I see this regularly with patients who come in for depression, fatigue, anxiety -- if I can talk them into regular exercise, their symptoms improve. Of course, I'm doing acupuncture and herbs at the same time. But, therapeutic movement really seems to speed the treatment. The flip side of this is that over-training, pushing the body too hard -- especially without adequate nutrition and rest -- can cause anxiety.
This article looks at scientific research to explain why exercise reduces anxiety. In a nutshell, it seems to be that exercise induces the growth of new neurons that are less reactive to the hormonal and neurotransmitter effects of stress. It takes at least three weeks for these changes in the brain to begin to appear.
“Something happened between three and six weeks,” says Benjamin Greenwood, a research associate in the Department of Integrative Physiology at the University of Colorado, who helped conduct the experiments. Dr. Greenwood added that it was “not clear how that translates” into an exercise prescription for humans. We may require more weeks of working out, or maybe less. And no one has yet studied how intense the exercise needs to be. But the lesson, Dr. Greenwood says, is “don’t quit.” Keep running or cycling or swimming. (Animal experiments have focused exclusively on aerobic, endurance-type activities.) You may not feel a magical reduction of stress after your first jog, if you haven’t been exercising. But the molecular biochemical changes will begin, Dr. Greenwood says. And eventually, he says, they become “profound.”