Low intensity long duration training on the treadmill is history. Research shows that high intensity interval training will give you much better results in terms of post workout caloric expenditure. H. I. I. T. (high intensity interval training) is a method to do short intensive and very productive cardio workouts.
Every once and awhile I have a client who asks me to design a program only for her/his abs. Unfortunately having a nice visible six-pack has almost nothing to do with training hard abs. Low body fat is the only key to see your abs, for most men this mean body fat percentage under 10% and 14% for the women.