What is Aerobic Exercise?
- Aerobic exercise is the type of moderate-intensity physical activity that you can sustain for more than just a few minutes with the objective of improving your cardiorespiratory fitness and your health.
- "Aerobic" means "in the presence of, or with, oxygen."
- You know you're doing aerobic exercise when your heart's thumping and you're breathing faster than you do at rest but you can sustain the activity for extended periods of time. I recommend the cue "warm and slightly out of breath" to determine if your activity level is aerobic.
- Walking, jogging, biking, dancing, and swimming are examples of activities that can be performed aerobically.
- Anaerobic, on the other hand, means "the absence of, or without, oxygen."
- Anaerobic exercise is performed at an intensity that causes you to get out of breath quickly and can be sustained for only a few moments. Weight lifting and sprinting are examples of anaerobic exercise.
What is the difference between aerobic and anaerobic exercise?
A single activity can include elements of both aerobic and anaerobic exercise. For example, interval training, where you alternate cycles of low-intensity (aerobic) and high-intensity (anaerobic) work during the same workout, has elements of both. So does a game of tennis where you might sprint at one moment (anaerobic) and then move less aggressively for several minutes (aerobic) as you hit ground strokes from the baseline.
Most activities can be performed aerobically or anaerobically. For example, you could walk briskly on the treadmill at 3.5 miles per hour and feel warm and slightly out of breath (aerobic), or you could walk very briskly at 4.5 miles per hour and feel very out of breath (anaerobic). The same is true for biking, swimming, dancing, or virtually any other activity. The intensity of the workout determines whether an activity is aerobic or anaerobic, and all you need to do is pace yourself to elicit the type of training you desire.
Biologic Basis of Aerobic Exercise
A. Oxygen Delivery
Breathing increases during aerobic exercise to bring oxygen into your body. Once inside your body the oxygen is (1) processed by the lungs, (2) transferred to the bloodstream where it is carried by red blood cells to the heart, and then (3) pumped by the heart to the exercising muscles via the circulatory system, where it is used by the muscle to produce energy.
B. Oxygen Consumption
"Oxygen consumption" describes the process of muscles extracting, or consuming, oxygen from the blood. Conditioned individuals have higher levels of oxygen consumption than deconditioned individuals ("couch potatoes") due to biological changes in the muscles from chronic exercise training. For example, a deconditioned individual might have a maximal oxygen consumption of 35 milliliters (ml) of oxygen per kilogram of body weight per minute (ml/kg/min), whereas an elite athlete may have a maximal oxygen consumption up to 92 ml/kg/min! Values like this are expressed as VO2 (volume of oxygen consumed) and can be measured with special equipment in a laboratory.
C. Burning Fat
A higher percentage of fat is burned during aerobic exercise than during anaerobic exercise. Here's why. Fat is denser than carbohydrate (fat has nine calories per gram and carbohydrate has four), and so it takes more oxygen to burn it. During aerobic exercise, more oxygen is delivered to the muscles than during anaerobic exercise, and so it follows that a higher percentage of fat is burned during aerobic exercise when more oxygen is available. When less oxygen is present, like during anaerobic exercise, a higher percentage of carbohydrate is burned.
Keep in mind that both fuels are almost always burned simultaneously, except during the most intense, short-term bursts of energy, like sprinting and weightlifting. It's the percentage of fat and carbohydrate burned that changes during a workout depending on the intensity, but you almost never burn just one exclusively. You burn fat while you're at rest, and you burn it during virtually every moment of exercise. It's a myth to think that it takes 20-30 minutes of exercise before your muscles start burning fat.
How do I calculate my target heart rate?
You can use the cue "warm and slightly out of breath" to gauge your aerobic activity, or you can get more precise and use heart rate. I recommend the heart rate reserve method for calculating a target heart rate. The formula and an example of the method for someone 27 years old, assuming a resting heart rate of 70 beats per minute (bpm), and a training range of 70%, may be found below. Aerobic exercise falls in the range from 40% to 85%. You can plug in your own values to find your aerobic range.
Here's the heart rate reserve formula:
- 220-Age = Max HR
- Subtract resting heart rate from Max HR = Heart Rate Reserve (HRR)
- Multiply HRR times percent at which you want to train
- Add back resting heart rate
Assuming a resting heart rate of 70 bpm, 27 years old, and 70% training range:
- 220 - 27 = 193
- 193 - 70 = 123
- 123 x .70% = 86
- 86 + 70 = 156
- So this 27-year-old exerciser will try to maintain an hear rate of 156 beats per minute while doing aerobic exercise.
What are the benefits of regular aerobic exercise?
You will accrue many health and fitness benefits if you perform regular aerobic exercise. Here's a partial list:
How much do I need to do to gain the benefits of aerobic exercise?
It doesn't take all that much aerobic exercise to accrue lots of fitness and health benefits. There are two physical activity recommendations to choose from in the United States. One is the Surgeon General's "lifestyle" recommendation, where you can accumulate activity and incorporate it into your day (a nice way to save time for busy people), and then there's the formal "workout" recommendation from the American College of Sports Medicine (ACSM).
- Surgeon General: The Surgeon General recommends 30 minutes or more of accumulated moderate intensity physical activity on five or more days per week to improve health and fitness. "Accumulated" means you can do it in shorter bouts throughout the day (for example, 10- or 15-minute intervals throughout the day), and "moderate intensity" means you feel warm and slightly out of breath when you do it. You can read more about the Surgeon General's "lifestyle" recommendation at: www.cdc.gov/nccdphp/sgr/sgr.htm.
