If the only change 32 miles a week had on your body was blisters then you must of been in rather great shape to begin with. No cardio improvement? No muscle gain? No weight loss? For the vast majority of Americans I have a feeling this would not be the case.
I transitioned to running in college when I got too old for most basketball leagues so I was in pretty good at the time.
I started running again a few years ago after a 5 year hiatus from any regular physical activity. I logged my Time, Avg/Max HR, and Calories burned for each run and there really wasn't much of a change in metrics over the 3 year period I tracked them. My heart rate was surprisingly stable and run times reduced gradually but only about a minute a year.
Maybe if I was incredibly unhealthy but I generally eat well and at my worst I've only been 20-30lbs over weight. I know that sounds like a lot but I'm 6'5" and my "ideal" body weight is 190lbs which is kind of ridiculous.
