Exercise is a state of mind

For several decades we8217;ve known about one effect of exercise on the brain, the 8220;endorphin high8221; that makes us feel good during and right after exercise. Recently, scientists have uncovered some longer-lasting effects of exercise on the brain. Regular exercise improves your mood, decreases anxiety, improves sleep, improves resilience in the face of stress and raises self-esteem. All these benefits don8217;t come because you notice what you8217;ve lost around your waist. Rather, they come from exercise-induced alterations inside your head.

With exercise, several biological changes occur that make your nerve cells more robust. The blood and energy supply to the brain improves. The genes in nerve cells signal the production of proteins called neurotrophic factors or growth factors. These substances induce nerve cells to grow, branch and make connections with one another neuroplasticity and8212;in some brain areas8212;give rise to new nerve cells neurogenesis. These important biological processes, which are essential to adaptation and learning, tend to slow down with age and also in response to stress, after brain injury and in depression. Exercise can speed the process back up again, making it a respectable, though partial, antidote to stress and aging.

Exercise is a pretty good antidepressant, too8212;equal to drugs or psychotherapy in some studies. Exercise and antidepressant medications also appear to be biologically equivalent. Consider the hippocampus, a seahorse-shaped region in the temporal lobe of the brain. It is involved in regulating mood and storing memories. When neuroplasticity and neurogenesis are sluggish, the hippocampus gets smaller.

Neuroscientists see this in brain scans of people with depression. Antidepressants and electroconvulsive therapy appear to spur nerve growth in this region. Exercise probably relieves8212;and likely also prevents8212;depression through the same mechanism.

Just knowing what exercise can do for your brain won8217;t guarantee that you8217;ll jump off your couch and start jogging down the road. You still need motivation, but where does it come from? Even that is under genetic control.

Recent research finds that the brain governs how much activity your body is ready for, in part using signals from your muscles as a guide. The theory goes that the brain needs to be in charge, to regulate energy output and preserve the integrity of the whole body.

In this model, the brain decides when you need to be active and when you don8217;t. How good a job your brain does at managing this is genetically determined. And, just as with weight control, the brain isn8217;t always right: just as the brains of overweight people often make them hungry, the brains of some inactive people often encourage even more inactivity.

Indeed, some researchers are beginning to wonder if genes that make a person vulnerable to depression also make exercise less pleasant8212;or less reinforcing. Exercise has been demonstrated so effective at reducing health risks with so few adverse effects that it should be an easy sell. Yet no one has yet found the most effective way to promote a healthy lifestyle. Information about the positive effects of exercise does not seem to be enough. To improve motivation for exercise, it would help us to better understand how our genes control our experience of exercise.
MICHAEL CRAIG MILLER Newsweek