- The definition of physical fitness can vary, but most experts agree that there are five components of physical fitness. These components represent how fit and healthy the body is as a whole: 1. Cardiovascular Fitness — The cardiovascular system (also called the circulatory system) consists of the heart (cardio) and the blood vessels (vascular). It's the system that supplies oxygen and blood throughout the body. Cardiovascular fitness is the body's ability to supply oxygen and blood to the working muscles during exercise that lasts for an extended period of time. Aerobic Exercise improves cardiovascular fitness. 2. Muscular Strength — Muscular strength is the amount of force a muscle or muscle group can exert against a