Mental muscle.

One of the first pieces of evidence that linked exercise and the brain came in the 1990s, when geneticist Fred Gage found that exercise could lead to the growth of new brain cells in mice. But a few years ago, while writing my book Brain Power: Everything you need to know for a healthy, happy brain, I dug into the literature on exercise and the mind. "We've seen that exercise could be potentially one of the biggest factors to prevent Alzheimer's disease and other types of dementia", says Eef Hogervorst, who studies exercise and cognition at Loughborough University in the UK. All of these are short-term shifts in brain activity, but both Hillman and Lubans have found evidence that exercise can cause long-term structural and functional changes to the brain, too. [Extracted from the article]