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Brain Rule #2

Exercise boosts brain power.

IF THE CAMERAS WEREN’T rolling and the media abuzz with live reports, it is possible nobody would have believed the following story:

A man had been handcuffed, shackled, and thrown into California’s Long Beach Harbor, where he was quickly fastened to a floating cable. The cable had been attached at the other end to 70 boats, bobbing up and down in the harbor, each carrying a single person. Battling strong winds and currents, the man then swam, towing all 70 boats (and passengers) behind him, traveling 1½ miles from Queensway Bridge. The man, Jack LaLanne, was celebrating his birthday.

He had just turned 70 years old.

Jack LaLanne, born in 1914, has been called the godfather of the American fitness movement. He starred in one of the longest-running exercise programs produced for commercial television. A prolific inventor, LaLanne designed the first leg-extension machines, the first cable-fastened pulleys, and the first weight selectors, all now standard issue in the modern gym. He is credited with inventing an exercise that supposedly bears his name, the Jumping Jack. LaLanne lived to the age of 96. But even these feats are probably not the most interesting aspect of this famed bodybuilder’s story.

If you watch him during an interview late in his life, your biggest impression will be not the strength of his muscles but the strength of his mind. LaLanne is mentally alert. His sense of humor is both lightning fast and improvisatory. “I tell people I can’t afford to die. It will wreck my image!” he joked to Larry King. He once railed: “Do you know how many calories are in butter and cheese and ice cream? Would you get your dog up in the morning for a cup of coffee and a donut?” (He claims he hasn’t had dessert since 1929.) He has the energy of an athlete in his 20s, and he is possessed of an impressive intellectual vigor.

So it’s hard not to ask, “Is there a relationship between exercise and mental alertness?” The answer, it turns out, is yes.

Survival of the fittest

Though a great deal of our evolutionary history remains shrouded in controversy, the one fact that every paleoanthropologist on the planet accepts can be summarized in two words:

We moved.

A lot. As soon as our Homo erectus ancestors evolved, about 2 million years ago, they started moving out of town. Our direct ancestors, Homo sapiens, rapidly did the same thing. Because bountiful rainforests began to shrink, collapsing the local food supply, our ancestors were forced to wander an increasingly dry landscape looking for more trees to scamper up and dine on. Instead of moving up, down, and across complex arboreal environments, which required a lot of dexterity, we began walking back and forth across arid savannahs, which required a lot of stamina. Homo sapiens started in Africa and then took a victory lap around the rest of the world. The speed of the migration is uncertain; the number changes as we find new physical evidence of habitation and as we’re better able to isolate and characterize ancient DNA. Anthropologists can say that our ancestors moved fast and they moved far. Males may have walked and run 10 to 20 kilometers a day, says anthropologist Richard Wrangham. The estimate for females is half that. Up to 12 miles: That’s the amount of ground scientists estimate we covered every day. That means our fancy brains developed not while we were lounging around but while we were exercising.

Regardless of its exact speed, our ancestors’ migration is an impressive feat. This was no casual stroll on groomed trails. Early travelers had to contend with fires and floods, insurmountable mountain ranges, foot-rotting jungles, and moisture-sucking deserts. They had no GPS to reassure them, no real tools to speak of. Eventually they made oceangoing boats, without the benefit of wheels or metallurgy, and then traveled up and down the Pacific with only the crudest navigational skills. Our ancestors constantly encountered new food sources, new predators, new physical dangers. Along the way they routinely suffered injuries, experienced strange illnesses, and delivered and nurtured offspring, all without the benefit of textbooks or modern medicine. Given our relative wimpiness in the animal kingdom (we don’t even have enough body hair to survive a mildly chilly night), what these data tell us is that we grew up in top physical shape, or we didn’t grow up at all. These data also tell us the human brain became the most powerful in the world under conditions where motion was a constant presence.

If our unique cognitive skills were forged in the furnace of physical activity, is it possible that physical activity still influences our cognitive skills? Are the cognitive abilities of someone in good physical condition different from those of someone in poor physical condition? And what if someone in poor physical condition were whipped into shape? Those are scientifically testable questions. The answers are directly related to why Jack LaLanne can still crack jokes about eating dessert. In his nineties.

Will you age like Jim or like Frank?

Scientists discovered the beneficial effects of exercise on the brain by looking at aging populations. Years ago while watching television, I came across a documentary on American nursing homes. It showed people in wheelchairs, many in their mid- to late 80s, lining the halls of a dimly lit facility, just sitting around, seemingly waiting to die. One was named Jim. His eyes seemed vacant, lonely, friendless. He could cry at the drop of a hat but otherwise spent the last years of his life mostly staring off into space. I switched channels. I stumbled upon a very young-looking Mike Wallace. The journalist was interviewing architect Frank Lloyd Wright, in his late 80s. I was about to hear a most riveting conversation.

