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BCAA
L-Glutamine
Citrulline Malate
What Are Branched-Chain Amino Acids?
The BCAA Are A Group Of Three Essential Amino Acids:
1. Leucine
2. Isoleucine
3. Valine
The BCAA are different from the other 17
amino acids in that they are primarily metabolized in skeletal muscle (Layman, 2003) and
metabolized at a much lower rate in the liver (Norton,
2005). The rate limiting enzyme in BCAA catabolism is Branched Chain Keto Acid Dehydrogenase,
which is much more active in skeletal muscle than in the liver (Norton, 2005).
Point blank,
exercise promotes increased BCAA oxidation (Shirmomura et al., 2004). This increased degradation
of BCAA helps maintain energy homeostasis by providing carbon as
a direct energy
source and glucose homeostasis by providing substrates for the citric-acid cycle and
gluconeogenesis.
Amino acids are categorized as glucogenic,
ketogenic, or a combination of glucogenic and ketogenic. A glucogenic amino acid when metabolized
gives rise to pyruvate
or other
TCA
cycle intermediates
that can be used for the production of glucose through gluconeogenesis.
A ketogenic
amino acid is metabolized via the fatty acid pathway and gives rise to actyl-CoA, a fatty
acid precursor. Leucine is completely ketogenic, valine is completely
glucogenic,
and isoleucine is both glucogenic and ketogenic. Valine and isoleucine can both be
used to produce
intermediates for glucose production via gluconeogenesis.
Due to leucine's metabolic
properties (discussed below), increasing attention is being given to it and its metabolism.
Research has shown plasma leucine levels to
decrease
during both
aerobic and anaerobic exercise (Mero, 1999).
According to Freund and Hanani (2002), "Complete
oxidation of leucine in the muscle yields more adenosine triphosphate molecules
on a molar basis than complete oxidation of glucose." So
leucine can provide skeletal muscle with more ATP than an equal amount of glucose,
which is due to leucine being completely ketogenic and metabolized via the fatty
acid pathway.
In order to meet the increased demand for
BCAA during exercise the body breaks down muscle tissue to supply additional BCAA. By supplying
the body
exogenous
BCAA during
exercise,
one can meet the increased demand for BCAA oxidation without breaking down
muscle tissue to supply
the needed BCAA.
Because BCAA serve as a "fuel" for
skeletal muscle, supplementing with additional BCAA during your workout improves your performance
without the added calories or insulin spike
(which can lead to fat storage) caused by carbohydrates.
Leucine Stimulates
Leptin Expression through mTOR activation in Adipocytes
Intake of leucine stimulates expression
of the hormone leptin in adipocytes (the primary site of leptin secretion) through activation
of the mTOR pathway
(Meijer
and Dubbelhuis,
2003).
Leptin is a very complicated hormone; the gist of it is involved in the
regulation of metabolism, body weight, and appetite.
Leptin secretion is linked with body
fat levels; higher body fat is associated with higher leptin secretion and lower body fat
is associated with lower
leptin levels.
When you
diet and lose fat, the amount of leptin you secrete decreases, which
makes your body "crave" food
in an attempt to bring your body fat level back up to where the body
is comfortable (known as the body fat "set point").
Leucine has the ability
to activate leptin expression and will cause the body to think it is "fed" or
receiving "adequate" calories, which will keep things running
(specifically your metabolism) smoothly. BCAA and the Glucose-Alanine Cycle
The BCAA's are involved in maintaining
glucose homeostasis through the glucose-alanine cycle (see figure 1). The glucose-alanine
cycle involves pyruvate (derived from glucose/glycogen)
being transaminated in muscle to form alanine, with the BCAA serving as the main nitrogen source
(donors) for the synthesis of alanine (Holecek, 2002).
The newly synthesized alanine is released
in the blood stream and sent to the liver where it is converted into glucose through gluconeogenesis.
This glucose can then be sent from the liver
back to the working muscle to be used as fuel. Supplementing with BCAA allowing your body
to create glucose to use for fuel without the added calories or insulin spike (which can
lead
to fat storage) caused by carbohydrates. L-Glutamine
Glutamine is a glucogenic (glucose creating),
nonessential amino acid that has multiple roles in the body. Glutamine is synthesized mainly
in skeletal
muscle and the liver and acts as a "nitrogen
shuttle" between organs, a fuel for cells of the immune system and intestines, and a precursor
for nucleotide synthesis (Holecek, 2002).
