Brain Rules (Updated and Expanded). John Medina
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happens in the human brain. Imaging studies have shown that exercise increases blood volume in a region of the brain called the dentate gyrus. That’s a big deal. The dentate gyrus is a vital constituent of the hippocampus, a region deeply involved in memory formation. This blood-flow increase, likely the result of new capillaries, allows more brain cells greater access to the blood’s waitstaff and hazmat team.
Another brain-specific effect of exercise is becoming clear. Early studies indicate that exercise also aids in the development of healthy tissue by stimulating one of the brain’s most powerful growth factors, BDNF. That stands for brain-derived neurotrophic factor. “I call it Miracle-Gro, brain fertilizer,” says Harvard psychiatrist John Ratey. “It keeps [existing] neurons young and healthy, and makes them more ready to connect with one another. It also encourages neurogenesis—the creation of new cells.” The cells most sensitive to this are in the hippocampus, inside the very regions deeply involved in human cognition. Exercise increases the level of usable BDNF inside those cells. Most researchers believe this uptick also buffers against the negative molecular effects of stress, which in turn may improve memory formation. We’ll have more to say about this interaction in the Stress chapter.
Redefining normal
All of the evidence points in one direction: Physical activity is cognitive candy. Civilization, while giving us such seemingly forward advances as modern medicine and spatulas, also has had a nasty side effect. It gives us more opportunities to sit on our butts. Whether learning or working, we gradually quit exercising the way our ancestors did. Recall that our evolutionary ancestors were used to walking up to 12 miles per day. This means that our brains were supported for most of our evolutionary history by Olympic-caliber bodies. We were not sitting in a classroom for eight hours at a stretch. We were not sitting in a cubicle for eight hours at a stretch. If we sat around the Serengeti for eight hours—heck, for eight minutes—we were usually somebody’s lunch. We haven’t had millions of years to adapt to our sedentary lifestyle. That lifestyle has hurt both our physical and mental health. There is no question we are living in an epidemic of fatness, a point I will not belabor here. The benefits of exercise seem nearly endless because its impact is systemwide, affecting most physiological systems. Exercise makes your muscles and bones stronger, improving your strength and balance. It helps regulate your appetite, reduces your risk for more than a dozen types of cancer, improves the immune system, changes your blood lipid profile, and buffers against the toxic effects of stress (see the Stress chapter). By enriching your cardiovascular system, exercise decreases your risk for heart disease, stroke, and diabetes. When combined with the intellectual benefits exercise appears to offer, we have in our hands as close to a magic bullet for improving human health as exists in modern medicine. So I am convinced that integrating exercise into those eight hours at work or school will only make us normal.
All we have to do is move.
More ideas
I can think of a few simple ways to harness the effects of exercise in the practical worlds of education and business.
Recess twice a day
Because of the increased reliance on test scores for school survival, many districts across the nation are getting rid of physical education and recess. Given the powerful cognitive effects of physical activity, this makes no sense. Dr. Yancey described a real-world test: “They took time away from academic subjects for physical education … and found that, across the board, [adding exercise] did not hurt the kids’ performance on the academic tests. [When] trained teachers provided the physical education, the children actually did better on language, reading, and the basic battery of tests.”
Cutting off physical exercise—the very activity most likely to promote cognitive performance—to do better on a test score is like trying to gain weight by starving yourself. A smarter approach would be to insert more, not less, exercise into the daily curriculum. They might even reintroduce the notion of school uniforms. Of what would the new apparel consist? Simply gym clothes, worn all day long. If your children’s school isn’t on board, consider how you could help your kids get 20 to 30 minutes each morning for aerobic exercise; and 20 to 30 minutes each afternoon for strengthening exercises. Most studies show a benefit from exercising only two or three times a week.
You could apply the same idea at work, taking morning and afternoon breaks for exercise. Conduct meetings while you walk, whether in the office or outside. You just might see a boost in problem solving and creativity.
Treadmills and bikes in classrooms and cubicles
Remember the experiment showing that when children aerobically exercised, their brains worked better, and when the exercise stopped, the cognitive gain soon plummeted? These results suggested to the researchers that one’s level of fitness is not as important as a steady increase in oxygen to the brain. Otherwise, the improved mental sharpness would not have fallen off so rapidly. So they did another experiment. They administered supplemental oxygen to young healthy adults, and they found a cognitive improvement similar to that of exercise. This suggests an interesting idea to try in a classroom. (Don’t worry, it doesn’t involve oxygen doping.)
What if, during a lesson, the children were not sitting at desks but walking on treadmills or riding stationary bikes? Students might study English while peddling comfortably on a bike that accommodates a desk. Workers could easily do the same, composing email while walking on a treadmill at one to two miles per hour. This idea would harness the advantage of increasing the oxygen supply and at the same time harvest all the other advantages of regular exercise.
The idea of integrating exercise into the workday or school day may sound foreign, but it’s not difficult. I put a treadmill in my own office, and I now take regular breaks filled not with coffee but with exercise. I constructed a small structure upon which my laptop fits so that I can write while I walk. At first, it was difficult to adapt to such a strange hybrid activity. It took a whopping 15 minutes to become fully functional typing on my laptop while walking 1.8 miles per hour.
Office workers can sometimes choose their own desk setups, integrating exercise on an individual basis. But businesses have compelling reasons to incorporate such radical ideas into company policy as well. Business leaders already know that if employees exercised regularly, it would reduce health-care costs. There’s no question that halving someone’s lifetime risk of a debilitating stroke or Alzheimer’s disease is a wonderfully humanitarian thing to do. But exercise also could boost the collective brain power of an organization. Fit employees are more capable than sedentary employees of mobilizing their God-given IQs. For companies whose competitiveness rests on creative intellectual horsepower, such mobilization could mean a strategic advantage. In the laboratory, regular exercise improves problem-solving abilities, fluid intelligence, and even memory—sometimes dramatically so. It’s worth finding out whether the same is true in business settings, too.
Brain Rule #2
Exercise boosts brain power.
• Our brains were built for walking—12 miles a day!
• To improve your thinking skills, move.
• Exercise gets blood to your brain, bringing it glucose for energy and oxygen to soak up the toxic electrons that are left over. It also stimulates the protein that keeps neurons connecting.
• Aerobic exercise just twice a week halves your risk of general dementia. It cuts your risk of alzheimer’s by 60 percent.
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Brain Rule #3
Sleep