Performance Enhancing Drugs Education

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    The National Strength and Conditioning Association is committed to supporting and disseminating researched-based knowledge and its practical application as pertains to sport science. Unfortunately, illicit performance enhancing drugs are part of the competitive world at multiple levels. Thus the NSCA is committed to provide the most recent and applied information to strength and conditioning professionals, athletes, parents and coaches. Drug use in sport is a multi-factorial problem and having long-term, sustainable solutions is the essence of the answer.

    Three Primary Tenets

    Performance Enhancing Drug Education: An overview of what performance enhancing drugs are, how they work, what are the effects of usage and other fundamental information is presented. The depth of this information will vary depending on who the target population is.

    Strength and Conditioning: In order for athletes and individuals to reach their physical best they need a sound training program. This tenant addresses the fundamental training principals and their application.

    Nutrition: A fundamental nutrition program is a building block of peak performance. The six essential nutrients, their correct amounts and meal timing should be addressed. Additionally safe, legal and effective sport supplements could be an option.

    Please use navigation tab to browse articles, resources, and downloads.

    There are four types of performance enhancing drugs:

    • Anabolic steroids
    • Masking Agents
    • Stimulants
    • Erythropoietin
    Learn more about each of these steroids by following the links on the left.

    1.  What is one of the main functions of anabolic steroids?

    a.   Build red blood cells

    b.   Decrease body fat

    c.   Assimilate protein

    d.   Accentuate aggressive behavior


    2.  What does the term "anabolic" mean?

    a.   With oxygen

    b.   Without oxygen

    c.   Muscle wasting

    d.   Muscle building


    3.  The drug EPO serves what function?

    a.   Build muscle

    b.   Build protein

    c.   Produce white blood cells

    d.   Produce red blood cells


    4.  Masking agents are used to do what?

    a.   Protect from germs and bacteria

    b.   Hide the presence of a drug use

    c.   Enhance the effect of an anabolic steroid

    d.   Enhance the effect of EPO


    5.  Three tenants of a performance enhancing drug education program maybe?

    a.   Masking agents, anabolic steroids and stimulants

    b.   Physical, mental and emotional

    c.   Drug education, strength and conditioning, and nutrition

    d.   Pre-pubescence, puberty and adult


    6.  What is a dose-response relationship?

    a.   more of the drug is better

    b.   more of the drug has no effect

    c.   there is an optimal dose accompanied by a specific response

    d.   more of the drug is consumed there will be a greater response


    7.  What are some side effects of stimulants?

    a.   Alterations on mood and concentration

    b.   Alterations on mood and alertness

    c.   Possible increase in heart rate and blood pressure, restlessness, nervousness, insomnia, increased urination, and tremors

    d.   All of the above


    8.  Diuretics maybe considered a what?

    a.   Stimulant

    b.   Anabolic steroid

    c.   Masking agent

    d.   Doping agent


    9.  Epitestosterone maybe considered a what?

    a.   Stimulant

    b.   Anabolic steroid

    c.   Masking agent

    d.   Doping agent


    10.  What are some possible side effects of anabolic steroid use?

    a.   Increase the risk for certain medical conditions

    b.   Lipid profile changes, elevated blood pressure, acne

    c.   Arrest longitudinal bone growth

    d.   All of the above


    ANSWERS: 1. c  2. d  3. d  4. b  5. c  6. d  7. d  8. c  9. c  10. d  


    These files can be downloaded and handed out to parents, coaches, and athletes to further combat the use of performance enhancing drugs.

    Additional Web Resources


    Understanding Anabolic Steroid Use, Goldberg, L. Healthy Learning and NSCA.

    Anabolic steroid use is increasing among adolescents in the United States. Featuring two separate video programs on one DVD (Understanding Anabolic Steroid Use and Preventing Anabolic Steroid Use), Anabolic Steroid Use reviews the current problem of anabolic steroid use and the intake of other illicit and controlled substances and athletic supplements by adolescent athletes. The DVD also covers the benefits and risks of anabolic steroid use, the risk factors involved in such use among young athletes, and how the marketing of steroid images focuses on only the benefits of steroids and downplays their potent and dangerous side effects. In addition, two state-of-the-art programs that are designed to help effectively reduce substance abuse among young athletes are discussed. Produced in cooperation with the National Strength and Conditioning Association.


