What physiological changes occur in the cardiovascular system with chronic endurance training?

Chronic endurance training leads to several adaptations in the cardiovascular system that enhance its efficiency and capacity. One of the most significant physiological changes is the increase in cardiac output and stroke volume.

Cardiac output is the volume of blood the heart pumps per minute, and stroke volume is the amount of blood pumped by the heart with each beat. With consistent endurance training, the heart becomes more efficient. This efficiency comes from several factors, including hypertrophy of the cardiac muscle, particularly the left ventricle, which allows it to hold and eject more blood. Trained individuals typically exhibit a lower resting heart rate due to increased stroke volume, meaning the heart can pump more blood in fewer beats.

As stroke volume increases, the overall cardiac output may also increase, especially during exercise when the demand for oxygen-rich blood becomes greater. This allows trained athletes to perform at higher intensities for extended periods without reaching their lactate threshold too quickly.

This adaptation supports better oxygen delivery to muscles during prolonged physical activity, contributing to improved endurance performance. Thus, the increase in both cardiac output and stroke volume is a hallmark of the cardiovascular adaptations that result from chronic endurance training.