The term �ergogenic� stems from the Greek roots � �Ergon� and �genes,� meaning �work� and �born,� respectively. Any means of enhancing energy production or utilization may be described as an ergogenic aid.1 Ergogenic aids have classically been classified into five categories: mechanical, psychological, physiologic, pharmacologic, and nutritional.2 The present use of the term �ergogenic aid� usually revolves around the physiologic, pharmacologic, and nutritional categories.
While ergogenic aids have been linked to athletic �doping,� the terms are not synonymous. Doping is a term used by the International Olympic Committee (IOC) to describe the administration or use of a substance by a competing athlete with the sole intention of increasing in an artificial and unfair manner his or her performance in competition.3 Not all ergogenic aids are banned by the IOC. A partial listing of substances banned by the United States Olympic Committee is found in Table 1.2,3 Table 2 provides a list of commonly used athletic ergogenic aids.
AAS are believed to exert their main effect by increasing anabolic processes and inhibiting catabolic processes via specific receptor mediated responses within the target cells.5 Effects of AAS include: the anabolic build-up of muscle mass, the androgenic development of secondary male sexual characteristics, an anti-catabolic reversal of cortisol�s action, and a direct psychological effect thought to allow a more intense and sustained workout.2,5-8 Early studies of AAS and athletes produced mixed results.5,6 More recent reviews support the notions that AAS can provide significant increases in muscle mass and strength in athletes.2,5,6 In order to maximize the effects of AAS on strength and power athletes, an adequate diet and exercise regimen is needed.5 There seems to be little advantage gained while using AAS in the untrained individual.5,9 Benefits obtained from AAS are more established in strength-dependent sports. Data supporting increased aerobic capacity and improved endurance with AAS use is limited and inconclusive.4 AAS effect on endurance sports is currently an area of great interest given the large number of endurance athletes who still use AAS.4,10
An intricate terminology describing the dosing practices of athletes has evolved. Athletes will commonly use AAS over 6 to 12 week �cycles.�4 �Pyramiding� describes a�gradual escalation in the dose of AAS taken over a cycle.2,11 �Stacking� involves the use of more than one AAS, usually with staggered cycles of the individual drugs.2-4 An �array� describes the practice of using other drugs to counteract side effects or enhance the effects of AAS.3 The practices of cycling, pyramiding, and stacking are used by athletes in an attempt to minimize the negative effects of AAS while maximizing the desired enhancements.2,4 At the current time, no solid scientific support exists for these practices.2,4,5
The adverse effects attributed to AAS abuse have been historically overstated.4,12 The majority of AAS side effects are considered minor and reversible following the cessation of use.4 While the incidence of serious side effects from AAS use has been low, devastating consequences have been reported.13 Documented fatalities from myocardial infarc- tion, stroke, and hepatocarcinoma have been attributed to AAS use.2,3 The long-term effects of AAS use are generally unknown.3,11
The mechanism of action of DHEA is poorly understood but most likely revolves around the conversion of DHEA to testosterone in peripheral tissues.4,14 Preliminary studies suggest that DHEA may have a broad range of clinical uses including anti-Alzheimer and anti-Parkinson capabilities, however randomized, double-blinded clinical studies are�lacking.5
DHEA is a pre-cursor to testosterone and theoretically may enhance athletic performance in a manner similar to AAS. Investigations of DHEA use and athletic performance are scarce.14 Existing studies do not support a significant increase in lean body mass, strength, or testosterone levels with the use of DHEA in athletes.14,16-18
Long-term side effects of DHEA use are currently un- known but are probably similar to those associated with AAS use.6,14
Similar to DHEA, the mechanism of action and side ef- fects attributed to androstenedione are poorly understood and thought to be related to the conversion of androstenedione to testosterone in the peripheral tissues.5
Despite manufacturers� claims to the contrary, there is little scientific evidence of the purported ergogenic aid effects of androstenedione.2,5,16,20 Recently concerns have grown over the unfavorable alterations in blood lipid and coronary heart disease profiles seen in men using androstenedione as an ergogenic aid.2,20,21
Multiple studies of isolated ephedrine alkaloids have shown no significant enhancement of power or endurance at dosages considered to be safe.24,27-31 In contrast, the combination of caffeine with ephedrine has been associated with improvements in performance and may promote metabolic effects that are conducive to body fat loss.26,32
The actual content of ephedra alkaloids in 20 ephedra- containing dietary supplements was studied using high- performance liquid chromatography.33 Ten of the twenty supplements exhibited marked discrepancies between the label claim for ephedra content and the actual alkaloid content. Between 1995 and 1997, 926 cases of possible Mahuang toxicity were reported to the Food and Drug Ad- ministration.34 A temporal relationship between Mahuang use and severe complications including stroke, myocardial infarction, and sudden death was established in 37 of the 926 cases. In 36 of these 37 cases, the Mahuang use was reported to be within the manufacturers� dosing guidelines.
