Yoo, a 25‑year‑old KAIST graduate student, collapsed near the finish line of the Seoul Race on Oct. 11 and died, with the cause not disclosed. Her death triggered a wave of “mourning run” and “memorial run” posts on social media, sparking a heated debate.

Many runners shared photos of their runs with the hashtags #mourningrun and #memorialrun, dedicating their distances to Yoo. Some critics said the posts were a bid for attention, while supporters argued that finishing the unfinished distance was a meaningful tribute.

South Korea’s running boom means more than 10 million people now identify as regular runners. The number of official marathon events grew from 19 in 2020 to 254 in 2024, showing how popular mass races have become.

In response, the Korean Medical Association urged tighter safety management for mass events. It recommended that every race include emergency medical staff and automated external defibrillators, and that runners stop and seek help if they feel chest pain or similar symptoms.

For everyday runners, the controversy highlights the need to respect both grief and safety. Following the KMA’s advice can help prevent tragedies while still allowing participants to honor fellow athletes responsibly.