What is
creatine?
Creatine (methylguanidine-acetic acid) is a naturally occurring
constituent found in food, and is involved in human metabolism. The body stores
creatine in both free and phosphorylated forms (PCr). The body's skeletal muscle
stores about 95% of total creatine, with higher concentrations in fast-twitch
muscle fibers.
Who uses creatine?
Sources cite that creatine supplementation may have been used by
athletes in Eastern European block countries as early as the 1960's. Many recent
newspaper articles report that creatine is a popular dietary supplement among
Olympic and professional athletes. Many of today's well known athletes
acknowledge their use of creatine, including Mark McGwire, who broke the single
season home run record by hitting 70. Creatine supplements are also used
frequently by groups involved in resistance training or bodybuilding. A 1998
report showed that the U.S. Navy Seals use several nutritional supplements to
increase muscle mass, strength and power, and that creatine is one of the five
most commonly used supplements.
How does creatine
work?
All cells use ATP (Adenosine Triphosphate) as an immediate energy
source. The energy needed to provide maximum effort exercise is primarily
derived from ATP stored in the muscle. Although ATP stores can support very high
exercise intensities, they last only 1 to 2 seconds. During high intensity
exercise, phosphorylated creatine (PCr) is broken down and the resulting energy
allows the ATP pool to be resynthesized several dozen times. PCr acts as a
temporary energy buffer during periods of intense muscle contraction, when ATP
consumption exceeds synthesis.
How can creatine
supplements help me?
Recent theories indicate that
creatine supplementation provides benefits such as increasing levels of PCr to
serve as an immediate buffer to ATP use during exercise, increasing levels of
free creatine (FCr) to increase PCr resynthesis during and after exercise,
promoting energy translocation to sites of ATP utilization, and reducing muscle
acidity. This simply means that creatine supplementation may benefit performance
in a variety of exercise or sports programs such as very high intensity sprint
performance; repetetive, high-intensity exercise tasks with frequent rest
intervals; longer anaerobic exercise tasks; and resistance-type sports tasks
dependent on increased muscle mass, and associated gains in strength and power.
How do I use
creatine?
The most common creatine usage programs involve a loading phase
and a maintenance phase. The loading phase usually consists of ingesting 20-30g
of creatine monohydrate daily in four equal doses of 5-7g dissolved in liquid
for a period of 5-7 days. Once the loading phase is complete, most research
studies suggest a maintenance dosage of 5-10g of creatine per day. Please note,
these dosages are for at least 99% pure creatine monohydrate. Some manufacturers
use fillers in their creatine supplements resulting in a lower intake of
creatine per dose. Dosage may vary according to the manufacturer so reading the
product labeling is strongly advised.
Is creatine safe?
Hundreds of newspaper, magazine and internet articles have been
written over the past few years about the safety of using creatine supplements.
Unfortunately, many of these reports were anecdotal in nature and presented
inaccurate information about the safety and effectiveness of creatine
supplementation. Numerous articles stated that creatine supplements cause muscle
cramping, muscle tears, dehydration, diarrhea or a combination of these
symptoms. The USA Today ran a front-page story in 1998 reporting that the
FDA (Federal Drug Administration) had issued a warning on the use of creatine.
However, the FDA issued a statement indicating that there was no such warning
specifically about creatine and that the FDA was not investigating creatine at
all. To date there has been no evidence from any well-controlled clinical study
which would suggest that creatine supplementation causes any of the side effects
that have been anecdotally reported. One must consider however, that few
long-term studies on creatine supplementation have been conducted. It is
possible that taking excessive amounts of creatine, poor quality of
manufacturing, and/or interactions with other factors such as ingesting multiple
dietary supplements may account for the adverse reactions that may have occured
in some people.
Sources:
Williams, Melvin H. PhD, Kreider, Richard B. PhD, Branch, J. David
PhD. 1999. Creatine, The Power Supplement. Human Kinetics. CH. 1-3,9
