Tweeti'm sticking to the thought process that high intensity cardio (anything getting your heart rate over 140) is catabolic. now for one trying to get into shape, sure, that's fine. but someone who is maybe dieting for a show, or just has the time to get lean and wants to maintain muscle, low intensity is the way to go. for example, my cardio sessions are anywhere from 40-60 minutes, and range from 2 to 3 miles. i ramp up speeds anywhere from 2.8mph to 3.3 and inclines ranging from 5 to 10. the low end of my sessions yeild about 350 cals, and the hour long sessions are closer to 600.