AIS WEBSITE FACT SHEET – AIS SPORTS SUPPLEMENT PROGRAM

Creatine

Supplement Overview

Creatine is a naturally occurring compound found in large amounts in skeletal muscle and brain as a result of dietary intake and endogenous synthesis from amino acids. Dietary intake from animal muscle (e.g. meat, fish) is 1-2 g/d or half the daily turnover.

Muscle creatine content varies between individuals, perhaps related to gender, age or fibre type. Vegetarians do not consume a dietary source of creatine and are reliant on body synthesis of creatine; studies have shown that vegetarians have lower residual muscle creatine concentrations than meat-eaters (Burke et al. 2003).

Phosphorylated creatine provides a number of important functions related to fuel supply in the muscle. The most well known role is as a source of phosphate to regenerate ATP. The phosphocreatine system is the most important fuel source for sprints or bouts of high-intensity exercise lasting up to 10 seconds.

In 1991, studies initiated by Professor Roger Harris showed that muscle creatine and phosphocreatine content could be increased by ~20% by dietary creatine supplementation up to a to a threshold of ~150-160 mmol/kg of dry weight muscle. High dietary intakes temporarily suppress endogenous creatine production.

There is considerable variability in response to creatine supplementation. Individuals with the lowest initial levels, such as vegetarians, may show the greatest responses, while individuals with resting creatine content near to the muscle threshold may not show additional enhancements. Although initial studies showed that a significant proportion (30%) of individuals failed to achieve a worthwhile increase in muscle creatine content in response to supplementation, this appears to be overcome by strategies that enhance creatine uptake into the muscle such as simultaneous intake with a carbohydrate-rich meal or snack.

Creatine supplementation has been shown to enhance the performance of exercise involving repeated sprints or bouts of high intensity exercise, separated by short recovery intervals. Therefore, competition or training programs involving intermittent high-intensity work patterns with brief recovery periods (<1 min), or resistance training programs may be enhanced by creatine loading. Performance enhancements may be seen as a result of an acute loading protocol, but chronic creatine use to promote superior training adaptations may offer the greatest benefits.

Studies have shown that prior creatine loading enhances glycogen storage and carbohydrate loading in a trained muscle. The performance implications of this finding have not been well studied.

Although there is a robust literature supporting the benefits of creatine supplementation on exercise capacity/performance, most studies have not been undertaken with elite athletes or a sports specific outcome.

There is also a robust literature supporting the therapeutic uses of creatine supplementation with applications for a number of disorders including muscular dystrophy, polymyositis, ageing, Parkinson’s disease and Huntingdon’s disease.

Creatine supplementation also appears to increase creatine concentrations in the brain. This may have some functional benefits to enhance cognitive function in situations of impaired brain function such as sleep deprivation, ageing and brain hypoxia due to stroke. Further studies on this application of creatine supplementation are required with sports situations including treatment of concussion. There is preliminary evidence (Benton et al. 2011) that creatine supplementation by vegetarians is associated with increased cognitive function while this effect is not seen in meat-eaters. This is presumably because resting brain creatine concentrations of vegetarians are lower due to the lack of a dietary creatine source.

Products and protocols The most well-researched dietary creatine supplement is creatine monohydrate, with a number

of protocols of loading being established: o Rapid loading may be achieved by 5 days of repeated doses (e.g., four x 5 g doses) of

creatine (Hultman et al. 1996). o Slow loading will occur over a longer period (28 days) with a daily dose of 3 g

(Hultman et al. 1996). o Maintenance dose of 3 g/d will allow elevated levels to be sustained (Preen et al.

2003). o Unloading: Once the muscle creatine content has been saturated it will take at least

4 weeks to return to resting levels.

Consuming creatine doses with a substantial (50-100 g) amount of carbohydrate (Green et al. 1996) enhances creatine uptake and storage into the muscle. Taking creatine doses with a carbohydrate-rich meal or snack may help all individuals to respond to creatine supplementation and reach the muscle creatine storage threshold.

A weight gain of 600-1000 g is typically associated with acute loading and may represent water retention. Although it has been suggested that the slow loading protocol may circumvent this weight gain, this theory has not been properly studied. It is possible that any weight changes associated with slow loading are masked by normal body mass fluctuations or the outcomes of longer term training and diet interventions.

Creatine monohydrate is the common source of creatine in commercially available supplements and the experience of 20 years of research and use of this product according to established protocols suggests that it is safe and effective. A number of other forms of creatine have been included in newer supplements with claims of being a superior creatine course; these include creatine serums, creatine malate and creatine ethyl esters. The efficacy, safety, and regulatory status of most of these newer forms of creatine found in dietary supplements have not been well established. Additionally, there is little to no evidence supporting marketing claims that these alternative creatine sources are more stable, digested faster, more effective in increasing muscle creatine levels and achieving performance outcomes or associated with fewer side effects (Jager et al. 2011).

