By Michael Pitzer, MD
The use of performance enhancing supplements by athletes is as old as sport itself. Competitors trying to get an edge are seen in the legends of the Ancient Greek Olympics. Now, an $18 billion supplement industry fuels American athletes at all levels. (1) Athletes want to use supplements and ergogenic aids to promote adaptation to training, improve training responses, optimize recovery and improve performance in competition. (2) Supplement use is surprisingly high. In middle school and high school athletes, the use of ergogenic supplements is estimated to be 24-29%. (3) A 2004 survey showed that high school athletes frequently use supplements including sports drinks, vitamins and minerals, energy drinks, creatine, protein and coenzyme Q10. (4) A 2006 NCAA report indicated that two thirds of supplement use started before college, and one in ten athletes began to use supplements before high school. (5) Thus, the products are out there and our adolescent patients are using them. (4) Supplements can be helpful in the appropriate setting and physicians have the onus to know when our adolescent athletes might benefit from athletic dietary supplements.
Many physicians worry about the safety and efficacy of dietary supplements because supplements do not undergo a rigorous FDA approval process like prescription medications. However, there is a common misconception that there is no regulation of the dietary supplement industry, which is not true. Dietary supplements are regulated by both the FDA and the Federal Trade Commission (FTC) (6), although the regulation process is much less rigorous than the approval process for new medications. The FDA is responsible for product safety and labeling of supplements, and the FTC regulates the advertising of dietary supplements. (7) The FDA and the FTC do not monitor the efficacy of dietary supplements; however, they do hold companies accountable for the accuracy of claims made concerning the product. (6) Moreover, the Dietary Supplements Health and Education Act of 1994 (DSHEA) requires that companies prove the safety of their product to the FDA if the product contains a “new dietary ingredient,” and the FDA has accepted fewer than 30% of new dietary ingredient submissions since 1994. (6) Products out before 1994 are presumed to be safe. The safety and efficacy of dietary supplements on the market is clearly suboptimal, but physicians should be aware that two governing bodies are monitoring and regulating the US dietary supplement market to improve safety and reduce false claims about efficacy.
Creatine is a nonessential amino acid that is naturally made in the liver. Creatine is believed to be multifaceted in its ability to aid athletic performance. In skeletal cells, creatine aids in the rephosphorylation of ATP during short-duration exercise, meaning muscles maintain their energy during short-duration exercise. (8) Creatine is thought to assist in cellular energy transport and prevent intracellular acidosis, and is also thought to decrease protein breakdown and increase protein synthesis. (6) There have been a number of studies examining the prevalence of creatine use in high school athletes, and most of the studies found that 5-20% of all high school athletes use the supplement, with an increase in prevalence in males and football, hockey and basketball players. (6) Creatine was reported in one high school to be used by 9% of male and 2% of female athletes. (9) Multiple studies have concluded that creatine is effective at increasing power and force in short bouts of increased exertion and in repeated efforts of maximal exertion, and Beben and Lamont (10) showed that creatine has a proven benefit if “dynamic or isotonic peak force” is assessed as the outcome measure.( 8,11,12,13) It is important to note here that creatine has been extensively evaluated in adults, and only a few studies have been published evaluating creatine use in adolescent athletes. The few studies that have looked at adolescent creatine use have found athletic benefits similar to studies on adult athletes.6 Moreover, when used at appropriate doses, creatine seems to be safe in healthy athletes of all ages, and therefore, using a trusted brand of creatine might be appropriate for some high school athletes.
Protein powder and supplements are another common finding on health store shelves. Athletes of all ages supplement with protein to increase body mass and strength. The use of protein supplementation in athletes and sedentary people is well studied, and the recommended protein intake for sedentary individuals is 0.8-1.0 g/kg/d, where as some athletes require 1.6-1.7 g/kg/d.(13,14) The increase in protein requirement is necessary to maintain a positive nitrogen balance. Supplementing with manufactured powder protein is not necessary, as the increased amount of protein required by athletes can easily be consumed with simple changes to the diet. Where protein supplements may be the most helpful are in athletes with restrictive diets, including vegetarians, wrestlers and gymnasts, who may not be able to ingest adequate amounts of protein in their diets in order to maintain their lifestyle, appropriate weight and figure. (6) For these types of athletes, amino acid supplementation is prudent to reach their desired protein intake without an unacceptable increase in fat and other caloric intake. (2) Moreover, there is some evidence that using the correct protein supplement in relation to the timing of exercise may affect how an athlete’s body responds to training. (6) First, ingesting the right cocktail of amino acids after exercise can stimulate pancreatic insulin release which stimulates muscle anabolism. Secondly, intake of branch-chain amino acids at specific dosages and in combination with exercise may stimulate growth hormone (GH) secretion, which can lead to muscle anabolism. (15) Leucine seems to be the most important amino acid in producing these desired effects, and whey protein and casein protein contain the right combinations of leucine and other amino acids for the human body to use for these purposes. (6) Our adolescent athletes have easy access to protein supplementation and may benefit from correct use.
