We all know regular exercise is good for the body, lowering our risk for heart disease and cancer and helping us to keep the weight off. But now research is showing that exercise is equally good for the brain.
The prime reason: Exercise increases blood flow to gray matter, keeping brain cells, or neurons, healthy.“Neurons are the engine that drives your brain,” says Sandra B Chapman, Ph. D., chief director of the Center for BrainHealth ® at The University of Texas at Dallas.“When they’re healthier, you’re going to have more efficient brain function.”
Size Really Does Matter
The size of the hippocampus, which is the area of the brain responsible for memory and spatial navigation, shrinks by one to two percent every year. But regular aerobic exercise may reverse that decline. In a study published in the Proceedings of the National Academy of Sciences in 2011, researchers measured the results of two types of exercise on the brains of 120 people ages 55 to 80. Half the people walked for 40 minutes three times per week, and half stretched and toned muscles using resistance bands. One year later, people who stretched had a 1.4 percent decline in the volume of their hippocampus, but those who walked increased their hippocampal volume by two percent, essentially reversing their age-related loss in volume by one to two years.
As we age, regular exercise may also shield us from conditions that sabotage memory. According to a 2011 study in Neurology, older people—their average age was 70—who regularly did moderate to vigorous exercise were 40 percent less likely to have a small brain lesion, also called a silent stroke, which may raise the risk of memory problems, dementia and stroke, than people who didn’t exercise.
The brain-boosting benefits of exercise aren’t just apparent in grown-ups. At the University of Illinois at Urbana-Champaign, researchers found that while both fit and unfit 9- to 10-year olds did well learning the names of regions on a fictitious map, the fittest youngsters were much better at recalling the names a day later.
The Exercise-Mind Connection
So far, researchers haven’t been able to say exactly which types of exercise are best for the brain. The bulk of the research has been on aerobic activities—primarily walking. Nor can experts say precisely how long and how often you should exercise to boost your brain. A study published in Frontiers in Aging Neuroscience in 2010 reported that people 59 and older who walked at their own pace for 40 minutes three times a week for a year improved connections in brain networks involved in functions like planning, scheduling, working memory, and multitasking.
Still, some of exercise’s mind-sharpening powers may show up in as little as 12 weeks, Dr. Chapman and her colleagues have found. In the study, published in 2013 in Frontiers in Aging Neuroscience, one group of people ages 57 to 75 did three weekly hour-long aerobic workouts for three months. They alternated between riding a stationary bike and walking on a treadmill at 50 to 75 percent of their maximum heart rate. Another group served as the control group. Everyone took a series of memory tests at the start of the study, mid-way through and at the end. They also underwent brain MRIs to monitor blood flow.
The upshot: People who did aerobic exercise increased their immediate memory.“If I give you a phone number and you can recall it right away, that’s immediate memory,” explains Dr. Chapman. But the exercisers were also good at recalling the phone number 30 minutes later–so-called gradual memory. “That is a lot harder and shows more robust improvement in memory function,” says Dr. Chapman.
What’s more, blood flow to a region of the brain called the anterior cingulate rose by an impressive 38 percent in the exercisers. “That’s the part of the brain that is the major hub for info being distributed across the brain,” says Dr. Chapman.
One promising small study published in the Journal of Physical Activity & Health in 2013 did find that after doing 20 minutes of Hatha yoga, college students scored better on cognitive tests that measured reaction times and accuracy than they did after they walked or jogged on a treadmill at a moderate pace for 20 minutes.
“The mind-body element of yoga may play a role in improving cognitive performance,’ says study co-author Neha Gothe, Ph.D., assistant professor of kinesiology at Wayne State University in Detroit. Whereas running and walking are “habitual activities” that allow your mind to wander, she explains, that’s not the case with yoga. “Yoga is very in the moment. You are focused on your breath and your mind and are constantly aware of how you are moving,” says Dr. Gothe. Another possible reason:“Yoga reduces anxiety and stress,” she adds.“If you are less stressed and anxious, you’ll do better on cognitive tests.”
What It Takes
It’s good to know that even short blips of exercise can bolster the brain. But experts say to keep your mind sharp for the long haul you need to get serious about physical activity.
“It looks like the amount of time you spend in an aerobic state is important,” says Dr. Chapman. Until researchers know more about how much exercise it takes to sharpen your mind, aim for about an hour of exercise at a time at least three times a week. That said, if you can only squeeze in a half hour, go for it. “Whatever you do is better than nothing,” says Dr. Chapman.
It doesn’t matter whether you walk or run, bike or dance, or even practice yoga. Just make sure you enjoy whatever it is you do. (That way, you’ll be more apt to stick with it!) And make sure you exert yourself: “Getting your heart rate up is key,” says Dr. Chapman. When you work out, “it should be a little bit hard to carry on a conversation,” she adds. So turn off the cell phone.
And finally, stick with it. Once you stop physical activity, brain gains disappear. “You lose them very quickly,” says Dr. Chapman. “Exercise does have to be a regular habit.”