How Does Exercise Improve Mental Health?

We know that exercise has positive effects on the brain. Researchers at Duke University demonstrated several years ago that exercise has antidepressant properties. Other research has shown that exercise can improve the brain functioning of the elderly and may even protect against dementia. How does exercise improve mental health?
One theory for some of the benefits of exercise include the fact that exercise triggers the production of endorphins. These natural opiates are chemically similar to morphine. They may be produced as natural pain relievers in response to the shock that the body receives during exercise. However, researchers are beginning to question whether endorphins improve mood. Studies are showing that the body's metabolism of endorphins is complex, and there are likely additional mechanisms involved in the mental health effects of exercise.
Some studies have found that exercise boosts activity in the brain's frontal lobes and the hippocampus. We don't really know how or why this occurs. Animal studies have found that exercise increases levels of serotonin, dopamine and norepinephrine. These neurotransmitters have been associated with elevated mood, and it is thought that antidepressant medications also work by boosting these chemicals.
Exercise has also been found to increase levels of "brain-derived neurotrophic factor" (BDNF). This substance is thought to improve mood, and it may play a role in the beneficial effects of exercise. BDNF's primary role seems to be to help brain cells survive longer, so this may also explain some of the beneficial effects of exercise on dementia.
The bottom line is that most of us feel good after exercise. Physical exercise is good for our mental health and for our brains. Someday we will understand it all better -- but we can start exercising today.