    Anabolic Steroids in Sport and Exercise, 2nd Edition, Yesalis, C., 2000, Human Kinetics.

    This up-to-date text features the latest research and references on steroid use among professional, high school, collegiate and Olympic level athletes. All aspects of steroid use are covered including use, abuse, dependency, physical and psychological side effects, intervention, withdrawal, treatment and legal issues.

    Essentials of Strength and Conditioning , Baechle, T., Earle, R, 3rd edition, 2008, Human Kinetics. 

    Students, coaches, strength and conditioning specialists, personal trainers, athletic trainers, and other sport science professionals will find state-of-the-art, comprehensive information on structure and function of body systems, training adaptations, testing and evaluation,exercise techniques, program design (aerobic and anaerobic) and training facility organization and administration.

    Performance Enhancing Substances in Sport and Exercise

    Two well-known and highly respected authorities on performance-enhancing substance use in sport and exercise have assembled the contributions of leading experts in the field. This authoritative and heavily referenced book includes everything from anabolics and stimulants to gene transfer therapy and beyond. It presents the following:

    • The history of doping in sport and exercise
    • The latest clinical and scientific research and reference material available concerning the use and abuse of performance-enhancing substances among professional, Olympic-level, college, and high school athletes
    • Important developments in the legal aspects of use in sport and exercise
    • New information related to substance and drug testing
    • The issues surrounding assessment of the efficacy of performance-enhancing substances
    • Information on the new and emerging technologies-such as gene transfer therapy and new drug delivery systems-that have potential for abuse by athletes  


    1. Leone, J, Gray, K, Rossi, J and Colandreo, R. Using the Transtheoretical Model to Address Androgenic-Anabolic Steroid Use in Adolescents and Young Adults: Part One. Strength and Conditioning Journal 30(6): 47-54, 2008.
    2. Leone, J, Gray, K, Rossi, J and Colandreo, R. Using the Transtheoretical Model to Address Androgenic-Anabolic Steroid Use in Adolescents and Young Adults: Part Two. Strength and Conditioning Journal 31(1): 13-22, 2009.
    3. Riewald, S. Are we Dopes to Ignore Gene Doping? Strength and Conditioning Journal 27(1). 36-37, 2005.

    Position Stand on Androgen and Human Growth Hormone Use

    Hoffman, JR, Kraemer, WJ, Bhasin, S, Storer, T, Ratamess, NA, Haff, GG, Willoughby, DS, and Rogol, AD.

    Journal of Strength and Conditioning Research 23(5): S1-S59, 2009

    Article as PDF.


    Perceived yet often misunderstood demands of a sport, overt benefits of anabolic drugs, and the inability to be offered any effective alternatives has fueled anabolic drug abuse despite any consequences. Motivational interactions with many situational demands including the desire for improved body image, sport performance, physical function, and body size influence and fuel such negative decisions. Positive countermeasures to deter the abuse of anabolic drugs are complex and yet unclear. Furthermore, anabolic drugs work and the optimized training and nutritional programs needed to cut into the magnitude of improvement mediated by drug abuse require more work, dedication, and preparation on the part of both athletes and coaches alike. Few shortcuts are available to the athlete who desires to train naturally. Historically, the NSCA has placed an emphasis on education to help athletes, coaches, and strength and conditioning professionals become more knowledgeable, highly skilled, and technically trained in their approach to exercise program design and implementation. Optimizing nutritional strategies are a vital interface to help cope with exercise and sport demands (516-518). In addition, research-based supplements will also have to be acknowledged as a strategic set of tools (e.g., protein supplements before and after resistance exercise workout) that can be used in conjunction with optimized nutrition to allow more effective adaptation and recovery from exercise. Resistance exercise is the most effective anabolic form of exercise, and over the past 20 years, the research base for resistance exercise has just started to develop to a significant volume of work to help in the decision-making process in program design (187,248,305). The interface with nutritional strategies has been less studied, yet may yield even greater benefits to the individual athlete in their attempt to train naturally. Nevertheless, these are the 2 domains that require the most attention when trying to optimize the physical adaptations to exercise training without drug use.

