PEDIATRICS Vol. 108 No. 2 August 2001, pp. 421-425

Creatine Use Among Young Athletes

Jordan D. Metzl, MD^*, Eric Small, MD, Steven R. Levine, MD^§, and Jeffrey C. Gershel, MD

From the ^* Sports Medicine Service, Hospital for Special Surgery, Department of Pediatrics, Cornell Medical College, New York, New York;  Department of Pediatrics, Mount Sinai Medical Center, New York, New York; ^§ Department of Pediatrics, Northern Westchester Hospital Center, Mt Kisco, New York;  Department of Pediatrics, Jacobi Medical Center, Bronx, New York.

	ABSTRACT

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Objective.  Creatine is a nutritional supplement that is purported to be a safe ergogenic aid in adults. Although as many as 28% of collegiate athletes admit taking creatine, there is little information about creatine use or potential health risk in children and adolescents. Although the use of creatine is not recommended in people less than 18 years of age, numerous anecdotal reports indicate widespread use in young athletes. The purpose of this study was to determine the frequency, risk factors, and demographics of creatine use among middle and high school student athletes.

Methods.  Before their annual sports preparticipation physical examinations, middle and high school athletes aged 10 to 18 in Westchester County, a suburb north of New York City, were surveyed in a confidential manner. Information was collected regarding school grade, gender, specific sport participation, and creatine use.

Results.  Overall, 62 of 1103 participants (5.6%) admitted taking creatine. Creatine use was reported in every grade, from 6 to 12. Forty-four percent of grade 12 athletes surveyed reported using creatine. Creatine use was significantly more common (P < .001) among boys (53/604, 8.8%) than girls (9/492, 1.8%). Although creatine was taken by participants in every sport, use was significantly more common among football players, wrestlers, hockey players, gymnasts, and lacrosse players (P < .001 for all). The most common reasons cited for taking creatine were enhanced performance (74.2% of users) and improved appearance (61.3%), and the most common reason cited for not taking creatine was safety (45.7% of nonusers).

Conclusions.  Despite current recommendations against use in adolescents less than 18 years old, creatine is being used by middle and high school athletes at all grade levels. The prevalence in grades 11 and 12 approaches levels reported among collegiate athletes. Until the safety of creatine can be established in adolescents, the use of this product should be discouraged.  Key words:  creatine, nutritional supplements, ergogenic aids, adolescent sports medicine, preparticipation examination.

Creatine is a nutritional supplement that falls under the broad category of products known as ergogenic aids, substances designed to chemically improve athletic performance. Certain ergogenic aids, such as anabolic steroids, growth hormone, and erythropoietin, are banned by major sports organizations including the International Olympic Committee, the National Athletic Association, and the United States Olympic Committee.¹ These prohibited substances have been shown to offer an unfair advantage to competitors and to predispose athletes to life-threatening health risks such as increased cancer risk and stroke.^2-4

Nutritional supplements, largely made up of naturally occurring compounds, are marketed as safe and legal performance-enhancing alternatives to banned agents. The Proxmire Amendment of 1993 limited the jurisdiction of the Federal Food and Drug Administration (FDA) over nutritional supplements, greatly reducing federal control over the content or use of these products.⁵ Because nutritional supplements are not subject to FDA testing, the safety profiles of these products often are unknown. Recently, ephedryl alkaloid (Ma Juang), a popular nutritional supplement, was implicated as the cause of death or permanent disability in 23 previously healthy athletes over a 2-year period.⁶

Creatine is the most popular nutritional supplement, with yearly sales over $400 million.⁷ In the most recent position statement on creatine use, the American College of Sports Medicine discouraged creatine use in people less than 18 years old because of unknown potential adverse health effects.⁸ Creatine is readily available for purchase, both in health food stores and over the Internet.

Creatine is formed by combining the amino acids glycine, arginine, and methionine and is produced in physiologic amounts by the liver, kidneys, and pancreas.⁹ In addition to natural synthesis, creatine is also found in protein-rich sources such as meat and fish. The total daily requirement of creatine is 2 g/d, approximately half of which comes from in vivo production and the other half from dietary sources.¹⁰

The role of creatine during exercise lies in the following reaction: Acting as a substrate for hydrogen ions, creatine facilitates the production of adenosine triphosphate (ATP) from adenosine diphosphate (ADP), thus increasing the amount of free energy available for muscle contraction.¹¹ Several studies have documented that creatine supplementation improves baseline strength in adults.^11,12 No studies have shown the effectiveness of creatine supplementation in people less than 18 years old.

There are no data documenting the safety of creatine in children or adolescents.¹³ Because creatine has not been studied thoroughly, both the short-term and long-term effects of routine use, especially in adolescents, are of great concern. There are currently 2 documented cases of adult-onset renal failure with creatine use reported in the medical literature.^14,15

	METHODS

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Sports preparticipation physical examinations were performed at 5 schools in the spring of 1999. These schools represented a sample of middle school and high school students in Westchester County, a suburb of New York City. Study participants included all 6th- to 12th-grade students who were considering participation in any school-sponsored sport during the coming academic year (1999-2000). These sports included football, lacrosse, hockey, wrestling, hockey, gymnastics, swimming, cheerleading, skiing, tennis, baseball, soccer, field hockey, and track teams and athletes involved in weight training.

