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Office pediatricians need to be prepared to evaluate a patient?s suitability to participate in the sport of his or her choosing. Most significant findings can be uncovered by taking a thorough medical history.
|Jump to:||Choose article section... How the PAE is conducted Optimal timing Asking the right questions High-risk behavior screening Do more than run through the history Sudden cardiac death Marfan syndrome Past injury Exercise-induced bronchospasm Concussions Brachial plexus injuries Seizure disorder Heat illness Unilateral organs Ergogenic aids and nutrition Prescription stimulant medications Female athletes Sickle cell anemia Staying focused|
Office pediatricians need to be prepared to evaluate a patient's suitability to participate in the sport of his or her choosing. Most significant findings can be uncovered by taking a thorough medical history.
More than 7 million young men and women participate in high school athletics each year. Nearly all these adolescents will need to undergo a preparticipation athletic evaluation (PAE) before being allowed to compete. Many students will be evaluated during mass screenings at high schools and sports medicine clinics. And, as you well know, many other students will come to your office seeking medical clearance for athletic participation.
Is there more to the "sports physical" than signing the required forms? Do you consider it a waste of time for both you and the patient? How prepared are you to make this a meaningful experience for the athlete?
The PAE has long been a nebulous exercise for all parties involved. Historically, the purpose of the PAE was to detect disqualifying physical conditions and fulfill any insurance requirements. The purpose of the PAE still stirs debate, with many experts arguing that it should be seized on as an opportunity to screen for, and educate adolescents about, high-risk health behaviors.13 Given the limited time available for the encounter, the PAE should, in my opinion, focus on sports participation. It must be emphasized when the appointment is made that the PAE is not intended to be a comprehensive medical encounter or to replace an annual health maintenance examination. Metzl recently outlined three clear objectives of the PAE that can be accomplished if the clinician is properly trained and motivated (see Table 1, available int he print edition, is adapted from Metzl JD: Preparticipation examination of the adolescent athlete: Part 1. Peds Rev 2001;22:199).4
The purpose of this two-part review is to provide an overview of how best to approach the PAE. (For a comprehensive guide to the PAE, I strongly recommend purchasing the Preparticipation Physical Evaluation monograph,5 available online through several organizations, including the American Academy of Pediatrics [AAP].) Part 1 of this article offers an introduction to the PAE and focuses on key points that should be covered during the history portion of the evaluation. Part 2, covers the physical examination component. After reading both parts, the clinician should be able to recognize that he or she need not be a "sports medicine physician" to give young athletes a complete and beneficial PAE.
The PAE can be performed in one of three distinct formats:
The "assembly-line," or "locker room," physical. A single practitioner screens large numbers of athletes. Although sometimes necessary, the assembly-line physical should be avoided if possible, as it allows little time to thoroughly review the athlete's medical history and no privacy for the exam or a discussion of concerns.
The "station-based" examination. This is most appropriate when performing a mass PAE at a school or clinic; on the downside, it requires multiple personnel. Athletes proceed through a series of stations for height and weight measurements, blood pressure reading, cardiovascular examination, orthopedic screening, and final clearance. This exam format is the most effective and efficient PAE format.6
The "office-based" examinationand the focus of my discussion here. This type of PAE allows privacy for examination and discussion, as well as more (but not always sufficient) time. Also, the athlete is likely to be an established patient with a well-known medical history. The main disadvantage of the office-based PAE has been the great variation with which it is conducted.
Parents and school officials should be urged to schedule the PAE in the early summer, or at least six to eight weeks before the start of the athlete's season. Early timing makes it possible to complete any required consultations and injury rehabilitation before competition. The PAE may also be used for summer camp clearance.
Most authorities recommend performing an initial, comprehensive PAE upon entry to high school for all freshmen or students new to a school, followed by an interim history and focused examination in each of the remaining school years. The required frequency of the PAE varies by state or school district, however, and the evaluation may be required once a year. The American Heart Association (AHA) recommends preparticipation screening of high school athletes at two-year intervals.7
Although often overlooked, the PAE history and examination form is extremely important, as it provides a vital tool in eliciting and documenting a meaningful history. There are no national standards for PAE forms, and only 17 of 43 state forms evaluated in one study were judged to be "adequate" in regard to AHA recommendations for cardiovascular screening (see Table 2 in the print edition, from: Maron BJ, Bodison SA, Wesley YE, et al: Results of screening a large group of intercollegiate competitive athletes for a cardiovascular disease. J Am Coll Cardiol 1987;10:1214).8
Great variation also exists within states. A recent study of PAE forms used by high schools in Oregon showed that less than half the schools surveyed were using forms considered adequate by AHA standards.9 Therefore, given the wide variation of forms you may be asked to sign, I strongly recommend using the form available in the Preparticipation Physical Evaluation monograph,5 or one of similar content. The form we use in Oregon is available at www.osaa.org/forms (scroll down to "School Sports" in the directory).
