I admit I only skimmed. Somewhat muddled as cycling and walking are grouped and the distiction between recreationa vs. tranportation cycling/walking.

Phx metro area listed as bottom for recreational walking, but high in percentage of parks (I belive we have the worlds largest metro park - South Mountain). Other factors are at play, summer temps, urban planning (strip mall car culture vs. urban centers). I also wonder if recreational walking includes hiking outside (and inside) the city - a very popular activity here.

Al