Personnel who were not involved directly in the sports evaluations administered a confidential questionnaire ("Appendix") to all students before their preparticipation examination. Information was collected on school grade, sex, and sports in which the student planned to compete. Athletes were asked whether they had thought about using creatine, knew someone using it, or had tried creatine themselves. They were also asked about factors influencing their decisions whether to use creatine.

² analysis, with Yates correction when indicated, was used to compare creatine users and nonusers. This information was cross-referenced with variables including sport, age, sex, knowledge about creatine, and reasons why each student chose to use or not use creatine. In addition, each school was separately analyzed to detect individual rates of creatine use, both overall and by sex and grade, and then compared with the other schools in the study. The questionnaire form is listed in appendix 1.

	RESULTS

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Sixty-two of 1103 participants (5.6%) admitted taking creatine. The prevalence of creatine use varied greatly among the schools, from 1.9% in school A to 9.3% in school C. Of the 5 schools sampled, creatine use was most prevalent in the private high school (Table 1). Boys were significantly (P < .001) more likely to take creatine (53/604, 8.8%) than girls (9/492, 1.8%). As shown in Table 2, the prevalence of creatine use was similar in 6th through 10th grades but increased significantly in 11th and 12th grades (P < .001). The creatine use rate in the 12th grade student athlete population was 44%.

Participants in every sport tried creatine. As summarized in Table 3, use was significantly more common among strength-dependent athletes such as football players, wrestlers, hockey players, and lacrosse players (P < .001 for all). However, creatine use was reported among athletes involved in every sport. Young athletes involved in weight training were statistically more likely to take creatine than those who did not lift weights (P < .001).

The most frequently reported expectations of creatine use were enhanced performance (74.2% of users), improved appearance (61.3%), improved endurance (45.2%), and improved speed (40.3%). The most common reasons cited for not taking creatine were safety concerns (45.7% of nonusers), ignorance about creatine (39.5%), lack of perceived benefit (19.7%), and expense (13.0%). In addition, 32.9% of the participants knew someone taking creatine, and 13.6% had thought about trying it.

	DISCUSSION

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This study confirms the disturbing trend of ergogenic aid use among middle school and high school student-athletes.¹⁶ Popular belief has been that athletes participating in sports emphasizing strength, such as football, wrestling, and weightlifting, predominantly used ergogenic aids. These results demonstrate that creatine is being taken not only by young athletes involved in strength sports but also by those in activities such as tennis, cheerleading, and field hockey. Young athletes participating in every sport studied reported taking creatine. Although girls were significantly less likely to use creatine than boys, there was a 1.8% prevalence among girls, including 5 middle school students.

The overall prevalence of athletes taking creatine was 5.6% (62/1103). User rates were similar in the 6th through 10th grades (ranging from 2.9% to 4.6%). In the 11th and 12th grades the user rate increased significantly, approaching reported levels among collegiate athletes.¹⁷ Because the physical examination sessions were intended for students planning to participate in sports during the following school year, fewer 12th graders were studied compared with other grades. However, the rate of creatine use among them was exceptionally high (12 of 27, 44.4%).

There were no statistically significant differences in creatine use among the 3 different high school socioeconomic populations (public middle class, public middle and upper class, private). Comparing all 5 schools, however, the user rate was the highest in the private high school, 9.3% of all student athletes. The issue of correlation between socioeconomic class and creatine use deserves additional study among a wider cross-section of students to assess whether use is related to family income. In addition, it is possible that in other regions of the country, young athletes are taking creatine at rates that are different from those found in suburban New York. This issue also warrants additional investigation.

There are a number of possible explanations for creatine use in young athletes. First, creatine and other nutritional supplements are touted as safe and natural methods of improving sports performance. They are widely marketed through television, radio, and print media and are readily available for purchase over the Internet. Young athletes may be especially vulnerable to these aggressive marketing initiatives. Second, the trickle-down phenomenon is important to consider. Initially, high-level Olympic and professional athletes began using ergogenic aids, followed by collegiate athletes. More recently, ergogenic aid use has been reported among high school and middle school athletes.¹⁸ Teenage users may be taking ergogenic aids to imitate famous athletes. Finally, young athletes are under increased pressure from parents, coaches, and peers to succeed in athletics, and the win-at-all-costs mentality has emerged in youth sports. In our study, most athletes reported taking creatine to improve sports performance. Based on the growing numbers of young athletes participating in organized sports,¹⁹ the use of this product probably will increase in the future.

