Creatine is an
essential, natural substance required for energy metabolism,
muscular movement and human existence. Creatine is as essential
to life as protein, carbohydrates, fats, vitamins and minerals.
Creatine deficiencies have been associated with certain physical
muscular disorders that can be fatal in humans and animals.
It can be synthesized glycine, arginine, and
methionine. In humans, the enzymes involved in the synthesis
of creatine are located in the liver, pancreas and kidneys.
Creatine can be produced in any of these organs and then transported
into the muscle via the bloodstream.
Approximately 95% of the total creatine pool
is stored in skeletal muscle tissue. The remaining 5% can be
found in the heart, brain and testes. It is estimated that a
70 kg (154 lbs.) male will have a total creatine pool of approximately
140 grams in his body. The total creatine pool in humans refers
to the combined amount of creatine in its free form and phosphocreatine
In skeletal muscle tissue, phosphocreatine
accounts for two-thirds of the total creatine pool, with free
form creatine making up the balance. In the absence of exogenous
(from the diet) creatine, the rate of creatine excreted in the
form of creatinine has been estimated to be around 1.6% per
day in humans.
Thus, with a bodyweight of 70kg (154 lbs.)
and a total creatine pool of 140 grams, a human will lose approximately
2 grams of creatine per day from normal everyday activity. This
turnover of creatine will increase with greater physical activity
and must be replaced by the diet or the bodies own natural production.
Dietary creatine is found mostly in meat,
fish and other animal products. Plants contain only trace amounts.
The average daily diet of meats and vegetables contains an estimated
creatine level of 1 gram. As only some of the daily requirement
of creatine can be attained from diet, the body must synthesize
Food Type Creatine Content (g/kg)
Role of Creatine
Creatine plays a very powerful role in energy
metabolism as a muscle fuel. The immediate energy source for
a skeletal muscle contraction is from a molecule called ATP
(Adenosine Triphosphate).All fuel sources, carbohydrates, fats
and protein are first converted through various chemical reactions
to ATP which is then available as the only molecule the body
uses for energy.
Everything must be first converted to ATP
before it can be used as fuel.ATP is a simple chemical consisting
of one molecule of adenosine and three molecules of phosphate.
When ATP releases its energy to fuel muscle contractions, a
phosphate group is split off and a new molecule are formed called
ADP (Adenosine diphosphate). This reaction is reversible by
the energy-rich compound phosphocreatine.
Phosphocreatine delivers a phosphate group
to ADP resynthesizing it back into an ATP molecule, thus making
it ready again to release energy to fuel continued muscle contractions.
The remaining free form creatine is accumulated in the active
muscles and then rephosphorylated back into phosphocreatine.
During a brief period of high intensity exercise,
the ATP demand in the working muscles increases significantly
to several hundred times higher versus when at rest. High intensity
exercise can totally deplete phosphocreatine stores within 10
seconds. The depleted stores of ATP and phosphocreatine must
be steadily replenished in order for muscular contractions to
continue at peak levels of frequency and intensity.
Oral supplementation of creatine monohydrate
has been shown in several studies to increase the total creatine
pool. Optimum daily dosages varied widely from individual to
individual, but not significantly from trained to untrained
subjects. One study using a single dosage of 5 grams showed
a rise in plasma creatine levels from 50 to 100 mol/L to over
500 mol/L within 1 hour after ingestion.
And recent studies have examined the administration
of creatine monohydrate in varying dosages over different periods
of time. An initial loading phase of 4 to 6 dosages of 5 grams
each for 3 days showed a significant increase in the total creatine
pool. But it also showed that there exists an upper limit of
creatine which can be stored in muscle.
For most subjects, this upper limit seems to
be around 160 mmol/kg (kg dm).One recent study concluded that
after 6 days of creatine administration of 0.3 grams per day
per kilogram of bodyweight maintained maximum total creatine
levels for a subsequent 4-week period, during which time the
dosage was reduced to 0.03 grams per day per kilogram of bodyweight.
It is currently unclear the mechanisms influencing
creatine uptake by the cells from the bloodstream but several
factors have been noted that effect creatine uptake. Creatine
uptake in exercised muscle has been found to be higher than
in non-exercised muscle. So, it may be concluded that a trained
muscle will have a greater potential for creatine uptake than
a non-trained muscle.
Creatine uptake may also be enhanced when
administered with a carbohydrate solution. The rise in blood
sugar levels causes an insulin reaction, which increases the
uptake of glucose into the muscle tissue. The increased release
of insulin may also increase the uptake of creatine into the
muscle tissue along with glucose.
Creatine supplementation can help the athlete
train harder for a longer period of time. Therefore, increased
intensity of muscle training will generate faster muscle growth
and strength. An example of increased intensity of muscle training
can be found in a study done by Conrad Earnest and co-workers.
The study was conducted on weight trainers
at Texas Southwestern Medical Center and The Cooper Clinic in
Dallas, Texas. Creatine supplementation and maximum strength
was measured in experienced athletes who consumed 20 grams of
creatine per day for 28 days. The average increase in bench
press strength was 18 lbs.
