Initially the workout is slow moving because everything is being explained to you. Eventually, once you learn the workout and you're going through the motions, it becomes aerobic. You can get a cardiovascular workout when you're on the equipment and working at an advanced level, because it's more physical. And some classes like The Reformer Jumpboard combines cardio moves with sequences of heart-rate boosting exercises for a double-duty effect. You have to work towards it, but Pilates can be cardiovascular.