I know all you guys are trying to preserve muscle while doing cardio, so you try to stay within the "fat burning zone". Now it seems logical that if I burn more calories, I will burn more fat (I usually do HIGH intensity cardio 1-2 times a week 75-92% of max heart rate).So my question is, why does everyone say stay within 65-70% of max heart rate? If I burn less calories, why is it so much more beneficial to stay in "the zone"? Thanks in advance!