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GROWTH HORMONE
Growth Hormone is produced by the pituitary gland and is a very powerful anabolic
stimulus. In order to promote anabolism you have to increase the amount of Growth
Hormone released from the pituitary gland. The pituitary gland releases Growth
Hormone when it is stimulated by Somatocretin, another hormone. In order to
increase the levels of Somatocretin in the brain, and hence the levels of Growth
Hormone released by the pituitary gland, levels of brain neurotransmitters must
first be increased.
Neurotransmitter levels are influenced by amino acids which get into the brain
by crossing what is known as the blood-brain barrier, a mechanism designed to
protect the brain from external influences. In order to get across the blood-brain
barrier, amino acids have to be carried by specific transport molecules. There
are four types of transport molecule and each will only carry a specific class
of amino acid, each transport molecule has a limited transport capacity and
once full no more amino acids can be transported for some time. The following
table details which amino acids are carried by each type of transporter. In
order to optimise release of Growth Hormone you should use this chart to ensure
that you are not ingesting two amino acids from the same class at the same time,
as, due to the limited transport capacity of each transporter molecule, amino
acids from the same class will compete with each other and consequently fewer
of each will be able to cross the blood-brain barrier at any one time.
TRANSPORTER TYPE AMINO ACID CARRIED
Large Neutral
Tryptophan
Phenylalanine
Tyrosine
Methionine
Histidine
Leucine
Isoleucine
Valine
Small Neutral
Asparagine
Glutamine
Proline
Serine
Acidic Glutamic Acid
Aspartic Acid
Basic Arginine
Ornithine
Lysine
Once stimulated, the pituitary gland releases Growth Hormone into the bloodstream
in bursts. Only a small proportion of the Growth Hormone released in each burst
travels to the muscle tissue to promote growth, mostly it is carried to the
liver where it is destroyed. In order to promote muscle growth it is therefore
vital that the size and frequency of these bursts are optimised, a greater amount
of GH released regularly will stimulate greater muscle growth. This is not as
simple as it sounds. You cant increase the level and frequency of GH bursts
with amino acids alone as the bursts only occur under particular circumstances.
It is known that the human body produces the greatest amount of GH 30-60 minutes
after falling asleep and during intense exercise. Regular sleep and exercise
coupled with the appropriate use of amino acids is therefore the key to optimising
the release of GH and consequently muscle growth.
It has also been shown that the production of Somatocretin, the GH releasing
hormone, only occurs in the presence of the enzyme Alpha-Amidating Monooxygebase
which requires vitamin C to act as a co-factor. The amount of Somatocretin,
and hence the amount of GH, that can be produced, is therefore limited by the
availability of vitamin C in the body.
It should be noted that simply increasing levels of GH within the body is only
the first step towards achieving muscle growth. Most of the Growth Hormone produced
by the body travels to the liver where it is destroyed, however, before it is
destroyed it stimulates the production of Insulin-like Growth Factor I (IGF-I)
which mediates the effects of GH. For optimum muscle growth high levels of both
GH and IGF-I are required.
GH is also known for its ability to promote fat loss as it stimulates triglyceride
hydrolysis (the breakdown of fat cells) in adipose tissue. It is therefore a
vital component for the building of muscle tissue and the breakdown of fats.
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