ABCNEWS.com : Study: Exercise Keeps the Brain Sharp The researchers used high-resolution magnetic resonance imaging to study the brains of 55 volunteers between the ages of 56 and 79. They found that those who were physically fit had lost far less of their brain's gray and white matter than those who got very little exercise.
"People who are most fit showed the largest benefit," says psychologist Arthur F. Kramer of the University of Illinois at Urbana-Champaign. "They showed the least amount of reduction in brain volume."