Which of the following is a benefit of cardiovascular endurance training?

Cardiovascular endurance training primarily benefits the body by improving cardiovascular health and respiratory function. Engaging in activities such as running, cycling, or swimming enhances the efficiency of the heart and lungs. This leads to a greater capacity for oxygen intake and utilization, which is essential for sustained physical activity. Improved respiratory function ensures that the body can deliver oxygen to the muscles more effectively, thereby supporting endurance performance.

In contrast, options that relate to increased muscle bulk or enhanced flexibility do not specifically pertain to cardiovascular endurance training. Increased muscle bulk is typically associated with strength training, while flexibility improvements stem from activities such as stretching or yoga. Decreased metabolic rate does not align with the outcomes of cardiovascular endurance training, as such training usually encourages a higher metabolic rate, which can aid in weight management and overall health.