How Does Exercise Reduce Stress?

05/21/2013 08:42 am ET | Updated May 21, 2013
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How, exactly, does exercise make you less stressed out? Especially when exercise raises levels of the stress hormone, cortisol?

We've all read that exercise lowers levels of anxiety, depression and stress. And that holds true even for people who are stressed out by the idea of exercise. But how exactly does it do that?

Exercise attacks stress in two ways, according to Matthew Stults-Kolehmainen, Ph.D., a kinesiologist at the Yale Stress Center. He told HuffPost Healthy Living that raising one's heart rate can actually reverse damage to the brain caused by stressful events: "Stress atrophies the brain -- especially the hippocampus, which is responsible for a lot, but memory in particular. When you’re stressed, you forget things."

Exercise, by contrast, promotes production of neurohormones like norepinephrine that are associated with improved cognitive function, elevated mood and learning. And that can improve thinking dulled by stressful events -- some research even shows how exercise can make you smarter.

In fact, many researchers posit that improved communication could be the basis of both greater reserves of the neurochemicals that help the brain communicate with the body and the body's improved ability to respond to stress. The American Psychological Association reported:

[Exercise] forces the body's physiological systems -- all of which are involved in the stress response -- to communicate much more closely than usual: The cardiovascular system communicates with the renal system, which communicates with the muscular system. And all of these are controlled by the central and sympathetic nervous systems, which also must communicate with each other. This workout of the body's communication system may be the true value of exercise; the more sedentary we get, the less efficient our bodies in responding to stress.

But going for a rigorous jog or bike ride (or even for a walk or out dancing) can actually cause immediate stress reduction. On a common psychiatric metric, PALMS, those who are just post-workout rate higher for mood, memory and energy -- and lower for depression, tension and anxiety.

That's particularly surprising because, as our question-asker points out, rigorous exercise temporarily raises our level of circulating cortisol -- the hormone that rises when we experience stress. The key word in this instance is temporary: For most people, cortisol rates return to normal following even intense exercise.

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