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Ask Dr. Sue
CREATINE IN SPORTS
Dear Dr. Sue,
I am considering using Creatine. I have heard from
many sources that it is entirely safe and effective,
including friends who have used it. My parents
said that they wouldn't let me use it unless I asked you
if it were safe and what you thought about its benefits.
High School Athlete
Dear Athlete,
Creatine is a substance that is naturally made in the
body, mainly in the kidney and liver, and then carried
in the bloodstream to be used by the muscles. It
is then broken down by the kidney to be cleared from the
body. Taking extra creatine raises the level of
muscle stores of this substance. Taking more than the
recommended dose raises the muscle stores to the same
level as taking the recommended amount; any excess is
just dumped through the kidneys as extra waste (in the
form of creatinine). The demand for creatine by
athletes at all levels has been driven by word of mouth,
exactly as in your case. It is readily available
at grocery stores, health food stores, and through the
Internet. However, its use has definitely outpaced
scientific knowledge about its benefits and its risks.
Studies have shown that anywhere from 1/3
to 1/2 of various groups of college-aged athletes were
using creatine supplements. In the only study I
found that looked at high school aged athletes, only 8%
had tried creatine in the past. Of those, some had
taken it rarely, some weekly, and some daily. More than
half either had no idea what dose they had taken or had
taken significantly more than the recommended dose.
There have been no studies at all that looked at
long-term effects of creatine in athletes younger than
18.
Why do people take creatine at all? You probably
know the answer to this, since you are wanting to take
it. I suspect that you are looking for increased
strength, increased performance in your sport, and maybe
a little more muscle bulk, as well.
Does it work? Studies have produced
conflicting results, partially because each study used
different amounts of supplement, for different lengths
of time. They also used products produced by
different companies. The intensity of exercise
varied too, as did exercise duration and the level of
fitness of the study participants. MOST of the
studies looked at single or repeated sprints on a
stationary bicycle in a lab; few involved actual field
sport performance. To summarize the various
findings: creatine supplementation probably does
increase performance by 4% to 18% when the exercise
duration is only 6 to 30 seconds long. There is no
change in peak power output or total work performed (in
other words, endurance). Many other studies have
supported this lack of improvement in overall
performance in tasks lasting longer than 30 seconds:
triathletes did not have improved endurance, elite
bicyclists had no improvement in cycling time to
exhaustion, female members of a university swim team had
no increased performance, and competitive rowers in a
1000-meter race were not helped, either.
Studies looking specifically at weight-lifting did show
an increase in lifting strength for a single repetition
and an increase in the total number of repetitions
possible at maximal weight.
In one study using a six kilometer run, creatine user's
times were slower. The weight gain that is usually
seen with creatine may be responsible for this.
The weight gain comes from greater muscle mass, but this
increased mass is actually just due to retention of
water within the muscle cells.
What about potential side effects? There have been
reports of muscle cramping, muscle strains, dehydration,
stomach upset and vomiting, diarrhea and seizures.
Creatine supplementation was initially blamed for the
deaths of three wrestlers who died after using severe
dehydration measures, but the Centers for Disease
Control and the FDA later concluded that it was not to
blame in those deaths.
Since creatine is cleared by the kidneys, there is a
possibility that high doses could have an adverse effect
on kidney function.
Any food supplement carries the potential for
contamination with herbs, heavy metals, or other drugs.
Allergic reactions can occur to any natural product in
certain sensitive persons.
In teens, there is a theoretical concern that rapidly
increasing strength in someone who is skeletally
immature may make tendon and growth plate injuries more
likely.
One pharmaceutical journal makes this statement: since
there have been no long-term studies evaluating any
negative effects of creatine supplementation, athletes
of all ages should be aware that they take this
substance at their own risk. If they decide to
take it, they should be advised that daily maintenance
doses in excess of 2 grams (or .03 grams per kilogram of
body weight) are not of additional benefit and may be
detrimental to kidney function.
Creatine should not be taken along with other
medications that can have negative effects on kidney
function, including regular doses of ibuprofen.
Persons taking cimetidine (Tagamet, often used for
excess acid production) should be aware that they may
increase their blood levels of creatine, which may raise
the risk of adverse events. Caffeine (as in Coke,
Pepsi, Mountain Dew, and coffee) antagonizes creatine's
effects, causing a complete loss of its already limited
benefits on exercise performance.
In my opinion, the very small benefit obtained by
creatine supplementation along with its many unknowns
make it fail the risk versus benefit test. I would not
advise any high school athlete to use it.
 
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