What does creatine do?
Creatine has a number of major functions as a sports supplement. All of these functions revolve around its function as an energy replenisher through it forming the creatine phosphate (CP or phosphocreatine) molecule.
* Creatine replenishes ATP
ATP is the molecule which when broken down releases energy for the muscle to contract. When used up, ATP needs to be replenished by re-acquiring phosphates. CP acts as a phosphate transporter. CP gives up its phosphate to ATP freeing creatine to form the bi-product creatinine for excretion.
Numerous studies have demonstrated that the more creatine that is present in muscle cells, up to a maximum storage level, the more efficiently ATP can be replenished, and, hence more ATP is available for energy. The richest food source of creatine is meat and fish, but it has been found that muscles can store far more CP than is possible to obtain from food (Hultman, et al 1996), so by supplementing with creatine monohydrate you can maximise stores. Thus creatine allows you to have more energy to help lift heavier weights, train harder and at higher intensity.
* Creatine stimulates protein synthesis
It has been demonstrated that creatine may also promote muscle growth by stimulating protein synthesis in two ways. Firstly, is from the increased work you are able to do as a result of its energy replenishing actions. Secondly is that the more CP that is stored in muscle, the more water is drawn into muscle making it fuller and stronger. With more CP and water in muscle, the volume increases, and the muscle cell is 'volumised' or 'super-hydrated'. A volumised muscle helps to trigger protein synthesis, minimise protein breakdown and increase glycogen synthesis (Haussinger 1996; 1996). If a muscle is then trained properly, this could lead to enhanced muscle growth. The muscle 'pump' experienced when using creatine is reported to be much more intense, and this is as a result of the cell volumising effect.
* Creatine may buffer lactic acid
Creatine may also act as a lactic acid buffer and improve exercise recovery time. Lactic acid is a bi-product from anaerobic (without oxygen) exercise, such as weight training. Lactic acid is responsible for the 'burning' sensation when the muscle becomes fatigued. When you cannot train anymore, it is due to you either having run out of energy or a build up of lactic acid. Creatine may act as a buffer for this lactic acid, which helps to delay the onset of fatigue.
* Creatine increases body weight
Most users experience notable weight increases when they commence a course of creatine, up to six or seven pounds (about three kilograms), especially the first time they use it. Most of this weight gain is from the cell volumising effect which is not permanent.
Some weight gain is from an increase in muscle tissue, and not just water, due to the positive effects of creatine. Studies have shown that creatine supplemented subjects significantly gained more lean body mass than non-creatine-supplemented individuals, but total body water was no different from before and after the study (Kreider; et al 1995; 1996). Most size and strength gains from creatine are during the first month of its use.