Adolescents are at risk of injury or illness from a variety of behavior-related maladies. Because healthy adolescents rarely seek medical care, many experts stress that the PAE should be used to screen for, and educate the patient about, risk-taking behaviors. I was once a proponent of this PAE model,3 but my view has changed. I find it disingenuous to shift the focus of the encounter from what the athlete intended it to be. These patients expect a discussion of athletics-related topics and may have a variety of pertinent questionsonly to find a physician asking them about sexual activity and drug use. Even without additional, unrelated topics, there may not be enough time to cover the variety of sports-related issues during the encounter. I firmly believe it is better to concentrate on the athlete's concerns and build trust. Once trust is established, it is likely that the patient will return for other concerns or maladies. Of course, if the athlete does have any nonathletics-related questions at the time of the PAE, they should be addressed. In addition, it is appropriate to mention the deleterious effects of smoking tobacco on athletic performance.
The majority of important findings uncovered by the PAE will be discovered by taking a thorough medical history. Because much of the examination is directed by the history, parental or guardian histories must be obtained before proceeding with the athlete's evaluation. Again, this shows the importance of a good history form; the parent can fill out the form and provide comments on any positive answers before the athlete comes in for the PAE. The parent and athlete should fill out the form togetherone study showed a poor correlation between the medical history assessment given by the adolescent and that given by the parent.10
The following discussion represents key points that should be covered during the history portion of the PAE. Questions on these points are included in the history portion of recommended PAE forms, in addition to questions eliciting basic history information such as past surgeries and hospitalizations, current medications, and allergies.
Over the past two decades, a few highly publicized deaths of college and professional athletes has led to greater emphasis (perhaps too great) on screening for potentially fatal cardiovascular conditions.11 Sudden cardiac death (SCD) can be defined as a nontraumatic, nonviolent, unexpected death due to cardiac causes within one hour of the onset of symptoms (this definition is not universally accepted).12 A detailed review of the etiology and diagnosis of conditions that may raise the risk of SCD is beyond the scope of this discussion. However, a few important issues need to be discussed, as SCD screening has taken on a disproportionate importance in the overall schema of the PAE.
As devastating as these events are, they remain rare (approximately one in 200,000 athletes), and efforts at prevention have not been proved to be effective.1315 Disturbingly, Maron and colleagues found that, of 115 victims of SCD who they reviewed,16 only 4 (3%) had been suspected of having cardiac disease after undergoing a PAE. It is unclear whether this reflects the clinically silent nature of potentially fatal cardiac lesions or an inadequate preparticipation screening process.
More than 20 pathologic entities have been assigned as causes of SCD in young athletes (Table 3). Only a few lesions are responsible for the majority of deaths, however. Among 134 athletes who died of SCD,16 the most common causes were hypertrophic cardiomyopathy (36%) and possible hypertrophic cardiomyopathy (10%), and aberrant coronary arteries (13%). Other coronary anomalies accounted for 6% of deaths; ruptured aortic aneurysm, for 5%; tunneled coronary artery, 5%; and aortic valve stenosis, 4%. Most of these conditions cannot be detected by physical examination alone. Historical clues such as syncope or chest pain during exercise and a history of sudden death in any first-degree relative younger than 50 years old may, however, indicate increased risk of SCD.
Multiple studies have concluded that a thorough history and physical examination is as effective as diagnostic screening tests in finding potentially dangerous cardiovascular conditions.1315 A consensus panel appointed by the AHA concluded that a careful history and physical examination should be the standard for preparticipation cardiovascular screening,17 because screening electrocardiograms (ECG) and echocardiography are complicated by high false-positive rates.13,15,18,19 The panel developed "recommendations and guidelines for the most prudent, practical, and effective screening procedures and strategies" (Table 2).
