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The Role of Protein in Training
Written by NFPT Staff Writer
Proteins are indeed the building blocks of the body. They also play a vital role in resistance and
The role of protein and amino acids in building body tissue is well known. Amino acids are the
end product of ingesting protein. Amino acids are used for three basic functions in the body:
- They provide material for body tissue repair and synthesis.
- They are the synthesis of hormones, enzymes, and blood proteins.
- They provide for energy through deamination.
Specific amino acid combinations are predetermined through genetic nitrogenous base coding
to be synthesized into living body tissues, muscle tissues, hormones, and blood proteins.
While other specific amino acid combinations are synthesized by the liver into the very enzymes
and hormones that convert free amino acids, body protein and fatty tissue, into energy through
deamination and catabolism.
Deamination is the removal of an amino group, NH2, from an organic compound. It is the
process by which amino acids are broken down if there is an excess of protein intake. This
process takes place primarily in the liver. It is important to note that whenever energy is
produced, some amount of amino acid deamination is unavoidable. It is equally important to
realize that free amino acids are available in the bloodstream for 3-4 hours for combining with
other amino acids for the uptake and synthesis of body tissues.
If after this approximate length of time, amino acids are still free in the bloodstream, they will be
degraded and/or deaminated by liver enzymes into energy. This amino acid deamination results
in the toxic bi-product ammonia, which the liver then converts into urea nitrogen for excretion.
The amino group is removed from the amino acid and converted to ammonia. The rest of the
amino acid is made up of mostly carbon and hydrogen, and is recycled or oxidized for energy.
Enzymes convert ammonia to urea or uric acid through the addition of carbon dioxide molecules in the urea cycle, which also takes place in the liver -- and is not a deamination process. Urea
and uric acid can safely diffuse into the blood and then be excreted in urine.
How much protein is too much?
The most accurate way of determining sufficient protein intake is to closely monitor the nitrogen
intake (16% of all protein is nitrogen), and then compare this amount to the excreted nitrogen
through Urinary Urea Nitrogen (UUC) testing.
There are two primary metabolic conditions during which a high protein level exists:
- In the presence of sufficient total calories, a level of protein intake that is greater than the
body's need will likely result in a positive nitrogen balance, but at the expense of over stressing
the liver, which is already lcharged with breaking down the toxin ammonia into urea for
excretion. The greater the excess amino acids the harder the liver has to work. Overabundant
amino acid presence in the blood accelerates metabolism and more water is lost during these
increased chemical reactions, possibly causing dehydration in varying degrees. An alternative
to decreasing the protein intake under these conditions is the consideration of increasing the
intensity of exercise. This will minimize the excess circulating amino acids. The best way to
optimize protein intake is through UUN testing and then altering resistance training intensity.
- In the absence off sufficient calories, whether protein ingestion is high or not, a high level
of circulating "broken-down" body proteins and resulting amino acids will result in a negative
nitrogen balance, as well as the liver's production of keto acids, which are toxic to brain
function. This, low-calorie, overabundant amino acid presence is clearly a more critical
metabolic situation than when total calories are sufficient, as mentioned earlier, and it is
undesirable regardless of health and fitness goals. This situation occurs during prolonged and
Of course, any fat loss goal and takes a back seat whenever health is threatened. Maximizing
fat loss results does sometimes call for a substantial restriction of total calories, however, using
acetate testing (similar to UUN testing), adjustments to total calories can be made that result in
a less threatening trace measurement of acetate.
It is important to keep in mind that increasing protein intake while also reducing carbohydrate
intake with fat loss in mind will have positive fat loss effects, since amino acid deamination
constitutes more work and accelerates metabolism. However, it is not suggested to maintain an
extremely low calorie, high protein intake for periods longer than a few weeks. Increased water
intake must be an integral part of this short-term dietary fat loss measure.
How low is too low?
In the presence of sufficient total calories, low protein ingestion will not easily accommodate the
building of new tissue. It becomes extremely important, if one is ingesting little or no protein,
that energy needs are being completely provided by ingested carbohydrates and fats, thus
allowing what few amino acids are present in the blood to be synthesized from body proteins to
include muscle tissues.
When too little protein is being ingested and intense resistance training is performed, catabolism
is prolonged and a long-term negative nitrogen balance can be expected.
While there is known that several natural complex carbohydrates contain protein, it is
acknowledged that several essential amino acids are missing from these carbohydrates.
In most cases, when ingested proteins are insufficient even for the required synthesis and repair
of vital blood proteins and organ tissues, the body uses catabolic enzymes to degrade existing
'low priority' body tissues using their bi-products as building blocks instead. Since antibodies, for
example, are among these 'unneeded' body tissues that are cannibalized, the body's immune
system can suffer as a result.
In the absence of sufficient total calories, while performing little or no strenuous activity, it is
likely that few amino acids will escape the deamination process. In addition, the synthesis of
protein based hormones, enzymes, blood proteins and various body tissues will be
compromised. The performance of strenuous resistance exercise under these low-calorie, lowprotein
dietary conditions will likely result in the continued cannibalism of various structural body
tissues to include muscle and organ tissues.
Optimizing Protein Intake
In an effort to maintain a "positive nitrogen balance" (ingesting more nitrogen than excreting),
the intention should be to provide a steady flow of ingested protein (every 3-4 hours), consisting
of a wide variety of amino acids allowing for all possible combinations. Thus, insuring the
continued synthesis of body tissues, proteins and enzymes (positive nitrogen balance). It is
important to realize that amino acids are most effectively spared from the process of
deamination in the presence of sufficient bloodglucose energy that results primarily from
carbohydrate ingestion. So long as protein intake is sufficient, the ingestion of more total
carbohydrate calories will contribute to a positive nitrogen balance.
In addition, similarly to glucose, insulin must carry amino acids into muscle tissues, and
carbohydrate ingestion causes insulin release, so it would make good sense to ingest proteins
with carbohydrates to optimize insulin-carried amino acid uptake and utilization in body tissues.
All protein foods have varying Protein Efficiency Ratios (PERs), with milk and egg proteins
rating highest on the list of "complete" proteins. The steady provision of protein throughout the
day will generally result in a positive nitrogen balance. Where activity is concerned, the greater
the intensity and duration of resistance exercise, the greater the required protein ingestion.
For those who are not currently training for size and strength, consider letting the level of activity
dictate protein intake. For example, if someone trained today with at a greater intensity than
usual, then consider ingesting additional proteins every 3-4 hours. If exercise intensity lwas
somewhat low today, then concentrating protein intake will not be as important. For an
endurance athlete performing aerobic activity for 60 + minutes, consider the ingestion of
proteins rather than carbohydrates during the activity. Protein ingestion may act to maintain
blood sugar levels longer.