Cardio, or aerobic training, comes from the Greek work kardia, which means heart. Few people would argue that the most important muscle in the body, is your heart. Despite that fact, the great big pendulum of fitness trends seem to have swung aerobic training out the door all the way in to the doghouse.
WHAT IS AEROBIC TRAINING?
Steady state training, endurance training, cardiovascular exercise or simply "cardio" are all different terminology used to define aerobic training. In other words, no one has or probably never will be able to decide on a final name or set a standardized definition of what this type of training actually means or should be called officially.