When you're training for endurance, you're conditioning your body to perform efficiently during prolonged physical activity. It's not just a matter of getting used to running, bicycling or swimming longer distances. Regular endurance training produces changes in your cardiovascular response, improving oxygen efficiency, strengthening your heart and raising your resting metabolism.
The cardiovascular system, made up of your heart, blood vessels and blood, makes physiological adjustments to accommodate the increased demand for oxygen generated by physical activity. Moderate to vigorous intensity exercise raises your heart rate, which increases your metabolism. This metabolic response triggers your muscles to demand more oxygen, which your body needs to meet its immediate demand for energy. When you exercise aerobically on a regular basis, your cardiovascular systems adapts to meet your energy needs during extended physical activity.
When you first start exercising aerobically at moderate to vigorous intensity, your breaths are short and rapid. You feel as though you're not taking in enough oxygen and may even find yourself yawning in response. This is because the rate at which your muscles are demanding oxygen exceeds your cardiovascular system's capacity to supply oxygen. Fast forward to the sixth week of regular training and you'll generally notice a marked difference in your breathing patterns because your body has learned to perform more efficiently.
Endurance training produces changes in heart size, heart rate, blood flow, blood pressure, blood volume and stroke volume, according to Lewis-Clark State College. Endurance training can increase your maximal oxygen uptake, or VO2 max, which means your body learns to move and use oxygen with more efficiency during exercise. Your heart gets stronger, which means it doesn't have to work as hard to pump blood, even at rest. Endurance training decreases resting blood pressure and may increase blood volume because of increased blood plasma. This, in combination with your body's improved ability to deliver blood to muscles during exertion, ensures that oxygen gets distributed more effectively when you're exercising and when you're resting.
Endurance training builds a healthier cardiovascular system. Benefits include improved good cholesterol levels and reduced risk for heart disease, diabetes and high blood pressure, according to the American Council on Exercise. Sustained aerobic training builds the capacity of the lungs, heart and circulatory system to transport oxygen to your muscles. Consult with your doctor before undertaking an endurance program if you've been inactive or suffer from a chronic health condition.