Rx: "Waldspaziergang" (A Walk in the Woods)


Another case of Pseudo-scientific Over-reach, brought to you by the BBC this week: “‘Green’ exercise quickly ‘boosts mental health.'” This, (loosely) based on a paper by Jo Barton & Jules Pretty of the University of Essex [published in Environmental Science & Technology, under the catchy title, “What is the Best Dose of Nature and Green Exercise for Improving Mental Health? A Multi-Study Analysis”]. The authors did a statistical meta-analysis of 10 completely unrelated studies involving people of various ages engaging in various outdoor activities, and answering questionnaires purporting to measure changes in their self-esteem and mood, at the intervals of 5 minutes into the exercise, 10 to 60 minutes, “half a day,” and/or “a whole day.”

The groups studied ranged in age from “youths” to ” the elderly.” The activities they engaged in ranged from walking [apparently, not part of all 10 studies] to cycling, horse-riding, fishing, sailing, gardening, and “farming activities.” All the studies took place near Essex in England, at some time over the past 6 years; and the 1252 participants were “self-selecting using an opportunistic sampling method.” [I think that means, these were the ones who completed their questionnaires.]

Before we get to the “data,” let’s ponder how on earth one “completes” 2 questionnaires after 5 minutes of horse-riding. Is it like the Kentucky Derby, where a lady with a wireless microphone rides up beside you and interviews you? Is there a staggered start to the pony trek, so she can interview each participant exactly at their 5-minute mark? Wouldn’t it take longer than 5 minutes per participant, to ask & answer the 20 questions? How about the cyclists? Is it like the Tour de France, with an interviewer in a chase car? These intriguing logistical problems were not addressed in the “Materials and Methods” section of the paper.

Anyway, now for their “Results.” For both self-esteem and mood, the “greatest changes come from 5 minutes of activity, and thus suggest that these psychological measures are immediately increased by green exercise.” They go on to report that “the changes are lower for 10-60 min and half-day, but rise again after a whole day duration.” Looking at the many data charts in the article, unless the same chipper 5-min subjects bum out @ the 10-60 min and half-day point, and then perk up a bit after the whole day, it appears that each participant was assessed at only one point. There’s a clue in the “Discussion” section: “Whole-day activities are likely to be qualitatively different activities, involving in some cases camping overnight and in others significant conservation achievements.”

Hmm, wouldn’t it be useful to know just which Green Activities yielded “The 5-minute Fix”? I’m thinking, unless you’re a professional jockey, not horse-riding. Not fishing, either. Nor, indeed, sailing. I’m thinking, probably walking. So, why not try that first? Take yourself [and any handy companion, 2- or 4-footed] on a little walk among the trees, and just see if it doesn’t “boost [your] mental health.” That’s what the Austrians were doing to lift their spirits, decades before Freud had them lying on his couch: Waldspaziergang in the Vienna Woods. [I hear a waltz…]

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Filed under confounds, murky research

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