I must have a really big brain, or at least I will when I am older. Ever since a study came out last spring that found that in order for most women to maintain a normal weight they must exercise 60 minutes a day instead of the formerly recommended 30, I have been on my treadmill each night squeezing in an hour of walking. The latest research finds that walking is not only a healthful exercise for the body, but seniors who are committed to walking actually have larger gray matter volume and less cognitive impairment than those who are sedentary.

The study was led by Kirk Erickson PhD of the University of Pittsburgh and published in the journal Neurology. He and his colleagues studied 299 cognitively normal senior adults who were participating in the Cardiovascular Health Study, a large study that was designed primarily to examine risk factors for coronary heart disease and stroke. The average age of the participants at enrollment was 73.

The participants reported how much they walked on an average week; these were grouped into four "quartiles" based on number of blocks walked: 8, 21, 45, and 156. At the end of the nine-year study, the participants had MRI scans of the brain. After 13 years, they were assessed for cognitive impairment or dementia.

Those who walked the most (in the highest quartile) were shown on the MRI to have an increased volume of gray matter in three regions of the brain: the inferior frontal gyrus (associated with verbal working memory), the hippocampus (regulates emotion and memory), and the supplementary motor area (involved in planning complex movements). And the increase was significant — more than 10% greater in each region.

The researchers found that the goal for seniors to reap the benefits of walking was at least 72 blocks per week (roughly equal to 6-9 miles).

Of course, walking provides many other health benefits, including strengthening your heart, normalizing blood sugar to prevent type 2 diabetes, increasing bone density, reducing the risk of cancer, and — if your walking burns more calories than you take in — weight loss.

Fred offers some great tips for increasing physical activity through walking in his article "8 Ways to Help Walk Away Your Cancer Risk". MedicineNet.com also offers a wide variety of resources, including stretching, interval training, and what type of shoe to wear.

Hippocrates said "Walking is man's best medicine." How can you argue with that?