The Effect of Exercise on Mood
For years, I’ve heard that exercise enhances mood. How does physiological activity affect psychological states such as anxiety and depression? Is it the placebo effect or is there a scientific link between the two? Based on my experience, I believe there is causation. I have watched clients gain confidence in direct proportion to their strength gains. And I have seen exercise have a profound effect on the well-being of folks with limited mobility.
But, these are purely anecdotal observations. Since I’m an empirical gal, I set off on a literature review of current scientific research on the link between exercise and mood. Here is a brief summary of what I found.
Because of a growing understanding of the biochemistry of brain activity, scientists are beginning to tease out how exercise makes the brain more resistant to stress. Researchers at Princeton University recently discovered the brain neurons of exercising rats respond differently than the brain neurons of their slothful pals. Scientists have known for some time that exercise stimulates the creation of neurons in the brain, but not how these neurons are functionally different from other neurons.
The researchers at Princeton performed an experiment in which one group of rats were allowed to run and a second group was kept sedentary, forced to eat little rat Doritos on little rat couches (a little embellishment on my part). They then made both groups of rats swim in cold water, which I learned, rats are loathe to do (I understand completely). After this, the scientists examined the animals’ brains. They found that the stress of swimming activated neurons in all of the brains. They knew which brain neurons were activated because these neurons activated specific genes in response to stress. But the brains neurons created by running were less likely to activate stress genes and these neurons generally remained quiet. They concluded that the neurons created from exercise had created rat brains that seemed biochemically calm.
Other researchers have looked at how exercise alters the activity of dopamine and serotonin, neurotransmitters in the brain. Dopamine affects brain processes that control movement, emotional response, and ability to experience pleasure and pain. There are many researchers who believe that an imbalance in serotonin levels may influence mood in a way that leads to depression.
The general conclusion of the research I reviewed is the positive stress of exercise prepares cells, structures, and pathways within the brain so that they are more equipped to handle stress from other sources. But this process doesn’t happen overnight, as all researchers observed. In most of the experiments, rats that had run a shorter time didn’t have the same benefit as those who had run longer.
Rat research is one thing, but does this translate to humans? And there is no measure of the intensity needed to bring about mood enhancement.
I do know this. I’m most happy when I feel healthy, slim, and strong. I imagine you do too.