Beta-hydroxy-beta-methylbutyrate (HMB), a metabolite of leucine, is promoted as a supplement that prevents muscle breakdown during exercise (6), also has some anabolic properties as a cholesterol precursor. (16) Products on the market claim quicker recovery after exercise, and increased lean body mass and strength from using HMB. (6) Studies of this supplement have shown improved muscle strength and body composition in sedentary populations starting an exercise regimen, but little benefit in trained athletes. (6) Due to HMB’s effect on physical appearance, without a positive effect on muscle performance and its initial benefit after a period of sedentary life, HMB is attractive to many adolescents and one-sport athletes who do not compete all year long. This supplement also benefits from a lack of adverse effects in multiple studies. (6) In athletes, HMB used in association with creatine has been shown to increase lean body mass and strength in progressive resistance exercise training. (17,18) HMB in combination with alpha-ketoiso-caproic acid supplementation may reduce signs and symptoms of exercise-induced muscle damage in non-resistance trained males following a single bout of resistance exercise. (19) Further evaluation of HMB in high school athletes is necessary, but evidence from adult populations and in physiologic studies is promising for its benefit to the adolescent athlete.
Supplementation of vitamins and minerals is also common in athletes. There is no benefit to supplementation of vitamins and minerals above the recommended daily amounts, which can be consumed through a well-balanced diet. Vitamin and mineral use beyond the daily recommendations will not enhance performance. (13) Experts have suggested that vitamin and mineral supplementation in athletes following restrictive diets (i.e. wrestlers) may benefit the athlete. (6) Athletes should be counseled about vitamin and mineral use, and high school athletes in diet restricted sports should be counseled on the potential benefit of vitamin and mineral supplementation.
The use of stimulants in athletics has a long and storied history. Despite one in four adolescent athletes reporting caffeine use for performance enhancement in the US (6), caffeine is not well studied in the adolescent athlete. Caffeine has been shown to enhance submaximal aerobic and endurance activities in adult athletes. (13,20) Caffeine has multiple physiologic affects that are beneficial in athletics including mobilizing free fatty acids to be used by exercising muscle, increasing the contractility of skeletal and cardiac muscles, increasing metabolic rate, increasing cortisol levels and increasing antioxidant activity. (6) Caffeine can reduce perception of fatigue and increase time to exhaustion in submaximal exercise of 30- to 60-minute duration (i.e. running and cycling). (13,20) Caffeine may also have some benefit in activities that require repeated short bursts of exertion interspersed in more prolonged activity. (21,22) Only moderate amounts of caffeine are necessary to provide performance benefits (3 mg/kg body mass). (23) Caffeine has many adverse effects and can produce physiologic dependence; it should be used cautiously. Notably, high levels of caffeine are banned by multiple athletic organizations including the NCAA. However, at least one in four teenage athletes recognizes the benefits of caffeine, and they should be counseled on the appropriate and legal use of caffeine in athletic competition.
This article is only intended to discuss the possible benefits of legal dietary supplementation in high school athletes. In summary, many supplements on the US market are safe, with varying efficacy. Creatine is likely the most used supplement in high school athletes, and limited studies have showed it improves an athlete’s response to short bouts of increased exertion and improves an athlete’s response in repeated efforts of maximal exertion. Protein supplementation can specifically benefit athletes in weight-based or figure-sensitive sports, and certain combinations of amino acids may naturally induce muscle anabolism though pathways involving increased GH and insulin levels. HMG has some known anabolic and anticatabolic properties, and studies suggest that it can improve an athlete’s response to the initiation of training. Vitamin and mineral supplementation may be helpful in high school athletes with restricted diets. Caffeine can also enhance athletic performance and is commonly used by high school athletes; these athletes need to be counseled on safe and legal means of use. In comparison to supplement studies on adult populations, the data on safety and efficacy in childhood and adolescent populations is very limited. However, the available evidence is promising that supplements can be used safely and efficaciously in high school athletes.
References can be found at http://www.amssm.org/Content/pdf%20files/Mar13_SR_Ref.pdf
