Marathon runners’ bodies have a surprising snack — their own brains

Enlarge this image Runners compete in the New York Marathon in New York City on November 3, 2024. New research suggests that marathon runners may deplete a fatty substance in their brain called myelin. Photo by DAVID DEE DELGADO/AFP via Getty Images hide caption toggle caption Photo by DAVID DEE DELGADO/AFP via Getty Images Runners compete in the New York Marathon in New York City on November 3, 2024. New research suggests that marathon runners may deplete a fatty substance in their brain called myelin. Photo by DAVID DEE DELGADO/AFP via Getty Images Running an entire marathon takes a lot of energy. Neuroscientist Carlos Matute knows this: he’s run 18 of them. He wondered how runners’ bodies get the energy they need to make it to the finish line. His new research in the journal Nature Metabolism may be the first step in answering the question – and suggests their brains might be (temporarily) depleting a fatty substance that coats nerve cells called myelin. Myelin makes up about 40% of the brain. It helps electrical signals travel around. After scanning the brains of 10 marathon runners, Matute and his team saw that myelin decreased in areas important for things like motor coordination – how we move our bodies – and sensory and emotional integration. Sponsor Message The changes were temporary – so runners, no need to panic – but Matute thinks the study could be a step towards understanding conditions like multiple sclerosis, where myelin decreases in the brain and typically doesn’t return. Have other questions about the brain? Let us know by emailing [email protected]! Listen to Short Wave on Spotify and Apple Podcasts. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave. This episode was produced by Berly McCoy and Mia Venkat. It was edited by Geoff Brumfiel and Christopher Intagliata. Tyler Jones checked the facts. Kwesi Lee and Jimmy Keeley were the audio engineers.