    Recent surveys indicate that the prevalence of androgen use among adolescents has decreased over the past 10-15 years (154,159,246,253,370,441,493). The decrease in androgen use among these students may be attributed to several factors related to education and viable alternatives (i.e., sport supplements) to substitute for illegal drug use. Although success has been achieved in using peer pressure to educate high school athletes on behaviors designed to reduce the intent to use androgens (206), it has not had the far-reaching effect desired. It would appear that using the people who have the greatest influence on adolescents (coaches and teachers) be the primary focus of the educational program. It becomes imperative that coaches provide realistic training goals for their athletes and understand the difference between normal physiological adaptation to training or that is pharmaceutically enhanced. Only through a stringent coaching certification program will academic institutions be ensured that coaches that they hire will have the minimal knowledge to provide support to their athletes in helping them make the correct choices regarding sport supplements and performance-enhancing drugs.

    The NSCA rejects the use of androgens and hGH or any performance-enhancing drugs on the basis of ethics, the ideals of fair play in competition, and concerns for the athlete's health. The NSCA has based this position stand on a critical analysis of the scientific literature evaluating the effects of androgens and human growth hormone on human physiology and performance. The use of anabolic drugs to enhance athletic performance has become a major concern for professional sport organizations, sport governing bodies, and the federal government. It is the belief of the NSCA that through education and research we can mitigate the abuse of androgens and hGH by athletes. Due to the diversity of testosterone-related drugs and molecules, the term androgens is believed to be a more appropriate term for anabolic steroids.

    1. Androgen administration in a concentration-dependent manner increases lean body mass, muscle mass, and maximal voluntary strength in men. However, the upper concentration for maximum effects remains unknown.
    2. Combined administration of androgens and resistance exercise training is associated with greater gains in lean body mass, muscle size, and maximal voluntary strength in men than either intervention alone.
    3. Testosterone therapy is approved only for the treatment of hypogonadism in adolescent and adult men. However, the anabolic applications of androgens and selective AR modulators are being explored for the functional limitations associated with aging and some types of chronic illness.
    4. The magnitude and frequency of adverse effects among androgen users have not been systematically studied. Potential adverse effects of androgen use in men include suppression of the hypothalamic-pituitary-gonadal axis, mood and behavior disorders, increased risk of cardiovascular disease, hepatic dysfunction with oral androgens, insulin resistance, glucose intolerance, acne, gynecomastia, and withdrawal after discontinuation. In addition, the polypharmacy of many androgen users (psychoactive and accessory drugs) may have serious adverse effects of their own.
    5. The adverse effects of androgen administration in women are similar to those noted in men. In addition, women using androgens may also experience virilizing side effects such as enlargement of the clitoris, deepening of the voice, hirsutism, and changes in body habitus. These changes may not be reversible on cessation of androgen use.
    6. In pre- and peripubertal children, androgen use may lead to virilization, premature epiphyseal closure, and resultant adult short stature.
    7. Since 1990, the use of androgens for a nonmedical purpose is illegal. Androgens are labeled as a schedule III drug. Possession of any schedule III substance including androgens is punishable by fine, prison time, or both. Prescribing androgens for bodybuilding or enhanced athletic performance is also punishable as noted above.
    8. Human growth hormone increases lean body mass within weeks of administration; however, the majority of the change is within the water compartment and not in body cell mass.
    9. Human growth hormone is unlikely to be administered as a single agent but often in combination with androgens.
    10. Combined administration of hGH and resistance exercise training is associated with minimal gains in lean body mass, muscle size, and maximal voluntary strength in men compared with resistance exercise alone.
    11. Human growth hormone is approved for the therapy of children and adolescents with growth hormone deficiency, Turner syndrome, small for gestational age with failure to catch-up to the normal growth curves, chronic kidney disease, Prader-Willi syndrome, idiopathic short stature, Noonan syndrome, and SHOX gene deletion. For adults, hGH is approved for the treatment of GH deficiency, AIDS/HIV with muscle wasting, and short bowel syndrome.
    12. The magnitude and frequency of adverse events associated with hGH use are clearly dose related. Potential adverse events include suppression of the hypothalamic-pituitary GH/IGF-1 axis, water retention, edema, increased intracranial pressure, joint and muscle aches, and those of needle injection (hepatitis and HIV/AIDS). These should be the same in women as well as in men.
    13. Continued effort should be made to educate athletes, coaches, parents, physicians, and athletic trainers along with the general public on androgen and hGH use and abuse. Educational programs should focus on potential medical risks of these illegal performance-enhancing drugs use, optimizing training programs and concurrent nutritional strategies to enhance physiological adaptation and performance. In addition, educating coaches on setting realistic training goals and expectations for their athletes will help reduce the pressures to use illegal PED and assist in potentially identifying potential users of illegal PED.
    14. The NSCA supports and promotes additional research funding to be directed toward effective educational programs, documentation of both acute and long-term adverse effects of androgen and hGH abuse, strategies for optimizing athletic performance through training and nutritional interventions, strategies to help athletes discontinue androgen and hGH use, and strategies for the detection of abuse of androgens and hGH.


