More evidence that exercise is good for the brain.

Poor physical fitness as measured by VO2 max linked to deterioration of vital nerve fibers in the brain and memory decline.

The study found that lower fitness levels were associated with weaker white matter, which in turn correlated with lower brain function.

This was an observational study which means causation cannot be established; however, randomized controlled trials have also found that exercise increases brain volume and improves cognitive function.