“When I walk into St. Patrick’s Cathedral … here in New York City, I am enveloped in a feeling of reverence,” said Wallace, tapping his cigarette.

The old man eyed Wallace. “Sure it isn’t an inferiority complex?”

“Just because the building is big and I’m small, you mean?”

“Yes.”

“I think not.”

“I hope not.”

“You feel nothing when you go into St. Patrick’s?”

“Regret,” Wright said without a moment’s pause, “because it isn’t the thing that really represents the spirit of independence and the sovereignty of the individual which I feel should be represented in our edifices devoted to culture.”

I was dumbfounded by the dexterity of Wright’s response. In the space of a few moments, one could detect the clarity of his mind, his unshakable vision, his willingness to think outside the box. The rest of the interview was just as compelling, as was the rest of Wright’s life. He completed the designs for the Guggenheim Museum, his last work, in 1957, when he was 90 years old. But I also was dumbfounded by something else. As I contemplated Wright’s answers, I remembered Jim from the nursing home. He was the same age as Wright. In fact, most of the residents were. I was beholding two types of aging. Jim and Frank lived in roughly the same period of time. But one mind had almost completely withered, seemingly battered and broken by the aging process, while the other mind remained as incandescent as a light bulb.

What was the difference in the aging process between men like Jim and the famous architect? This question has intrigued the research community for a long time. Attempts to explain these differences led to many important discoveries. I have grouped them as answers to six questions.

1) Is there one factor that predicts how well you will age?

When research on aging began, this question was a tough one to answer. Researchers found many variables, stemming from both nature and nurture, that contributed to someone’s ability to age gracefully. That’s why the scientific community was both intrigued and cautious when a group of researchers uncovered a powerful environmental influence. One of the greatest predictors of successful aging, they found, is the presence or absence of a sedentary lifestyle.

Put simply, if you are a couch potato, you are more likely to age like Jim, if you make it to your 80s at all. If you have an active lifestyle, you are more likely to age like Frank Lloyd Wright—and much more likely to make it to your 90s. The chief reason for the longer life is that exercise improves cardiovascular fitness, which in turn reduces the risk for diseases such as heart attacks and stroke. But researchers wondered why the people who were aging well also seemed to be more mentally alert. This led to an obvious second question.

2) Were they more mentally alert?

Just about every mental test possible was tried. No matter how it was measured, the answer was consistently yes: A lifetime of exercise results in a sometimes astonishing elevation in cognitive performance, compared with those who are sedentary. Exercisers outperform couch potatoes in tests that measure long-term memory, reasoning, attention, and problem-solving skill. The same is true of fluid-intelligence tasks, which test the ability to reason quickly, think abstractly, and improvise off previously learned material in order to solve a new problem. Essentially, exercise improves a whole host of abilities prized in the classroom and at work.

What about people who aren’t elderly? Here, the number of studies done thins out. But in one case, researchers looked at more than 10,000 British civil servants between the ages of 35 and 55, grading their activity levels as low, medium, or high. Those with low levels of physical activity were more likely to have poor cognitive performance. Fluid intelligence, the type that requires improvisatory problem-solving skills, was particularly hurt by a sedentary lifestyle.

Not every cognitive ability is improved by exercise, however. Short-term memory, for example, and certain types of reaction times appear to be unrelated to physical activity. And, while nearly everybody shows some improvement, the degree varies quite a bit among individuals. It’s one thing to look at a group of people and note, as early studies did, that those who exercise are also smarter. It’s another thing to prove that exercise is the direct cause of the benefits. A more intrusive set of experiments needed to be done to answer the next question.

3) Can you turn Jim into Frank?

Like producers of a makeover show, researchers found a group of elderly couch potatoes, measured their brain power, exercised them, and then reexamined their brain power. The researchers consistently found that all kinds of mental abilities began to come back online—after as little as four months of aerobic exercise. A different study looked at school-age children. Children jogged for 30 minutes two or three times a week. After 12 weeks, their cognitive performance had improved significantly compared with prejogging levels. When the exercise program was withdrawn, the scores plummeted back to their preexperiment levels. Scientists had found a direct link. Within limits, it does appear that exercise can turn Jim into Frank, or at least turn Jim into a sharper version of himself.

As the effects of exercise on cognition became increasingly clear, scientists asked the question dearest to the couch-potato cohort:

4) What type of exercise must you do, and how much?

