Walking - Part Of Why It Is Good For You

In healthy adults, the hippocampus — a part of the brain important to the formation of memories — begins to atrophy around 55 or 60. Now psychologists are suggesting that the hippocampus can be modestly expanded, and memory improved, by nothing more than regular walking. In a study published on Jan. 31 in The Proceedings of the National Academy of Sciences, researchers randomly assigned 120 healthy but sedentary men and women (average age mid-60s) to one of two exercise groups. One group walked around a track three times a week, building up to 40 minutes at a stretch; the other did a variety of less aerobic exercises, including yoga and resistance training with bands.  After a year, brain scans showed that among the walkers, the hippocampus had increased in volume by about 2 percent on average; in the others, it had declined by about 1.4 percent. Since such a decline is normal in older adults, “a 2 percent increase is fairly significant,” said the lead author, Kirk Erickson
http://www.nytimes.com/2011/02/08/health/research/08fitness.html?src=me&ref=health