Ephedra and related ephedrine alkaloids are currently banned by the U.S.O.C. and cannot be recommended for general use given their association with potentially life- threatening side effects.2,34
Creatine is synthesized from amino acids primarily in the liver, pancreas, and kidney and is excreted by the kidneys. Creatine is found in skeletal muscle, cardiac muscle, brain, retinal, and testicular tissues.2,37 The interest in creatine as an ergogenic aid revolves around its ability to participate as an energy substrate for muscle contraction.14 Creatine, which easily binds phosphorus, can act as a substrate to donate phosphorus for the formation of ATP. Furthermore, creatine-phosphate (PCr) can help buffer lactic acid because hydrogen ions are used when ATP is regenerated.14,36,38 This role of creatine in exercise is governed by the following reaction:
PCr + ADP (adenosine diphosphate)�? Creatine + ATP.(metzl) Creatine kinase
Normally PCr stores deplete within 10 seconds of short, high-intensity exercise.14,39 Increasing the level of PCr in skeletal muscle, in theory, should result in the ability to sustain high-power output longer and lead to a greater re-synthesis of PCr after exercise.14 The beneficial effects of creatine in response to resistance training are most likely mediated by the following sequence: increased muscle creatine concentration, increased training intensity, which lead to an enhanced physiologic adaptation to training with increased muscle mass and strength.36
Studies evaluating the effectiveness of creatine as an er- gogenic aid are mixed.2,36,40 Multiple reports do conclude that short-term creatine supplementation signi cantly enhances the ability to maintain muscular force and power output dur- ing high-intensity exercise.2,36,41,42 Data on results of creatine supplementation with highly trained athletes is inconclusive. While some papers report improvements with creatine use in highly trained individuals with regards to high-intensity exercise, many show no improvements.2,36,43
Most investigators agree that creatine supplementation does not seem to enhance aerobic-oriented activities.2,36,44
Human muscle is thought to have a maximum concen- tration of creatine that it can hold.14,45 There appears to be no additional bene ts of increasing creatine supplementa- tion above this storage capacity of muscle as the excess is simply excreted by the kidneys.2,46 Humans have differing baseline levels of muscle creatine.14 Accordingly, athletes with lower baseline levels of creatine may be more sensi- tive to creatine supplementation than those with a relatively higher baseline creatine level.14,36 The terms �responder� and �nonresponder� have been used to describe two groups of athletes: those with relatively low baseline creatine levels that may show signi cant performance enhancement with creatine supplementation, and those with high baseline creatine levels that do not show marked improvements with creatine supplementation.14,36,47 These differences in creatine concentrations are thought to play a signi cant role in the varied results on performance found in the literature examin- ing creatine supplementation.14
Reported side effects from creatine use have been scarce.2,14 The major reported side effect associated with creatine use is weight gain, which is thought to be primarily a result of water retention.2,14,48 Some reported longer-term side effects include dehydration, muscle cramping, nausea, and seizures.2,49 Given the relative lack of studies, caution still remains about the long-term effects of creatine usage.14 As creatine use among younger athletes continues to increase, concern is growing over the lack of studies that examine the possible side effects speci c to this age group.14,38
Potential benefits of hGH abuse in athletes revolve around�its anabolic effect on the body.4 Human growth hormone is thought to increase muscle mass, and spare muscle glycogen by stimulating lipolysis during exercise.2,3 The popularity of hGH among athletes is furthered by the fact that hGH re- mains extremely difficult to detect by current drug screening processes.3,51 Human growth hormone may be particularly attractive to female athletes as the virilization side effects associated with AAS use are not thought to occur with hGH.4
