Washington: Physical fitness is linked with brain development in small children, says a research.

Those who are more fit tend to have a bigger hippocampus and perform better on a test of memory than their less-fit peers.

The hippocampus is a major component of the brain, known to be important in learning and memory.

A bigger hippocampus in nine and 10-year-old children appears to boost their performance on a relational memory task, said University of Illinois doctoral student Laura Chaddock.

The new study, which used magnetic resonance imaging (MRI) to measure the relative size of specific structures in the brains of 49 child subjects, appeared in the journal Brain Research.

"This is the first study I know of that has used MRI measures to look at differences in brain between kids who are fit and kids who aren't fit," said University of Illinois psychology professor Art Kramer, said an Illinois release.

He led the study with Chaddock and kinesiology and community health professor Charles Hillman. "Beyond that, it relates those measures of brain structure to cognition."

Previous studies in older adults and in animals have shown that exercise can increase the size of the hippocampus. A bigger hippocampus is associated with better performance on spatial reasoning and other cognitive tasks.

Rather than relying on second-hand reports of children's physical activity level, the researchers measured how efficiently the subjects used oxygen while running on a treadmill.

"This is the gold standard measure of fitness," Chaddock said.

The physically-fit children were "much more efficient than the less-fit children at utilizing oxygen," Kramer said.

When they analyzed the MRI data, the researchers found that the physically-fit children tended to have bigger hippocampal volume - about 12 percent bigger relative to total brain size - than their out-of-shape peers.

The children who were in better physical condition also did better on tests of relational memory - the ability to remember and integrate various types of information - than their less-fit peers. IANS