South Korean Running Influencer Yoo Ji-won Dies After Collapsing Near Seoul Half Marathon Finish

South Korean running influencer and KAIST graduate student Yoo Ji-won, who shared her running journey with her vast online following, has passed away after collapsing about 500 meters (550 yards) from the finish line of a half marathon in central Seoul. She was 25.

Yoo became unconscious at 8:49 a.m. Sunday, around 20.6 kilometers (12.8 miles) into the half marathon at the 2026 Seoul Race, according to a statement the organizing committee released on Monday. The standard half marathon distance is 21.0975 kilometers (13.1 miles).

A race official found her unconscious on a downtown street near Jonggak subway station, which alerted emergency services. She was subjected to CPR prior to being taken to a hospital in an ambulance; however, she never regained consciousness and died shortly thereafter.

“We pray for the repose of the deceased and extend our deepest sympathy to the bereaved family facing this sudden sorrow,” the committee stated, adding that it will carefully investigate the case and take appropriate actions.

The exact cause of death has yet to be officially determined. An initial comment from a race official to local media suggested that Yoo may have fainted after straining herself too much, but no official findings have been released yet.

The race, organized by the Seoul Metropolitan Government and the Dong-A Ilbo newspaper, drew around 12,000 runners to a half marathon and a shorter 11-kilometer (6.8-mile) race through central Seoul, including landmarks such as Gwanghwamun and Heunginjeongmun, the city’s historic eastern gate.

Born in 2001, Yoo was a graduate student at KAIST, researching semiconductors for artificial intelligence. She started running in 2022 and gained a large following by sharing online how she balanced lab work and training.

Her rise to fame happened rather quickly for an amateur runner. She improved her best over 10 kilometers (6.2 miles) to about 36½ minutes and clocked 1 hour, 22 minutes, 1 second at the New Balance Half Marathon in March. On April 5, she won the women’s amateur division over 10 kilometers at the Gunsan Saemangeum Marathon.

In a March interview with YouTube, Yoo said she arrives at the lab at 9 a.m. every day and runs for about two hours starting at 8 p.m., adding that she has been actively chasing personal records since the previous summer.

She often encouraged her followers to treat running as a lifelong activity, stay healthy, and steadily improve.

Tributes poured onto her social media after the news of her death broke out. “She was a runner I truly admired and always cheered for,” one commentator said.

A fellow running influencer posted Monday to dispel rumors circulating online that Yoo had been discharged and was recovering at home. The friend said that Yoo stayed in the hospital all the time and asked followers to pray for her.

Her death triggered a warning from Hwang Young-jo, the 1992 Barcelona Olympic marathon champion. In the video posted Tuesday on his YouTube channel, Hwang warned that amateur runners are usually too eager to run faster and to get a better ranking, and that race organizers are not always ready for emergencies.

“Knowing when to quit makes you a better runner,” Hwang said. He encouraged runners to rest when their bodies tell them to and race organizers to keep eight to ten ambulances on standby. In the video description, he said South Korea currently has about 10 million recreational runners.

Yoo died a week after Treyton Lara, 24, a youth pastor, collapsed near mile 20 of the Portland Marathon in Oregon and died. His wife told KPTV that doctors said he had gone into cardiac arrest.

Cardiac arrests during long-distance races are rare events. According to a study published last year in JAMA, there were 176 cardiac arrests among roughly 29.3 million participants in U.S. marathons and half marathons between 2010 and 2023, about 0.6 per 100,000 runners.

The proportion of those runners who died dropped to 34%, from 71% in the previous decade. The researchers suggest that faster emergency response and wider availability of defibrillators may explain the improvement.