Final answer:
Endurance training enhances cardiovascular functioning by increasing the heart's size and efficiency, leading to greater cardiac output and tissue perfusion during rest and exercise, and can significantly reduce the risk of heart disease.
Step-by-step explanation:
Effects of Endurance Training on Cardiovascular Functioning
Endurance training has a profound effect on cardiovascular functioning both at rest and during exercise. The heart, being a muscle, benefits significantly through improved cardiac function. Engaging in aerobic exercises, such as running or swimming, can substantially improve cardiovascular health. For instance, cardiac output, which is the product of heart rate and stroke volume, increases from an average of about 5.0 liters per minute at rest to up to 20 liters per minute during exercise in nonathletes. In well-trained athletes, these numbers are even more impressive, with a resting cardiac output of approximately 5.3 liters per minute and a maximum of over 30 liters per minute during intense exercise.
Moreover, endurance training leads to an increase in the size and mass of the heart. A nonathlete's heart typically weighs around 300 g, whereas an athlete's heart might weigh up to 500 g, making it stronger and more efficient at pumping blood. As the heart grows stronger, its cardiac reserve—its capacity to pump additional blood during activities—also increases. This enhances tissue perfusion, ensuring that muscle tissue receives more oxygen and nutrients during exercise.
Performing endurance exercises for even 30 minutes daily can have significant health benefits, including reducing the risk of heart attack by nearly 50%. An improved cardiovascular system from moderate exercise can contribute to better overall health, even for individuals who are overweight yet physically fit, compared to those who are slender but sedentary.