How Exercise Affects the Brain

It is difficult to imagine anyone not realizing at this point the benefits of regular exercise for the body. We are constantly reminded of this by news reports of scientific studies that prove how important exercise is in reducing the risks of heart disease and obesity, and in building a strong, healthy immune system. But is it only our bodies that are affected by exercising?

Does exercise affect our bodies, our brains, or both?

Science has long suspected that exercise has an equally profound effect on the brain, and on our abilities to think, concentrate, and find peace of mind. Animal studies have shown for years, for example, that mice who are allowed to live sedentary lives tend to perform badly on intelligence tests like finding their way through mazes, tend to display depressed behavior, and lose brain mass. Add exercise to these animals’ lives, however, and the same mice start to become less depressed, perform better on tests, and – most fascinating – start to regrow the lost brain mass. Their brains literally start to become larger.

Exercise can make you feel happier and calmer

Recent research on human beings seems to indicate that the same thing happens with us. Exercise improves blood flow to the brain, and thus improves its functioning. Exercise also stimulates the release of endorphins – the “feel good” chemicals such as serotonin and dopamine that cause us to feel happy, calm, and euphoric. A study at Duke University divided subjects over 50 who had been diagnosed with depression and treated them with either exercise (walking), the antidepressant drug Zoloft, or a combination of the two. All three groups felt better and less depressed, but interestingly enough follow-up studies six months later showed that the exercise group showed significantly lower rates of relapse into depression than the other two groups.

Regular exercise can actually make your brain larger

One of the most exciting aspects of recent research is that – as was seen in earlier animal studies – regular exercise actually increases the size of our brains. It has been suggested that the reason for this is that exercise triggers neurogenesis – the creation of new neurons. These new neurons are created in the hippocampus, the area of the brain that controls learning and memory. Regular exercise seems to trigger the expression of the BDNF (Brain-Derived Neurotrophic Factor) gene, creating proteins that stimulate the growth of new brain cells. BDNF not only activates the growth of new neurons, it serves to protect existing neurons and increase their ability to transmit signals from neuron to neuron, which is considered to be the basis of learning and memory. In other words, the effects of increased BDNF are not only generative (causing new brain cell growth), they are regenerative (repairing existing brain cells).

This is important because, as humans, we start to lose brain tissue after age 30. Gentle aerobic exercise such as walking has been shown to not only slow this loss of brain mass, but to reverse it by growing new brain tissue and improving the functioning of existing neurons. Exercise increases the number of dendrite connections between neurons, improving their ability to store and process information. In one 2006 study, the brain volume of subjects who performed regular aerobic exercise (walking) significantly increased, compared to subjects who performed non-aerobic exercise (stretching and toning). Most of this increase in brain volume was found in the frontal and temporal lobes of the brain, those areas most involved with memory and learning.

When should I start exercising?

One facet of the latest research on exercise and the brain is that although our brains benefit from exercise at any age, the effect is strongest and most long-lasting if we develop the habit of exercising regularly early in life. In other words, there is a positive cumulative effect of exercise in our brains, one that we can take advantage of by developing healthy exercise habits early in life. But the benefits of exercise on the brain can be experienced at any age. Several studies have noted significant improvements in Alzheimer’s patients who started exercising regularly in their 60s and 70s.

The evidence seems clear – exercise is not just good for your body; it’s good for your brain, too. As Dr. John J. Ratey of Harvard Medical School has said, “Exercise is really for the brain, not the body. It affects mood, vitality, alertness, and feelings of well-being.”