[53] Studies in the United States have shown that AAS users tend to be mostly middle-class men with a median age of about 25 who are noncompetitive bodybuilders and non-athletes and use the drugs for cosmetic purposes.

[58] A recent study has also shown that long term AAS users were more likely to have symptoms of muscle dysmorphia and also showed stronger endorsement of more conventional male roles.

These sports include bodybuilding, weightlifting, shot put and other track and field, cycling, baseball, wrestling, mixed martial arts, boxing, football, and cricket.

Testosterone can be administered parenterally, but it has more irregular prolonged absorption time and greater activity in muscle in enanthate, undecanoate, or cypionate ester form.

[97] Other side-effects can include alterations in the structure of the heart, such as enlargement and thickening of the left ventricle, which impairs its contraction and relaxation, and therefore reducing ejected blood volume.

[citation needed] Low doses of AAS such as oxandrolone are used in the treatment of idiopathic short stature, but this may only quicken maturation rather than increasing adult height.

[106][107][108] A short (1–2 months) use of androgenic-anabolic steroids by men followed by a course of testosterone-boosting therapy (e.g. clomifene and human chorionic gonadotropin) usually results in return to normal testosterone production.

[109]) Female-specific side effects include increases in body hair, permanent deepening of the voice, enlarged clitoris, and temporary decreases in menstrual cycles.

A 2005 review in CNS Drugs determined that "significant psychiatric symptoms including aggression and violence, mania, and less frequently psychosis and suicide have been associated with steroid abuse.

[123] A 2008 study on a nationally representative sample of young adult males in the United States found an association between lifetime and past-year self-reported AAS use and involvement in violent acts.

[126] Androgens such as testosterone, androstenedione and dihydrotestosterone are required for the development of organs in the male reproductive system, including the seminal vesicles, epididymis, vas deferens, penis and prostate.

[77] A commonly used protocol for determining the androgenic:anabolic ratio, dating back to the 1950s, uses the relative weights of ventral prostate (VP) and levator ani muscle (LA) of male rats.

[75] Theories for the dissociation include differences between AAS in terms of their intracellular metabolism, functional selectivity (differential recruitment of coactivators), and non-genomic mechanisms (i.e., signaling through non-AR membrane androgen receptors, or mARs).

[75] The measurement of the dissociation between anabolic and androgenic effects among AAS is based largely on a simple but outdated and unsophisticated model using rat tissue bioassays.

[75] 5α-reductase is widely distributed throughout the body, and is concentrated to various extents in skin (particularly the scalp, face, and genital areas), prostate, seminal vesicles, liver, and the brain.

[75] In addition, DHT is inactivated by high activity of 3α-HSD in skeletal muscle (and cardiac tissue), and AAS that lack affinity for 3α-HSD could similarly be expected to have a higher myotrophic–androgenic ratio (although perhaps also increased long-term cardiovascular risks).

[158] However, women with complete androgen insensitivity syndrome (CAIS), who have a 46,XY ("male") genotype and testes but a defect in the AR such that it is non-functional, are a challenge to this notion.

[177] Many 19-nortestosterone derivatives, including nandrolone, trenbolone, ethylestrenol (ethylnandrol), metribolone (R-1881), trestolone, 11β-MNT, dimethandrolone, and others, are potent agonists of the progesterone receptor (PR) and hence are progestogens in addition to AAS.

[181] In contrast to most other AAS, 17α-alkylated testosterone derivatives show resistance to metabolism due to steric hindrance and are orally active, though they may be esterified and administered via intramuscular injection as well.

[75] Some AAS that are or can be 5α-reduced, including testosterone, DHT, stanozolol, and methyltestosterone, among many others, can or may modulate the GABAA receptor, and this may contribute as an alternative or additional mechanism to their central nervous system effects in terms of mood, anxiety, aggression, and sex drive.

[75][189][70] Conversion to DHT,[190] nandrolone,[75] metandienone (Dianabol),[191] chlorodehydromethyltestosterone (Turinabol),[192] fluoxymesterone (Halotestin),[193] and boldenone (Equipoise):[194] DHT to stanozolol (Winstrol),[195] metenolone acetate (Primobolan),[196] oxymetholone (Anadrol),[197] and methasterone (Superdrol):[198] Nandrolone to trestolone,[199] trenbolone,[200] norboletone,[201] and ethylestrenol:[202] The most commonly employed human physiological specimen for detecting AAS usage is urine, although both blood and hair have been investigated for this purpose.

A number of the drugs have common metabolic pathways, and their excretion profiles may overlap those of the endogenous steroids, making interpretation of testing results a very significant challenge to the analytical chemist.

[141] The isolation of gonadal steroids can be traced back to 1931, when Adolf Butenandt, a chemist in Marburg, purified 15 milligrams of the male hormone androstenone from tens of thousands of litres of urine.

[214] The development of muscle-building properties of testosterone was pursued in the 1940s, in the Soviet Union and in Eastern Bloc countries such as East Germany, where steroid programs were used to enhance the performance of Olympic and other amateur weight lifters.

In response to the success of Russian weightlifters, the U.S. Olympic Team physician John Ziegler worked with synthetic chemists to develop an AAS with reduced androgenic effects.

[7] Three major ideas governed modifications of testosterone into a multitude of AAS: Alkylation at C17α position with methyl or ethyl group created POly active compounds because it slows the degradation of the drug by the liver; esterification of testosterone and nortestosterone at the C17β position allows the substance to be administered parenterally and increases the duration of effectiveness because agents soluble in oily liquids may be present in the body for several months; and alterations of the ring structure were applied for both PO and parenteral agents to seeking to obtain different anabolic-to-androgenic effect ratios.

[224][225] In reality, all AAS have essentially similar AR-mediated effects,[231] even if some may differ in potency to a degree in certain tissues (e.g., skin, hair follicles, prostate gland) based on susceptibility to 5α-reduction and associated metabolic amplification or inactivation or lack thereof.

[240] The same act also introduced more stringent controls with higher criminal penalties for offenses involving the illegal distribution of AAS and human growth hormone.

It's not that we set out to target cops, but when we're in the middle of an active investigation into steroids, there have been quite a few cases that have led back to police officers," says Lawrence Payne, a spokesman for the United States Drug Enforcement Administration.

[250] The FBI Law Enforcement Bulletin stated that "Anabolic steroid abuse by police officers is a serious problem that merits greater awareness by departments across the country".