We often refer to the brain as a muscle—and new research now shows that the two are more similar than previously thought.
A 2012 study out of Japan investigates how working up a sweat might also increase energy levels in the brain. The paper, published in The Journal of Physiology, is based on careful measurement of glycogen levels in rats before and after exercise.
Glycogen: energy for both brain and body
Glycogen is a critical energy source for neurons and muscles alike, and it decreases as you spend energy during exhaustive exercise. In muscles, it has long been known that a phenomenon called supercompensation reelevates glycogen levels 24 hours after exercise. Supercompensation bumps glycogen above even pre-exercise base levels, hence the term.
The question: does supercompensation work on brains like it does on muscles? It does in rats, according to the study. Glycogen levels in five different rat brain areas (which have corresponding human brain areas) decreased by 50-63% during exercise. But 6 hours later, glycogen levels rose to peak at 29-63% higher than the pre-exercise levels. The boost in energy available to the brain may account for the mental alertness that many people report after a workout.
Exercise has longer-term effects
Even better, researchers found that the effects of exercise in the brain were longer-lasting.
The 2012 study also included a group of rats trained to exercise regularly 5 days a week for 3 weeks. Compared to a control group of sedentary rats, these exercise-trained rats had 7% and 9% higher levels of glycogen in the cortex and hippocampus, respectively.
While the 2012 study was done on rats, not humans, it provides valuable insight into ways that exercise can change the brain. The paper’s authors posit that increased glycogen levels are how the brain responds to difficult metabolic environments—just another example of how the brain can adapt in the face of new challenges.
– Pam Zhang studied Creative Nonfiction Writing and Cognitive Science at Brown University (and a smattering of Egyptology too). All this has left her with an itch for unearthing all the weird and wonderful connections between our brains, our bodies, and our ideas of self. Now writing for Lumos Labs, she’d like to know what facets of neuroscience you want to read about! Find me on Google+