The widespread use of creatine in young athletes is troubling for 2 main reasons. First, the safety of creatine in people less than 18 years old is not known, and use is not advised in this age group. The short-term and particularly the long-term health risks in adolescents and preadolescents are unknown. Second, we believe that young athletes taking performance-enhancing nutritional supplements and young athletes taking banned substances such as anabolic steroids represent 2 points on a continuum. Adopting a permissive attitude toward nutritional supplement use in young athletes might encourage a more lenient attitude toward the use of more dangerous performance-enhancing products. This point is especially important in light of the recent Sydney Olympics, where performance-enhancing drug use was highlighted in the international media. A consistent message of disapproval toward all performance-enhancing substances should come from the medical community to help the athletic community deal with the issue of performance-enhancing drug use.

However, young athletes and their parents often are receptive to information about optimum nutrition and training. Educational opportunities include annual physical examinations, sports preparticipation examinations, and other episodic visits to health care providers. Because the preparticipation examination is the most frequent interaction between medical system and the otherwise healthy adolescent,²⁰ it is an especially important time to address the issue of ergogenic aid use. Health professionals must take advantage of these opportunities to discuss the importance of healthy behaviors with their patients, including the potential hazards of ergogenic aids such as creatine. The 13.6% of nonusers who reported considering creatine use may be a specific subgroup that would benefit from an educational program on the potential side effects of ergogenic aids.

Open communication is needed among a team of physicians, nurses, coaches, and athletic trainers, all of whom are responsible for the health and safety of young athletes. Until more information is available about safety in children and adolescents, health care providers should actively discourage use of creatine in their young patients.

	FOOTNOTES

Received for publication Apr 13, 2000; accepted Mar 22, 2001.

Reprint requests to (J.D.M.) Hospital for Special Surgery, 535 E 70th St, New York, NY 10021. E-mail: MetzlJ{at}HSS.EDU

	ABBREVIATIONS

FDA, US Food and Drug Administration; ATP, adenosine triphosphate; ADP, adenosine diphosphate.

	REFERENCES

Top Abstract Methods Results Discussion References

1. Stricker PR Other anabolic agents. Clin Sports Med 1998; 17:283-297 [Medline]
2. Ekblom B Blood doping and erythropoietin. Am J Sports Med 1996; 24:S40-S42
3. Elashoff JD, Jacknow AD, Shain SG, Effects of anabolic steroids on muscular strength. Ann Intern Med 1991; 115:387-393
4. Deyssig R, Frisch H, Blum WF, Effect of growth hormone treatment on hormonal parameters, body composition, and strength in athletes. Acta Endocrinol 1993; 128:313-318
5. Short SH, Marquart LF Sports nutrition and fraud. N Y State J Med 1993; 93:112-116 [Medline]
6. Haller CA, Benowitz NL Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000; 343:1886-1887 [Free Full Text]
7. Kramer W. Proceedings of the American College of Sports Medicine Advanced Team Physician Course. Orlando, FL: American College of Sports Medicine; 1999
8. Tjerung RL, Clarkson P, Eichner ER, The physiological and health effects of oral creatine supplementation. Med Sci Sports Exerc 2000; 32:706-717 [Medline]
9. Balsom PD, Soderlund K, Ekblom B Creatine in humans with special reference to creatine supplementation. Sports Med 1994; 18:268-280 [Medline]
10. Kambler M, Koster M, Kreis R, Creatine supplementationPart I: performance, clinical chemistry, and muscle volume. Med Sci Sports Exerc 1999; 31:1763-1769 [Medline]
11. Kreider RB, Ferreira M, Wilson M, Effects of creatine supplementation on body composition, strength, and sprint performance. Med Sci Sport Exerc 1998; 30:73-82 [Medline]
12. Birch R, Noble D, Greenhaff PL The influence of dietary creatine supplementation on performance during repeated bouts of submaximal exercise. Eur J Appl Physiol 1996; 69:268-270
13. Metzl JD Strength training and nutritional supplement use in adolescents. Curr Opin Pediatr 1999; 11:292-296 [Medline]
14. Prichard NR, Kaltra PA Renal dysfunction accompanying oral creatine supplements. Lancet 1998; 351:1252-1253 [CrossRef][Medline]
15. Koshy KM, Griswold E, Scheenberger EE Interstitial nephritis in a patient taking creatine [letter]. N Engl J Med 1999; 340:814-815 [Free Full Text]
16. Buckley W, Yesalis C, Freidl K, Estimated prevalence of anabolic steroid use among high school seniors. JAMA 1988; 260:3441-3445 [Abstract]
17. LaBotz M, Smith BW Creatine supplement use in an NCAA Division I athletic program. Clin J Sports Med 1999; 9:167-169 [Medline]
18. Faigenbaum AD, Zaichowsky D, Gardner DE, Micheli LJ. Anabolic steroid use by male and female middle school students. Pediatrics. 1998;101(5). URL: http://www.pediatrics.org/cgi/content/full/101/5/e6
19. National Federation of Youth Sports. Participation Survey: 1998-1999. Kansas City, MO: National Federation of State High Schools; 1999
20. Hergenroder AC The preparticipation sports examination. Pediatr Clin North Am 1997; 44:1525-1541 [Medline]