    Anabolic steroids are manmade derivatives of the male hormone "testosterone". Testosterone is produced by the testes in males and relatively smaller quantities in the adrenal glands and ovaries of females. Exogenous testosterone itself is not as effective in building muscle as chemically altered derivatives of testosterone. These derivatives of testosterone are what most people understand anabolic steroids to be. "Juice" is a synonymous term for steroids in the non-medical community. 

    Function and Use 

    Testosterone has many different functions in the body. One of the main functions is to synthesize protein resulting in additional muscle size and strength which is obviously compelling to athletes, competitive and otherwise. 

    In order for steroids to be effective they must be taken in dosages that exceed the bodies' natural production. The level needed will depend on age, gender and each person's unique physiology. There is a dose-response relationship that exists with the use of steroids. This means if more of the drug is consumed there will be a greater response, both negative and positive. Recent research has also indicated that there has been an upward trend in the total amount of steroids ingested by users compared to users ten years prior. 

    "Stacking" of steroids is a practice used that incorporates the administration of two or more steroids or illicit muscle building agents simultaneously. Stacking will often gradually increase the amount used over the course of weeks and then taper the use toward the end of the cycle (duration of time used).

    Side Effects 

    Some of the side effects that are associated with steroid use are increased body hair, male-pattern baldness, aggressive behavior and stimulation of the sebaceous glands contributing to acne. It also should be noted that the degree and severity of these side effects are often transient and reverse with the cessation of steroid use. Additionally, individuals will respond differently depending on each person's unique body physiology. 

    Steroid use is known to increase the risk for certain medical conditions. Although many of the physiological and psychological changes associated with anabolic steroid use may be transient (e.g. lipid profile changes, elevated blood pressure, acne), individuals with underlying disease may be at risk for serious adverse events. In women, some of the masculinizing effects from steroid may be permanent, and steroid use by adolescent males may prematurely arrest longitudinal bone growth, resulting in prematurely reaching their maximum height.

    Take Home Message 

    Both the risks and the benefits of steroid have been exaggerated by the lay press and general public. Athletes and coaches alike are confused about what fact and what is myth concerning steroids. The NSCA encourages honest and full disclosure of known risks and benefits of steroids in drug education programs in an attempt to stem the abuse of steroids. 



    Masking agents are drugs or compounds that are taken with the express purpose of hiding or "masking" the presence of specific illegal drugs that are screened for athletic drug testing (4). Masking agents have the potential to impair or conceal the banned substance in the urine (4). The most common masking agents include diuretics, epitestosterone, probenecid and plasma volume expanders (4, 8). Each of these categories is addressed. 

    Function and Use 

    Diuretics: Diuretics have been placed on the prohibited list for some time because of two reasons: 1) they facilitate weight loss via their ability to enhance rapid water loss via urine excretion and 2) they have the potential to rapidly dilute the urine by increasing renal flow. When utilized as a "masking" agent diuretics dilute the urine, which results in lower levels of the banned substance being excreted from the body. This can therefore make it more difficult for the laboratories conducting doping controls to detect (8). 

    The dosage of diuretic administered varies depending upon the actual drug that is administered. When looking at the diuretic furmosimide the clinical dosage for adults is to give 20-80 mg as a single dosage. However, if needed the same dosage can be give 6-8 hours later. With this dosage scheme a very rapid secretion of urine occurs (1).

    Epitestosterone: When athletes take exogenous testosterone two basic methods can be employed to "mask" the use of these compounds: 1) Utilize transdermal delivery mechanisms or 2) use epitestosterone in conjunction with testosterone use. 