Certainly, diagnostic tools such as ECG and echocardiography may identify a small number of individuals at risk of SCD. However, the emotional and financial costs are high, considering the limits of available screening instruments. Given the low prevalence of cardiac anomalies, it has been estimated that 200,000 individual athletes would need to be screened to identify the single individual who may die.20 That means that even if a near-perfect screening test for SCD existed, one with a specificity and sensitivity of 99%, we would be left with only one true positive testand 1,999 false-positive results. One can easily extrapolate the number of false-positive results that would be produced nationwide if the millions of high school students who participate in sports were screened.
An infrequent cause of SCD that can be recognized during the PAE is Marfan syndrome. This autosomal dominant, inherited connective tissue disorder occurs in about one in 10,000 people. Affected people are at increased risk of SCD from progressive dilatation of the aortic root culminating in complete dissection or rupture of the aorta.
The diagnosis of Marfan syndrome is based on clinical criteria, although genetic testing may be appropriate in families with multiple affected members. History and physical exam findings that suggest Marfan syndrome include a family history of the condition; heart murmur or midsystolic click; kyphoscoliosis; anterior thoracic deformity (pectus excavatum or carinatum); arm span greater than height; myopia; ectopic lens; and an upper:lower body ratio more than one standard deviation below the mean. Additional clinical features that may be present include tall stature; long thin limbs (dolichostenomelia); long, thin facies; hyperextensible joints; and ability to significantly overlap the thumb and fifth digit while encircling the thin wrist.
If you suspect the disorder, seek cardiology and ophthalmology consultation, and follow with referral to a geneticist. Decisions regarding sports participation should be made by the consulting cardiologist.
Most significant positive findings during the PAE relate to the musculoskeletal system,21 and almost all of those findings are apparent following a detailed history.22 Past studies have found that the single most important predictive factor of injury in an upcoming sports season is having suffered an injury to the same body part the previous year.23 Athletics injuries are often not rehabilitated properly, even if initially diagnosed and treated correctly. A simple review of past injuries that have kept the athlete out of participation or limited full participation may reveal a number of positive findings.
As many as 90% of people with asthma also have exercise-induced bronchospasm (EIB), and it is estimated that as many as 10% of athletes without a history of asthma may have EIB. Unfortunately, the diagnosis of EIB is not easy to make based on the history and physical examination alone. Screening questions, including those on the recommended PAE form, are somewhat specific but highly insensitive for establishing the diagnosis. The cost-effectiveness of mass-population EIB screening of athletes has not been studied.
Athletes with a suspicious history should undergo exercise testing to confirm or exclude the presence of the disease. The gold standard for diagnosing EIB remains spirometry performed five to 10 minutes after four to eight minutes of high intensity exercise. A drop of 10% or more in FEV1 (forced expiratory volume in one second) is diagnostic for EIB.
Any athlete who has suffered a concussion is at increased risk of sustaining a subsequent one.24,25 Recent evidence suggests that multiple concussions have a cumulative effect, with each subsequent injury resulting in further cognitive deficit. In addition, although the occurrences have been rare, a series of case reports suggests that young athletes may be at risk of devastating brain injury if they suffer a subsequent concussion while still symptomatic from a prior injury (the so-called second impact syndrome).26
When reviewing an athlete's concussion history, pay specific attention to the duration of symptoms following the injury. Also inquire about the specific types of symptoms (dizziness, headaches, memory loss) and the duration and degree of their effect on work or school performance. A history of loss of consciousness has far less clinical relevance than the severity and duration of "posttraumatic amnesia (confusion)."27,28 In addition, brief symptoms following a violent collision, often referred to as "having your bell rung," should be elicited, as many athletes believe that such episodes are a normal part of collision sports.
The clinician should become familiar with at least one standardized concussion grading scale to objectively classify the severity of each reported head injury. More than 20 such scales have been developed; I prefer Cantu's latest guidelines (Table 4).28
Do not clear for athletic participation any athlete who is still symptomatic from a concussion. Strongly consider neurology consultation and psychometric testing for any athlete who has suffered more than two or three grade 1 concussions, or more than one or two grade 2 or 3 concussions.
Football players, particularly offensive and defensive lineman, may have a history of "burners" or "stingers." These injuries involve a stretching and compression of the brachial plexus, resulting in a surge of pain radiating down the length of the arm. Numbness, tingling, and weakness may persist for minutes or days. Any athlete with a history of brachial plexus injury requires a detailed physical examination focused on assessing neck range of motion and arm and shoulder strength, and an upper extremity neurologic exam. If an athlete has a history of multiple brachial plexus injuries, or abnormal findings on physical exam, do not clear him (or her) for contact sports until he has been evaluated by a neurosurgeon.
