You asked for it and here it is!! Cardio Abs means your heart rate will be elevated more than standard crunches and the more your feet leave the ground, the more your heart rate will spike. But, if you need low impact, that's ok too and you can modify all of these by leaving your feet on the floor and doing the movement with your arms instead. Try it and let me know how many reps you get through! This can be a great five or ten minute ab routine!