    One mechanism for "masking" testosterone use is to use transdermal preparations which have the potential to raise circulating testosterone and are only detectable by doping controls via blood profiles in the period of 4-8 hours after administration (2). If the athlete were to utilize transdermal solutions in a systematic method they may be able to administer a low dosage of testosterone that would be below the testing standards. No pharmaceutical dosages for epitestosterone are available because epitestosterone is only available as a chemical (2).

    Probenecid: Probenecid has been shown to reduce the excretion of anabolic steroids into the urine (3), thus potentially reducing the level of androgens below the levels established. In animal studies it has been reported that the co-administration of probenecid and the anabolic steroid stanozolol results in an increased disappearance of the anabolic steroid from the plasma. Additionally, the co-administration of these drugs results in a decrease in the total amount of stanozolol excreted into the urine (7). 

    Alpha-Reductase Inhibitors: Alpha-reductase inhibitors are generally used for the treatment of prostate hypertrophy and androgenic alopecia (1). It appears that alph-reductase inhibitors have the potential to significantly impact steroid profiles which are used in drug testing. Specifically, they appear to complicate or even prevent the detection of some prohibited substances. 

    The recommended medical dosage for the common alpha-reductase inhibitor, Dutasteride is 0.5 mg taken once daily. However, studies have shown that between 5-40 mg of Dutasteride can be taken per day with minimal adverse side effects. The recommended clinical dosage of Finasteride, another common alpha-reductase inhibitor, is 1 mg per day. Dosages of 80-400 mg per day have been shown to produce minimal adverse reactions (1).

    Plasma Volume Expanders: Plasma volume expanders (i.e. albumin, dextran or hydroxyethyl startch) can be used by athletes for several reasons: 1) to prevent dehydration (6) or 2) in order to mask recombinant erythropoietin use (5). When plasma volume expanders are taken with recombinant erythropoietin they can elevate the blood volume while maintaining a blood profile level that is within the legal range (6). 

    Generally plasma expanders such as albumin are administered with other compounds such as blood, plasma, or saline. Generally, the total dose and rate of infusion relies on the individual's condition and response to treatment. When plasma expanders are administered to adults for medical reasons the general amount used is between 250-500 ml, but dosages should be individualized (1).

    Side effects 

    Diuretics: The utilization of diuretics may result in the occurrence of heart arrhythmias, dehydration, muscle cramping, blood volume depletion, significant drops in blood pressure and severe electrolyte imbalances. These arrhythmias can occur as a result of a deficiency of potassium in the blood and dehydration (4). 

    Probenecid: Probenecid use generally results in very few minor side effects. These side effects can include the formation of kidney stones, acute gouty arthritis, hair loss, skin rash, headache, nausea, sore gums, fever and in very rare cases severe anemias (1).

    Alpha-Reductase Inhibitors: The most significant side effects associated with the use of some of these masking agents are associated with reproductive dysfunction (1). Reproductive side effects include a decreased libido, increased occurrence of erectile dysfunction, and an increase occurrence in ejaculation disorders (1).

    Plasma Expanders: The use of plasma expanders such as albumin can very rarely result in adverse effects. These effects are usually marked by nausea, fever, chills or hives. 


    1. Physicians' Desk Reference. Montvale, NJ: Thomson, 2004.

    2. Catlin DH, Hatton CK, and Starcevic SH. Issues in detecting abuse of xenobiotic anabolic steroids and testosterone by analysis of athletes' urine. Clin Chem 43: 1280-1288, 1997.

    3. Duntas LH and Parisis C. Doping: a challenge to the endocrinologist. A reappraisal in view of the Olympic Games of 2004. Hormones (Athens) 2: 35-42, 2003.

    4. Furlanello F, Bentivegna S, Cappato R, and De Ambroggi L. Arrhythmogenic effects of illicit drugs in athletes. Ital Heart J 4: 829-837, 2003.

    5. Guddat S, Thevis M, and Schanzer W. Identification and quantification of the plasma volume expander dextran in human urine by liquid chromatography-tandem mass spectrometry of enzymatically derived     isomaltose. Biomed Chromatogr 19: 743-750, 2005.

    6. Gutierrez Gallego R and Segura J. Rapid screening of plasma volume expanders in urine using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 18: 1324-1330, 2004.

    7. Ryu JC, Kwon OS, Song YS, Yang JS, and Park J. The effects of probenecid on the excretion kinetics of stanozolol, an anabolic steroid, in rats. J Appl Toxicol 12: 385-391, 1992.

