many had red faces from the cold.

Brooke Bissell, event director with Cupid’s Charity, said the run benefits the Children’s Tumor Foundation and raises money for, and awareness of, the battle against neurofibromatosis.

Runners ranged in age from 21 to 70.

Bissell said the event’s unusual theme actually makes it easier to generate conversations about neurofibromatosis.

“What brings more attention to a cause than a bunch of people running in their underwear in the freezing cold in February?” she asked with a laugh.