Marathon races top ER admissions, doctor warns of 'brain cooking'

Amid a string of safety incidents at recent marathon events, an emergency medicine specialist is warning runners against pushing past their physical limits.

Nam Goong-in, a professor in the emergency medicine department at Ewha Womans University Mokdong Hospital, said marathon races generate more emergency patients than any other public event, in an interview with YouTube channel Sseoldak.

"When a marathon is held, our hospital receives an official notice to stand by — and patients always come in without fail," Nam said. "These days, with races ranging from 10 to 20 kilometers, patients arrive in waves throughout the day."

Nam said many participants strain their bodies in pursuit of a personal best. "Everyone is so dedicated and mentally tough that they push hard and ultimately end up overexerting themselves," he said. "Running 5 to 10 kilometers is good for your health, but I do not think running 40 to 50 kilometers is."

Long-distance running can trigger severe dehydration and energy depletion, he said. "Running a marathon drains the body of energy while causing extreme dehydration," Nam said. "Around the 30-kilometer mark, the body hits a wall — energy runs out and it becomes incredibly difficult to keep going."

Heat stroke is the most common reason runners collapse mid-race. The body generates heat while running, and when temperatures and humidity are high, it cannot shed that heat fast enough, creating a dangerous situation.

"Running means the body is constantly producing energy, and that process generates heat," Nam said. "Heat stroke, by definition, is the brain cooking. When the brain cooks and shuts down, you collapse."

He added that marathons are not held in midsummer for exactly that reason. "If they were, everyone would collapse," he said. "When the weather is hot and humid, the body cannot properly release its internal heat, and runners can go down."

Some patients arrive at the emergency room with body temperatures as high as 41 to 42 degrees Celsius, he said. "Because their brains have essentially cooked on the way in, some are delirious, thrashing around — one patient even asked me, 'Doctor, am I dead?' thinking I was the Grim Reaper," Nam said.

"No matter what kind of exercise you do, pushing yourself too hard will inevitably strain your body," he said. "You must take breaks, slow your pace, and stay hydrated while you run."