South Korean running influencer Yoo Ji-won , 25, died after collapsing just 500 metres from the finish line of the Seoul Race half-marathon on October 11, 2026. She was rushed to a medical facility after the incident but could not be saved, according to the race organisers. Ji-won was also an artificial intelligence semiconductor researcher at the Korea Advanced Institute of Science and Technology (KAIST). She had built a following of more than 8,000 people on Instagram by sharing her running journey and race results. The cause of her death has not been publicly confirmed.



Yoo Ji-won was a KAIST researcher who shared her running journey onlineYoo Ji-won balanced her work in science with her passion for running. She researched artificial intelligence semiconductors at KAIST while sharing her training sessions and race performances with her Instagram followers.




Her account, under the handle @mta1n_0ne, had attracted more than 8,000 followers. She regularly posted about her runs, giving people a look at her progress and achievements in the sport.




Her final Instagram post, shared on October 4, showed her timing from a 10-kilometre run. Following news of her death, the post became a place for friends and followers to share their condolences and remember her.




According to South Korean media reports, Ji-won had also achieved strong results in local races. She won the women’s masters 10-kilometre category at the Gunsan Saemangeum Marathon in April 2026. She had also completed the full Seoul Marathon in March, finishing in two hours, 56 minutes and 32 seconds, according to the International Business Times UK.



Yoo Ji-won collapsed at 20.6km as Seoul Race organisers confirm deathThe incident happened at around 8:49 am on October 11 during the 2026 Seoul Race half-marathon. Ji-won collapsed at the 20.6-kilometre mark, with roughly 500 metres left before the finish line of the 21.1-kilometre race.




The Seoul Race Organizing Committee confirmed the death in a statement shared on Instagram. It said emergency first aid was provided at the scene before an ambulance took the participant to a medical facility for treatment.




The committee’s statement read: “Around 8:49 AM on October 11, an emergency situation occurred when a participant in the Seoul Race Half Course collapsed at the 20.6km mark. After providing emergency first aid at the scene, the individual was transported to a medical facility via a 119 ambulance for treatment; however, sadly, the participant passed away.




“We offer our deepest condolences to the bereaved family facing this sudden tragedy and pray for the repose of the soul of the deceased. We also extend our sympathies to the participants, whose hearts must be heavy upon hearing this tragic news. The Organizing Committee will closely examine the matter and take necessary follow-up measures,”




The organisers said they would review what happened and take the necessary follow-up measures. However, they did not announce a cause of death. No official medical explanation for Ji-won’s collapse has been made public.




The news also prompted an emotional tribute from her friend and fellow content creator Bummy, who described seeing a crowd near the finish line before learning what had happened.




“Near the finish line of the Seoul Race, I saw a crowd gathering and thought someone must have been hurt. As soon as I crossed the finish line, I looked for you on the awards podium, but then came the unsettling news, and I began to sense a reality I didn’t want to believe,” Bummy wrote.




His account reflected the shock of learning that a fellow runner had died during an event where participants had gathered to complete their races. For Ji-won’s friends and followers, her final running post has become a place to remember her achievements and share messages of support for her family.