Which component of fitness refers to the ability of your heart and lungs to supply oxygen during sustained physical activity?

The correct choice highlights cardiovascular endurance, which is crucial for sustaining physical activity over an extended period. This component of fitness involves the efficiency with which the heart, lungs, and muscles work together during exercise. When engaging in activities like running, swimming, or cycling, cardiovascular endurance is key to ensuring that your body can deliver adequate oxygen to working muscles, allowing you to maintain your pace and energy levels over time.

Improving cardiovascular endurance not only enhances physical performance but also contributes to overall health by reducing the risk of heart disease, increasing metabolic efficiency, and promoting recovery from exercise. It is assessed through various means, including VO2 max tests, which measure the maximum amount of oxygen the body can utilize during intense exercise.

In contrast, muscular strength focuses on the maximum amount of force a muscle can exert, flexibility involves the range of motion in joints, and body composition refers to the proportion of fat and non-fat mass in the body. Each of these components serves a distinct purpose in overall fitness but does not directly relate to the specific ability of the heart and lungs to supply oxygen during sustained activities as cardiovascular endurance does.