The myelin content of the brain decreases after running a marathon
In marathon runners, the myelin content of specific regions of the brain is reversibly reduced, according to a study carried out in the Basque Country. This observation is consistent with animal evidence suggesting that myelin lipids - a substance that surrounds neurons - can act as energy reserves in extreme metabolic conditions, as detailed by the authors in Nature Metabolism. The analysis is based on magnetic resonance imaging of eight men and two women before and after running a marathon. According to the study, the myelin content was fully recovered two months after the race.