Found this intresting article by Philip Bray on The Effects of Aerobic Exercise on Lean Tissue and have republished it here.
Written by Philip Bray
There are many theories out there about aerobic or cardiovascular
exercise breaking down the lean tissue in the body. Aerobic exercise
(exercise w/oxygen) should be a vital part of your regular fitness
program. You are not only burning calories but you are using the most
important muscle in your body - the heart.
As your heart is
pumping blood throughout the body you are increasing the amount of
oxygen and the size of the blood vessels in your body. These blood
vessels supply oxygen to the tissues including your muscles. The oxygen
also carries out waste products to help with recovery and growth of
tissue.
What type of cardiovascular activity is best for you and
your goals? Running, jogging and jumping rope are all examples of high
impact aerobics and may tend to break down muscle tissue, burn more
calories and with the presence of an improper nutrition program may
lead to muscle loss. Walking, cycling and stair climbing are examples
of non-impact to low ior low impact cardiovascular activities that will
potentially minimize the breakdown of muscle tissue.
Determining
what your ultimate goals are, whether overall weight loss, body fat
loss or gaining lean body mass, will help you determine what type of
cardiovascular exercise is best for you to reach your goals. It is very
important to choose a type of exercise you will enjoy and will not
cause boredom. Cardiovascular exercise must be performed for no less
than 20 minutes. A slow, steady and long duration program will achieve
greater fat loss results when done on a consistent basis.
One
tip to achieving faster results is to complete your aerobic activity
first thing in the morning prior to breakfast with plenty of water.
Since your body has been burning calories during the nights sleep, body
fat will be utilized as energy in the absence of glycogen in the blood
stream.
In conclusion, the muscle tissue in your body is vitally
important for longevity and ultimate weight control. By incorporating a
regular weight training and cardiovascular exercise program in your
daily routine, you can add years to your life and life to your years.
Source: http://brayfitness.blogspot.com/2008/12/effects-of-aerobic-exercise-on-lean.html