Steady-state exercise affects many aspects of your body's function. You may notice a decline in your blood pressure and heart rate, and your overall aerobic endurance will improve after you consistently perform steady-state exercise over several months. These are just a few of the adaptations your body will make to meet the demands of aerobic exercise.
Steady-state aerobic exercise causes the body to increase the amount of blood pumped by the heart. Cardiac output is determined by stroke volume and heart rate. Stroke volume is the quantity of blood pumped with each heartbeat. Going from rest to steady-state exercise, cardiac output begins to increase rapidly, then more gradually until it reaches a plateau. Over time, you develop an increased number of capillaries, greater opening of existing capillaries, more effective blood redistribution and increased blood volume. The changes to the capillaries improve your body's ability to deliver oxygen and nutrients to your muscles as well as to remove waste products.
Blood pressure is affected both during and after steady-state exercise. During steady-state exercise, there is a temporary increase in systolic and a decrease in diastolic blood pressure. These numbers represent the pressure in your arteries while your heart is contracting and between heart beats, respectively. Long-term steady-state aerobic training can reduce overall blood pressure over time. Resting blood pressure generally is reduced by endurance training in those with borderline or moderate hypertension, according to Jack H. Wilmore and David L. Costill, authors of "Physiology of Sport and Exercise."
Regular steady-state exercise can result in a decrease in resting heart rate. After a six-month endurance training program of moderate intensity, decreases in heart rate of 10 to 30 beats per minute are common at the same standardized submaximal rate of work, the decrease being greater at higher rates, according Costill and Wilmore. These decreases in heart rate show the heart is becoming more adept at performing essential functions.
Lactate threshold is a strong indicator of endurance capabilities. The lactate threshold is the point in which blood lactate begins to accumulate above resting levels during exercise of increasing intensity. Lactate threshold is determined by the percentage of maximal oxygen uptake. Having a higher percentage of maximal oxygen uptake reflects a higher lactate threshold. Over time, your lactate threshold can improve, enabling you to exercise for longer periods of time without fatiguing.