The average bench press repetitions each athlete
could perform at a weight equaling 70% of their 1-rep. maximum
increased from 11 reps to 15 reps the subjects in this study
also increased lean mass an average of 3.5 lbs over the 28 day
period. Increases in lean muscle tissue verses water retention
was observed and attributed to increased muscle overload and
greater muscle tissue growth stimulation.
Age Limitation for Creatine
Generally, there is no age limitation for
safe creatine supplementation. In fact, there are some children
who suffer from an inborn gene defect called GAMT deficiency.These
children are treated with dietary creatine supplementation.
Considering the physical development of young
individual. It is our recommendation that unless prescribed
by a medical doctor, creatine supplementation should only be
used by adults.Athletes should understand that creatine supplementation
is only a part of training and diet routine, and not a substitute
for proper training and dietary habits.
Generally the dosage of creatine monohydrate
should be as high as necessary, but as low as possible to be
effective. The scientific studies with dosages of 5 to 10 grams
per day are effective, but many athletes have taken greater
than 10 grams per day with no adverse side effects.The body
has an upper limit as to how much creatine can be stored in
the muscle tissue.
Therefore, an initial loading phase is used
to fill the creatine pool, followed by a maintenance phase to
replenish the lost creatine. A period of no supplementation
would allow the body to readjust to synthesizing creatine again
As for general guidelines we recommend for
strength athletes the following:
20 grams per day for 3 days
5 grams per day for the next 8 weeks
followed by 4 weeks off with no supplementation
then repeat the cycle again
The above dosage amounts are offered as a
guideline to loading and maintenance procedures.Athletes may
start a creatine supplementation program with lower dosages
and monitor improvements in performance. Remember, more is not
necessarily better. Too much creatine will only be excreted
in the urine.
There have been no indications of adverse
side effects from long term creatine usage in existing creatine
literature. Currently, long term studies are under way to try
and measure the effects of long term chronic use. Until these
studies are completed, excessive creatine supplementation should
Creatine that is not stored in the total creatine
pool, as either creatine or phosphocreatine,is processed out
of the body by the kidneys as creatinine. Creatinine is a natural
by-product of creatine production and considered a waste product
by the body.Creatine supplementation in excess of the required
amount needed to saturate the creatine pool is processed out
of the body through the kidneys in the same manner.
There has been a great deal of attention to
the issue of muscle cramps and creatine usage. It has been proposed
by some athletes and sports professionals that there may exist
a possible association of creatine supplementation and the increased
incidence of muscle cramps. To date, research has not shown
association between pure creatine monohydrate supplementation
and muscle cramps.
The main cause of muscle cramps is an imbalance
of the electrolytes, calcium and magnesium in the blood or the
muscle tissue stemming from insufficient fluid intake. Thus,
creatine monohydrate users should use only creatine monohydrate
free of impurities while also consuming a minimum of 2 liters
of water per day up to as much as 5 liters per day depending
on the duration and intensity of the exercise.
It is possible to prevent muscle cramping
by consuming sufficient amounts of fluids and isotonic electrolyte
drinks prior to, during, and after exercise. A balanced diet
will also contribute trace elements, vitamins and minerals which
are key to efficient metabolism and electrolyte balance. The
bottom line is that lack of sufficient fluid intake or nutritional
deficiencies cause cramping, and not creatine at reasonable
Other Medical Uses for
Creatine is a critical energy intermediary
to the production of ATP and muscular energy. It is essential
to life because abnormalities or deficiencies may lead to related
health problems. Creatine has been researched in several ways
that are not sports orientated.
Under medical supervision, creatine monohydrate
supplementation has been utilized to treat certain physiological
and physical disorders as well as being used to help special
populations with special needs. For example: Creatine supplementation
has shown a positive effect on the reduction of plasma total
cholesterol, triacylglycerois and VLDL.
Creatine has been found to possess anti-inflammatory
activity on acute inflammation, local irritancy and chronic
inflammation conditions (i.e. arthritic conditions).The creatine/phosphocreatine
system seems to have a protective effect on the nervous system
and central nervous system under ischemic and hypoxic conditions.
An inborn birth defect call guanidinoacetate-methyltranferase
(GAMT) which leads to a creatine deficiency in the brain and
correlated to mental and muscular retardation is treated through
oral creatine supplementation.Creatine supplementation is used
to treat diseases that involve muscle atrophy, creatine depletion
and neuro-muscular disorders.
Creatine has been used to improve the symptoms
of gyrate atrophy; a hereditary and very complex dystrophic
eye disease that causes an enzyme inhibition of the creatine
bio-synthesis.Creatine is being researched for its possible
benefits in inhibiting the growth of certain types of tumors
Creatine supplementation has been shown to
positively effect athletic performance of vegetarians. During
chronic heart failure cardiac creatine levels are depressed.
Creatine supplementation to patients with chronic heart failure
increases skeletal muscle energy-rich phosphocreatine and performance
in regards to strength and endurance.
Essential to life, health, and well-being,
creatine is a unique and somewhat miraculous substance. Scientific
studies support the anecdotal testimonials to the improvements
in sports performance and overall energy levels. Proper usage
can lead to positive effects.
The important considerations for all consumers
are the safe and proper dosage of a high quality source of creatine.
Creatine is a great addition to an athletes training regime
and, as researchers may soon show, beneficial for the non-athletes
health as well.