Which aspect of fitness is primarily improved through cardiovascular training?

Cardiovascular training primarily improves cardiorespiratory capacity, which refers to the efficiency of the heart, lungs, and blood vessels in supplying oxygen to the working muscles during sustained physical activity. This type of training enhances the ability of the cardiovascular system to transport oxygen, thereby supporting endurance activities such as running, cycling, and swimming. As a result, individuals can perform longer and at a higher intensity due to improved aerobic capacity, allowing more effective oxygen utilization and energy production in muscles.

In contrast, flexibility refers to the range of motion available at a joint and is typically developed through stretching exercises, not primarily through cardiovascular training. Muscular endurance involves the ability of a muscle or group of muscles to sustain repeated contractions over time. It is more associated with specific resistance training rather than the aerobic demands of cardiovascular exercise. Lastly, body composition relates to the distribution of fat and lean mass in the body, which can be influenced by various forms of exercise, including strength and cardiovascular training, but is not the primary focus of cardiovascular workouts.