Sure, we knew about the improvements it can provide to aerobic capacity, not to mention muscles and joints, but two recently released studies show that walking can enhance brain function, too.
Walking or other repetitive exercise can change the brain in a number of ways, says Dr. Gary Small, professor of psychiatry and aging at the Semel Institute for Neuroscience and Human Behavior, at the University of California, Los Angeles. The heart pumps more blood, affecting not only muscles but also the brain. "Your brain needs blood, because in the blood are nutrients and oxygen, which are good for the cells and will make the brain healthier," he says. "The vessels that deliver the nutrients also branch out and become more effective."
The act of doing a movement over and over also can stimulate the brain's neuro-circuits, he adds, resulting in activity in various regions of the brain. That activity may decrease over time as the body becomes more efficient at the activity. But other stimulation can have an effect -- when a person walks outside with a friend, for example, the brain is guiding a number of activities, such as talking and observing.
In one study, stroke patients put through a walking program could walk better and faster afterward, and the repetitive movements activated different areas of their brain. Researchers expected to see most activity in the cortex, which governs motor skills, but instead much activity was seen in the subcortical region, which, says lead author Dr. Andreas Luft, "has some role in walking, but maybe we've underestimated it. We're actually putting this idea back as a potential mechanism of how walking is controlled."
About half of 71 study subjects with some movement disability were asked to walk on a safety-rigged treadmill three times a week for up to 40 minutes, increasing intensity to a moderate level as the study progressed. The others did assisted stretching exercises for the same amount of time. All were tested in the beginning and after six months for speed and aerobic capacity; about half in each group were given functional magnetic resonance imaging tests before and after to determine brain activity.
The walking group increased its speed by 51 percent, while the stretching group improved by 11 percent. The walkers' fitness levels also increased, with aerobic capacity rising about 18 percent, while the stretching group's fitness levels decreased slightly.
Functional MRI tests revealed intensified activity in the subcortical region in the walking group, which surprised the researchers (the stretching group showed no change). "We found that change can not only happen in the superficial layers of the brain, but in the deeper brain levels as well," said Luft, professor of neuro-rehabilitation at the University of Zurich in Switzerland. The study appeared in the August issue of the journal Stroke.
"The movement repetition that typically goes on in a physical therapy session is very low," says Dr. Daniel Hanley, a professor of neurology at Johns Hopkins Medical Institutions and a co-author of the study, which was conducted at Johns Hopkins, the University of Maryland and the Department of Veterans Affairs' Maryland VA Medical Center. "We did a lot of repetition with the same leg, and we think that is associated with the brain changes." The researchers say they believe the brain is either relearning how to walk, or reprogramming itself to compensate for regions damaged by stroke.
In the other study, a walking regimen boosted cognitive scores in adults who were encouraged to exercise at home for 24 weeks in a moderately intense regimen (most chose walking). Researchers at the University of Melbourne in Australia did randomized tests on 170 adults age 50 or older who didn't have dementia but were considered at increased risk due to memory problems. All participants received education materials on memory loss, stress management, diet, alcohol consumption and smoking, but not on physical activity. Half -- the control group -- were not encouraged to exercise. The others were asked to exercise for three 50-minute sessions per week. Cognitive function was measured over 18 months with the Alzheimer Disease Assessment Scale-Cognitive Subscale, which measures cognitive dysfunction in people with Alzheimer's and other forms of dementia.
Those in the exercise group showed a small improvement in cognitive scores compared with the control group, according to results published in the Sept. 3 issue of the Journal of the American Medical Association. They also displayed better delayed recall. Researchers said they believed the progress was significant, considering participants engaged in only moderate amounts of physical activity.