It is not a controlled or banned substance by the NCAA or the International Olympic Committee. 

Both creatine and PCr play an important role in the production of ATP.  ATP is the primary energy source for muscle.  During high intensity, short- burst exercise, ATP can only be produced chemically in the muscle.  The presence of both forms of creatine aid the production of ATP within the muscle. 

Creatine supplementation increases the stores of PCr.  It can increase PCr concentration in the muscle by 6% to 16%.  The theoretical effects ...  

1)  The higher PCR concentrations allow for enhanced ATP production during maximal exercise.   
2)  The higher concentrations allow enhanced resynthesis of PCr during recovery periods between short bouts of maximal exercise. 

Finally, it should be noted that PCr is used only in short duration, high intensity exercise.  This means there is no potential ergogenic effect for endurance activities.  

It’s commonly believed that creatine supplementation will improve all sprinting type performance. This belief is extrapolated from the cycling sprinting data.  But there is a world of difference between sprinting on a stationary bike in the laboratory, and running on the track or the lacrosse field.  In reality, there are more studies showing creatine had no effect on running sprints or swimming sprints than showing it improved performance.  

Speculation is the weight gain from creatine supplementation hinders performance in runners and swimmers.  Weight gain occurs as quickly as 1-2 days after use.  During the 5-day “loading phase” there is weight gain of 1 to 3.5 pounds.  This will increase with prolonged use.  This weight gain is primarily due to water retention. 

And what does it do?  It improves repeated stationary cycling, apply that information at your own risk.  Creatine supplementation will improve your strength performance in the weight room.  The real benefit of creatine supplementation is it may allow higher levels of strength training in the weight room, which will increase your training benefit over time. 

Another method is to dose on the basis of body weight and avoid the “loading phase” all together.  An example is shown in the table below.  Another consideration is to cycle supplementation.  This avoids prolonged continuous use.  An example would be to supplement for 3-6 weeks, then cycle off supplementation for 1-3 weeks.  
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There is much “word of mouth” evidence that creatine may result in muscle cramps, and stomach disturbances.  Because creatine results in water-retention within the muscles, there is also concern that it may lead to dehydration when competing in hot weather.  We have had several athletes at Stockton experience severe cramps that resulted in muscle strains and significant loss of playing time.  Unortunately, there are no research studies dealing with these problems.  

In an informal survey of NFL players who used creatine, 55% reported muscle strains, muscle cramps, or dehydration.  34% of these players missed between 1-14 days of competition.  However, there is no way to determine if creatine actually was the cause of these injuries. 

There are also potential effects of creatine on the kidneys.  Particularly there is concern during the “loading phase” when urinary creatine excretion increases as much as 90x’s.  More research needs to be done here, though.  Presently athletes with preexisting kidney disease or diabetes should avoid creatine supplementation.  

Creatine is naturally found in many places in the body, including the heart, brain, and testicles. But it is presently unknown what effect oral supplementation has on creatine concentration in the heart, brain, and reproductive organs.  When creatine intake is increased with supplementation, natural synthesis is suppressed in the body.   The body’s synthesis increases when supplementation is decreased.  This appears to be a good reason to “cycle” if supplementing with creatine. 

• Do not use it during the pre-season or in-season, use it as an off-season training tool.
• Since it may be related to dehydration increase your intake of fluids appropriately.
• Creatine and hot, humid weather probably are not a good combination.
• Expect to gain weight due to water retention, which may slow you down.
• Take creatine at your own risk.

Other References used:: 
2) A Creatine a Day. Storlie, J. Training & Conditioning. 1997;7(6):21-28. 
3) Usage of Creatine Offers Food for Thought. Laquale, K. NATA News. 1999;March:19-21. 
4) A Suvey of Creatine Use and Related Trends in Injury Patterns in Professional Football. Trulock, S.  Pro Football Athletic Trainer. 1999;17(1):4-5.