Physical activity after school provides mental as well as physical benefits to children, according to a new study from the University of Illinois.

Children were found to improve attention skills, were better able to switch between ideas, and were less distracted, after participating in at least one hour a day of physical activity.

Investigators examined 221 children, who had not yet reached puberty, over the course of nine months. Subjects were pre-screened, including brain scans and cognitive testing. Half of the participants were randomly assigned to participate in the physical education program, while the remaining subjects were placed on a wait-list group, to be used as a control for the experiment.

Young people taking part in physical activity were monitored using pedometers and heart monitors, so that researchers could easily quantify the amount of activity in which the children were participating. During exercise, children averaged 4,500 steps and heart rates increased to levels normal for moderate to vigorous levels of exercise.
 
"Those in the exercise group received a structured intervention that was designed for the way kids like to move. They performed short bouts of exercise interspersed with rest over a two-hour period," Charles Hillman, a kinesiologist with the University of Illinois and leader of the study, said.

Physical fitness improved six percent for those in the FITKids program, and less than one percent for subjects in the control group. Mental abilities also improved more among those participating in physical activity than for children in the control group, the study found. Skills which benefited from exercise include the ability to remain focused when presented with distractions, as well as cognitive flexibility, which measures an individual's skills at quickly switching from one mental task to another.

"Kids in the intervention group improved two-fold compared to the wait-list kids in terms of their accuracy on cognitive tasks. 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," Hillman told the press.

Physical activity for children in the FITKids groups was directed in a manner similar to the CATCH exercise program, which is being adopted by a growing number of schools around the nation.

Hillman and his team cautioned that the study did not examine how much physical activity added to the improvement in cognitive skills and how much was due to social interactions. Sports in the FitKids program were designed for children to engage on a social level with their peers while participating in exercise.

Study of how physical activity affects the mental development of pre-pubescent youth was detailed [pdf] in the journal Pediatrics.