There are no studies that demonstrate signi cant increases in athletic performance with the use of hGH.3,52,53 Neither human or animal studies show any signi cant strength gains with supplemental hGH use in non-de cient individuals.4 The abuse of hGH is thought to be increasing despite the lack of scienti c evidence linking hGH to improved athlete performance.3,52 A survey of high school males revealed that as many as 5% reported past or present use of hGH.54 The purity of hGH abused by athletes may be poor as Drug Enforcement Agency estimates project that up to 30% to 50% of the hGH products sold are phony.4,55
Adverse effects of exogenous hGH use are extrapolated from the ndings seen in patients with endogenous over- secretion of hGH.2 Adults with high levels of hGH are at risk for the clinical syndrome of acromegaly. Medical complications associated with acromegaly include: diabetes, hypertension, coronary heart disease, cardiomyopathy, men- strual irregularities, and osteoporosis.2,4 High levels of hGH in individuals with open physis may lead to gigantism.2
There are few studies evaluating the use of r-EPO in healthy athletes; however, numerous studies have shown a signi cant increase in work capacity due to r-EPO use in patients with renal disease.14 Berglund and Ekblom reported an increased maximal oxygen consumption and increased time to exhaustion in male athletes after a 6 week trial of r-EPO.56
The risks associated with r-EPO abuse involve the potential for dangerously high hematocrit levels.14 A resulting hyperviscosity syndrome may lead to a decreased cardiac output, hypertension, and potential heart failure.3 Further- more, thrombosis could be manifest as myocardial infarction, pulmonary embolism, or cerebrovascular accidents.2,3 Although the use of r-EPO has been banned by the IOC since 1990, its use is extremely difficult to detect with current drug screening measures.2,14
HMB is a relatively new ergogenic aid and published results are considered preliminary.14,58 Although there is evidence for a potential ergogenic aid advantage with HMB use in resistance and endurance training, its use can not be recommended until more studies are performed and potential side effects are elicited.
Side effects associated with caffeine use include anxiety, diuresis, insomnia, irritability and gastrointestinal discom- fort.2,6 Higher doses of caffeine ingestion can lead to more serious consequences such as cardiac arrhythmia, hallucina- tions, and even death.2,3
The legal urine level of caffeine for athletes is 12 ?g/ml (IOC standards) and 15 ?g/ml (National Collegiate Athletics Association standards).6 An athlete would need to drink six to eight cups of coffee in one sitting and be tested within 2 to 3 hours to reach urine levels over the IOC legal limit.3 The amount of caffeine needed to produce ergogenic benefits is potentially far less than that required to exceed the athletic�legal limit.3
Claims championing exotic substances that produce healing or ergogenic powers have been around for centuries. The�competitive, peer-pressured environment enveloping today�s athletes and adolescences makes these groups particularly susceptible to the uproar surrounding the current ergogenic aid market. Presently, it seems that rumor and anecdotal information overwhelms the available scientific data. While there is evidence that some touted ergogenic aids do indeed enhance performance, there are many unanswered questions about product safety, efficacy, and long-term consequences. A working knowledge of specific ergogenic aids is essential for the treating physician in order to best advise patients and athletes as to the possible benefits and risks of any substance they may be using.
By Adam Bernstein, M.D., Jordan Safirstein, M.D., and Jeffrey E. Rosen, M.D.
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