After years of investigating aging populations, researchers’ answer to the question of how much is not much. If all you do is walk several times a week, your brain will benefit. Even couch potatoes who fidget show increased benefit over those who do not fidget. The body seems to be clamoring to get back to its active Serengeti roots. Any nod toward this evolutionary history, be it ever so small, is met with a cognitive war whoop. In the laboratory, the gold standard appears to be aerobic exercise, 30 minutes at a clip, two or three times a week. Add a strengthening regimen and you get even more cognitive benefit. Individual results vary, of course, and exercising too intensely, to exhaustion, can hurt cognition. One should consult a physician before embarking on an exercise program. The data merely point to the fact that one should embark. Exercise, as millions of years traipsing around the globe tell us, is good for the brain. Just how good took everyone by surprise, as they delved into the next question.

5) Can exercise treat dementia or depression?

Given the robust effect of exercise on typical cognitive performance, researchers wanted to know if it would have an effect on atypical performance. What about diseases such as age-related dementia and its more thoroughly investigated cousin, Alzheimer’s disease? What about affective (mood) disorders such as depression? Researchers looked at both prevention and intervention. With experiments reproduced all over the world, enrolling thousands of people, often studied for decades, the results are clear. Your lifetime risk for general dementia is literally cut in half if you participate in physical activity. Aerobic exercise seems to be the key. With Alzheimer’s, the effect is even greater: Such exercise reduces your odds of getting the disease by more than 60 percent.

How much exercise? Once again, a little goes a long way. The researchers showed you have to participate in some form of exercise just twice a week to get the benefit. Bump it up to a 20-minute walk each day, and you can cut your risk of having a stroke—one of the leading causes of mental disability in the elderly—by 57 percent.

Dr. Steven Blair, the man most responsible for stimulating this line of inquiry, did not start his career wanting to be a scientist. He wanted to be an athletics coach. Surely he was inspired by his own football coach in high school, Gene Bissell. Bissell once forfeited a winning game. He realized after the game that an official had missed a call, and he insisted that his team be penalized. Young Steven never forgot the incident. But Bissell encouraged Blair to continue his interest in research, and Blair went on to write a seminal paper on fitness and mortality. The study stands as a landmark example of how to do work with rigor and integrity in this field. His analysis inspired other investigators. What about using exercise not only as prevention, they asked, but as intervention, to treat mental disorders such as depression and anxiety? That turned out to be a good line of questioning.

A growing body of work now suggests that physical activity can powerfully affect the course of both diseases. We think it’s because exercise regulates the release of most of the biochemicals associated with maintaining mental health. In one experiment on depression, rigorous exercise was substituted for antidepressant medication. Even when compared to medicated controls, the treatment outcomes were astonishingly successful. For both depression and anxiety, exercise is beneficial immediately and over the long term. It is equally effective for men and women. The longer the person exercises, the greater the effect. Although exercise is not a substitute for psychiatric treatment (which usually involves therapy along with medication), the role of exercise on mood is so pronounced that many psychiatrists prescribe physical activity as well. It is especially helpful in severe cases and for older people.

In asking what else exercise can do, researchers looked beyond our oldest members to our youngest.

6) Does exercise help kids do better in school?

The number of studies in children is downright microscopic. Still, the data point in a familiar direction. Physically fit children identify visual stimuli much faster than sedentary ones. They appear to concentrate better. Brain-activation studies show that children and adolescents who are fit allocate more cognitive resources to a task and do so for longer periods of time. “Kids pay better attention to their subjects when they’ve been active,” Dr. Antronette Yancey said in an interview with NPR. “Kids are less likely to be disruptive in terms of their classroom behavior when they’re active. Kids feel better about themselves, have higher self-esteem, less depression, less anxiety. All of those things can impair academic performance and attentiveness.”

Of course, many ingredients make up academic performance. Finding out what those components are—and then which are most important for improving performance—is difficult. But these preliminary findings hint that exercise may be one key ingredient.

An exercise in road building

Why exercise works so well in the brain, at a molecular level, can be illustrated by competitive food eaters—or, less charitably, professional pigs. The crest of the International Federation of Competitive Eating proudly displays the motto In Voro Veritas—literally, “In Gorging, Truth.” Like any sporting organization, competitive food eaters have their heroes. The reigning gluttony god is Takeru “Tsunami” Kobayashi. He is the recipient of many eating awards, including the vegetarian dumpling competition (83 dumplings downed in eight minutes), the roasted pork bun competition (100 in 12 minutes), and the hamburger competition (97 in eight minutes). Kobayashi also is a world champion hot-dog eater. One of his few losses was to a 1,089-pound Kodiak bear. In a 2003 Fox-televised special called Man vs. Beast, the mighty Kobayashi consumed only 31 bunless dogs compared with the ursine’s 50, all in about 2½ minutes. The Tsunami would not accept defeat. In 2012, Kobayashi ate 60 bunless dogs in that amount of time. But my point isn’t about speed.

