I'm in the middle of reading this report from the National Trust. It's really interesting reading so far. I know despite being home educated, my kids still do get less outdoor time than I did as a child. I spent hours outside playing with the neighbours. TV only showed kid's programming for limited hours a day, and although we had a video player, the same videos over and over didn't always appeal. We do try and get out and explore a lot of our local nature resources. Perhaps I'm feeling it a bit more because it's winter. In summer I tend to kick them out with a picnic and tell them to explore for a few hours, this summer Maia may even be old enough to join them if they're staying in our little neighbourhood. She'd be thrilled to go with them I think!
The trend towards spending lots of time inside with screens - TV, computer, DS, tablet, phone - must have lots of effects for children (and adults of course!). The more time they're watching something like that, the less time they're active. Playing outside requires a lot more imagination than watching a TV show.
I'm going to go and finish reading the report now, but I know I'm going to make a concerted effort to give my kids more time outside and less screen time.