What’s more, the more complex the tests, the bigger the difference between the fit and unfit children. On simple memory tests, the variance isn’t too distinct; it’s on the difficult tests that the fit children do much better.
One single training session produces results
Just as exercise has an immediate impact on the adult brain, the same quick, strengthening benefit takes effect in children’s brains. When nine-year-olds were physically active for twenty minutes—in one single session—they became markedly better at reading. One short burst of exercise altered the kids’ academic abilities! Why this happens we don’t know for sure, but we are certain that children’s attention spans improve immediately after they are physically active; as a result, we can assume that attention span has an important role to play in this context.
When nine-year-olds were physically active for one twenty-minute session, they improved markedly on their reading comprehension. One short burst of activity affected the kids’ academic abilities!
In the same way that we’ve examined the minimum amount of training required for adults to see an improvement in fitness, we’ve checked to see how little training is needed to improve the attention span of children. The results are astonishing! When teenagers jogged for twelve minutes, both their reading comprehension and what is called visual attention improved. The effect lasted the better part of an hour, but a bout of activity as brief as four minutes (yes, you read that right!) can improve our ability to stay focused and alert and can get ten-year-olds to remain undistracted.
Attention span and memory are not the only things that improve in children who are physically active. Today we know that physically active kids between the ages of four and eighteen will show improvement in practically all of their cognitive faculties. Multitasking, working memory, and focus—everything seems to get better. The same goes for the ability to make decisions (i.e., executive control).
Executive control might sound like a trait only company directors need to have. However, even children need to be able to show initiative and make decisions. They need to be able to plan, to organize, and to stay focused on what they are doing in the present, even when they’re distracted by, say, their cell phones. Children must also be able to stop themselves from giving in to every single impulse they feel. Thus, it’s not exactly rash to say that executive control is necessary for children to do well academically.
Less stressed children
It’s true that the effects of being physically active in childhood have positive results that go far beyond academic success and proper executive control. Kids also become less sensitive to stress. Two hundred and fifty-eight Finnish second-graders were studied to see how they reacted to stressful situations, and whether there was a connection between their vulnerability to stress and their level of physical activity. Asking nine-year-olds how active they are does not yield reliable answers, so the kids were outfitted with pedometers. Their stress resilience was measured by administering tests that mimicked daily stressors, such as being timed while doing arithmetic or giving presentations to one another—situations that are deemed just as high-stress for children as for adults.
Turns out, the connection was obvious. Children who took a lot of steps every day didn’t react as strongly to stress as the kids who didn’t walk as much. And it didn’t just show in their calmer demeanor: the levels of the stress hormone cortisol didn’t rise as much in the physically active children as in the sedentary kids when they completed high-stress arithmetic and presentation tests. If anything, this is strong evidence that physically active children are more resilient to stress.
I completely understand how easy it is to feel guilty when reading about these studies, especially if you have children who aren’t interested in gym or sports and who are glued to their computers. How do you go about making them active? A good starting point is to let your kid pick what he or she enjoys doing. American scientists tried this tactic by letting overweight elementary school children, who were not into gym activities and who were mostly sedentary in their free time, get together and be physically active during after-school hours. To get the children to join in, they let them choose an activity they thought would be fun, so long as they did something. Some kids ran, some jumped rope, and some played ball sports. The outcome was that the kids improved in math without having to take extra lessons. The more physically active they became, the more their math scores improved, even though they hadn’t completed any extra class work. Twenty short minutes of exercise produced results, but the kids who saw the most improvement were active for at least forty minutes and had increased their heart rate substantially, preferably up to 150 beats per minute.
But these positive effects didn’t stop at improved math comprehension. A few of the overweight kids who did not like sports and who had been encouraged to become active were examined by MRI. The images showed that the activity in the prefrontal cortex—the area behind the forehead and our center for abstract thinking, concentration, and planning—had risen. The study’s authors summarized this finding in a way that numbers or tables could not come close to doing: “For children to reach their full potential, they need to be active.”
In the short term and long term
When we fit the pieces of the puzzle together, the amazing effect that exercise has on children’s brains becomes obvious, both in the short term and long term. A single bout of activity increases attention span and improves concentration and reading comprehension. It continues
to do so for one to several hours, before it wears off. Like adults, children reap significant, long-term benefits if they exercise regularly for several months. Again, as with adults, the choice of activity is not of much import. Running, playing, competing in tennis or soccer—all seem to have the same positive impact. What is vital is raising the heart rate. The critical thing is not what the children do to be physically active; it’s that they are physically active.
From the brain development’s perspective, is there an age at which we should be especially mindful that our kids exercise? We don’t know that in detail yet, but many clues suggest that children of elementary school age reap the most benefits from being active.
