Running is full of health benefits, but is there a point where you can go way too far for way too long?
Scientists in Europe sought to answer that by closely monitoring 44 runners in the 2009 Trans Europe Foot Race, a grueling 4,500-kilometer run (about 2,700 miles) from Italy to Norway in 64 days (about 43 miles a day). According to New Scientist, “The team took a portable MRI scanner with them, and periodically scanned the legs, feet, heart, brains and cardiovascular systems of the athletes, as well as taking blood and urine samples.”
Granted, a 2,700-mile race is farther than almost any ultramarathon out there, but what scientists found was fascinating. Specifically, the runners’ brains shrunk by an average of 6 percent over the course of the race.
Lead researcher Uwe Schütz at the University Hospital of Ulm in Germany presented his study at the Radiological Society of North America annual meeting last week, according to New Scientist.
Why did their brains shrink? It’s hard to say. Extreme fatigue and undernourishment are obvious theories, but Schütz has another idea. He thinks it could be lack of stimulation from doing the same thing (staring at the road and trail in front of you) for 64 straight days.
The good news? It’s not permanent.
“It is hard to explain what’s going on,” says Schütz told New Scientist. “But we do see total recovery after six months.”
Schütz told New Scientist that people who run normal marathons won’t experience the same effects.
MORE: New Scientist