Training your cardiovascular endurance will increase your body's aerobic capabilities. Aerobic fitness can be trained via running, walking, biking, swimming, stepping and resistance circuit training. According to Scott Powers, author of "Exercise Physiology: Theory and Application to Fitness and Performance," aerobic fitness gains can will increase in varied training methods as well, such as interval and long-slow distance training. Stated by the National Strength and Conditioning Association, aerobic fitness gains from endurance training necessitates progressive training, variation in exercise duration, increased exercise intensity and continuous overload if physiological gains are to occur.
Endurance training will increase your maximum oxygen uptake -- or VO2max -- which is a gold standard of measuring how well your body utilizes oxygen. As exercise intensity increases, oxygen consumption must increase as well. Thus, the body as a system will begin to adapt to the increased oxygen needs as you progressively partake in endurance training and increase intensity with the process. The National Strength and Conditioning Association showed in a study that previously untrained subjects increased their average maximum oxygen uptake from 47 ml/kg/min to 55 ml/kg/min after three to six months of endurance training.
Your heart works and functions in a more energy efficient manner when partaking in endurance training. According to the American College of Sports Medicine, your resting heart rate decreases and resting stroke volume per heart beat increases from endurance training. This in turn creates a higher functional capacity for cardiac output. Due to an increased cardiac output, your exercising heart rate and stroke volume will run more efficiently. Endurance training causes exercise heart rate to stay decrease from initial value, and allows exercising stroke volume to increase. This is an example of the body performing more work with less energy.
Your lungs increase in effectiveness as well. A more efficient exchange of oxygen and carbon dioxide within the cells occurs after partaking in endurance training. Also, your respiratory muscles become stronger. This will allow more air to be taken in and out per breath, as well as allow the diaphragm to handle consistently stronger breaths while exercising. In a study done by the National Strength and Conditioning Association, it was found that cardiovascular endurance training increased previously untrained subjects' average maximal pulmonary ventilation per minute from 123 L to 142 L. The average resting pulmonary ventilation decreased from seven L/min to six L/min. The subjects trained for three to six months.
Stamina and Exercise Economy
The National Strength and Conditioning Association reports that endurance training increases an individuals aerobic fitness by 5 to 30 percent from their starting levels of aerobic power and fitness. This fact dictates that your body learns how to function longer and more effectively after engaging in endurance training for at least three to six months. Endurance training will allow your body to deal with physical exertion in a less taxing manner on the body, and increase your ability of exercising for longer durations before fatigue sets in.