Like the Tsunami’s, the brain’s appetite for energy is enormous. The brain gobbles up 20 percent of the body’s energy, even though it’s only about 2 percent of the body’s weight. When the brain is fully working, it uses more energy per unit of tissue weight than a fully exercising quadricep. In fact, the human brain cannot simultaneously activate more than 2 percent of its neurons at any one time. More than this, and the brain’s energy supply becomes so quickly exhausted that you will faint.

That energy supply is glucose, a type of sugar that is one of the body’s favorite resources. After all of those hot dogs slide down the Tsunami’s throat, his stomach’s acid and his wormy intestines tear the food apart (not getting much help from the teeth, in his case) and reconfigure it into glucose. Glucose and other metabolic products are absorbed into the bloodstream via the small intestines. The nutrients travel to all parts of the body, where they are deposited into cells, which make up the body’s various tissues. The cells seize the sweet stuff like sharks in a feeding frenzy. Cellular chemicals greedily tear apart the molecular structure of glucose to extract its sugary energy.

This energy extraction is so violent that atoms are literally ripped asunder in the process. As in any manufacturing process, such fierce activity generates a fair amount of toxic waste. In the case of food, this waste consists of a nasty pile of excess electrons shredded from the atoms in the glucose molecules. Left alone, these electrons slam into other molecules within the cell, transforming them into some of the most toxic substances known to humankind. They are called free radicals. If not quickly corralled, they will wreck havoc on the innards of a cell and, cumulatively, on the rest of the body. These electrons are fully capable, for example, of causing mutations in your DNA.

The reason you don’t die of electron overdose is that the atmosphere is full of breathable oxygen. The main function of oxygen is to act like an efficient electron-absorbing sponge. At the same time the blood is delivering glucose to your tissues, it is also carrying these oxygen sponges. Any excess electrons are absorbed by the oxygen and, after a bit of molecular alchemy, are transformed into equally hazardous—but now fully transportable—carbon dioxide. The blood is carried back to your lungs, where the carbon dioxide leaves the blood and you exhale it. So whether you are a competitive eater or a typical one, the oxygen-rich air you inhale keeps the food you eat from killing you. How important is oxygen? The three requirements for human life are food, drink, and fresh air. But their effects on survival have very different timelines. You can live for 30 days or so without food, and you can go for a week or so without drinking water. Your brain, however, is so active that it cannot go without oxygen for more than five minutes without risking serious and permanent damage. When the blood can’t deliver enough oxygen sponges, toxic electrons overaccumulate.

Getting energy into tissues and getting toxic electrons out are essentially matters of access. That’s why blood—acting as both waitstaff and hazmat team—has to be everywhere inside you. Any tissue without enough blood supply is going to starve to death, your brain included. More access to blood is better. And even in a healthy brain, the blood’s delivery system can be improved.

That’s where exercise comes in.

It reminds me of a seemingly mundane little insight that literally changed the history of the world. John Loudon McAdam, a Scottish engineer living in England in the early 1800s, noticed the difficulty people had trying to move goods and supplies over hole-filled, often muddy, frequently impassable dirt roads. He had the splendid idea of raising the level of the road using layers of rock and gravel. This immediately made the roads less muddy and more stable. As county after county adopted his process, now called macadamization, people instantly got more dependable access to one another’s goods and services. Offshoots from the main roads sprang up. Pretty soon entire countrysides had access to far-flung points using stable arteries of transportation. Trade grew. People got richer. By changing the way things moved, McAdam changed the way we lived.

What does this have to do with exercise? McAdam’s central notion wasn’t to improve goods and services, but to improve access to goods and services. You can do the same for your brain by increasing the roads in your body, namely your blood vessels, through exercise. Exercise does not provide the oxygen and the food. It provides your body greater access to the oxygen and the food.

How this works is easy to understand. When you exercise, you increase blood flow across the tissues of your body. Blood flow improves because exercise stimulates the blood vessels to create a powerful, flow-regulating molecule called nitric oxide. As the flow improves, the body makes new blood vessels, which penetrate deeper and deeper into the tissues of the body. This allows more access to the bloodstream’s goods and services, which include food distribution and waste disposal. The more you exercise, the more tissues you can feed and the more toxic waste you can remove. This happens all over the body. That’s why exercise improves the performance of most human functions. You stabilize existing transportation structures and add new ones, just like McAdam’s roads. All of a sudden, you are becoming healthier.

The same 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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