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New Study: Green Exercise Improves Mental Health—Fast

By L.K. Regan

Exercise isn't all about big muscles (really—it isn't). There are also the broader mental and physical health benefits that come with even a little activity. And a new study indicates that if you do that exercise in nature, a very little goes a long way. Time to get out of the gym, and hit the trail.

There is a lot of evidence that green exercise promotes mental health. "Evidence shows," co-authors Jo Barton and Jules Pretty write in a study appearing in the journal Environmental Science & Technology, "that exposure to natural places can lead to positive mental health outcomes, whether a view of nature from a window, being within natural places, or exercising in these environments." But it has never been clear just how much nature was needed to get health benefits. "For the first time in the scientific literature, we have been able to show dose-response relationships for the positive effects of nature on human mental health," said study co-author Jules Pretty. And her research shows that the ideal dose is a mere five minutes.

The study's authors describe "green" exercise as physical activity conducted out in nature, whether that's a park, a garden (even in your back yard), or a nature trail—anywhere you encounter the natural world, and a bit of green. To test its impacts, they analyzed 1,252 people drawn from 10 British studies. The study's subjects were observed walking, gardening, cycling, boating, fishing, riding horses and farming. They were evaluated for key measures of short-term mental health: self-esteem and mood. All social and age groups saw some improvement from the activity,but there were some differences in the intensity and type of effect.

"For self-esteem," the authors write, "the greatest change was in the youngest category, with diminishing effects with age; for mood, the least change was for the young and old. This suggests that younger people will see more self-esteem improvements, and the middle-aged from mood." The physical impact of these psychological effects is a next area of study: "Although good self-esteem and mood are known to be protective against future long-term health threats, these mental health measures should also be assessed in conjunction with a range of further health markers, such as blood pressure, cholesterol, stress hormones... and inflammatory markers."

Pretty much any kind of natural setting would generate improvement, even a park in the middle of a city. (That said, water near a green area generated better results.) But the remarkable aspect is the duration: the highest mood and self-esteem returns came from the shortest studied duration: five minutes. In other words—no need to save up your outdoor time for Saturday; a five minute walk in the park on a daily basis may do your spirit more good.