During a race, brain tissue is used as fuel in marathon runners.
- Myelin is a membrane essentially made up of lipids, which insulates and protects nerve fibers.
- During a race, marathon runners’ bodies call on the brain to provide energy, leading to a reduction in myelin.
- Two weeks after prolonged physical exertion, myelin levels partially recover.
“Previous data suggests that the lipids of myelin (i.e. a membrane that insulates and protects certain nerve fibers) could serve as energy reserves in the event of glucose deficiency, a hypothesis that has not yet been firmly proven. “ This is what Spanish researchers wrote in a study published on the site BioRxiv. As part of this work, they wanted to know how the brains of athletes continued to function after intense exercise had depleted their body’s energy reserves. For this, the scientists recruited four marathon runners. Athletes had to have an MRI before and after a race. Two of them had another scan two weeks later.
Brain: a reduction in myelin one or two days after the race
The results showed that marathon runners show a robust and widespread decrease in myelin one or two days after prolonged physical exertion. This reduction concerns white and gray matter and includes primary motor and sensory cortical areas and pathways. This reduction in myelin in the brain indicates that the membrane surrounding the nerve fibers has become thinner. According to the authors, marathon runners appear to rely on myelin to provide them with energy during the race. Two weeks later, much of the myelin had returned, thickening again around the nerve fibers.
In an interviewMustapha Bouhrara, neuroimaging researcher at the National Institute on Aging in Baltimore, suggested that dehydration during physical exertion would be responsible for the reduction in myelin. “In our opinion, this is not the case. The team scanned the runners several days after their race, giving them time to rehydrate. Additionally, the volume of the runners’ brains remained virtually the same. even before and after the marathon. Dehydrated brains would probably be smaller. We found that there was no brain shrinkage at all,” explained Carlos Matute, author of the research.
Neurodegenerative diseases: studying myelin to develop treatments
The authors believe that this work could have therapeutic implications. Understanding how athletes’ myelin regenerates so quickly could help develop potential treatments, particularly for people who have lost myelin due to aging or neurodegenerative disease. Now they want to see whether the reduction in myelin in marathon runners changes brain function and how long it takes for it to fully recover.
