10 Photos of Yoo Ji-won: Running Influencer Dies at 25 After Collapsing 500 Metres From Seoul Half-Marathon Finish Line

Yoo Ji-won, a 25-year-old South Korean running influencer and KAIST graduate student researching artificial intelligence semiconductors, has died after collapsing just 500 metres from the finish line of a half-marathon in Seoul. Yoo lost consciousness at the 20.6-kilometre mark during the 2026 Seoul Race on Sunday, 11 October, according to organisers. She received emergency treatment at the scene and was taken by ambulance to a medical facility, where she later died.

Her death was confirmed by the Seoul Race Organising Committee on 12 October. The exact cause of her collapse and death has not been publicly disclosed, and organisers said the incident would be examined.

Yoo Ji-won Collapses Near Seoul Half-Marathon Finish

The Seoul Race began at Seoul Plaza and featured half-marathon and 11-kilometre courses, with approximately 12,000 runners taking part. According to the organising committee, the emergency happened at about 8:49am when a participant in the half-marathon collapsed at 20.6 kilometres. The full distance is 21.0975 kilometres, leaving roughly 500 metres to the finish.

An official who found the runner near Gwancheol-dong in Seoul's Jongno District called emergency services and performed CPR, according to the Seoul Metropolitan Government. She was then transported to hospital by ambulance. The organising committee later expressed condolences to her family and said it would 'closely examine' the incident and take necessary follow-up measures.

Who Was Yoo Ji-won?

Yoo was a graduate student at the Korea Advanced Institute of Science and Technology, known as KAIST, where she researched artificial intelligence semiconductors. Alongside her academic work, she built a following on Instagram under @mta1n_0ne by documenting her training, races and personal milestones. She had more than 9,000 followers.

She began running in 2022 and later focused increasingly on improving her race times. In a March interview, she described balancing laboratory work with long evening runs.

Her results reflected that commitment. On 15 March 2026, she completed the Seoul Marathon in 2 hours, 56 minutes and 32 seconds, breaking the three-hour mark. She also won the women's masters 10-kilometre category at the Gunsan Saemangeum Marathon in April.

Yoo Ji-won's Final Instagram Post

Yoo's last reported Instagram update was shared on 4 October, one week before her death, and showed her result from a recent 10-kilometre race.

Her account has since become a place for friends, fellow runners and followers to leave tributes. One commenter recalled watching her running videos and described her as an 'amazing runner'.

Her friend and fellow running content creator Bummy also paid tribute after learning of the emergency. In a post, Bummy said he saw a crowd near the finish line after completing his own race and initially thought someone had been hurt.

After crossing the line, he looked for Yoo near the awards podium before learning what had happened. He then rushed to the hospital, hoping to see her one last time.

'I am so sorry I couldn't stay by your side until the very end,' Bummy wrote.

Yoo had described running as a major part of her daily life while continuing her research at KAIST. Her social media showed race results, training sessions and progress towards faster times.

Following her death, a friend also corrected online rumours that she had been discharged from the hospital, saying she had remained there after the collapse and asking people to respect her family.