Exercise strengthens different areas in the child’s brain
We know how physical activity strengthens the adult brain; we also know that a child’s brain changes with physical activity. Furthermore, we know what happens inside the brain. We can tease the brain into gray and white matter. The gray matter, also called the cerebral cortex, is the brain’s outermost layer. It measures a few millimeters in thickness, and it isn’t gray but rather more of a shade of pink due to all the blood vessels that provide the brain with blood. It’s in the gray matter that sophisticated activity takes place. Information is sorted and memories are stored. One can deduce that this is where the “magic” happens because of all the energy it consumes. Gray matter uses over 90 percent of the brain’s total energy needs, even though it makes up about 40 percent of the brain’s volume.
The white matter lies beneath the gray matter, and it passes information along between the different areas of the brain. It’s made up of long projections (called axons) from the nerve cells, which brain cells use to communicate with one another. Imagine the gray matter as a bunch of computers, and the white matter as cables that pass signals between the computers.
The pale coloring of the white matter is from the axons being insulated with a substance called myelin, which contains a lot of fat. Myelin improves the signal reception between the brain cells.
Both the gray and the white matter are vital to how we function. The gray matter does indeed perform most of the heavy lifting, but if the axons aren’t effective and can’t transmit the signals, the brain won’t work properly. That makes sense; a computer can only run if all its parts are properly connected.
What changes most in children who are physically active, the gray or the white matter? Both! Growth of gray matter is first noticed in the hippocampus (which
is part of the gray matter); however, white matter is also strengthened by exercise and training. Children who are physically active regularly show alteration in white matter. Like gray matter, it becomes thicker and more compact. This almost certainly means that it’s becoming more efficient. In science, we call this white matter integrity.
To bring back the metaphor of white matter acting as cables between computers, it appears that the connection works better in physically active children. This means that information is transmitted more efficiently between the different areas of the brain, making the entire brain run better.
There’s no doubt that gray matter is essential to cognitive ability, but it looks like the same goes for white matter, too. In fact, white matter has been specifically linked to academic performance. When elementary school children’s brains were examined by DTI (Diffusion Tensor Imaging)—an extremely advanced medical technique—the scans showed that white matter in the left side of the brain is related to mathematical ability. We can’t say for sure if it’s the strengthening of white matter that’s responsible for making fit children do better in school, but there are still good reasons to believe that it helps.
Fortunately, exercise’s benefits on white matter—the brain’s cable system—doesn’t just affect children. Exercise and training seem to boost the white matter of people, no matter their age. There is a very strong correlation between white matter in older people and how active they are. The greatest effect on white matter doesn’t come from heavy-duty exercise, but rather from everyday activity and by not sitting too much. There’s no need for running marathons.
You think better on your feet
It has become popular to use standing desks at the office. For most, the biggest reason for standing is probably to burn extra calories while we’re working. It’s true that you use up more energy while standing compared to sitting—almost twice as much—but the increased calorie expenditure is far outshined by what happens in the brain. The main benefit of standing, whether you’re at school or at work, is simply that the brain functions better when you stand.
When the academic performance of seventh graders was measured using a series of cognitive tests, the kids showed clearer focus and had better working memory and executive control after they had begun using standing desks at school. The tests measured qualities that are essential for getting good grades, such as reading comprehension, remembering facts, and the ability to solve problems in several steps. The differences were significant; the test results indicated an improvement by an average of 10 percent.
Naturally, the authors weren’t satisfied with only the results of these cognitive tests; they also scanned the students’ brains with MRI. (My guess is that you might be noticing a pattern in these types of studies by now: first there are mental tests, followed by MRI examinations to see how the brain works.) The test results might even start to look familiar: children who had been standing before the scan just so happened to have increased activity in areas of the frontal lobe that are essential for working memory and executive control.
Scientists could see the same type of result in children who stood in class—increased activity in the frontal lobe, meaning better working memory and better focus—just like in adults and children who run, walk, or are otherwise physically active. The conclusion is simple: we think better on our feet! At school, children who stand are better at concentrating and at learning.
SMART JOCKS
Just a few years ago, not many believed that children’s or adults’ brains could change in such a dramatic way by engaging in physical activity. But we have learned that exercise makes us feel and tolerate stress better, it improves our memory, and we become more creative and focused. These are abilities we commonly refer to as cognitive or mental. The collective measure of all our cognitive abilities is our intelligence. If cognitive abilities are strengthened by us moving around, then exercise should increase our IQ. But is that the case? Can training make us smarter? If so, it would almost be too good to be true.
