Marathoners May Tap Into Brain Insulation for Energy
In an intriguing discovery, a team of scientists has found that marathon runners may rely on a surprising source of energy during a race: myelin, the fatty tissue that insulates nerve fibers in the brain.
The study, posted on bioRxiv.org, suggests that the runners' brains burn through so much energy during the marathon that they need to tap into a new fuel supply to keep operating smoothly. Myelin, which had previously been thought to have a straightforward role in insulating nerve fibers, appears to be a dynamic structure that can be broken down to provide energy.
"This is definitely an intriguing observation," says Mustapha Bouhrara, a neuroimaging scientist at the National Institute on Aging in Baltimore. "It is quite plausible that myelin lipids are used as fuel in extended exercise."
If the study's findings are confirmed, they could have implications for the treatment of people who have lost myelin due to aging or neurodegenerative disease. Understanding how runners' myelin recovers so rapidly could lead to the development of new therapies.
The study's authors used an MRI to scan the brains of four marathon runners in the days before and after the race, and two of the runners two weeks later. They found that the runners' myelin levels decreased significantly in the days after the race, but then bounced back to nearly prerace levels two weeks later.
The researchers say that their findings do not mean that running is bad for the brain. In fact, they believe that using and replenishing energy reserves may be beneficial because it exercises the brain's metabolic machinery.
However, they caution that more research is needed to determine the long-term effects of marathon running on the brain.