Your brain eats itself when you run a marathon—study says
What's the story
A recent study has uncovered a phenomenon among marathon runners.
The research indicates that during extreme endurance events such as a 26.2-mile (over 40km) race, the brain may actually break down its own protective covering, called myelin, to use it as an emergency energy source.
This suggests the brain may utilize its own resources to sustain prolonged physical exertion when other nutrients are depleted.
Myelin explained
Myelin: The brain's protective covering
Myelin is a fatty substance that coats nerve fibers, similar to how insulation coats an electrical wire.
It is critical for accelerating and improving the transmission of nerve signals, which are essential for motor coordination and sensory processing.
During endurance events like marathons, runners mainly depend on carbohydrates broken down into glucose as their primary energy source.
Research findings
Study reveals temporary myelin depletion in marathon runners
In a study by Spanish researchers, 10 marathon runners were scanned using MRI before and after a 42.2km race.
The findings showed that all participants had reduced myelin levels after the race, especially in the brain regions responsible for motor coordination, sensory integration, and emotional processing.
However, they started recovering soon after the race and normalized within two months, suggesting this depletion is temporary and reversible.
Expert insights
Myelin as an emergency energy source in endurance exercise
Dr. Pedro Ramos-Cabrer, a research professor at CIC biomaGUNE, said myelin appears to serve as an energy source when other brain nutrients are exhausted during endurance exercise.
He stressed that further research is needed to determine how extreme exercise correlates with the amount of myelin in the brain.
The study authors also mentioned they did not evaluate if this loss affected runners' cognitive functions or physical abilities.
Potential applications
Implications for understanding myelin recovery
The study raises new questions about the role of myelin in the brain, not just in healthy people but also in those impacted by aging or disease.
Dr. Carlos Matute from the University of the Basque Country suggested understanding how runners' myelin recovers quickly may provide clues for developing treatments for demyelinating diseases like multiple sclerosis (MS).
In MS, permanent loss of myelin leads to severe brain damage and degeneration.