How Exercise May Help Combat the Stress You're Facing

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Stress can wreak havoc on your body. It also can harm your brain.

Whether it's short-term stress (17 people are coming for dinner and your oven just went on the blink) or long-term stress (a loved one is seriously ill), the body releases powerful fight-or-flight stress hormones (adrenaline, cortisol).

While these hormones do sharpen attention and spur us to take needed action, humans weren't designed to handle high levels of stress hormones day after day, year after year.

Indeed, in the brain those stress hormones weaken blood vessels, kill off neurons and even shrink the hippocampus, a known risk factor for Alzheimer's disease. But there are ways to fight back.

"Exercise is essential for anyone under chronic stress, and that includes most of us," says Elissa Epel, a professor of psychiatry at the University of California, San Francisco. Exercise short-circuits the stress response by triggering the release of BDNF (brain-derived neurotrophic factor), which nourishes cell growth, as well as endorphins (serotonin, dopamine and norepinephrine), brain chemicals that boost feelings of well-being, ease muscle tension and improve sleep.

The cognitive functions and brain regions showing the most significant decay in late adulthood are the same regions that may benefit the most from exercise, says Benjamin L. Willis, an epidemiologist at the Cooper Institute in Dallas and coauthor of a long-term study highlighting the importance of exercise in reducing dementia risk.

So don't procrastinate: Carve out 150 minutes a week of moderate aerobic exercise. Couch potatoes should start slowly — 10 to 15 minutes every other day, working up to 30 to 45 minutes, five days a week. After all, you're not competing in Olympic trials. Just walk briskly, jog, swim or bike — anything you enjoy doing that gets your heart pumping a bit faster and makes you break a sweat.

A study by Scottish researchers found that simply strolling through a green leafy park, as opposed to the concrete jungle of a busy city, actually lowers cortisol levels in the brain, easing "brain fatigue."

Don't forget resistance training (20 minutes every other day, using exercise bands or light weights) to boost muscle tone, balance and flexibility. Never done any of that? You can sign up for an orientation class at a health club, but push-ups (on the floor, against a wall) and squats in your living room work, too.

Learn more about the research in this article

• "The association between midlife cardiorespiratory fitness levels and later-life dementia: a cohort study," Annals of Internal Medicine, February 2013. In this study, researchers examined data from 19,458 middle-aged adults who had been part of the Cooper Center Longitudinal Study (CCLS) for more than 30 years. The researchers found that those who were the most physically fit had the lowest risk of developing dementia. Study limitations include the fact that most participants were white, healthy and had access to preventive health care, and that, as a population study, it shows a correlation but does not prove cause and effect. Read the full study.

• "Green Space and Stress: Evidence from Cortisol Measures in Deprived Urban Communities," International Journal of Environmental Research and Public Health, September 2013. Building on an earlier study of residents in “socially disadvantaged districts” in Scotland, researchers recruited 106 people ages 35 to 55 who did not have jobs. Participants measured their own levels of cortisol in their saliva at specific times over two days. Those living in areas with more green space showed lower levels of physiological stress, as measured in amounts of cortisol. Read the full study.