Children who participate in an after-school exercise program may have better cognitive function than their peers, according to a recent study.

New research from the University of Illinois at Urbana-Champaign shows that prepubescent children who engaged in moderate-to-vigorous physical activity for at least 60 minutes a day after school saw substantial improvements in their ability to pay attention, avoid distraction and switch between cognitive tasks.

For the study, researchers conducted a nine-month long, randomized controlled trial involving more than 221 prepubescent children. Half of the study subjects were randomly assigned to the exercise program and the rest were placed on a wait list. All participants underwent cognitive testing and brain imaging before and after the intervention.

"Those in the exercise group received a structured intervention that was designed for the way kids like to move," Charles Hillman, who led the study, said. "They performed short bouts of exercise interspersed with rest over a two-hour period."

The intervention, called FITKids, was based on the CATCH exercise program, a research-based health promotion initiative that was initially funded by the National Institutes of Health and now is used by schools and health departments across the United States. The children in the FITKids exercise group wore heart-rate monitors and pedometers during the intervention.

Children in the exercise group also demonstrated substantial increases in "attentional inhibition," a measure of their ability to block out distractions and focus on the task at hand. And they improved in "cognitive flexibility," which involves switching between intellectual tasks while maintaining speed and accuracy. Children in the wait-list control group saw minimal improvements in these measures, in line with what would be expected as a result of normal maturation over the nine months, Hillman said.

"Kids in the intervention group improved two-fold compared to the wait-list kids in terms of their accuracy on cognitive tasks," he said. "And we found widespread changes in brain function, which relate to the allocation of attention during cognitive tasks and cognitive processing speed. These changes were significantly greater than those exhibited by the wait-list kids."

However, the study did not distinguish improvements that were the result of increased fitness from those that might stem from the social interactions, stimulation and engagement the children in the intervention group experienced.

The findings were published in the journal Pediatrics.