What Is Creatine?
A French scientist discovered creatine
in 1835. Creatine is a natural constituent of meat, mainly found in red
meat. Creatine is manufactured naturally in the body from the amino
acids glycine, arginine, and methionine. This process takes place in the kidneys, liver, and pancreas.
Approximately 40% of the body's creatine
stores are free creatine (Cr), while the remaining 60% is stored in
form of creatine phosphate (CP). The typical male adult processes 2
grams of creatine per day, and replaces that amount through dietary
intake and fabrication within the body.
Creatine is used for the resynthesis of
ATP. ATP, or adenosine triphosphate, is the "power" that drives
muscular energetics. When a muscle is required to contract, the bonds
in the ATP molecule are split, yielding ADP (adenosine-diphosphate).
The energy released by breaking this bond powers the contraction of the
muscle.
When ATP is depleted within the cell,
the cell can no longer contract. There are several methods by which the
body rebuilds ATP. The fastest method, without oxygen, is through CP.
Creatine phosphate is "split" to yield the phosphate portion of the
molecule.
This phosphate portion bonds to the ADP,
turning it back to ATP. Once CP stores within the cell are depleted,
the body must use other methods to replenish ATP.
Supplementation with creatine
increases Cr and CP within the muscle, allowing further capacity to
regenerate ATP. In other words, the creatine enhances the ability of
the muscle to maintain power output during brief periods of
high-intensity exercise. The periods are brief because the ability of a
cell to store CP is limited, therefore the body will quickly move to
other methods of replenishing ATP.
The majority of studies regarding creatine supplementation have used creatine monohydrate, the form of creatine bound to a water
molecule. Some studies suggest that the combination of creatine and
carbohydrate will enhance absorption or "uptake" of creatine. Science
shows that creatine is unstable in liquid form, meaning that serum or
liquid delivery systems are currently not supported by scientific
literature.
The creatine rapidly degrades to
creatinine, which is not useable by the body. There is very little
support for the notion that creatine in any type of mixture, including
an effervescent mixture, is absorbed more efficiently by the body. A
company known as Albion Laboratories, Inc. claims to have found an
effective delivery mechanism by chelating creatine to magnesium (a chelate is an organic compound that is typically absorbed more readily by the body than individual elements).
What Does Creatine Supplementation Do?
The common mechanism for creatine
supplementation is known to be the increase of intramuscular creatine
stores. It is known that CP is used to replenish ATP, and that the
amount of CP naturally present is well below the maximum amount of CP
that the body can store. Increasing dietary creatine allows the maximum
amount of CP storage to be reached, which in turn provides more
capacity to regenerate ATP.
An interesting effect of creatine supplementation appears to be enhanced ability for the muscle to store glycogen.
Glycogen
is a form of carbohydrate stored inside the muscle that is used to fuel
anaerobic activity (i.e. activity that is too intense to allow the
cardiopulmonary system to deliver adequate oxygen).
The ATP-CP pathway is used during the
initial few seconds that work is performed. The next dominant system
uses glycolysis, which requires glycogen to fuel activity. After
several seconds to a few minutes, the dominant system becomes the
oxidative or cardiovascular system - in other words, aerobic exercise.
Many studies have shown that replenishing glycogen stores may aid recovery
and hypertrophy (muscle growth). Bodybuilders use a protocol known as
"carb-loading" to supersaturate their muscles with glycogen. Glycogen
requires water to enter the muscle cell, therefore having higher
glycogen levels means more fat-free mass and larger, fuller muscles.
If creatine does indeed increase the amount
of glycogen storage achievable through super compensation or "loading",
it stands to reason that a well-timed creatine cycle in conjunction
with carb-loading will not only create incredible muscle fullness, but
also potentially create an environment suited to optimal muscle growth.
It should be noted that the super compensation was most pronounced when
performed following a period of creatine supplementation, not during
the initial period of supplementation itself.
An interesting effect of creatine
supplementation is possible interaction with satellite cells. There are
several different fiber types used to classify muscle tissue. In
general, muscle tissue can be considered "endurance" fiber - able to
perform multiple repetitions and highly resistant to injury - or
"explosive" fiber - able to perform maximal workload for a short
duration of time and highly susceptible to injury. There is a special type of muscle fiber known as "transitional fiber".
This fiber can be considered the
"fight or flight" fiber - despite an individual's lack of overall
fitness, when faced with a potentially dangerous situation, these
fibers can "activate" to provide enormous bouts of strength.
These fibers are easily damaged, but it has been shown that if cortisol
levels are blocked subsequent to this damage occurring, instead of
being "swept" away by the body, these cells fuse with "satellite" cells.
Satellite cells are special
structures that are not true muscle cells until they fuse with
transitional cells. The resulting cell is much larger and stronger. If
these transitional fibers are appropriately activated and subsequent
cortisol levels appropriately managed, creatine supplementation may
help induce a significant hypertrophy effect.
By Jeremy Likness for bodybuilding.com