CREATINE: One of the hottest sports supplement
aim of this article is simply to inform the reader of the basic principles and
foundations behind creatine and its
supplementation. Its popularity is evident
and likely a result of the fact that, short of macronutrients, it is one of the
most researched exercise nutrition supplements to date; this compound actually
has been shown in well-controlled scientific studies to be quite effective in
producing desired results, unlike many, many available to the unwary athlete
A Brief Description:
Creatine is an
amino acid. It
is normally produced in the body from arginine, glycine and methionine. Creatine
plays a vital role in cellular energy production as creatine phosphate (phosphocreatine)
in regenerating adenosine triphosphate (ATP) in skeletal muscle. Without ATP,
muscle contraction is not possible.
administration of creatine increases muscle stores and may increase muscle
strength and improve exercise
performance. In the diet, creatine is found in meat and fish - although cooking
destroys most of it.
Creatine is a naturally occurring, key component of the energy compound creatine
phosphate, whose importance in muscle contraction has been apparent since the
early 1900's. Creatine synthesis occurs in kidney, where two amino acids,
arginine and glycine, react to form
This compound is transported to the liver, where a methyl group is irreversibly
transferred from -adenosylmethionine to guanidinoacetate to form methyl
guanidine-acetic acid, otherwise known as creatine.
Once synthesized, creatine is transported to the blood stream and enters the
muscle tissue by an action depending on extra-cellular sodium ions and
In the muscle, it is phosphorylated by adenosine triphosphate (ATP), forming
creatine phosphate, or phosphocreatine.
Function: The Creatine Phosphate Energy Pathway:
a muscle adenosine triphosphate (ATP) molecules are liberated, and the resultant
energy is used to fuel the movement (forming adenosine diphosphate, ADP);
however, the free ATP pool in muscle tissue can suffice only for a very short
period. Thus, during contractile activity, creatine phosphate transfers a
phosphate group (catalyzed by magnesium ions and creatine kinase) to ADP,
thereby reforming ATP, providing further energy for muscular activity.
Creatine phosphate is basically an essential storehouse for energy,
which provides for muscular contraction to continue past the handful of seconds
ATP allows; without it, we would be severely limited in our ability to sustain
extended periods of intense
has been hypothesized that supplementing the diet with additional creatine may
enhance muscular contraction (at least for short period and therefore
performance). Basis for this lies within the assumption that additional creatine
will be added to the existing pool in the
will allow for more creatine phosphate to be produced (re-synthesized) and
eventually be drawn upon for energy during intense muscular action. Due to the
nature of creatine's function, it can be assumed that enhancing its muscular
pool concentration will noticeably affect only those activities that rely
heavily upon this anaerobic energy pathway.
A number of studies on creatine and athletic performance have clearly
shown that its benefits are limited to anaerobic sports such as like
sprinting and jumping. No direct performance benefit of creatine has been shown
for endurance athletes.
In other words, endurance activity, which relies primarily on aerobic methods
of energy production, will not benefit from creatine supplementation. Studies
performed examining creatine's ergogenic effects on endurance activity have
shown this to be true. It can also be extrapolated in a limited fashion from
existing studies that creatine supplementation is most effective in improving
performance in activities with particular rest-to-work ratios.
For example, running has a rest-to-work ratio of approximately 1:1, meaning
the rest phase is roughly equal to that of the work phase. Exercises such as
football, basketball, rowing, or weightlifting have greater ratios phase. Thus,
it can be assumed that greater creatine resynthesis will occur, allowing more
room for benefit, according to this hypothesis.
While it is possible to obtain sufficient creatine in the diet, it would be
necessary to consume approximately 2.4 pounds of raw beef per day to receive an
average maintenance dose of creatine (5grams) (heating severely reduces
creatine's bioavailability). It is necessary to "load" your body
with exogenous creatine for a period of time in order to sufficiently saturate
you body's capacity.
relative recommendation for a typical loading phase would be to consume 285
mg/kg body weight/day (usually spaced into 5 equal servings) for 5 to 7 days. A
more general recommendation would be to consume 5 grams, 4 to 5 times per day
for 5 to 7 days. This has been shown to be sufficient in "maxing out" the
muscles' creatine phosphate storage ability, after which a maintenance dose
generally 2 to 5 grams/day, should be undertaken to sufficiently sustain these
elevated muscle creatine pools.
Intake of this compound at this rate has indeed been shown to increase
muscular strength during brief, intense exercise during numerous controlled
trials. It has also been noted that creatine supplementation increases muscular
water retention (dubbed "cell volumizing"), likely due to fluid being
transported into the cells (with creatine the
experienced with initial creatine supplementation is due to this water
retention). This is not standard water retention, as the fluid actually is
contained within the cells, and therefore is much less likely to fluctuate as
extracellular fluid does.
The most common regimen for creatine supplementation follows a two-phase
cycle with a 5-10 day loading phase (20-25 g/day) followed by a variable length
maintenance phase (2-5 g/day) to maintain muscle saturation.
water accumulation promotes a fuller look to the muscles, in contrast to the
puffy, bloated appearance associated with extra-cellular retention. It has been
noted that only 20% of subjects who ingest creatine alone have an increase in
muscle content approaching the maximal total concentration of 160 mmol of
creatine/kg dry muscle. In fact, around 20 to 30% of people do not respond to
creatine supplementation at all.
However, it has been shown that individuals who ingest creatine in solution
combined with simple
(370 g/day), such as with a juice or
can increase their muscle creatine accumulation by 60%, including those who do
not respond to solitary creatine consumption.
This may be attributed to the enhanced insulin flux associated with simple
carbohydrate ingestion. Insulin shuttles carbohydrates (and fatty acids) into
muscle cells, and it can be assumed creatine is taken up much more efficiently
with greater quantities of this hormone circulating.
effects reported anecdotally include gastrointestinal distress, nausea,
dehydration and muscle cramping - but none of these effects have been documented
in scientific studies. Besides, creatine is often confused with anabolic
steroids. Steroids, which mimic the effects of the male sex hormone
testosterone, can result in a wide variety of adverse side effects such as acne,
hair loss, testicular shrinkage and psychological problems.
Although no serious side effects have been scientifically verified in
subjects using relatively brief (less than 4 weeks) creatine regimens, there are
anecdotal reports of muscle cramping associated with the creatine supplements.
Some athletes have reported muscle cramps, muscle tears and
dehydration. A cautionary note is also advised, for people with
kidney disorders and for those at risk for dehydration (such as exercise in
extreme heat or during cutting weight for wrestling or lightweight crew).
clearly not everything is known about creatine or its supplementation, a
plethora of support suggests it to be a safe, relatively inexpensive, and
effective supplement when used appropriately. Creatine appears to be effective
in specific situations - those activities which are high-intensity and require
short bouts of repeated activity (e.g. weight lifting and football).
it can, at this point, be relatively safely predicted that this is one sport
nutrition supplement that indeed enhances intense muscular action with
negligible-to-non-existent side effects.