A study published in Nature Metabolism has revealed intriguing findings about the impact of marathon running on the brain’s myelin content. The research utilized magnetic resonance imaging to investigate the effects of this intense endurance exercise on brain structure in humans.

The study uncovered a reversible reduction in the myelin water fraction, a marker of myelin content, in specific brain regions associated with motor coordination, sensory processing, and emotional integration following marathon running. However, the myelin content was observed to recover within two months post-marathon.

The research sheds light on the temporary and reversible nature of the decrease in brain myelin content induced by strenuous exercise, aligning with recent evidence from animal studies suggesting that myelin lipids might serve as energy reserves for glial cells during extreme metabolic conditions.

Marathon runners heavily rely on carbohydrates as their main energy source during races. When glycogen levels deplete, the body, including the brain, switches to utilizing fats for energy production. Fats, being a rich energy source, can sustain prolonged endurance exercise.

Myelin, a crucial component that envelops and supports nerve fibers, is primarily composed of lipids. Oligodendrocytes, the cells responsible for myelin production, may utilize myelin lipids as a source of energy during glucose deprivation, akin to how body fat fuels muscle activity during exercise.

The study employed advanced magnetic resonance imaging techniques to assess myelin content in the brains of marathon runners. The results showed a clear reduction in myelin water fraction in specific brain regions immediately after the marathon, with subsequent recovery over the following weeks.

The study authors analyzed the myelin water fraction changes across various brain regions, highlighting significant reductions in densely myelinated white matter areas post-marathon. The observed myelin content changes were consistent with alterations in regions involved in motor function, coordination, and sensory processing.

The research also addressed potential confounding factors such as dehydration and iron levels, emphasizing that the observed myelin changes were unlikely to be influenced by these factors. The study provided robust evidence of reversible myelin alterations in response to endurance exercise, suggesting a novel concept of “metabolic myelin plasticity.”

The findings open up new avenues for understanding how the brain adapts to metabolic challenges during intense physical activity and recovery periods. The study underscores the importance of further research to explore the transient effects of myelin changes on brain function and cognitive processes following prolonged endurance exercise.