A generic term used mostly by non-medical sorts to describe any sort of aerobic exercise. But at its root is the Greek word “kardia”, which has to do with the heart. So, cardio, formally is anything that affects the action and health of the heart. Combining the previous two terms, this refers to the integrated action of the heart and blood vessels: Cardio + vascular. So cardiovascular fitness is then the capacity of that system to do what it evolved to do, both in steady state and when responding to sudden needs.
