Also perhaps some selection bias in that the participants that sign up for an Exercise Study may already be pretty fit. And we see some of that in the baseline characteristics.
If you were to compare these groups to physically inactive groups I'm sure you would have seen quite a big difference.
We (society/physicians/etc) need tools to get people to exercise. This is more a study of how effective one of those tools might be (ie supervised exercise vs recommendations). If supervised exercise is no better than recommendations, I find that pretty disappointing. Because as we all know, recommendations don't work very well, or at least most people don't adhere to them.
One simple thing is making sure our infrastructure makes it safe to do so. Living in the south, I can't tell you how many side walks just end. How many roads have no crosswalks. Don't even get me started on bike infrastructure!
The car is king here, and I sincerely hope that ends some day.