A seizure disorder does not automatically disqualify an athlete from participation. AAP guidelines specify that an athlete with a well-controlled seizure disorder may participate in a variety of conventional school-sponsored athletic events. However, special consideration should be given to sports that may be considered high-risk, such as high apparatus gymnastics, high diving, and skiing. In these circumstances, consultation with a neurologist may be considered. Any athlete with a poorly controlled seizure disorder (seizures within the last six months) should be carefully considered for only a small variety of non-contact sports. Obviously, any athlete with seizures triggered by physical activity should not be cleared until seizures have been controlled.
Heat stroke is a leading cause of death in young athletes, with football players at particularly high riskheavy equipment and late-summer climate are a potentially lethal combination. Obtaining a history of heat-related illness is important because athletes who have suffered heat stroke are at increased risk of additional occurrences. A thorough history of the event must be taken. Precipitating factors include obesity, febrile illness, poor acclimatization, dehydration, and medications such as antihistamines, antidepressants, or psychomotor stimulants. There is also a growing belief that so-called nutritional supplements such as ephedra and creatine may contribute to heat-related illnesses (further discussion on this later). Athletes should not be disqualified based on a history of heat illness, but preventive measures should be taken.
Few restrictions are warranted for athletes with unpaired organs. For athletes with a single kidney, the AAP recommends individual assessment for contact, collision, and limited-contact sports. I caution athletes with one kidney about the risks of sports participation and do not give clearance for participation in a contact or collision sport unless the patient and parent understand those risks. A protective "flak" jacket should be worn when feasible, even by those participating in a limited-contact sport (such as baseball, volleyball, and downhill skiing).
Athletes with a single testicle should wear a protective cup in all sports, even though risk of further injury is low. A single ovary requires no special considerations because the ovaries are well insulated from trauma.
An athlete who has a best-corrected vision of less than 20/40 in one eye is considered to have one functional eye. These athletes and their parents must carefully consider the consequences of participating in sports with a high risk of eye injury (football, racquetball, baseball, basketball). If they choose to participate, protective eyewear is mandatory.
The importance of obtaining a complete history of nutrition and use of supplements from the young athlete cannot be overlooked. Perhaps no population is more vulnerable to the aggressive advertising and exaggerated claims of the diet and supplement industries. You will be in a much more credible position to discuss the risks and benefits of such products if you have a basic understanding of their claimed benefits. A brief discussion of dietary supplements appears in "Supplement use by adolescents". You can also refer to "Nutritional supplements and the young athlete: What you need to know" in the July issue 2001.
Attention must also be paid to a history of unusual eating habits or patterns (Table 5). Some studies show a prevalence of eating disorders in athletes ranging from 5% to 33%, compared with 1% to 3% in the general population.29 More than 95% of those with eating disorders are female. The incidence of such problems is increased in weight-class sports (wrestling, weightlifting, crew), aesthetic sports (gymnastics, figure skating, diving), and endurance sports (long distance running, swimming, cycling).
Although the signs and symptoms of anorexia nervosa and bulimia nervosa are sometimes subtle, the overall problem of "disordered eating" may be more apparent. Many young athletes do not meet diagnostic criteria for an eating disorder but display a wide variety of unhealthy, and potentially dangerous, eating behaviors that must be addressed. [For more on this topic, see "Aiming for healthy weight in wrestlers and other athletes," in the September 2001 issue, and "When you suspect an eating disorder" in the November 1996 issue.]
The increasing use of stimulant medications for the treatment of attention deficit hyperactivity disorder (ADHD) is an area of uncertainty in the field of sports medicine. The majority of ADHD medications (Ritalin, Dexedrine, Adderall) are amphetamine derivatives and, therefore, are banned by the National Collegiate Athletic Association and International Olympic Committee. When given appropriate medication, young athletes with ADHD show not just benefits in the classroom but also increased ability to concentrate on tasks during athletic practices, along with improvements in balance and coordination (perhaps secondary to improved concentration).30 The ergogenic effects of these medications on this population are unknown. Athletes with ADHD should continue to take their medications as prescribed, regardless of athletic activity. Consideration may be given to withholding the medication during times of high heat and humidity, in an effort to decrease the risk, albeit small, of heat illness (see the previous discussion on heat illness).
