What type of exercise is typically recommended for improving cardiovascular endurance?

High-intensity interval training (HIIT) is particularly effective for improving cardiovascular endurance due to its structure, which alternates between periods of intense activity and periods of lower intensity or rest. This type of training elevates heart rate significantly during the intense intervals, which improves the heart's ability to pump blood and increases overall cardiovascular fitness. It also enhances the body’s capacity to utilize oxygen more efficiently over time, which is a key component of endurance.

In contrast, heavy weightlifting primarily focuses on building muscle strength rather than improving cardiovascular endurance, as it typically involves fewer repetitions and longer rest periods, which do not maintain an elevated heart rate. Static stretching is aimed at increasing flexibility and does not contribute to cardiovascular endurance. Isometric exercises involve muscle contraction without movement and do not significantly raise heart rate or improve aerobic capacity. Therefore, HIIT stands out as the most suitable choice for enhancing cardiovascular endurance.