I am hearing mixed thoughts on this. I wanted to hear what you guys think. I have heard that for cardio you can run hard on the tred mill for about 20-30 min. but for fat burn you should walk at like 3.5-4.5 on an incline for 40min or use the stairmaster for 30 - 40 min. What do you guys think is best? I know it all comes down to heart rate though. Let me know because I hate cardio!!