How does physical exercise help keep my brain healthy?

Exercise promotes blood flow to the brain and supplies the cells with oxygen and nutrients; in addition, it seems to boost brain hormones that help keep you focused, lowers memory-damaging amino acids and prevents—or possibly reverses—the natural brain shrinkage that begins in middle age.

Taiwanese researchers found that middle-aged mice trained to work out on a treadmill every day for five weeks grew 2.5 times more new brain cells than mice that didn’t work out. Not only was the quantity of brain cells superior in the mice that worked out, but the quality of these cells was as well. Also, mice that began exercising in early middle age fared even better than mice that took to the treadmill in later middle age.

Researchers at the University of Edinburgh in Scotland studied physical fitness and cognitive function in 460 human subjects, all surviving participants of the 1932 Scottish Mental Health Survey. They reviewed IQ data from the earlier study and administered the same cognitive test that participants had taken at age 11 to the 79-year-olds, looking at verbal reasoning, numerical and spatial skills. Then they tested their physical prowess, including grip strength, 6-meter walk time and lung function. What the researchers found was that higher fitness levels at age 79 were a significant predictor of higher cognitive test scores, indicating that physical fitness has a direct correlation to successful cognitive aging.

Keep Your Wits by Walking

A University of Illinois study used magnetic resonance imaging (MRI ) to measure brain volume in nearly 60 seniors. Half of the group was then put on a brisk walking regimen—one hour per day, three times a week—while the rest were assigned stretch-and-tone exercises. “After only three months, the people who [walked] had the brain volumes of people three years younger,” observed study coauthor Arthur Kramer, PhD. MRI s revealed no such improvements for the stretch-and-tone group, leading researchers to believe that walking pumps more blood to the brain, which in turn fuels the growth of new neurons.

Exercise to the Beat for an Extra Boost

A study in the New England Journal of Medicine found that among 450 seniors, all age 75, those who danced several times per week had the best defenses against mental deterioration. “The combination of music and exercise may stimulate and increase cognitive arousal while helping to organize cognitive output,” said study author Charles Emery, PhD.

Aerobic activity that gets the heart rate up for extended periods of time boosts brain-derived neurotrophic factor (BDNF), a chemical that plays a role in neurogenesis, or the growth of new brain cells. Think of BDNF as a sort of Miracle-Gro for your brain. When you exercise, your brain sprouts new cells. When your brain doesn't create as many new cells as it loses, aging occurs.

Research studies show that exercise generates new brain cells in the temporal lobes (involved in memory) and the prefrontal cortex (involved in planning and judgment). These new cells survive for about four weeks, then die off unless they are stimulated. If you stimulate these new neurons through mental or social interaction, they connect to other neurons and enhance learning. This is why you have to exercise consistently to encourage continual new cell growth in the brain. It also explains why people who work out at the gym and then go to the library are smarter than people who only go to the library.