A small pilot study suggests the brain may tap its own energy reserves during intense endurance efforts. Spanish researchers observed changes in brain white matter among marathon runners, hinting at a form of neuroplasticity that could help preserve function under extreme physical stress.
Researchers conducted MRI scans on ten endurance runners (eight men and two women) before and after a 42-kilometer race. The scans showed a measurable drop in myelin, the fat-rich sheath around nerve fibers that facilitates rapid signaling. The decrease was most evident in brain regions responsible for movement, balance, sensory processing, and emotion. Notably, myelin levels began to recover within 24 to 48 hours after the race and largely returned to baseline within two months for the six participants who had follow-up scans.
The team terms this metabolic myelin plasticity—a potential emergency energy strategy in which the brain uses myelin as fuel when nutrients are scarce. This challenges the traditional view that the brain minimizes fat use for energy, suggesting myelin may serve as a temporary metabolic safety net while preserving white matter integrity.
These findings align with existing research showing brief declines in reaction speed and memory immediately after a marathon, followed by a rapid cognitive rebound. The researchers speculate that the uneven distribution of myelin, which is denser in newer brain regions, could reflect an evolutionary adaptation to keep mental sharpness intact during prolonged physical challenges.
The study notes its small sample size and the speculative link between myelin and energy use. Still, observations echo animal studies that point to similar metabolic roles for myelin. If confirmed in larger trials, the results could broaden our understanding of myelin from a structural insulator to a dynamic resource that helps meet the body’s metabolic needs.
For Thai readers, the research offers insight into how energy and brain function are balanced during demanding activity. Endurance sports are growing in popularity in Thailand, and athletes may benefit from deliberate recovery and balanced training that safeguards cognitive performance alongside physical health.
The potential implications extend to neurological conditions such as multiple sclerosis, underscoring the need for broader research with diverse participants. Practical guidance remains clear: train with proper rest, monitor cognitive load during long efforts, and prioritize recovery to maintain overall brain health.
As scientists continue to decipher the brain’s response to stress, these insights could help athletes push further while protecting cognitive function and mental well-being.