Marathon Running Temporarily Depletes Brain Myelin but Recovers Within Weeks

While runners are familiar with the physical exhaustion and heavy legs that come with long endurance runs, new Spanish research reveals that the brain also endures significant stress during such efforts.

A marathon, for example, requires substantial energy not only from the body but also from the brain. Scientists have discovered that during prolonged physical exertion, the brain taps into its own protective fat layer as an energy source to sustain performance.

Impact of Endurance Running on Brain Myelin and Its Natural Recovery Process

To investigate the brain’s response to endurance running, Spanish researchers conducted MRI scans on ten marathon runners at different stages—before the race, immediately after finishing, and months later.

The scans revealed that after completing a marathon, the brain showed a decrease in myelin, a fatty substance that insulates and protects nerve cells. The most affected brain regions were those responsible for coordination, sensory perception, and emotional regulation. In some cases, myelin levels dropped by as much as 28 percent.

Despite the noticeable depletion of myelin post-marathon, runners need not be overly concerned. The study found that myelin levels began recovering within two weeks of the race, and by two months, they had returned to their original state. This suggests that while endurance running temporarily impacts brain function, the brain has a natural ability to heal itself over time.

Optimizing Brain Recovery After Endurance Runs: The Role of Nutrition and Rest

To support brain recovery, researchers recommend consuming healthy, high-fat foods such as fish, nuts, and avocados. These foods help replenish the myelin that is used during prolonged physical exertion. Additionally, getting adequate rest after a marathon or other endurance activities is essential to allow both the body and brain to recover effectively.

Although the findings are significant, the researchers emphasize the need for further studies. The study was conducted with a very small sample size—only ten athletes—which limits the ability to generalize the results. More extensive research will be necessary to fully understand how endurance running affects brain function and whether different training strategies or dietary approaches can mitigate the impact.