Exercise actually might improve brain function. This is probably not something that is in the forefront of anyone's mind when exercising but one can readily grant the logic of the statement. And the premise should come intuitively to anyone who has raised children: during the years of greatest brain development, children are in a constant state of exercise - except when they're asleep. Nothing produces more pride in a child (or the parents) than the accomplishment of a task like coloring within the lines that displays increased motor skills. Coloring within the lines is a major milestone, socially and neurologically. In adulthood, however, anyone who is not in denial eventually comes to the back side of the mountain and must admit that motor skills are ebbing. As we age, we do not engage in many of the rambunctious physical activities of youth and, at some point, we notice that we are no longer quite keeping our crayon strokes inside the lines. Since brain development was stimulated by physical activity when we were young, is it eroded by the wane of physical activity? It's an argument with some merit! Here's why.
Hillman, Castelli, and Buck2 analyzed the relationship between physical fitness and academic performance in preadolescent children. They found that physically fit children processed information faster and used a greater number of neurons when performing cognitive tasks than less fit children did. A follow-up study by Hillman, Buck, Themanson, Pontifex, & Castelli3 confirmed this, with the additional finding that physically fit children had a higher accuracy factor and greater executive control in tasks that demanded focused attention. Physical fitness vs. academic performance in both pre-adolescent and adolescent children was studied in Massachusetts by Chomitz and associates1 in 2009. They demonstrated that children who were physically fit performed better on standardized math and English tests compared to students who were not as fit. (Interestingly, math scores were seen to be more strongly related to physical fitness.) Looking at the issue from the other side, Li, Dai, Jackson, & Zhang4, demonstrated a negative performance correlation for obese and overweight children in similar activities. From this study, these researchers were able to hypothesize that blood vessel inflammation in the brain caused by obesity or being overweight (not present in a healthy weight child) might be the cause of some cognitive impairment. In short, then, aerobic fitness can positively affect the brain. And with that, it's not going beyond the pale of credibility to suggest that efforts to remain as active and as fit as possible to the ends of our lives might delay or even stop the physical and functional erosion of the brain we see in various dementias.
This line of reasoning is supported by the observed effects of physical exercise on the autonomic nerve system. The autonomic nerve system is part of the greater entity we call the peripheral nerve system (every nerve outside the skull and spinal column). This, in turn, is part of the complete package that includes the central nerve system (the brain and spinal cord). The autonomic nerve system is a key player in the balance between energy expenditure and body fat storage. To what extent physical activity in childhood years contributes to autonomic function is not entirely clear but to explore this relationship, Nagai and Moritani5 studied healthy Japanese children aged 6-12 years. While a causal link between autonomic performance and obesity was not definitely proven, two conclusions could be reached from their findings:
1) obese children generated reduced overall autonomic nerve activity;
2) regular sports activity enhanced autonomic nerve system performance in both lean and obese children.
Since children, both lean and obese, manifested superior autonomic nerve system function with physical activity, it was concluded that regular vigorous exercise might actually improve autonomic nerve system function. And as the differentiation between the central nerve system and the peripheral nerve system is just an arbitrary designation made by anatomists and physiologists, it is not hard to accept the proposition that vigorous physical activity might benefit the brain.
To sum it all up, then, we can say that, in all likelihood, the more physically active you remain throughout your life, the longer you will be able to color inside the lines!