Aerobic means ‘with oxygen’, whereas anaerobic means
‘in the absence of oxygen’.
Aerobic exercise is any activity done at a sufficiently high pace to increase the heart rate, while the muscles function
aerobically (using oxygen to generate the necessary energy).
Generally, aerobic exercise refers to activity of moderate
intensity, continuing over a longer period of time.
Anaerobic exercise, on the other hand, refers to activity of high intensity occurring in spurts
interrupted by brief pauses (e.g., strength training). Under these circumstances, the muscle
generates the necessary energy by burning glucose anaerobically (in the absence of oxygen).
Due to high exercise intensity, there simply isn’t enough oxygen available for the muscle to
produce the amount of energy required at the moment.
Anaerobic muscle metabolism is much less efficient than
aerobic metabolism, and can therefore be sustained for shorter periods of time. During anaerobic
metabolism, the muscle produces lactic acid and incurs what is called ‘oxygen debt’. After
completion of the exercise, the muscle switches back to aerobic metabolism, and uses oxygen to
convert the accumulated lactic acid into pyruvic acid. The pyruvic acid can then be burned
aerobically (with oxygen), releasing additional energy after the completion of the workout.
Aerobic exercise triggers an increase in heart rate and in metabolic rate, which results in
more calories being burned. The necessary energy is furnished by breaking down carbohydrates
and fats. At the beginning of exercise, the body tends to rely mainly on carbohydrates, since
they burn more easily than fats. As such, the muscle burns carbohydrates (glucose) aerobically,
releasing energy. However, as the amount of available glucose declines, the body turns
increasingly to fats as a source of energy. The fats (triglycerides) in adipose tissues start to be
broken down, yielding fatty acids and glycerol. Fatty acids are then burned by the muscle, releasing energy. energy. Glycerol may be used for the process of gluconeogenesis (i.e., the production of new
glucose), to replenish the depleted glucose reserves.
So the conclusion is: If aerobic exercise is continued for a certain duration of time, it is sure to burn fats and result in net weight loss. It is generally believed that 20 minutes of ongoing aerobic
exercise is the minimum required to achieve fat burning effects.
In addition to weight control, aerobic activity has distinct cardiovascular benefits:
- It strengthens the heart muscle and increases efficiency of cardiac contractions, thereby
reducing the heart rate at rest. (In other words, it establishes a more ‘economical’ way for the heart to function.)
- It improves lung function and air flow.
- It improves circulation and oxygen exchanges.
- As a result of the above, it may also be effective in reducing blood pressure.
The net result is a protective effect against cardiovascular diseases such as heart attack, stroke, atherosclerosis, etc. (Of course, one must be healthy enough to sustain an increased heart rate for the duration of the workout.) Due to its cardiovascular benefits, aerobics is frequently referred to as ‘Cardio’.
An effective aerobic workout should include 5-10 minutes of warm-up, followed by at least 20
minutes of moderate intensity exercise, and 5-10 minutes of cool-down.
- During the aerobic exercise itself, heart rate should be 70-80% of one’s maximal heart rate.
- During warm-up and cool-down, heart rate should be 50-60% of one’s maximal heart rate.
Which of course begs the question: What is the Maximal Heart Rate?
In essence, this is the highest heart rate achieved by the average person of a certain age
during strenuous exercise.
The Maximal Heart Rate is assumed to be equal to 220 minus the person’s age in years. So, the
maximal heart rate of a 40 year-old should theoretically be 180, whereas that of a 20 year-old
should be 200. As you can see, the younger the person, the higher the maximal heart rate.
However, please note that many individual variations exist, even in healthy persons.
Furthermore, many illnesses including obesity may prevent one from achieving maximal heart rate.
A person’s target heart rate during aerobic exercise is 70-80% of his or her maximal heart rate. If
you raise and maintain your heart rate in this range during your workouts, you are in the so-called
‘cardio zone’ or ‘cardio range’ which ensures maximum fat burning results.
Treadmills and other aerobic machines often indicate the heart rate achieved during exercise, and
you can use this to check if you are reaching your target (cardio range) heart rate.
For example: If you are 20 years old, your calculated maximal heart rate is 200. Your target
heart rate is 70-80% of that, which is 140-160 beats per minute. In order to maximize the efficiency of your aerobic workouts, your heart rate during exercise should be somewhere in that range.
Exercising above one’s target heart rate increases the risk of heart attack and cardiac
arrhythmia, especially in people who are significantly overweight or suffer from certain
conditions such as diabetes, coronary artery disease, etc.
