In simple terms, every second your heart pumps about four liters of blood to your extremities. With each beat, the heart pumps up to one and a half liters of blood into the circulatory system, and this lasts almost twenty seconds. What exactly happens during a cardio workout? The sharply increasing intensity of the cardiovascular system causes an increase in cardiac output, heart rate, blood pressure and peripheral vascular resistance. Physiological processes can be displayed as follows: breathing becomes more frequent, the minute volume of blood oxygen and the overall metabolic effect increase, the content of carbon dioxide and hydrogen in the blood increases. During this period, a significant expansion of capillaries becomes possible, the number of functioning capillaries increases