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Creatine Supplementation
What is Creatine?
• Naturally occurring
constituent found in food
• Also synthesized in the
kidneys, liver, and
pancreas from amino
acids arginine, glycine,
and methionine.
Where is Creatine Found?
• Creatine is a naturally occurring amino acid found
in the body (primarily muscle tissue)
• The daily requirement of creatine is about 2-3
grams/day
• About half of the daily needs are obtained from
the diet (primarily meat and fish)
• The remaining daily need for creatine is
synthesized from the amino acids glycine,
arginine, and methionine primarily in the liver
Creatine Stores
• Normal creatine content in muscle tissue is
120-140 mmol/kg dm (60% as PCr, 40% as
Cr)
• Dietary availability of creatine may result in
higher or lower stores
• Creatine supplementation can increase
creatine stores to as much as 160 mmol/kg dm
Forms of Creatine Supplements
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Creatine Monohydrate – Most Common
Creatine Phosphate
Creatine Citrate
Creatine blended w/CHO, Proteins, AA, Caffeine
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Powders
Tablets
Gel
Liquid
Supplement Strategies
• Load 20 g/day (4 equal doses 5g) - 5-7 days
– Increase TCr stores approx. 20% (Grande)
• Maintain 3-5 g/day (0.03 g/kg)
• Others recommend 2-3g/day over longer
load period (1mo.)- just as effective
Factors Affecting Cr Loading Success
• Cr w/ CHO (glucose) = Insulin Effect
– Studies shown 60% greater increase in TCr stores over
Cr only
• Ingestion following exercise is best
• Greatest increase occur in those with lowest initial
levels
• There are responders and non-responders (2030%)
• Best response is in Type II muscle.
• No differences between genders
Documented Side Effects
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Potential side effects are minor
Gastrointestinal (GI) distress
No renal or liver dysfunction
No cramping in controlled studies
Increased Body Mass (water retention in
muscle cell due to osmotic changes)
• Urinary Volume decrease during loading
Creatine Enhancing Performance
Function of Creatine
• The body only has limited stores of ATP & ADP
• When a Cr supplement is ingested, & enters the
intestines, a majority of Cr is absorbed into the
bloodstream.
• Cr from bloodstream is taken up by skeletal and
cardiac muscle through insulin-mediated active
transport
Function of Creatine (cont.)
• After absorption, a portion of Cr combines
with phosphate to form PCr
• This storage of Cr and PCr allows rapid
resynthesis of ATP to meet energy demands
via the creatine kinase (CK) reaction
• Theoretically, Cr supplementation will
increase Cr and PCr stores, providing more
PCr to be utilized in CK reactions
History of Cr Supplementation
• Soviets and Eastern block countries began using Cr
as potential performance (1960’s & 70’s)
• First real studies of Cr supplementation for
performance enhancement began in 1990’s in US
and GB
• GB Olympic Champions Linford Christie (100m)
and Sally Gunnell (400 hurdles) - 1992 Barcelona
games
Mechanisms of Performance Enhancement
• Increased PCr concentrations in
muscle should aid in rapid resynthesis
of ATP via the Cr kinase reaction
• Increases PCr diffusion between
mitochondria and myosin heads.
• Reduce muscle acidity by consuming
H+ in process of ADP-ATP
– Muscle can accumulate more lactic acid
before reaching limiting muscle pH =
Increase duration of high intensity
exercise
Mechanisms of Performance Enhancement
• Causes osmotic changes in muscle cell
which increases water content of cell
– Stimulus for protein synthesis
– Decreases rate of protein degradation
• Facilitates calcium uptake by the
sarcoplasmic reticulum which shortens
relaxation time.
Does IT Work?
• High intensity, short
duration activities
lasting < 2 min
especially repeated
with short rest periods
• Sprints, jumps, weight
lifting, sprinting, etc.
Does It Work? (cont.)
• No effect in continuous aerobic
activities
• Effective in both genders
• Effective in young and old.
• Effectiveness is greatest in
novice athletes.