Can that be true?? My mind is totally blown. There must be rather huge regional variations in this, though. In my part of the nation, the vast majority of people engage in outdoor recreation at least once per year -- and most much more often.
They define a discrete list of "outdoor activities" that are relevant to their members -- mostly equipment provides for niche sports/activities with expensive equipment needs (climbing, skiing, cycling, camping/backpacking, fishing, hunting, scuba diving, etc.).
In particular, someone who walks in their local park every day or plays pickup soccer/basketball at the local outdoor sports field would answer that they didn't participate in any of the listed activities.
For example, fishing and most forms of camping are relatively inaccessible to me. Public transit tends not to run to such places.
> only 18% of Americans played outside at least once a week
I doubt one in five Americans are driving out to national parks once a week, so "outdoor recreation" probably includes things like soccer in a city park or going for a bike ride.
That being said, I wish the article was less vague with its use of terms like "play outside" and "outdoor recreation" so we didn't have to read tea leaves to deduce the reality.
I have no idea if they included, say, reading in a park.