The studies so far haven’t addressed how long the effects last, but preliminary findings suggest adults will have to keep exercising to maintain the benefits.
Another approach is to start young, with findings that different types of exercise affect a child’s mental capacity in a number of ways. For example, if you want kids to focus for an hour — on a math test, say — the best bet is to let them have a quick run around first. That’s according to studies that show a simple 20-minute walk has immediate effects on children’s attention, executive function and achievement in mathematics and reading tests. Letting kids sprint or skip about has the same effect. A brisk walk can also help children with attention-deficit hyperactivity disorder to focus, although again it’s not yet clear how long the effects last.
These findings should be used to make decisions about the daily school routine, says Charles Hillman at the University of Illinois at Urbana-Champaign, who carried out some of the research. He agrees with current recommendations that children get at least an hour of exercise daily, but notes that it might be best spread over the course of the day. Because purely aerobic exercise keeps kids focused in the near term, giving them breaks to walk or move around every 2 hours might be the best way to promote learning.
In contrast, exercise that is highly structured and focused on specific skills, such as for a sport or to improve coordination, hampers attention. A bunch of drills and rules may be too taxing for children right before a test or a situation that requires sustained focus.
Instead, these kinds of specific exercises seem to build up attention span gradually over the long-term. In research yet to be published, Maria Chiara Gallotta at the University of Rome in Italy found that twice-weekly sessions of coordinative exercises, such as basketball, volleyball or gymnastics practice, over the course of five months helped children do better on tests that required concentration and ignoring distractions.
The cerebellum — the finely wrinkled structure at the base of the brain — has been long known to be involved in coordinating movement, but is now recognized as having a role in attention as well. Practicing complicated movements activates the cerebellum and, by working together with the frontal lobe, might improve attention in the process.
Making sure children are physically fit can have lasting cognitive benefits too, says Hillman. He has shown that children who are fit have larger hippocampi and basal ganglia, and that they perform better in attention tests. The basal ganglia are a group of structures important for movement and goal-directed behavior — turning thoughts into actions. They interact with the prefrontal cortex to influence attention, inhibition and executive control, helping people to switch between two tasks, such as going from sorting cards by color to sorting cards by suit.
Hillman focuses on children aged 8 to 11 because areas like the hippocampi and basal ganglia are still maturing, so intervening at a young age can make a big difference. And even small gains in fitness lead to measurable changes in the brain. In some of his studies, Hillman has put kids on year-long after-school fitness programs. Many are overweight, and while they don’t lose much weight, their brains do change. They’re going from being unfit to slightly less unfit, says Hillman. “But we’re still finding benefits to brain function and cognition.”
Adults too can reap brain gains from sporty challenges, says Claudia Voelcker-Rehage at Chemnitz University of Technology in Germany. Her research on older adults showed an increase in basal ganglia volume following coordination exercises that included balancing, synchronizing arm and leg movements, and manipulating props like ropes and balls, but not from aerobic exercise.
Voelcker-Rehage found that these types of exercise improved visual-spatial processing, required for mentally approximating distances — for instance, being able to assess whether you have time to cross the street before an oncoming car reaches you — more than aerobic exercise.
Another explanation comes from recent research by Tracy and Ross Alloway, both at the University of North Florida in Jacksonville. They found that just a couple of hours of activity of the type we often enjoy during childhood, such as climbing trees, crawling along a beam, or running barefoot, had a dramatic effect on working memory.
This is the ability to hold on to information and manipulate it in our minds at the same time. “It prioritizes and processes information, allowing us to ignore what is irrelevant and work with what is important,” says Tracy Alloway. “Working memory influences nearly everything that you do, from the classroom to the boardroom.”
So what is it about climbing trees or beam balancing that is so beneficial? The researchers only found positive results when the activities were a combination of two things. They needed to challenge the sense of proprioception — the position and orientation of the body — and also needed at least one other element, such as navigation, calculation or locomotion. Basically, the advantages came from exercises in which we need to balance and think at the same time.
The more we learn about the effects of exercise on the brain, the more different types of benefits are emerging, extending beyond cognition to changes in behavior.
One of the most popular fitness trends of the last few years is high-intensity interval training, which involves quick spurts of all-out exercise. Its sheer toughness is claimed to provide the same benefits as longer efforts in a fraction of the time. These workouts might have an extra advantage: short bursts of activity can help curb cravings. And although the tougher the better, they don’t necessarily have to be gut-busting hard.
To test the effects of intensity training on appetites, Kym Guelfi at the University of Western Australia in Perth invited overweight men to come into the lab on four separate occasions. On three of the visits, they spent 30 minutes on an exercise bike, but at different intensities — a moderate, continuous pace; alternating between intervals of high-intensity cycling for 1 minute followed by 4 minutes of moderate cycling; or alternating between very high intensity, 15-second sprints followed by one really easy minute. The fourth visit consisted of resting for the full 30 minutes.
Craving control: After the most intense intervals, the men ate less of the provided, post-workout porridge and less food overall for the next day and a half compared with days they cycled moderately or simply rested.
One explanation could be that the exercise reduced levels of the “hunger hormone”, ghrelin. This is responsible for telling the part of the brain that controls eating — the hypothalamus — when the stomach is empty. When full, ghrelin production shuts off and hunger wanes. Following the most intense intervals of exercise, ghrelin levels were lowest.
What is clear is that these effects can endure well into old age, and it’s never too late to start. The hippocampus shrinks as we get older, leading to the typical struggles with memory. Exercise not only prevents this loss — it reverses it, slowing the effects of getting older. Voelcker-Rehage has found that the brain requires less energy to complete certain tasks after exercise. “We would say that points to the fact that the brain is more efficient,” she says. “It works more like a young brain.”
And in a study looking at yogis that had been practicing for many years, Sara Lazar at Massachusetts General Hospital found that some brain regions were remarkably well preserved compared with those of healthy controls that were matched for age, gender, education and race. “The 50-year-old’s brain looked like a 25-year-old’s,” notes Lazar.
If you’re still unsure what to do, there’s some overlap between the different exercises and benefits, so Liu-Ambrose’s suggestion is simple: “If you’re not active, do something that you enjoy.” The best exercise is the kind that you’ll actually do.
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