actually the after burn effect has been proven to be true
yes there are diffrent studies out there. I believe as i wrote in my original post your Body adapts but i am not sure about the "after burn effect". It is intresting though. I still believe you can get great results from say 45 mins Walking. i do however believe 30 mins interval is so much better for Overall health. I feel great after a hard 30 min bike interval in the gym...i like to mix it up with a run in the Woods.
the major problem with it is that it cuts into recovery, whereas the walking doesn't cut into recovery so much
as cardio is so dull,, you have to play around with these kind of things to keep you sane..i love lifting weights, but cardio is like pulling teeth for me