The amino acid creatine was first isolated as a component that contributed to the proper function of human muscles in 1825. Amino acids are the organic building blocks of the proteins that form muscle cells in the human body. In its form as creatine monohydrate, creatine is important to the metabolism of skeletal muscle. It is used in muscle cells to assist in the storage of energy, particularly in those sports that require explosive movement.
Creatine is most applicable to the generation of muscular energy in the anaerobic alactic mode, in short-duration athletic activities of less than 10 seconds per interval, when the energy compound adenosine triphosphate (ATP) is available directly in the muscle, as opposed to being created through the other physical systems, which involve the metabolism of glucose and glycogen.
The value of creatine as a possible supplement to enhance sport performance was first recognized by Russian sport scientists in the early 1970s, a research initiative that paralleled their work with respect to the potential applications of anabolic steroids. Creatine acquired an underground cult following among bodybuilders and weightlifters into the 1980s, who used the compound to prolong their training sessions. Creatine achieved a measure of international notoriety with the revelation that muscular British sprinter Linford Christie, 1992 Olympic 100 m champion, had used creatine supplements as part of his pre-Olympic training program. Various international rowing programs also made creatine a part of the regular nutritional supplements provided to their athletes. In the late 1990s, a number of professional American baseball players, most notably homerun record setter Mark McGwire, acknowledged that their training included regular creatine use.
Creatine is not a banned substance in Olympic competition, nor is it found on the World Anti-Doping Agency (WADA) list of prohibited substances. There are a number of both chemical and philosophical distinctions to be drawn between creatine use and the other ergogenic (muscle-building) substances to which it is often compared, such as anabolic steroids.
The first distinction between these substances is that creatine is a naturally occurring chemical in the human body. The muscle building benefits of creatine are indirect, given the relationship of creatine to the generation of cellular energy, and they are not nearly so pronounced as those attainable through either the consumption of steroids or the injection of human growth hormones (HGH). Further, any adverse physical side effects attributable to creatine use are far less than those known to result from steroid use.
Creatine supplementation poses ethical considerations as opposed to legal consequences for athletes who seek to enhance performance.
Creatine is not flushed from the system as are minerals such as sodium and potassium; once created in the body through its natural processes, or ingested as a supplement, most creatine will be stored in the muscle cells. The creatine bonds with natural phosphates produced or ingested by the body, to create creatine phosphate. When the muscle requires an instant source of energy, creatine phosphate breaks down, and the energy released in this process is used in the creation of ATP. As the muscle store of creatine phosphate is depleted, the body cannot restore the prior creatine level, which results in a corresponding inability to produce ATP in the muscle. The body must then switch to the companion energy system, the anaerobic lactic system, which will generate ATP without oxygen for a further 60 to 90 seconds.
ATP, when present in the muscles, is used as an energy source only in anaerobic alactic activities, which by definition are high-intensity short-duration sports. Creatine supplements are consumed on the premise that the larger the store of creatine available to the body, the better the short-term high-intensity athlete, such as a 100-m sprinter or a weightlifter, will perform. Creatine is therefore of little or no benefit in any sport where the aerobic energy system is utilized. Creatine has a proven ability to increase body mass and muscle size when consumed in conjunction with an aggressive weight training program. In studies of athletes over a one-month period, where creatine was consumed at a rate of 15 g per day, the subjects typically gained an average of 3 lb (1.5 kg) of lean body mass.
Creatine users also have a demonstrated ability to train with greater intensity, and shorter rest intervals than athletes who do not use creatine. However, creatine has demonstrated benefits only where the accompanying training is focused and highly regimented. The simple ingestion of creatine will have little or no positive effect on the abilities of an athlete. There is no evidence that creatine will build up in a toxic fashion within the body; excess creatine is excreted through the kidneys and urine.
Creatine has a number of side effects, which have been the subject of incomplete scrutiny and scientific analysis. There is considerable evidence that the ingestion of creatine supplements is a contributing factor in the development of muscle cramps in hot or humid conditions. As with any other supplement program that involves weight training and potential weight gain, additional stresses are imposed upon the body, which may result in the muscle strain or other musculoskeletal stress.
see also Anabolic steroids; Muscle mass and strength; Muscle protein synthesis; Protein supplements.