Cardio or Aerobic?

Cardiovascular (cardio) exercise refers to exercise that strengthens the cardiovascular system. Aerobic just means in the presence of oxygen, and aerobic exercise refers to exercise that lasts long enough to require oxygen. The same type of exercise satisfies both of these qualifications, and the terms cardio and aerobic exercise are used interchangeably. Aerobic/cardio exercise uses large muscles, usually the legs, in a rhythmic fashion. Examples are running, walking, bicycling, swimming, cross-country skiing, rowing, skating, and machines such as stair steppers and elliptical trainers.