South Korean runner and AI researcher Yoo Ji-won died after collapsing just 500 metres from the finish of the 2026 Seoul Race half-marathon. The 25-year-old’s death has prompted tributes from the running community, while the medical cause remains unknown.
Yoo Ji-won, a 25-year-old South Korean runner and postgraduate researcher specialising in artificial intelligence semiconductors, has died after collapsing approximately 500 metres from the finish line of a half-marathon in Seoul. She was taken to hospital after receiving emergency treatment during the race on Sunday, 11 October 2026, but did not survive.
Runner collapses near finish of Seoul Race
The incident occurred during the 2026 Seoul Race, a major running event held through the streets of South Korea’s capital.
According to the Seoul Race Organising Committee, Yoo collapsed at approximately 8.49am local time while running the half-marathon course.
She had reached the 20.6-kilometre mark of the 21.0975-kilometre race, leaving just under 500 metres before the finish line.
Emergency assistance was provided at the scene before she was transferred to hospital by a 119 ambulance.
Reporting by VnExpress International, citing the Seoul Metropolitan Government, said a race official had called emergency services and performed CPR.
Despite efforts to save her, Yoo died after being taken to hospital.
The organising committee confirmed the death in an announcement on Monday, 12 October, and expressed its condolences to Yoo’s family. It also pledged to examine the circumstances surrounding the incident and take appropriate follow-up measures.
The race attracted approximately 12,000 participants across its half-marathon and 11-kilometre events.
Who was Yoo Ji-won?
Yoo Ji-won was more than an enthusiastic recreational runner.
Born in 2001, she was a postgraduate student at the Korea Advanced Institute of Science and Technology (KAIST), one of South Korea’s leading scientific research institutions.
Her academic work focused on artificial intelligence semiconductors, a field concerned with developing advanced computer chips capable of supporting AI systems.
Alongside her research, she had established herself as a competitive amateur distance runner.
She regularly shared training sessions, race results and running experiences through social media, developing a following within South Korea’s running community.
According to Korean news agency Newspim, Yoo began running in 2022 and made substantial progress over the following years.
Her achievements included:
- 15 March 2026: Completed the Seoul Marathon in 2 hours, 56 minutes and 32 seconds, breaking the three-hour barrier.
- March 2026: Recorded a half-marathon time of 1 hour, 22 minutes and 1 second at a New Balance event.
- 5 April 2026: Won the women’s masters 10-kilometre division at the Gunsan Saemangeum Marathon.
These performances demonstrated her ability to compete at a high level while maintaining the demanding schedule of a postgraduate researcher.
In an interview earlier in 2026, Yoo described balancing time in the laboratory with evening training sessions, sometimes returning to her research after completing her runs.
Tributes from South Korea’s running community
News of Yoo’s death prompted messages of condolence from friends, fellow runners and people who had followed her sporting achievements online.
South Korean news agency Newsis reported that runners who had encountered Yoo at previous events were among those leaving tributes.
One participant recalled running behind Yoo during the final kilometres of the Seoul Race and said they would remember her determination.
Others remembered her enthusiasm, positive attitude and the encouragement she gave to people involved in running.
Many of the messages focused on Yoo’s achievements, her commitment to research and her enthusiasm for a sport she had shared with thousands of followers.
Memorial runs prompt discussion online
Some runners have chosen to honour Yoo by dedicating their own training sessions to her memory.
Several shared running records on social media with messages of condolence, including a symbolic pledge to complete the remaining 500 metres that Yoo was unable to finish.
However, the practice has also prompted debate.
On 20 October, South Korean broadcaster SBS News reported mixed reactions to runners publishing their distances and times alongside memorial messages.
Some questioned whether sharing personal athletic achievements was appropriate when commemorating someone who had died during a race.
Others defended the gestures, arguing that running was a meaningful way for members of the community to remember a fellow athlete.
The debate reflects differing views about public expressions of grief rather than any established criticism of Yoo herself.
What caused Yoo Ji-won’s death?
The precise medical cause of Yoo’s collapse and subsequent death has not been publicly established.
Although her collapse occurred during a demanding endurance event, there is insufficient publicly confirmed information to attribute it to a particular medical condition.
Claims involving cardiac problems, dehydration, underlying illness or other possible explanations should therefore be treated as speculation unless supported by an official medical finding.
As of SBS News reporting on 20 October, no definitive cause of death had been disclosed.
The Seoul Race Organising Committee has said it intends to review the circumstances surrounding the incident.
It remains unclear whether that review will result in further public findings or changes to race safety procedures.
Remembering a talented young runner
Yoo Ji-won’s death has attracted international attention because of both the circumstances of her collapse and the achievements she had already made at the age of 25.
She had combined postgraduate research in an advanced technological field with competitive distance running, completing a marathon in under three hours and winning a major amateur 10-kilometre category.
Her death so close to the finish of the Seoul half-marathon has left many runners mourning someone they admired.
While questions remain about what caused her collapse, the confirmed circumstances are tragic enough without speculation.
For those who knew her or followed her progress, Yoo Ji-won will be remembered for her academic ambitions, sporting achievements and enthusiasm for running.
Sources
- VnExpress International: Race timeline and running achievements
- Newsis: Tributes to Yoo Ji-won
- Chosun: Organising committee’s account and condolences
- SBS News: Memorial-run debate, 20 October 2026
Video: Discussion of Yoo Ji-won’s death
The following third-party video discusses the incident. Its footage and narration have not been independently verified by Fish 4 News.
