What is a primary benefit of high-intensity interval training (HIIT) for cardiovascular health?

High-intensity interval training (HIIT) is particularly effective for improving aerobic capacity, which is a key component of cardiovascular health. During HIIT, short bursts of intense exercise are alternated with periods of rest or lower-intensity exercise. This method enhances the heart's ability to pump blood efficiently and increases the muscles' demand for oxygen. As a result, the body adapts by improving its overall aerobic capacity, allowing individuals to perform physical activities with greater endurance and lower perceived exertion. This adaptation is beneficial because it promotes better oxygen utilization, supports cardiovascular health, and can aid in overall fitness improvements.

The other options do not reflect the benefits associated with HIIT. For instance, reducing muscle mass is not a positive outcome of this training modality; in fact, it often helps to maintain or even increase muscle mass due to the intensity of the workouts. Increasing body weight typically indicates a lack of fitness benefits associated with HIIT, as the goal is often to maintain or reduce weight while promoting muscle tone. Finally, decreasing metabolic rate contradicts the effects of HIIT, as this form of training is known to elevate metabolic rate during and after exercise due to the high-energy demand.