Scientists attempted to answer the question of whether exercise could increase our intelligence as early as in the 1960s, but it proved to be easier said than done. The main snag is that we don’t know which is the chicken and which is the egg: if tests suggest that fit people are also highly intelligent, we don’t know if it’s the activity that has made them smarter, or if naturally smart people are more likely to exercise.
Data from over one million Swedish men were crucial in solving this mystery. Until a few short years ago, military service was compulsory for all eighteen-year-old Swedish males. Over the course of one trying day, a battery of tests was performed on the recruits. Among other things, endurance was gauged by having the recruit pedal to the point of failure on an exercise bike on which the resistance was continually increased. I went through the test myself, and I remember that it was incredibly hard—I could barely stand after getting off the bike. Once the biking bit was over, tests on muscle strength came next, ending with the psychological evaluation. The day of induction concluded with an IQ test.
Over the span of twenty-six years, more than 1.2 million eighteen-year-olds performed these tests. When the results were compiled recently, a very clear correlation cropped up: young men who were fit were, on average, smarter. Those who performed well on the fitness tests had a better score on their IQ test than recruits who were less fit.
Does training make us intelligent?
But was it training and fitness that made the young men smart, or did the smart recruits work out more than the others? To answer this, scientists looked at sets of identical twins. If there’s one factor more than any other that can explain your IQ, it’s your parent’s IQ, because intelligence is, to a high degree, inherited. Identical twins have the same set of genes and have, more often than not, grown up together. When identical twins take IQ tests, their scores are typically very close within range. Among the million or so military recruits, there were 1,432 pairs of identical twins. In some cases, one twin was fit while the other was not. As identical twins, they should have had similar IQs, but they didn’t. The fit twin generally scored better on the IQ test than his less fit brother. Therefore, fitness was correlated to better results on the IQ test, even among identical twins.
Collectively, everything points to the same conclusion: physical activity makes us smarter. But it’s food for thought that it’s only endurance—not strength—that can be associated with higher scores on the IQ test. The muscular recruits did not have better results.
The IQ test measures several types of intelligence, such as vocabulary comprehension, mathematical and logical reasoning, and the ability to see three-dimensional shapes. Good results in all these categories was associated with superior fitness. The strongest correlation was between high fitness and greater logic and vocabulary comprehension.
Today, we know that there are two areas of the brain that are especially important for logical thinking and vocabulary comprehension: the hippocampus and the frontal lobe. That the correlation was especially strong there ties in neatly with the fact that exercise’s strongest effect is right on the hippocampus and frontal lobe.
Higher salary and less depression later in life
The information on the military recruits has proven to be a real gold mine for scientists in search of fascinating correlations. For example, they discovered that being fit at eighteen led to higher educational achievement and a better job with a higher salary later in life (around forty years of age). Fit young men also suffered lower rates of depression. In addition, the incidence of clinical depression seemed to be lower because records showed that fewer committed—or attempted to commit—suicide later in life. As if the absence of mental disorders weren’t enough, other positive effects on the brain were also apparent. The physically fit eighteen-year-olds were less at risk of getting epilepsy or developing dementia later in life.
Everything points to the same conclusion: we become smarter if we’re physically active!
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sp; I’m not saying that all of this is because they were fit eighteen-year-olds. It’s probably more the case that someone who is fit at eighteen is more likely to be a fit at thirty and forty years old.
Why is it so difficult for us to understand this?
I spend a lot of time reading scientific papers, but sometimes when I come upon this type of research, I find it hard to stay interested. It’s as if I can’t quite absorb it. Perhaps it just seems too good to be true that fifteen minutes of play every day can improve reading comprehension and arithmetic in children—and this without the kids even having to read or practice any of the subjects!
If you feel the same way as I do, stick around a while longer and mull over what you’ve just read in this chapter. Think about what it means. Let it sink in, and think of how incredible it is that children’s brains not only do better academically, but function better overall if they’re physically active. The brain’s gray and white matter are strengthened in children who moved their bodies, just as muscles develop if you lift weights. Isn’t it amazing that training can make children and adults smarter? That is exactly what happens! It is the best reason to encourage kids to put down their tablets and cell phones and get them to move more—because what parent doesn’t want their child to become smarter and have a better-working brain?
Isn’t it amazing that training seems to make children and adults smarter? That is exactly what happens! It is the best reason to encourage children to put down their tablets and cell phones, and get them to move more—because what parent doesn’t want their child to become smarter and to have a better-working brain?
Have you been taken aback by the findings described in this chapter? I was, too. In fact, I was so surprised that I had to read some of the studies several times over to make sure that I had got them right.
The Real Happy Pill Page 16
