Brain scans conducted on runners in the days following a marathon showed a significant decrease in myelin content, followed by a near-complete recovery two weeks later.
Endurance athletes, particularly marathon runners, may harness the power of myelin, a fatty tissue surrounding nerve fibers, for energy during races, according to a study posted on bioRxiv.org. Brain scans conducted on runners in the days following a marathon showed a significant decrease in myelin content, followed by a near-complete recovery two weeks later.
This indicates that athletes tap into myelin as an additional energy source to maintain optimal brain function during extended physical exertion.
Mustapha Bouhrara, a neuroimaging scientist at the National Institute on Aging in Baltimore, finds this observation intriguing and believes that myelin lipids could serve as a fuel source during prolonged exercise. If confirmed, this discovery could have therapeutic implications for conditions involving myelin loss due to aging or neurodegenerative diseases.
Myelin, which sheathes nerve fibers, acts as an insulator facilitating rapid electrical communication between nerve cells in the brain. Previously viewed as a static structure, recent research suggests myelin exhibits dynamic properties, known as myelin plasticity. Fatty molecules and other components of myelin undergo regular turnover, indicating its adaptability in response to cellular conditions.
Carlos Matute, a neurobiologist and marathon runner, led a study using MRI scans to monitor the brains of four marathon runners before and after the race, with two follow-up scans two weeks later. The results revealed a noticeable reduction in myelin content shortly after the race, indicating a thinning of the myelin around nerve fibers. However, after two weeks, the myelin levels rebounded, thickening around neural fibers.
While the rapid decline and recovery of myelin tissue levels raise questions about potential dehydration effects, Matute argues that dehydration is unlikely to be the cause, as the runners were scanned days after the race, allowing time for rehydration. Additionally, the brain volumes remained consistent before and after the marathon, suggesting that dehydration-induced brain shrinkage was not a factor.
Matute’s team plans to investigate if the temporary dip in myelin levels impacts brain function and assess the duration of complete recovery. Matute emphasizes that the study does not imply that running is detrimental to the brain; in fact, utilizing and replenishing energy reserves through exercise may benefit the brain’s metabolic processes.