A detailed menstrual history should be obtained from all female athletes. Any history of primary amenorrhea (absence of menses by age 16), secondary amenorrhea (absence of menses for more than three consecutive cycles after regular monthly cycles have become established), or other irregularities should be explored. Many female athletes believe that menstrual irregularities (absent menses or scant flow) during the competitive season are normal, and will not perceive them as a problem unless specifically questioned. Such irregularity is typically indicative of poor nutritional intake, often the result of burning more calories than consumed. This energy (calorie) deficit may be unintentional (poor eating habits) or intentional (disordered eating).
Female athletes with a history of primary or secondary amenorrhea should be further evaluated. Nutrition education or referral to a nutritionist may also be appropriate. Any history of stress fractures should raise suspicion for the presence of the "female athlete triad" (anorexia, amenorrhea, osteoporosis) and should prompt a thorough training history (overload, poor technique, "too much, too soon") and a review of menstrual history and nutritional intake.
Athletes with sickle cell trait should be allowed to participate without restriction in all athletic activities. A study of military recruits several years ago that revealed a 20-fold increase in sudden death among those with sickle cell trait raised concerns about the safety of athletic activity in affected people.31 However, the military's mortality rate declined dramatically following efforts to prevent exertional heat illness. Therefore, caution should be taken during hot, humid weather. Athletes with sickle cell trait should take steps to become acclimatized during the preseason, stay well hydrated, and adjust their training schedule if indicated.
Despite the abundance of high-risk health behaviors that are topics for patient education, the PAE is best used for its intended purpose-to evaluate an athlete's suitability for sports participation and, barring any contraindications, to prepare him or her for safe competition. Once a complete medical history has been taken, attention turns to the physical examination, as detailed in "Making the preparticipation athletic evaluation more than just a 'sports physical,' Part 2."
1. Donahue P: Preparticipation exams: How to detect a teenage crisis. Phys Sportsmed 1990;18:53
2. Cavanaugh RM, Miller ML, Henneberger PK: The preparticipation athletic examination of adolescents: A missed opportunity? Curr Probl Pediatr 1997;27:109
3. Koester MC: Refocusing the adolescent preparticipation physical evaluation toward preventive health care. J Athl Train 1995;30:352
4. Metzl JD: Preparticipation examination of the adolescent athlete: Part 1. Peds Rev 2001;22:199
5. Smith DM, Kovan JR, Rich BSE, et al: Preparticipation Physical Evaluation, ed 2. Minneapolis, McGraw-Hill, 1997
6. DuRant RH, Seymore C, Linder CW, et al: The preparticipation examination of athletes: Comparison of single and multiple examiners. AJDC 1985;139:657
7. Maron BJ, Thompson PD, Puffer JC, et al: Cardiovascular preparticipation screening of competitive athletes: Addendum. An addendum to a statement for health professionals from the Sudden Death Committee (Council on Clinical Cardiology) and the Congenital Cardiac Defects Committee (Council on Cardiovascular Disease in the Young), American Heart Association. Circulation 1998;97:2294
8. Glover DW, Maron BJ: Profile of preparticipation cardiovascular screening for high school athletes. JAMA 1998;279:1817
9. Koester MC, Amundson CL: Preparticipation screening of high school athletes. Phys Sportsmed 2003;31:35
10. Carek PJ, Futrell M, Hueston WJ: The preparticipation physical examination history: Who has the correct answers? Clin J Sport Med 1999;9:124
11. Koester MC: A review of sudden cardiac death in young athletes and strategies for preparticipation cardiovascular screening. J Athl Train 2001;36:197
12. Myerburg RJ: Sudden death. J Contin Educ Cardiol 1978;13:15
13. Fuller CM, McNulty CM, Spring DA, et al: Prospective screening of 5,615 high school athletes for risk of sudden cardiac death. Med Sci Sports Exerc 1997;29:1131
14. Maron BJ, Bodison SA, Wesley YE, et al: Results of screening a large group of intercollegiate competitive athletes for cardiovascular disease. J Am Coll Cardiol 1987;10:1214
15. Murry PM, Cantwell JD, Heath DL, et al: The role of limited echocardiography in screening athletes. Am J Cardiol 1995;76:849
16. Maron BJ, Shirani J, Poliac LC, et al: Sudden death in young competitive athletes. JAMA 1996;276:199
17. Maron BJ, Thompson PD, Puffer JC, et al: Cardiovascular preparticipation screening of competitive athletes. Circulation 1996;94:850
