Photo courtesy of Benjamin I. Rapport and Charles S. Bond via Wikipedia Commons
Bella Delmonte ’27
Contributing Writer
It’s no secret that running is exhausting, but an early-stage research paper is exploring just how much it impacts the body.
According to an article by RunnersConnect, prolonged endurance running, such as marathons, may deplete the body’s carbohydrate stores, leading it to burn fat for energy. A preprint research paper recently submitted to bioRxiv suggested that the body turns somewhere unexpected to find its fat cells: the brain. The preprint reports found that brain tissue — specifically myelin — may be used as fuel in marathon running.
Myelin is a mixture of proteins and phospholipids in the brain that forms an insulating sheath around many nerve fibers, enabling fast travel between nerve impulses, as Verywell Health describes. Myelin may be naturally lost over time due to stroke, infection or neurodegenerative disease, according to the article.
According to the research paper, runners’ myelin levels significantly decreased after racing, followed by a rapid replenishment in the two weeks following the race. The researchers indicate this may be a new type of metabolic process wherein the body uses myelin as a fuel source during strenuous conditions and recovers it later on.
As Meghan Rosen of ScienceNews reported, researchers in the field of neuroscience have begun to consider the therapeutic possibilities that may result from understanding this process.
The team conducted brain scans on marathon runners one to two days after racing and two weeks following the race, as detailed in the research paper. They explained that runners’ brain scans showed a drastic depletion of myelin shortly after racing. Two weeks after racing, however, their myelin had nearly fully recovered to pre-race levels. According to the research team, this suggests that the runners were using myelin as a fuel source.
Glycogen stores, as the RunnersConnect article explains, are large chains of sugar stored in the liver and muscles — the primary fuel source for long-distance runners. The article went on to explain that when the body’s glycogen stores deplete, the body taps into fat as a fuel source.
The study by bioRxiv found that this may include myelin cells, which are composed of 70 to 80% lipids. They concluded in the paper that using myelin as a temporary fuel source implies an unprecedented metabolic process, one that researchers in the study refer to as “myelin plasticity.”
The idea that myelin can change over time has been supported by previous research, such as findings published by researchers from the University of Edinburgh. In an article by Frontiers in Cellular Neuroscience, these researchers suggested that myelin may be adaptable throughout a person’s life and is altered to regulate experience and learning.
Additionally, the researchers found that myelin, though stable once formed, may have the capacity to remodel if disturbed. The need for an alternative fuel source to glycogen, like when running a marathon, may just be the kind of disturbance that would prompt myelin to change.
The authors of the study explained that further research is required, and the bioRxiv paper has yet to be certified by peer review. However, in the aforementioned ScienceNews article, Rosen suggested therapeutic implications surrounding this research. For instance, she cites neuroimaging scientist Mustapha Bouhrara, who proposed that this new research could be a breakthrough in understanding and eventually treating myelin loss due to age or neurodegenerative diseases.