A Spanish study involving 101 overweight/obese children (aged 8-11) has found that aerobic capacity and motor ability is associated with a greater volume of gray matter in several cortical and subcortical brain regions.
Aerobic capacity was associated with greater gray matter volume in the premotor cortex, supplementary motor cortex, hippocampus, caudate nucleus, inferior temporal gyrus, parahippocampal gyrus, and the calcarine cortex. Three of these regions (premotor cortex, supplementary motor cortex and hippocampus) were also related to better academic performance.
Motor ability (speed and agility) was associated with a greater gray matter volume in two regions essential for language processing and reading: the inferior frontal gyrus and the superior temporal gyrus. Both of these were also associated with better academic performance.
Muscular strength showed no independent association with gray matter volume in any brain region.
The researchers suggest that increases in cardiorespiratory fitness and “speed-agility” may counteract the known harmful effect of obesity on brain structure and academic performance during childhood.
 A whole brain volumetric approach in overweight/obese children: Examining the association with different physical fitness components and academic performance. The ActiveBrains project. NeuroImage [Internet]. 2017 ;159:346 - 354. Available from: http://www.sciencedirect.com/science/article/pii/S1053811917306584