By Rickey Dale Crain
In the body, creatine is changed into a molecule called "phosphocreatine" which serves as a storage reservoir for quick energy. Phosphocreatine is especially important in tissues such as the voluntary muscles and the nervous system which periodically require large amounts of energy.
Studies have shown that creatine can increase the performance of athletes in activities that require quick bursts of energy, such as sprinting, weightlifting, powerlifting, etc and can help athletes to recover faster after expending bursts of energy.
Now so far everyone agrees to this point I believe.
Creatine is an essential player in the primary energy source used for muscle contraction. It exists in two different forms within the muscle fiber: as free (chemically-unbound) creatine and as creatine phosphate. This later form of creatine makes up two-thirds of the total creatine supply. When your muscles contract, the initial fuel for this movement is a compound called ATP. ATP provides its energy by releasing one of its phosphate molecules. It then becomes a different compound called ADP. Unfortunately, there is only enough ATP to provide energy for about 10 seconds, so for muscle contraction to continue, more ATP must be produced. Creatine phosphate comes to the rescue by giving up its phosphate molecule to ADP, recreating ATP. This ATP can then be burned again as fuel for more muscle contraction.
The bottom line is that your ability to regenerate ATP depends on your supply of creatine. More creatine, more ATP remade, and more ability to train your muscles to their maximum potential. It's that simple. This greater ATP synthesis also keeps your body from relying on another energy system called glycolysis, which has lactic acid as a byproduct. This lactic acid creates the burning sensation you feel during intense exercise. If the amount of acid becomes too great, muscle movement stops. But if you keep on using ATP because of all the creatine you have, you can minimize the amount of lactic acid produced and actually exercise longer and harder. This helps you gain strength, power and muscle size; and you won't get fatigued as easily. (i.e. you can work out a little longer and a little harder and recover a little faster)
Later (newer) studies show that a "loading" dose is unnecessary and may cause some side effects.
Most of the studies involved giving volunteers powder creatine monohydrate before a workout.
When you take creatine in powder form - it is in your blood stream for about 1.5 2.5 hours. For muscle growth the creatine must be absorbed into the muscles. So, if you are working out and deplete your creatine supply in your muscles AND you have creatine available in the blood stream, your muscles can replenish their creatine supply from the creatine in your blood.
Here is the important point - if your muscles are fully saturated with creatine and you are not working out (so you are not depleting your creatine stores) then after 1.5-2.5 hours the creatine in your blood will be converted into creatinine and excreted. (so your body can only hold so much creatine at a time).
Use creatine, but be smart about it.