Which statement BEST defines cardiorespiratory endurance?

• A. The maximum force a muscle can exert in a single effort
• B. The ability of the heart, lungs, and blood vessels to supply oxygen during sustained activity
• C. The proportion of fat versus fat-free mass
• D. The range of motion around joints

Answer: (B)

Cardiorespiratory endurance is about how well the body can deliver and use oxygen during prolonged activity. It hinges on the heart’s ability to pump blood, the lungs’ efficiency in exchanging gases, and the blood vessels’ capacity to transport oxygen to working muscles. When you train aeróbically, you improve how much oxygen your body can deliver and how effectively muscles use it, allowing you to sustain activity longer. That ongoing oxygen delivery and utilization during sustained effort is what this statement describes best.

The other ideas point to different aspects of fitness: maximal force a muscle can produce relates to muscular strength, the fat-to-fat-free mass ratio to body composition, and range of motion around joints to flexibility.