Cardiovascular fitness is best described as

• A. The maximum force a muscle can exert against heavy resistance.
• B. The degree to which a muscle can lengthen.
• C. The ability of the heart, lungs and vascular system to deliver oxygen-rich blood to working muscles during sustained physical activity.
• D. The number of steps taken daily.

Answer: (C)

Cardiovascular fitness is about how efficiently the heart, lungs, and blood vessels deliver oxygen-rich blood to working muscles during sustained physical activity. This reflects aerobic capacity and endurance, meaning the body can perform prolonged exercise by using oxygen effectively and removing waste. When fitness is high, the heart can pump more blood with each beat and tissues use oxygen more efficiently, supporting longer activity without fatigue. The other options describe different aspects: muscular strength is about how much force a muscle can produce against resistance; flexibility or range of motion refers to how much a muscle or joint can move; and daily steps measure overall activity level rather than how well the cardio-respiratory system sustains activity.