What component of fitness is primarily measured by a VO2 max test?

A VO2 max test primarily measures cardiorespiratory endurance, which is the ability of the cardiovascular and respiratory systems to supply oxygen to the muscles during prolonged physical activity. This test quantifies the maximum amount of oxygen the body can utilize during intense exercise, providing a direct assessment of aerobic capacity.

High VO2 max values indicate efficient oxygen transport and utilization capacities, crucial for endurance sports and activities. Cardiorespiratory endurance is essential for overall fitness and is a key indicator of an individual's cardiovascular health and physical performance. In contrast, muscular strength, flexibility, and body composition are evaluated through other specific tests and measurements that do not focus on the heart and lungs' performance in delivering oxygen during exercise. Therefore, the link between VO2 max and cardiorespiratory endurance establishes it as the correct answer.