CREATINE

Creatine supplements are athletic aids used to increase high-intensity athletic performance. Though researchers have known of the use of creatine as an energy source by skeletal muscles since the beginning of the 20th century, they were popularized as a performance-enhancing supplement in 1992.

Creatine is often taken by athletes as a supplement for those wishing to gain muscle mass (bodybuilding). There are a number of forms but the most common are creatine monohydrate, creatine complexed with a molecule of water, and Creatine ethyl ester (CEE). A number of methods for ingestion exist - as a powder mixed into a drink, or as a capsule or caplet. Once ingested, creatine is highly bioavailable, whether it is ingested as the crystalline monohydrate form, the free form in solution, or even in meat. Creatine salts will become the free form when dissolved in aqueous solution. Conventional wisdom recommends the consumption of creatine with high glycemic index carbohydrates, though research indicates that the use of high GI carbs in combination with protein is also beneficial.

There is scientific evidence that taking creatine supplements can marginally increase athletic performance in high-intensity anaerobic repetitive cycling sprints, but studies in swimmers and runners have been less than promising, most likely because these activities are sustained at a given intensity and thus do not allow for significant intra-exercise synthesis of additional creatine phosphate molecules. Ingesting creatine can increase the level of phosphocreatine in the muscles up to 20%. It must be noted creatine has no significant effect on aerobic endurance, though it will increase power during short sessions of high-intensity aerobic exercise.

Since body mass gains of about 1 kg can occur in a week's time, many studies suggest that the gain is simply due to greater water retention inside the muscle cells. Other studies however, have shown that creatine increases the activity of satellite cells, which make muscle hypertrophy possible. Creatine supplementation appears to increase the number of myonuclei that satellite cells will 'donate' to damaged muscle fibers, which increases the potential for growth of those fibers. This increase in myonuclei probably stems from creatine's ability to increase levels of the myogenic transcription factor MRF4.

In another study, researchers concluded that changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training when they discovered that fat mass did not change significantly with creatine but decreased after the placebo trial in a 12-week study on ten active men. The study also showed that 1-RM bench press and total body mass increased after creatine, but not after placebo.[11] The underlying effect of Creatine on body composition if there is indeed one has yet to be determined, as another study with a similar timeframe suggests no effect on body composition, but had less overall emphasis on metabolic effects.

Creatine use is not considered doping and is not banned by the majority of sport-governing bodies. However, in the United States, the NCAA recently ruled that colleges could not provide creatine supplements to their players, though the players are still allowed to obtain and use creatine independently.


Some current studies indicate that short-term creatine supplementation in healthy individuals is safe, although those with renal disease should avoid it due to possible risks of renal dysfunction, and before using it healthy users should bear these possible risks in mind. Small-scale, longer-term studies have been done and seem to demonstrate its safety. There have been reports of muscle cramping with the use of creatine, though a study showed no reports of muscle cramping in subjects taking creatine-containing supplements during various exercise training conditions in trained and untrained endurance athletes. The cause of the reported cramping by some users may be due to dehydration, and extra water intake is vital when supplementing with creatine.

In addition, experiments have shown that creatine supplementation improved the health and lifespan of mice. Whether these beneficial effects would also apply to humans is still uncertain. It also led to a rise in allergic lung reactions in an animal test on mice with pre-existent allergic disease.

Creatine supplementation, in the dosages commonly used, results in urinary concentrations that are 90 times greater than normal. The long term effects of this have not been investigated, but there is possibility for a variety of nephrotoxic, i.e., kidney damaging, events. There is potential for direct toxicity on renal tubules where urine is formed, and for acceleration of kidney stone formation. Creatine has been shown to accelerate the growth of cysts in rats with Polycystic Kidney Disease (PKD). Studies have not yet determined if Creatine supplementation will accelerate the growth of cysts in humans with PKD. PKD is prevalant in approximately 1 in 1000 people and may not be detectable until affected individuals reach their thirties.