Glutamine is also a powerful cell volumizer
(Haussinger et al. 1993). An increase in cell volume, also called cell swelling, stimulates
anabolic pathways
(synthesis of proteins and glycogen)
and inhibits catabolic pathways (protein degradation) (Haussinger, 1993).
According to Houston
(2001), "Glutamine content in skeletal muscle and other tissues appears
to have a regulatory role in whole body protein synthesis." Glutamine levels inside
muscle govern protein synthesis and nitrogen balance and therefore muscle growth (VanAcker
et al.
1999). Adequate glutamine concentrations are needed for optimal health and skeletal muscle hypertrophy.
Therefore one would want to keep glutamine levels elevated, especially during/post exercise.
Glutamine Metabolism and Exercise
During times of stress, such as exercise, skeletal muscle glutamine levels are depleted. This
glutamine released from skeletal muscle is derived from muscle proteins, the intramuscular
free amino acid pool, and newly synthesized glutamine (VanAcker, 1999). The newly synthesized
glutamine is created by using BCAAs obtained from muscle protein breakdown (Holecek, 2002).
Plasma and muscle glutamine levels are decreased post workout and it can take hours before
they are restored (Rowbottom, 1996). A study examining the effect of free-form glutamine and
glutamine peptide ingestion on muscle glycogen resynthesis found that plasma glutamine was
decreased by 20% post workout with the ingestion of glucose only (control), showed no change
with ingestion of whey protein or wheat protein hydrolysate plus glucose drinks, and a 200%
increase with ingestion of free-form glutamine plus glucose drink (VanHall, 2000). Free-form
glutamine supplementation was needed to elevate plasma glutamine levels post workout.
In addition to restoring and elevating plasma glutamine levels, oral glutamine supplementation
increases muscle glycogen storage to the same capacity as glucose (Bowtell, 1999). Glutamine
can replenish glycogen levels without the added calories or insulin spike (which can lead to
fat storage) caused by carbohydrates.
Mammalian Target of Rapamycin (mTOR)
The Mammalian Target of Rapamycin (mTOR) is one of the body's protein synthesis regulators.
mTOR functions as an energy sensor; it is activated when ATP levels are high and blocked when
ATP levels are decreased (AMPK is activated when ATP decreases, which works antagonistically
to mTOR).
The main energy-consuming process in the cell is protein synthesis. When mTOR is activated
(high ATP levels sensed) protein synthesis is increased and when mTOR is suppressed (low ATP
levels are sensed) protein synthesis is blunted.
MTOR activation is vital for skeletal muscle hypertrophy. Interestingly, mTOR is also a nutrient
sensor of amino acid availability, specifically of leucine availability. Research has shown
that regulation of mTOR by ATP and amino acids act independently through separate mechanisms
(Dennis et al., 2001).
It is my belief that combining supplements that increase/elevate ATP levels with BCAA will
lead to an increased activation of mTOR, and therefore protein synthesis. Our goal is to keep
ATP levels elevated while working out. To do so, we must supply the needed nutrients and substrates
before and after the workout to keep ATP levels elevated and our bodies primed for growth.
This can be accomplished by supplementing with Citrulline Malate.
Citrulline-Malate
Citrulline-Malate has been shown to increase the rate of oxidative ATP production during
exercise and the rate of phosphocreatine replenishment post exercise (Bendahan, 2002). Increasing
the rate of ATP production during exercise would assist in allowing mTOR to be activated by
the BCAA.
Citrulline-Malate also has anti-fatigue properties due to its ability to decrease ammonia
levels and prevent against metabolic acidosis (Callis, 1991). Decreasing the sensation of fatigue
would allow one to workout harder and longer, and thereby burn more calories and lose more
fat.
Supplement Facts
Serving Size: 2 Scoops (11.5 grams)
Servings Per Container: 30
Amount Per Serving % Daily Value*
Vitamin B6 (as Pyroxidine HCl) 10 mg 167%
L-Leucine 3.5 g
L-Glutamine 2.5 g
L-Isoleucine 1.75 g
L-Valine 1.75 g
Citrulline Malate 1 g
* Percent Daily Values are based on 2,000 calorie diet.
Daily Value Not Established.
Ingredients:
L-Leucine, L-Glutamine, L-Valine, L-Isoleucine, Citrulline Malate, Natural and Artificial Flavors,
Potassium Citrate, Citric Acid, Acesulfame Potassium, Sucralose, Pyridoxine HCl, Red #40,
Blue #1
Xtend 390G
Refreshing Lemonade
Flavour
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