By Real Simple
Updated July 19, 2011
Soles of sneakers
The evidence:Taking a walk a few times each week can increase the volume of the hippocampus, the part of the brain responsible for long-term memory, by 2 percent each year, according to a 2011 study published in the journal Proceedings of the National Academy of Sciences. That’s a significant gain, given that the hippocampus in older adults typically shrinks by 1 to 2 percent a year.How to do it: Regular strolls can prevent brain changes associated with higher risks of dementia. Walk for at least 40 minutes three times a week, and stick with it. In a 2010 study published in Frontiers in Aging Neuroscience, researchers examined the brains of senior citizens who had adopted walking routines and found little change after six months, but they observed increased connectivity between brain cells after a full year.
| Credit: Jens Mortensen

Go with running shoes if you mostly jog or walk, since they’re engineered for heel-to-toe motion. Why not walking shoes? “Running sneakers cater to a wider range of foot types and are built to last longer,” says Megan Leahy, a doctor of podiatric medicine at the Illinois Bone & Joint Institute, in Chicago.

Go with cross-trainers if your routine includes an activity like aerobics, weight training, or kickboxing (basically any exercise on a hard surface that involves side-to-side movement).