Brains of physically fit kids feature beefier white matter

The brains of kids who are more aerobically fit feature thicker, more fibrous amounts of white matter -- brain material associated with faster and more efficient nerve activity.
Previous research has shown physical fitness to be correlated with gray matter, the parts of the brain essential to learning and memory. Now it seems physical fitness and gray matter are also associated.
The research was carried out by scientists at the University of Illinois at Urbana-Champaign. After measuring the aerobic fitness levels of 24 nine and 10-year-olds, researchers used diffusion MRI brain scans to observe their white matter. This type of brain scan looks at how water diffuses into tissues. In this case, the less water the better -- as the less water that diffuses into the white matter, the more fibrous and compact that matter is -- both desirable traits.
"Previous studies in our lab have reported a relationship between fitness and white-matter integrity in older adults," said psychology professor and Beckman Institute director Arthur Kramer. "Therefore, it appears that fitness may have beneficial effects on white matter throughout the lifespan."
Because white matter serves neural tracts connecting different parts of the brain -- left and right hemispheres, the frontal and parietal lobes, the cerebral cortex and the brain stem -- denser white matter would suggest a brain that can work faster and more efficiently.
"All of these tracts have been found to play a role in attention and memory," said Laura Chaddock-Heyman, a postdoctoral researcher who helped conduct the study.
Though the study did not test cognitive performance, previous studies suggest a link between aerobic fitness and performance at certain cognitive tasks and in academic settings.
The researchers controlled for potentially troublesome variables, like social and economic status, IQ, the arrival of puberty, as well as the presence of learning disabilities. Their work was featured in the latest edition of the journal Frontiers in Human Neuroscience.