Aerobic means "oxygen-producing." Aerobic exercise, sometimes called endurance training, improves oxygen consumption by your body and strengthens your cardiovascular system and endurance. Activities like walking, running, swimming, and biking, in which you remain in motion and your heart rate increases for an extended period of time, are considered aerobic. When your heart is beating more rapidly, more blood is circulated around your body and more oxygen is provided to your tissues and cells.

Your heart is a muscle like any other in your body, and with regular exercise it will become stronger and slightly larger. (This is different from an enlarged, or hypertrophied, heart, in which the heart muscle thickens and actually becomes weaker.) A stronger heart can pump more blood with each beat, so that it takes fewer beats to circulate your blood. Your heart rate drops, and your heart is able to rest more between beats. But if you don't get enough exercise, your heart is weaker, has less muscle tone, and has to work harder to pump the blood. This raises your blood pressure and stresses your whole cardiovascular system.

As you progressively condition your heart with aerobic exercise, not only does your heart become stronger, but your entire body responds. New capillaries grow in your muscles and in the heart muscle itself. In fact, endurance-trained athletes have 40% more capillaries per muscle than untrained people. Your muscle cells themselves change in ways that allow them to extract greater amounts of oxygen and nutrients from the bloodstream and use them to produce energy. Your blood pressure lowers, and your body produces more red blood cells to transport oxygen.

Exercise strengthens bones ligaments and tendons by encouraging the laying down of connective tissue. Your joints become stronger and less prone to injury. Your bones will also lose less calcium as you age, helping to prevent osteoporosis.

Moderate Intensity vs. Short Bursts
It's long been thought that aerobic exercise works best when performed at moderate intensity over a long period of time. But new evidence shows that short, intense bursts of exercise may work just as well for cardiovascular health. In one study, doing about 50 minutes of moderate-intensity cycling 5 days a week provided the same benefits to the arteries as doing short, intense cycling sprints (resting between sprints) for a total of about 20 minutes, just 3 days a week. Consider this type of exercise if time is an issue for you, but consult your doctor first, as intense exercise may increase the risk of injury.

More on this topic

Understanding Wellness (VIDEO)
What Is Wellness?
Quit Smoking
Smoking & Your Arteries
Eat Healthy
Foods to Avoid
Foods to Enjoy
Fiber Helps Lower Cholesterol
Good Fats: Omegas 3 & 6
The Daily Nutrition You Need
Portion Control
Daily Exercise
Aerobic Exercise
Speed Up Your Metabolism
Benefits of Exercise
Lose Weight
Measuring Fat

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