Brain tissue may be fuel for marathon runners

A study suggests nerve cell insulation, or myelin, is an energy source during endurance exercise

A photo of several marathon runners running from left to right across the frame.

Long-distance runners may tap into myelin as a fuel source for the brain. The fatty tissue insulates nerve cells and seems to diminish just after a race, then build back up in the following weeks.

Michael Blann/gettyimages

In endurance athletes, some brain power may come from an unexpected source.