Scientists recently made a remarkable discovery about the brains of rats that exercise. It showed that their brain cells respond differently to stress than the neurons of slothful rats. It has been proven some time ago that the exercise stimulates the creation of new brain cells but scientists haven't figured out how these brain cells might be functionally different... until now. Here are the results (from Princeton University and University of Colorado):
1. Two groups of rats: one was allowed to run and the other one was not. The former one had created, through running, a brain that seemed molecularly and biochemically calm. Researchers concluded that "cells born from running" appeared to have been "specifically buffered from exposure to a stressful experience".
2. In another study the rats that ran for 3 weeks didn't show much reduction in stress induced anxiety but those that ran for at least 6 weeks did.
3. Anxiety in people and rodents has been linked with oxidative stress, which can lead to cell death, including in the brain. Moderate exercise seems to reduce the effects of oxidative stress as the rodent study showed. The non-exercised group of rats whose oxidative stress levels have been artificially increased was very anxious when put under stress. The exercised group of rats, on the other hand, seemed to have been much calmer, almost nonchalant. ;-)
As the scientific evidence shows, an exercise can directly affect mood, anxiety and other psychological states. So don't quit exercising, just keep at it. Remember, you're investing in your own health.