Aerobic exercise is cardiovascular conditioning that strengthens your heart and lungs. Aerobic means with oxygen and aerobic exercise refers to types of exercise fueled by breathing. This type of activity includes repeated continuous movement. Anaerobic exercise is high intensity exercise that is meant to be short and fast, for example High Intensity Interval Training or HIIT. During this exercise your body doesn't use oxygen to keep your muscles going but rather accesses the energy already stored in your muscles.