Cardiovascular endurance is one of the five health-related components of physical fitness. It refers to the ability of the heart and lungs to supply oxygen and nutrients to the muscles. In simple terms, someone with great cardiovascular endurance has a strong heart – one that actually grows in size and pumps more blood with every beat, resulting in a lower heart rate.As you can imagine, this can only happen when an individual regularly exercises. Typically, it’s aerobic exercise that improves.