Creatine is a naturally occurring molecule which is produced in the kidneys and the liver at a rate of about two grams per day. Creatine is manufactured by a reaction of glycine with arginine (two non-essential amino acids), generating guanidinoacetate. Guanidinoacetate reacts with ornithine to form creatine. Creatine travels in the blood stream and is mainly transported to skeletal muscles, but also to the heart, and other types of cells. When it enters muscle cells, it gains a phosphate group to generate phosphocreatine. Phosphocreatine acts as a phosphate carrier: it can donate this phosphate to ADP to form ATP in the absence of oxygen. ATP is the energy currency of cells, required for essentially every biological process, including muscle contraction. During the first two to seven seconds following an intense muscular contraction, ATP is generated via this process. Due to this short time interval, there is often insufficient ATP in our muscle cells to complete a gym workout of more than four to five reps. This is when our bodies crave that extra creatine supplement to enable us to manufacture ATP for an additional ten seconds. The alternative option that skeletal muscle cells use to replenish ATP levels is the breakdown of glycogen into glucose; glucose can then generate ATP through respiration. Creatine builds muscle indirectly; it provides energy so that we can lift heavier weights, increasing muscle growth. It is important to mix creatine with carbohydrates to increase the amount of fuel in your system, important for the muscle recovery process. What are the side effects of creatine? In fact, research is yet to find negative side effects directly linked to creatine consumption. Experimental trials have disproved a correlation between recommended creatine intakes and damage to the kidneys or liver. Thus, do feel free to take creatine responsibly.