Exercise your brain

Dear colleagues,

Do you want your brain to function in peak form? Exercising your body will provide amazing benefits to your brain.

As researchers and teachers, we know the importance of mental work: we read, analyse, discuss and write, thus developing our understandings and our capacities to think at more challenging levels. But the brain isn't independent of the body. Our mental performance depends on good diet, sleep, a suitable stress level - and exercise.

Knowledge about the effects of exercise has been growing in leaps and bounds. As recently as the 1980s, a lot of people still thought running was bad for your health. Researchers back then began a long-term study comparing a group of runners and a matched group of non-runners - all academics. After two decades the runners had half the disability and half the death rate as the non-runners.*

Most people now realise the benefits of exercise for physical health. But what about mental functioning? There's been a lot of research on this in the past decade.

In the book Spark: the revolutionary new science of exercise and the brain, psychiatry professor John J. Ratey has surveyed recent findings.

Ratey starts by telling about some Chicago high schools that started a fitness programme for all students. This wasn't a sports programme - typical sports don't have enough physical activity to provide significant aerobic benefits. In baseball or cricket, for example, few players are moving at any given time.

The Chicago students were given heart rate monitors and did aerobic exercise such as running to raise their heart rates to specified levels. Students were graded on heart rates, not speed or winning a race.

Within a few years, the students at these schools not only had extraordinarily low levels of obesity but also performed exceptionally well in international standardised tests. On average, US high school students as a whole are not good scholastic performers compared to some other countries, but the exercising US students are comparable to the best in the world.

Ratey then goes through the human and animal research that shows a wide range of benefits. Exercise stimulates the brain to grow new cells. Immediately after exercising, learning capacities are increased.

Exercise is good for all sorts of mental problems: anxiety disorders, depression, attention deficit disorders and addictions. It's also good for women dealing with hormonal changes. Ratey has a full chapter on each of these issues.

In one study, exercise was found to work just as well as a leading antidepressant, but instead of the results being trumpeted in the media, they were hidden in back pages. Ratey notes that if exercise could be put into a pill, it would be hailed like a blockbuster drug.

How much exercise is needed? The answer is that any exercise is better than no exercise. If you want maximum benefits to your brain, then you should raise your heart rate significantly for half an hour or more per day. Yes, it's a lot.

Ratey also recommends aerobic activity requiring mental challenge. Running on a treadmill doesn't stimulate the brain as much as dance routines or martial arts. You can buy Dance Dance Revolution and be challenged mentally and physically.

The book Spark is meant to provide an accessible treatment of lots of recent research. It isn't all easy reading. There are explanations of all sorts of chemicals and physiological effects. Here's a typical summary passage.

"Exercise combats the corrosive effect of too much cortisol, a product of chronic stress that can bring on depression and dementia. It also bolsters neurons against excess glucose, free radicals, and the excitatory neurotransmitter glutamate, all necessary, but they can damage cells if left unchecked. Waste accumulates and junks up the cellular machinery, and it starts turning out dangerous products - damaged proteins and broken fragments of DNA that trigger the latent and ultimately inevitable process of cell death that defines aging. Exercise makes proteins that fix the damage and delay the process." (p. 235)

But it's not all heavy going. There are also clear summaries and take-away messages, for example "exercise reduces stress and makes for more productive employees" (p. 83) and "exercise is the single most powerful tool you have to optimize your brain function" (p. 245).

One shortcoming of the book is the absence of any references. You have to go to a website to find them and then all you can get are long chapter bibliographies.

Ratey gives lots of standard advice about how to develop an exercise routine, such as to start gradually and exercise with a friend. But relying on individual motivation will have only a limited impact. Most people know exercise is good for them but still don't do it. The future lies in changes in policy and planning, such as carried out at the Chicago schools.

I haven't heard of any universities adopting policies to give a strong encouragement to exercise. Instead, they build more car parks, hire specialised staff to do jobs requiring physical effort, and put pressure on staff to work harder, but far less pressure to take exercise breaks. There are enormous potential benefits for universities that take seriously the exercise-brain connection.

Brian Martin
25 June 2009


John J. Ratey with Eric Hagerman, Spark: the revolutionary new science of exercise and the brain (New York: Little, Brown, 2008).

* Eliza F. Chakravarty et al., "Reduced disability and mortality among aging runners: a 21-year longitudinal study", Arch Intern Med. 2008;168(15);1638-1646. See also Liisa Byberg et al., "Total mortality after changes in leisure time physical activity in 50 year old men: 35 year follow-up of population based cohort", BMJ 2009;338;b668.


PS Thanks to Narelle Campbell, Karen Crowe, Helen Kilpatrick, Nicola Marks, Ian Miles, Chris Moore and Frances Steel for helpful comments on drafts.

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