Took me one minute to look this up:
Next time look harder it is on this website, but I got this article from Absolute Creatine.com though.
Provide additional energy for your muscles
Time for a quick and simple biology lesson. In your body you have a compound called ATP (adenosine tri-phosphate). Think of ATP as an energy containing compound. What is important to know about ATP is that the body can very quickly get energy from a ATP reaction. You have other sources of energy such as carbohydrates and fat - but they take longer to convert into a useable energy source. When you are doing an intense quick burst activity - such as lifting a weight or sprinting, your muscles must contract and need a quick source of energy. This immediate energy comes from ATP.
Okay - still with us? Here is where it gets interesting. When your muscles use ATP for energy a chemical process happens where the ATP is broken down into two simpler chemicals ADP (adenosine di-phosphate) and inorganic phosphate. This process of ATP turning into ADP releases the energy which gives your muscles the ability to contract. Unfortunately, we do not have an endless supply of ATP. In fact, your muscles only contain enough ATP to last about 10-15 seconds at maximum exertion. In case you were wondering - no, the ADP can not be used to create more energy for your muscles.
Here is where the creatine comes in - or more specifically the creatine phosphate (CP). We don’t want to go into great detail on creatine vs. creatine phosphate now (that is in a later article) - all you need to know now is that the majority of creatine that is stored in the muscles bonds with abundant phosphorus stores in the muscles and is converted into Creatine Phosphate (CP). CP is able to react with the ADP in your body and turn “useless” ADP back into the “super useful” energy source - ATP. More ATP in your body means more fuel for your muscles.
- Volumization of your muscles
Looks like we just made up that word -Volumization - doesn’t it? Actually, it’s just a fancy name for the process of pulling fluid into the muscle cells and thus increasing the volume of the muscles. Creatine has been shown to pull water into your muscle cells, which increases the size of your muscles. Don’t get to excited - it is not clear how great an effect this has. Point #1 is a much clearer benefit of creatine.
- Buffer Lactic Acid build-up
New research has shown that creatine can help buffer lactic acid that builds-up in the muscles during exercise. This leads to that nasty burning feel you get in your muscles. Scientifically it is a complicated process - basically the creatine bonds with a Hydrogen ion and that helps delay the build up of lactic acid. More research needs to be done to see if this point is true.
- Enhances Protein Synthesis
There is some data to indicate that creatine helps put the body in a more anabolic state where protein synthesis can occur. The more protein synthesis - the greater the muscle gain.
Well - there you have what creatine does in a very simplified nutshell. Of all 4 points - point #1 is the most use of creatine in the body. The other points are more debated - but still look to be valid.