What is aerobic exercise?
The term aerobic means "with oxygen." During an aerobic workout, the cardiovascular system, which includes the heart, lungs and blood vessels, responds to physical activity by increasing the oxygen that is available to the body's working muscles.

Aerobic activity involves an exercise routine that uses large muscle groups, is maintained for a long periods and is rhythmic in nature. Regular aerobic exercise improves your fitness as your heart becomes stronger and begins to work better. The result is that the heart can pump more blood (thus increasing oxygen delivery to the tissues) with each heartbeat. As your aerobic fitness increases, you can work out longer with greater intensity and recover quicker at the end of the session.

What are some examples of aerobic exercise?
Many activities can give you an aerobic workout. Some examples include cycling/biking, running, swimming, cross-country skiing, playing basketball, jumping rope, roller skating, walking briskly and dancing. In addition to these activities, you can get an aerobic workout through stationary exercise machines such as cycles, treadmills, stair-steppers and rowing machines. These can be found at a local gym or health club. Most of these machines can also be used at home.

Who can participate in aerobic exercise?
Virtually everyone can (and should) do some type of aerobic exercise. Because each type of aerobic exercise can be modified to varying intensity levels, people with different fitness goals, levels of physical conditioning and injury or illness history can participate.

If you are older than 40 or have a history of diabetes, heart disease, high blood pressure or other cardiovascular condition, are obese or have been inactive, talk with your doctor before starting any exercise program.

Aerobic exercise is can help people with conditions such as heart disease, diabetes, obesity, arthritis, anxiety and premenstrual syndrome.

What are the added benefits of aerobic exercise?
Along with strengthening your heart, studies show repeatedly that there are many benefits to aerobic exercise. Aerobic exercise can:

• Increase resistance to fatigue and give you more energy. Aerobic exercise can add life to your years along with years to your life.
• Improve mood and reduce depression and anxiety. Positive mood changes have been noted after as little as two to three weeks of starting aerobic exercise.
• Improve the quality of your sleep. Studies show people who exercise regularly fall asleep quicker and sleep better. However, finish your aerobic exercise routine one to two hours before bedtime.
• Increase good (HDL) cholesterol. This type of cholesterol is known to reduce the risk of heart disease.
• Help control and reduce body fat. Aerobic exercise combined with a healthy diet can lower body fat.
• Reduce the risk of certain types of cancer. Aerobic exercise has been associated with a reduction in the incidence of colon cancer in men and women, and the incidence of breast and reproductive organ cancers in women.

What to consider when developing an aerobic workout schedule
Here are the three important factors that affect an aerobic workout:

• Frequency. This refers to how many days you do an aerobic activity.
• Duration. This refers to how much time is spent in each aerobic session.
• Intensity. This refers to how difficult the activity is, usually determined by the percentage of your maximum heart rate achieved during the workout.

In general, the Centers for Disease Control and Prevention National Center for Chronic Disease Prevention and Health Promotion states that adults should try to exercise most days of the week and preferable daily. The Center states that adults should strive to meet either of the following physical activity recommendations.

• Adults should get moderate-intensity physical activities for at least 30 minutes on 5 or more days of the week.

OR

• Adults should get vigorous-intensity physical activity 3 or more days per week for 20 or more minutes per occasion.

Examples of moderate-intensity physical activities include walking briskly, mowing the lawn, dancing, swimming, or bicycling on level terrain, according to the Centers for Disease Control and Prevention. Examples of vigorous exercises include jogging, mowing the lawn with a nonmotorized pushmower, participating in high-impact aerobic dancing, swimming continuous laps, or bicycling uphill, carrying more than 25 lbs up a flight of stairs, standing or walking with more than 50 lbs.

With moderate intensity physical activity, you would expect some increase in breathing or heart rate. With vigorous activities, you would expect a large increase in breathing or heart rate (conversation is difficult or "broken").

Heart rates and target zones for aerobic exercise
For general guidelines used in determining your maximum heart rate and target heart rate ranges, refer to the chart below.

If you are just starting a workout program, your beginning workout time may need to be as little as 15 minutes, three days a week. Therefore, it may take several weeks or months to build up. Stick with it. Gradually increase your frequency, duration and intensity. This is especially true if you are overweight, out of condition, elderly, or are recovering from an illness or injury.

A warm-up and a cool-down period, both of which should incorporate stretching exercises, are essential parts of aerobic conditioning. Warming up helps your body prepare for exercise by slowly raising your heart rate and muscle temperature. This also decreases the likelihood of injury.

A cool-down allows the heart rate to slowly return to normal and to get the blood circulating freely back to the heart. Never abruptly stop an aerobic activity, no matter how tired you become, because this could cause dizziness or sudden fainting. If you can't keep up the pace of an aerobic workout, slow down and walk around for a few minutes before completely stopping activity.

Drink plenty of fluids before, during and after your workout.

How many calories does aerobic exercise burn?
The number of calories that you burn varies with the activity, duration and intensity of the workout. The table below is from the American Council on Exercise. Calories are given for one minute of activity. To determine how many calories you would burn in half an hour of aerobic activity, multiply the number shown by 30.

What type of equipment do you need for aerobic exercise?
The equipment depends upon your activity. For any kind of exercise, dress comfortably. High tech fabrics tend to pull moisture away from the body and help keep you cool. Women should wear a sports bra for support as needed.

Choose shoes designed for your activity. All sneakers are not the same. When buying shoes, make sure that they fit and are well-cushioned. If you feel any rubbing or irritation, don't buy the shoe.

You'll need a clock or watch with a second hand for finding your heart rate. You can buy devices that automatically calculate your heart rate, and many newer pieces of exercise equipment have heart rate monitors.

What are the disadvantages of aerobic exercise?
Like any new activity, it takes time for your body to get used to the change. You may have soreness and stiffness in the first few days of your workout. This will go away with stretching and as your body adjusts to regular activity.

Exercise can, of course, cause injury. Talk to your doctor if you have any concerns about pain or discomfort. The most common injuries resulting from aerobic workouts include joint and muscle strains and sprains. Serious pain should not be ignored. To lower your risk for injury, make sure you get a balanced workout that includes strength and flexibility training.

Glossary of terms

Aerobics: An activity that relies on oxygen to sustain the workout.

Duration: The amount of time spent at each aerobic session.

Flexibility: The ability of a bone joint or muscle to stretch.

Frequency: The number of days per week an aerobic activity is done.

Intensity: The amount of force or energy expended during a workout, usually monitored by the heart rate.

Maximum heart rate (MHR): The rate at which your heart pumps blood during a very vigorous workout. Do not exceed your maximum heart rate MHR = 220 minus your age.

Stretching: Exercise which increases the ease and degree to which a muscle or joint can turn, bend or reach.

Target heart rate (THR): A percentage of your maximum heart rate that should be achieved during aerobic exercise. THR can be anywhere from 60 percent to 90 percent of your MHR.

Workout: A planned series of exercises.

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External Sources American Dietetic Association. Position paper: nutrition and athletic performance. Journal of the American Dietetic Association. 2009;109(3):509-527. . Accessed March 11, 2009 President's Council on Physical Fitness and Sports American Council on Exercise. Healthy hydration. Accessed March 11, 2009 American Heart Association Scientific Statement. Diet and lifestyle recommendations. Revision 2006. Circulation. 2006;114(1):82-96.. Accessed May 19, 2009