Anabolic androgenic steroids are synthetic compounds related to the sex hormone testosterone, naturally produced in both male and female bodies. Testosterone-producing organs include adrenal glands, ovaries and especially Leydig cells of male testes. Testosterone, as other steroid hormones, is derived from cholesterol through series of chemical reactions. Testosterone converts into either dihydrotestosterone (DHT), a strong androgen, or to estradiol (a major estrogen) in a process called aromatization.
Testosterone and DHT can both activate androgen receptors in certain cells while estradiol activates estrogen receptors. Activating androgen receptors will cause primary and secondary male sexual characteristics, deepening of voice, typical hair growth (and later baldness), as well as muscle growth by protein synthesis. Activating estrogen receptors, on the other hand, will elicit very different reaction, causing gynecomastia (breast enlargement), decrease muscle mass, erectile dysfunction, hot flushes and reduced libido in men.
The negative effects of estrogen listed above usually come with excessive estradiol levels as a result of very high testosterone levels. As you can see, testosterone is not causing only anabolic-androgenic effects but also exactly the opposite effects through aromatization. For athletes, both excessive androgenic and estrogenic effects of anabolic androgenic steroids were always seen as their major problem.
The holy grail of non-medical steroid users would be a drug with maximum anabolic effects and minimum androgenic and estrogenic effects. Although such compound doesn´t exist, scientists synthesized many testosterone-related hormones with more favourable effects than those of testosterone. This means that some anabolic steroids (described elsewhere on this website) show much lower aromatization rate (do not readily convert to estrogens) or much lower androgenic effects (like baldness, prostate hypertrophy etc.) and still have anabolic properties.
Anyway, most if not all anabolic steroids, if used for muscle growth, will still require some ancillary medication â€“ either drugs blocking conversion of anabolic androgenic steroids to estrogen (usually by blocking the aromatase enzyme responsible for this conversion) or medicaments supporting the natural testosterone production.
The second group of medicaments is especially necessary because of the so called negative feedback that regulates production of testosterone and most other hormones in our bodies: if the receptors spot excess of a hormone, its natural production is stopped. If this situation lasts for more than two months, the natural production of that hormone can be irreversibly limited. As an example, take corticosteroids. This group of hormones, related to cortisol, is commonly prescribed for eczemas and other skin-diseases. But by using external cortisol, your body gets the information to stop production of this important hormone.
Therefore, corticosteroids can only be used for certain period of time, after which a recovery period must be allowed. The same is true for anabolic steroids, where the system of treatment/recovery is called cycling. Anabolic steroids negatively affect (although to various extents) natural testosterone production. They must be only used for a limited time (four to eight weeks) and same or longer time must be allowed for recovery. Because athletes take very high doses of anabolic steroids, just leaving the time for recovery is not enough and ancillary drugs may be necessary.
Probably the most underestimated property of some anabolic steroids is their long action. Bodybuilders often use their drugs for, say, eight weeks and call this a cycle. But some injectables will depress testosterone production for several weeks, which means that from medical point of view the cycle would be, for instance, 12 week-long, which is on the verge of causing life-long suppression of testosterone, despite the following treatment.
Here we are getting to the difference between oral and intra-muscular (IM) steroids. Oral anabolic steroids have one significant disadvantage (at least most of them do) and namely their liver-toxicity. It is almost unthinkable for a serious athlete to use oral steroids for a prolonged time-span and not develop serious liver disease. On the other hand, they are short-acting which makes them easy to control. I believe that oral steroids are only suitable for the beginners who don´t know how will their body react to the medication.
If any complications occur, treatment can be discontinued at once. Intra-muscular, injectable steroids give you several advantages: they only need to be administered once a week (there are some IM steroids that need to be injected daily, I do not advice on using them), do not pass through liver and there are some that are very well tolerated. On the other hand, if you are taking part in competitions and undergo testing for banned substances, IM steroids will be visible for months following last administration.
Word of caution regarding intra-muscular steroids: today, when most sportsmen use „gear“ made in underground laboratories, contamination became matter of utmost importance. Contaminated tablets are dangerous, but you will most likely cope with them. 1% of contamination is normal in injectables. Some underground laboratories sell products with 5% contamination-level, which is dangerous. 10% will easily kill you.