    8. Trout GJ and Kazlauskas R. Sports drug testing--an analyst's perspective. Chem Soc Rev 33: 1-13, 2004.



    Stimulants or amphetamines can be defined as an agent temporarily increasing functional activity by their actions on the sympathetic nervous system. The sympathetic nervous system is responsible for actions on the heart, lungs, and blood vessels to promote the "fight or flight" mechanism. Major stimulants used in athletes are caffeine, widely available in coffee, tea, or soda, and Ma Haung Extract a nutritional supplement similar to ephedra which has been banned in the United States by the Food and Drug Administration.

    Functions and Use

    The exact mechanism for amphetamines are unclear but has been hypothesized that they have an ergogenic effect by increasing oxidation of fats, enhancing thermogenesis, and perhaps a sparing of skeletal muscle glycogen as a result of the greater free-fatty acid utilization. 

    The preponderance of evidence would support the reasoning that amphetamines and other stimulants like caffeine can improve performance by delaying time to fatigue and masking pain. 

    Amphetamines or other stimulants can be ingested in a variety of different ways including, inhaled, injected or orally in the form of pills or included in a liquid such as coffee.

    The amount of caffeine needed to produce an ergogenic effect ranges between 250 to 700 mg which is the equivalent of three cups of coffee or six to eight sodas. Many athletes take caffeine in pill form to more easily reach these levels. 

    Side Effects 

    Too much caffeine can produce alterations on mood, concentration, and alertness. Additional effects include an increase in heart rate and blood pressure, restlessness, nervousness, insomnia, increased urination, and tremors. More adverse reactions include heart beating abnormalities, hypertension, and hallucinations. Of particular concern to the medical community are individuals who are taking other medications, experiencing allergic reactions and women who are pregnant or breast feeding. 


    As a drug, erythropoietin (EPO) is a man-made version of the hormone in the human body that stimulates the production of red blood cells (RBC). In the body, EPO is a naturally occurring hormone, produced by the kidneys, which stimulates the body to produce more RBCs. When administered to a human it stimulates greater RBC production. It was developed for treating the reduction in red blood cells that comes with kidney disease, HIV, cancer and those undergoing surgery. The use of EPO was classified as banned by the International Olympic Committee in 1990. Blood doping is a method of infusing extra red blood cells either from a donor or from one's own red blood cells that were previously removed. 

    Function and Use 

    The increase in red blood cells causes an increase in the number of hemoglobin molecules per unit blood. Hemoglobin is the primary molecule that carries oxygen in the blood. More oxygen in the blood allows more oxygen to be delivered to the exercising muscles. Studies have shown that blocking hemoglobin causes a reduction in exercise performance, or adding hemoglobin causes a clear increase in exercise performance. 

    Typically, blood doping involves removing 2 to 4 units (900-1800ml) of blood from an individual. The RBCs are spun and separated from plasma, then stored in glycerol. After a 2-3 month time delay, which allows for restoration of RBC in the athlete, and about 3-5 days before competition, the RBC are "washed" and reinfused. Because of the storage in glycerol, the RBC are well preserved. Donor blood can be used, but risk is increased due to the possibility of blood borne pathogens. The benefit of donor blood is that the individual does not have to go through the period of regeneration of their own RBCs.

    EPO is taken by IV or subcutaneous injection. For medical use the typical dosage is: Initial dosage-100IU/kg body weight 3 times/week for 8 weeks. The maintenance dosage is then 25-50IU/kg 3 times/week. The exact dosage is disease/individual dependent. For sport use, the dosage is usually 20-40IU/kg 3 times/week with no "loading" phase. 

    Side Effects 

    There appears to be minimal side effects associated with blood doping, including no problems in research. Less is known about illicit use. There no changes in BP, which was suspected because of inferred increase in viscosity that was presumed to occur with blood doping. Donor infusion has obvious potential problems, and blood doping could be detrimental if too much is reinfused.

    With EPO use, the most common side effect appears to be an increase in blood pressure. This increase is not explained by increased hematocrit and presumed viscosity, but may be a direct effect of the hormone on blood vessels, causing constriction. This constriction could possibly have very serious side effects, including death. It has been suggested that between 1987 and 1990, 19 Dutch and Belgian cyclists died from suspected misuse of EPO.