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 Aerobic Exercise
Get in Shape
| Aerobic Exercise |
Walking | Strength
Training | 5 Quick Tips
 Dear Dr. Suzy,
Q. I usually do some
type of aerobic exercise for 10-20 minutes, three or four times a week, but I
hardly notice any difference in my body as a result. Why is cardio not
working for me?
A.
I used to wonder the same thing myself and then one day, in
my own ongoing search for the truth about health and fitness, I discovered an
interesting fact in one of my exercise physiology textbooks. This little
nugget of truth has become one
of the core fundamentals for my own personal beliefs about exercise and fitness.
Like
most people, I used to spend fifteen or twenty minutes performing some type of
cardiovascular exercise and assume that I was burning fat the entire time.
Upon further investigation, I realized, however, that the process of
burning fat as a fuel is a little more complicated than I once believed.
At
the beginning or warm-up stage of an aerobic exercise session, the primary
source of energy that your body is burning as fuel comes from carbohydrates,
which are stored as glycogen in your muscles. For the next twenty minutes or so
as you continue exercising, your glycogen stores supply only about half of your
energy requirements, with the other half being provided by the breakdown of fat.
[1]
Now,
here is the really interesting part:
The longer you exercise past this point, the more your glycogen stores
are reduced, and a higher percentage of energy is supplied by the metabolism of
fat.
To
put it simply:
In
the warm up phase of aerobic exercise, you use mostly glycogen from
carbohydrates. The longer you continue exercising, the more you will burn fat as
a source of fuel. Only after about
twenty minutes does your body start to use fat as its primary energy source.
The
bottom line is that to begin truly burning from your fat stores, you may need to
participate in cardiovascular activities and exercises a little longer than you
are accustomed to. I have found that adding some variety to your usual aerobic
exercise routine and including outdoor activities that you truly enjoy make it
easier to obtain the proper amount of cardio that you need for a healthy balance
in your daily life.
The
wonderful thing about lengthier aerobic sessions is that they increase your
metabolism long after you stop sweating, in some cases for up to six or seven
hours. In addition to the fat
burning effects, regular physical activity enhances mental health, greatly
reduces the risk of dying from coronary heart disease, and also decreases the
risk of developing diabetes, hypertension, and colon cancer, according to The
Surgeon General’s Report on Physical Activity and Health.[2]
 If
more than twenty minutes seems like a lot to you, concentrate on simply taking
it one step at time. The key word
is “gradually”. It is crucial to listen carefully to your body and steadily
build a healthy momentum that is right for you and in line with your goals and
physical condition. Remember, play it safe, stay active and, above all, have
fun!
[1]
Reference: “Exercise
Physiology (Energy, Nutrition, and Human Performance)” McArdle, Katch,
& Katch
[2]
Surgeon General’s Report on Physical Activity & Health
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