18. Lewis JF, Maron BJ, Diggs JA, et al: Preparticipation echocardiographic screening for cardiovascular disease in a large, predominantly black population of collegiate athletes. Am J Cardiol 1989;64:1029
19. Corrado D, Basso C, Schiavon M, et al: Screening for hypertrophic cardiomyopathy in young athletes. N Engl J Med 1998;339:364
20. Ades PA: Preventing sudden death. Phys Sportsmed Sept 1992;20:75
21. Smith J, Laskowski ER: The preparticipation physical examination: Mayo clinic experience with 2,739 examinations. Mayo Clin Proc 1998;73:419
22. Gomez JE, Landry GL, Bernhardt DT: Critical evaluation of the 2-minute orthopedic screening examination. AJDC 1993;147:1109
23. DuRant RH, Pendergrast RA, Seymore C, et al: J. Findings from the preparticipation athletic examination and athletic injuries. AJDC 1992;146:85
24. Gerberich SG, Priest JD, Boen JR, et al: Concussion incidences and severity in secondary school varsity football players. Am J Public Health 1983;73:1370
25. Guskiewicz KM, Weaver NL, Padua DA, et al: Epidemiology of concussion in collegiate and high school football players. Am J Sports Med 2000;28: 643
26. Cantu RC: Second impact syndrome. Clin Sports Med 1998;17:37
27. Lovell M, Collins M, Field M, et al: Recovery from concussion in high school athletes. J Neurosurgery 2003;98:296
28. Cantu RC: Posttraumatic retrograde and anterograde amnesia: Pathophysiology and implications in grading safe return to play. J Athl Train. 2001;36:244
29. Garner DM, Rosen LW, Barry D: Eating disorders among athletes: Research and recommendations. Child Adol Psych Clin North Am 1999;7:839
30. Hickey G, Fricker P: Attention deficit hyperactivity disorder, CNS stimulants and sport. Sports Med 1999;27:11
31. Kark JA, Ward FT: Exercise and hemoglobin S. Semin Hematol 1994;31:18
The allure of college scholarships, professional contracts, and media adulation has put adolescent athletes under enormous pressure to succeed. The use of ergogenic supplements to achieve a competitive edge, once used only by professional and Olympic athletes, has now trickled down to the high school locker room. Many of these supplements are touted as safe and "natural" despite a lack of scientific proof.
Clinicians should be prepared to ask young athletes in a specific manner about their use of these products and to have an honest discussion about the use of supplements. Although many claims made by manufacturers are bogus, some products, such as creatine, have been shown to have at least some positive effect on strength development. Regardless of any actual benefit, all these products are expensive. Many adolescents will respond better to practical arguments against wasting money in the here and now rather than words about the "unknown long-term potential" that are intended to scare them.
The sport that the athlete participates in will likely have a bearing on what products he or she experiments with. Athletes involved in power sports such as weight lifting, throwing events, and football are more likely to use androstenedione, creatine, protein powders, amino acid supplements, and anabolic steroids. Athletes involved in speed and endurance sports or sports requiring the maintenance of a certain weight are more likely to utilize energy-enhancing supplements.
The accompanying table provides a useful reference. Only supplements available over the counter are listed. Illegal substances, such as gammahydroxybutyrate (claimed to promote the release of growth hormone during deep sleep) and anabolic steroids, are not included.
|Product category/product names||Claimed or perceived benefits||Comments|
|Amino acids||Increases muscle mass||No proven benefit|
|Specific amino acids||Stimulates release of growth hormone||Studies disprove theory. Can cause nausea and diarrhea in high doses|
|Androstenedione||Increases muscle mass and strength, achieved by raising the blood testosterone level||Reduces natural testosterone levels. Unknown long-term effects. Banned by IOC, NCAA and NFL|
|ß-hydroxy- ß-methylbutyrate||Improves muscle repair after a workout||One study found some benefits in strength development with no side effects|
|Creatine||Induces production of energy at the cellular level; increases conversion of ADP to ATP||Potential for renal damage muscle cramps, nausea and diarrhea. One of the few products with studies showing benefits|
|Dehydroepiandrosterone||Increases muscle mass and strength, achieved by raising the blood testosterone level||May be similar to androstenedione, but long term effects are unknown. Banned by IOC and NCAA|
|Ephedra/caffeine (mg||Increases metabolism (including burning of fat), energy, endurance, and reaction times||Associated with potential for heat illness and cardiac dysrhythmias|
|Estrogen inhibitors||Inhibits estrogen activity to enhance muscle development. Often used with androstenedione||Reduces estrogen activity. Unknown long-term effects|
Michael Koester. The preparticipation athletic evaluation--Part 1.