This is a type of exercise where intervals of higher intensity alternate with intervals of lower intensity, and the cycle is repeated a number of times.
Overall, interval training is believed to be more effective than exercising at constant moderate
intensity. Please note, however, that you still need to achieve a heart rate of 70-80% of maximal
heart rate for at least 20 minutes. (During the intervals of lower intensity, heart rate may drop
below these levels.)
An important benefit of interval training is that it allows the body to recover during the low
intensity intervals, which is helpful in preventing injury.
Aerobic exercise is especially useful for weight loss induction, when the goal is burn a sizable amount of fat. Aerobic exercise works great in combination with strength training (muscle
toning), and this combination is more effective than either type of exercise by itself. Increased
muscle mass accelerates the basal metabolism, so that more calories are burned at rest. In
conjunction with the fat-burning benefits of aerobic exercise, this makes for a highly effective
weight loss program.
Aerobics and strength training can be combined in the same workout, which in many regards is similar to interval training and carries the same benefits. A particularly effective regimen is to
alternate intervals of vigorous aerobic exercise with intervals of moderate strength training. Each type of
exercise allows the body to recover from the effort of the former exercise, while still continuing
to burn calories.
Sports that combine both aerobics and strength training are as follows:
- Swimming (at fast rate)
- Hiking on mountainous terrain
- Tae Bo and other Martial Arts
- Almost any other sport – as long as the intensity is ratcheted up to a level that exceeds the
muscles’ ability to produce energy aerobically. (Under these circumstances, the muscles
revert to anaerobic metabolism, which is the hallmark of strength training and over time
leads to increased muscle mass.)
Note: It must be understood that aerobic exercise (where the muscles use oxygen to produce energy) and strength training (where the muscles produce energy in the absence of oxygen)
overlap quite a bit in many sports activities. For example, jogging or running at moderate
pace is generally an aerobic activity. However, sprinting or running at high speed exceeds
the muscles’ capability of producing energy aerobically, and leads to anaerobic muscle
metabolism (same as a strength training workout). Similarly, swimming is an aerobic activity
if done at leisurely pace, but becomes more of a strength training workout as effort and speed
increase. Hiking uphill is an aerobic activity at low terrain incline, but as incline increases
the leg muscles tend to go into anaerobic metabolism (i.e., get a strength training workout).
The same is true of step climbing: Increasing step height causes a shift from aerobic to
You may also notice that at a given moment during a workout, some body muscles may be in
aerobic metabolism and others in anaerobic metabolism. For example, in boxing the upper
body muscles are working mainly anaerobically, while the lower body muscles function
aerobically. In reverse, during a hike uphill, the lower body muscles are working
anaerobically, while the upper body muscles are in aerobic metabolism.
When choosing an aerobic workout program, there are 2 major decisions that you have to make:
- Outdoor versus Indoor
- Gym versus Home
Outdoor activities have the advantage of being more entertaining, however a major disadvantage
is the fact they are subject to weather conditions. If you are so fortunate to live in a climate that
allows outdoor activities year-round, take advantage of this!
Good Outdoor Aerobic Activities are as follows:
- Walking at brisk pace
- Jogging or Running at moderate pace
- Walking your dog
- Hiking, especially mountain-hiking
- Ice skating
- Kayaking or Canoeing
Good Indoor Aerobic Activities are as follows:
It’s important to pick an activity that you resonate with and enjoy doing. Otherwise, chances are you won’t stick with the program. And with aerobics, the key to success is sticking with the
program. Remember that you must exercise for at least 20 minutes a day, 3-4 days a week, in
order to see results.
Whether you choose to work out at the gym or at home is entirely dependent on your personal preferences and time schedule. Of course, the cost of purchasing home equipment (i.e., aerobic exercise machines) also needs to be considered. For example, the cost of a treadmill ranges
between $1,000 and $3,5000. You can always shop around for cheaper equipment, but the
bottom line is: For a decent machine you are looking at a cost of in the hundreds to thousands of
dollars. Another problem is the space issue: Most aerobic machines occupy a fairly large chunk
of space, and their weight makes them difficult to move around. If possible, the best thing is to
designate an area of your house as the workout room, and park the steel monster there for further
For an in-depth discussion of various machines, follow the link below:
Aerobic Exercise Machines
Note: It is prudent to consult with your doctor prior to starting an exercise program, especially if you are new to exercise, suffer from any medical conditions, or are a woman over the age of 50 or a man over the age of 40.