- ACSM: The American College of Sports Medicine recommends 20-60 minutes of continuous activity, three to five times a week, at 60-90% of maximum heart rate, and two to three days of resistance training. You can read more about the ACSM formal workout recommendation at: www.acsm-msse.org/pt/pt-core/template-journal/msse/media/0698a.htm.
Both recommendations include aerobic exercise, and your health and fitness will improve if you follow either. Choose the Surgeon General's lifestyle recommendation if you are unable or unwilling to follow the ACSM workout recommendation, and stick with the ACSM recommendation if you're already putting in time at the gym or you like the buzz of vigorous exercise. Of course, incorporating lifestyle activity and formal workouts into your exercise plans will give you the best of both worlds.
How do I get started on an aerobic exercise program?
Select an activity with a high probability that you will stick with it. It doesn't necessarily have to be fun, it just has to be something realistic that you are willing and able to do. You're probably setting yourself up to fail if you work 12 hours a day, take care of three young children, and still plan to use a treadmill at a gym that's a 45-minute commute from where you work or live. Instead, choose something more convenient. I love the "five minutes out, five minutes back" plan to get started. Just like it sounds, you walk out for five minutes at a moderate intensity (aerobic exercise), turn around, and walk back. That's it. Ten minutes of walking and off you go about your day. If you feel ambitious, start with seven and a half or even 10 minutes out and back, and add some abdominal crunches if you like when you finish. Keep in mind that you can always add more later on. The important thing is to get started.
What are other options for aerobic exercise?
Recreation center or gym classes, exercise videos (check Collage Video, or rent one at your library), stationary or outdoor biking, hiking, swimming, dancing, or anything else that gets you warm and slightly out of breath will work.
How do I warm up for aerobic exercise?
Start your aerobic workout with a five to eight minute brief warm-up. That means start slowly and then speed up once your muscles and heart have accommodated to the work. Most people know when their body is warmed up. Muscles feel looser and you feel in the "groove."
How do I cool down from aerobic exercise?
Complete your workout with a three to five minute cooldown. It will give your muscles a chance to slow down gradually and reduce the risk of dizziness. Individuals who stop aerobic exercise abruptly can experience "pooling" of blood in the legs from standing still right after exertion. Cooling down is important after any aerobic activity, so always make sure to take three to five minutes at the end of your workout to slow down gradually.
Do I need to stretch after aerobic exercise?
Sometimes there's nothing like a good stretch to relax the mind and body after an aerobic workout. Take five or 10 minutes after aerobic exercise and treat yourself and stretch. If you tend to have tight muscles all the time and stretching at the end doesn't quite do it for you, then try warming up for five minutes to get the muscles filled with blood, stop and stretch, and then continue with your workout. You might really like the feeling.
Is aerobic exercise safe?
Though the risks of being sedentary far outweigh the risks of exercise, one should be prudent when beginning an aerobic exercise program. Safety guidelines from the ACSM state that individuals at low or moderate health risk can begin a moderate-intensity exercise plan without a medical exam or exercise stress test, whereas people at high risk should be evaluated by their doctor. You are at high risk if you have:
- Known cardiovascular, pulmonary, or metabolic (for example, diabetes) disease, including:
- History of a heart attack
- If your father or other male first-degree relative died suddenly before 55 years of age from a heart attack or before 65 years of age in your mother or other first-degree female relative
- High blood pressure
- Pain or discomfort in the chest, neck, jaw, arms, or other areas that may be due to ischemia (restriction of blood flow to the heart)
- Shortness of breath at rest or with mild exertion
- Dizziness or temporary losses of consciousness or posture
- Ankle swelling (edema)
- Palpitations (rapid heart beats)
- Intermittent claudication (pain after mild to moderate exercise that resolves with rest)
- Known heart murmur
- Unusual fatigue or shortness of breath with normal activities
Speak with your doctor if you have any question about whether it's safe to start an exercise program.
How do I set and aerobic exercise plan?
A good way to begin is to write down a weekly exercise plan, including when you will exercise each day, and continue to do so every week for three months if you are serious about sticking with exercise but concerned about your motivation. Write down what day(s) of the week, what time of day, minutes of activity, and the activity that you'll do when setting your plan. Be as specific and realistic as possible, and remember that it's not how much you do when you start that counts but that you simply do something. Getting started is usually the hardest part. You can always add more later on.
A Final Word on Aerobic Exercise
Aerobic exercise is chock-full of benefits, and you don't need to spend a lot of time doing it to reap the rewards. There's no time like the present to get started. Go ahead and set that weekly plan right now, and then get down to it!
How many calories does aerobic exercise burn?
Below is a list of aerobic activities with the approximate number of calories burned per hour for a 150-pound individual.
- Aerobics class: 450-500
- Bicycling (outdoor): 540-620
- Bicycling (stationary): 480-540
- Cross-country skiing: 530-630
- Dancing: 300-350
- Gardening: 270-300
- Hiking: 400-480
- Jogging: 530-630
- Jumping rope: 650-800
- Running: 650-750
- Skating: 470-550
- Swimming: 400-480
- Tennis: 470-550
- Volleyball: 200-240
- Walking (regular pace): 150-200
- Walking (fast pace): 250-300