Situations for Use in Sport There is robust evidence that creatine supplementation can enhance the performance of exercise

involving repeated sprints or bouts of high-intensity exercise, separated by short recovery periods. Enhancement of competition performance may be seen as a result of an acute loading protocol but also through chronic use to promote superior training adaptations. These situations include:

o A developed athlete undertaking resistance training to increase lean body mass. o Interval and sprint training sessions where the athlete is required to repeat short

explosive maximal efforts with brief recovery intervals. o Sports with intermittent work patterns (e.g. soccer, basketball, football, racquet

sports).

The application of creatine loading to enhance glycogen storage or brain creatine stores has not been sufficiently researched to allow clear recommendations, but further research is encouraged.

Further studies of creatine supplementation involving sports-specific applications and highly trained/elite athletes are also encouraged.

Concerns Associated with Supplement Use

Many athletes who use creatine either are unaware of correct supplementation protocols or persist in using unnecessarily high doses of creatine. Studies show that high doses of creatine do not further enhance creatine stores.

This weight gain associated with creatine loading may be counterproductive to athletes competing in sports where power-to-weight is a key factor in successful performance or in sports involving weight divisions.

The long-term consequences of creatine use are considered to be unknown, although there is now a 20 year history of creatine supplement use with few reports of adverse outcomes. There are anecdotal reports of an increased risk of muscle cramps, strains and tears, but studies to date have not reported an increased risk of these events. In fact, several studies show a reduced prevalence of muscle cramps and tears and enhanced thermoregulation during prolonged exercise in the heat in creatine users compared to a group receiving a placebo treatment. Creatine use in the evidence-based protocols outlined above has not been seen to cause changes to kidney function in otherwise healthy people.

Some individuals experience mild side-effects from creatine supplements in the form of gastrointestinal discomfort or an increased prevalence of headaches.

Many creatine supplements contain alternative forms of creatine that have not been shown to be efficacious or safe. In fact, some forms of creatine may be a waste of money: creatine is unstable in solution and a study of commercially available liquid forms of creatine known as “creatine serum” found that they contained little or no creatine, presumably due to its irreversible breakdown to creatinine (Harris et al. 2008).

Creatine supplementation should be limited to experienced and well-developed athletes. Young athletes are able to make substantial gains in performance through maturation in age and training, without the need to expose themselves to the expense or small potential for long-term consequences of creatine use.

Further reading Benton D, Donohoe R. The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores. Br J Nutr. 2011; 105(7):1100-5.

Burke DG, Chilibeck PD, Parise G, Candow DG, Mahoney D, Tarnopolsky M. Effect of creatine and weight training on muscle creatine and performance in vegetarians. Med Sci Sports Exerc. 2003; 35(11):1946-55

Jäger R, Purpura M, Shao A, Inoue T, Kreider RB. Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids. 2011; 40(5):1369-83

Green AL, Hultman E, Macdonald IA, Sewell DA, Greenhaff PL. Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans. Am J Physiol. 1996; 271(5 Pt 1):E821-6.

Harris RC, Almada AL, Harris DB, Dunnett M, Hespel P. The creatine content of Creatine Serum and the change in the plasma concentration with ingestion of a single dose. J Sports Sci. 2004; 22(9):851-7

Hultman E, Söderlund K, Timmons JA, Cederblad G, Greenhaff PL. Muscle creatine loading in men. J Appl Physiol. 1996; 81(1):232-7

Preen D, Dawson B, Goodman C, Beilby J, Ching S. Creatine supplementation: a comparison of loading and maintenance protocols on creatine uptake by human skeletal muscle. Int J Sport Nutr Exerc Metab. 2003; 13(1):97-111

Last updated November 2011

This Fact Sheet was prepared by AIS Sports Nutrition as part of the AIS Sports Supplement Program (www.ausport.gov.au/ais/nutrition/supplements ). Note that a Fact Sheet with additional information on this topic is available for Members of the AIS Sports Supplement Program at this site. The AIS Sports Supplement Program has been designed for the specific needs of AIS athletes and all attempts are made to stay abreast of scientific knowledge and of WADA issues related to anti-doping. It is recommended that other athletes and groups should seek independent advice before using any supplement, and that all athletes consult the WADA List of Prohibited Substances and Methods before making decisions about the use of supplement products. © Australian Sports Commission 2012