The Effects Of Aerobic Training Protocols

Aerobic training protocols can involve a variety of exercises, including biking, hiking, jogging, running, swimming and walking. Sports such as hockey, soccer and tennis are also aerobic in nature. Performing such exercises for at least 30 minutes or more each day increases your aerobic, or cardiorespiratory, endurance -- your body's ability to exercise continually for long periods of time. This is caused by numerous adaptations, or changes, that occur in your heart, lungs and muscles due to aerobic training.

Cardiovascular Adaptations

The cardiovascular system consists of your blood vessels and heart, which transport blood throughout your body, delivering nutrients and oxygen to it's tissues. Aerobic training helps the cardiovascular system operate more efficiently. The size of the heart, especially the left ventricle, increases due to aerobic training, allowing more blood to fill the chamber as the heart rests. Also, the walls of the left ventricle strengthen, which increases the force of each heart contraction, sending out a greater amount of blood with each beat -- called stroke volume. Regular aerobic exercise also causes your heart rate -- the number of times it beats per minute -- to decrease while you are resting and during low- to moderate-intensity exercise. Other cardiovascular changes may include increased blood flow, decreased blood pressure and increased blood volume.

Respiratory Adaptations

Like the cardiovascular system, the respiratory system, which involves the lungs, works with greater efficiency due to aerobic training protocols. The respiratory adaptations that occur are most evident during high-intensity exercise, when all the body's systems are under considerable stress. Maximal pulmonary ventilation, or breathing, increases from about 100 to 120 liters per minute to 130 to 150 liters per minute in previously sedentary individuals, according to exercise physiologists Wilmore, Costill and Kenney. Additionally, the exchange of gases in the alveoli of the lungs -- called pulmonary diffusion -- increases during high-intensity aerobic exercise.

Muscular Adaptations

The function and structure of the muscles you use during exercise sessions also change as a result of aerobic training protocols. Aerobic exercises recruit slow-twitch, or type I, muscle fibers more than fast-twitch, or type II, fibers, because such exercises typically do not require powerful muscle contractions. Therefore, the slow-twitch fibers get bigger and their percentage increases relative to the fast-twitch fibers. Second, regular aerobic exercise increases the number of capillaries that supply each muscle fiber, which improves blood flow to the working muscles. Also, aerobic training increases the amount of myoglobin, which stores oxygen, and the number of mitochondria, which use oxygen to produce energy, within the muscles. When combined with the cardiovascular and respiratory adaptations that occur due to aerobic training protocols, these changes make a significant impact on your level of aerobic endurance.