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How exercise revs brainpower

By Christie Aschwanden
New Scientist
20080408 Brain power
Nakahodo - MCT

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  • What kind of exercise is ideal?

    An aerobic workout is essential, but it doesn’t have to be too strenuous. Gentle activities, such as taking a walk a few times a week, worked wonders for some elderly volunteers, on researcher found, increasing the connectivity of their brain network and the size of their hippocampus and boosting overall recall.

    For those who are already in good shape, Harvard neuropsychiatrist John Ratey advocates high-intensity interval training , which consists of very short, very hard bursts of exercise.

    As evidence for HIIT’s effectiveness, Ratey cites a German study in which participants incorporated two three-minute intervals of high-intensity sprinting into a 40-minute run. They produced much higher levels of BDNF and noradrenaline, and the runners performed 20 percent better in a post-run vocabulary-building exercise than those who had taken more leisurely exercise.

    However, Ratey cautions that HIIT is something that inexperienced exercisers should build toward slowly. Ratey practices what he preaches, exercising at least three times a week for 20 minutes, with six 30-second high-intensity intervals in each session.



It has long been accepted that exercise cuts the risk of heart disease, and recent studies suggest a raft of more general benefits, such as reducing the risk of certain types of cancer and even preventing Type 2 diabetes. Now it seems that workout warriors can also expect a boost in brainpower, too.

Researchers are finding that fitness has a long-term influence on a wide range of cognitive abilities.

Physical activity seems to be important during childhood, powering the brain through the many changes that help us mature into adulthood. But it may also play a role as we reach advanced age, with a decline in fitness explaining why some people are more prone to dementia than others.

“It’s a really amazing effect,” says David Raichlen, a biological anthropologist at the University of Arizona in Tucson. Raichlen is investigating whether our ancestors’ athleticism may have accelerated the evolution of their intelligence millions of years ago. Our brains may, in fact, be a byproduct of our brawn.

The link between fitness and the performance of simple cognitive tasks was first suggested by studies in the 1960s, but its importance became more greatly appreciated about 30 years later.

Impressive research results

In the 1990s, one researcher found that exercise seemed to cultivate the growth of new neurons in mice. At about the same time, another researcher published a paper in the journal Nature showing that previously sedentary adults who undertook an aerobic fitness plan for six months boosted their performance in cognitive drills.

One German study, published in 2010, tracked 4,000 people older than 55 for two years. It found that those who rarely took part in physical activities were more than twice as likely to suffer from a cognitive impairment by the end of the study as those who engaged in exercise such as gardening, swimming or cycling a few times a week.

Another study, which had followed a group of nearly 1,500 people for 20 years, showed that these effects may be long-lasting. Those who exercised at least twice a week during middle age were much less likely to develop dementia by the time they reached their 60s and 70s.

In fact,the available evidence suggests that physical activity enhances brain health at every stage of life.

Better mood, less stress

What’s behind the link? A short-term mood boost might be bringing some of the benefits.

“People really enjoy that euphoric aspect of a runner’s high and the clarity of mind you get from a routine workout,” says Brian Christie, a neuroscientist at the University of Victoria in British Columbia.

Stress can inhibit your brain’s responses when solving a problem, blocking it from making the necessary connections. “If you go out for a walk, your stress levels usually plummet. And that’s when the answer comes to you,” Christie says. That may partly explain why fitter children tend to do better at their schoolwork, for instance.

Exercise probably contributes to more permanent changes, too. The brain relies on a steady supply of nutrients and oxygen through an intricate network of capillaries. Physical activity can encourage the construction of these supply lines, and it can also ease their maintenance.

Improved fitness also cuts the risk of diabetes and obesity. These problems disrupt the brain’s insulin system, which is thought to trigger a cycle of reactions that contribute to the buildup of the plaques linked to brain damage in people with Alzheimer’s disease.

‘Moving every day’

Exercise also has been found to spur the release of such neurotransmitters as serotonin, noradrenaline and dopamine, which help regulate signaling in the brain.

These neurotransmitters are the same ones that antidepressants and drugs for attention-deficit hyperactivity disorder act on, which is why time on a treadmill or bicycle is akin to taking a mix of Prozac and Ritalin, says John Ratey, a neuropsychiatrist at Harvard Medical School.

It also prompts the brain to send out growth factors such as insulin-like growth factor-1 and brain-derived neurotrophic factor . Ratey describes BDNF as “Miracle-Gro for your brain” because it creates an environment where neurons can flourish and promotes the formation of new connections between cells.

The brain-enhancing consequence of exercise has serious implications today. The Department of Health and Human Services is encouraging schools to offer more physical education, and the Institute of Medicine recommends that elementary school children get 30 minutes of physical activity a day, 45 minutes daily for middle and high school students. “We need to have kids moving every day, not just because it makes sense health-wise, but because it raises test scores,” Ratey says.

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