Anabolic substances or processes within the human body are those that either stimulate or facilitate the growth of bodily tissues. Anabolism is the antonym of catabolism, the term describing any process that breaks down or reduces tissue. Weight training causes micro-damage to muscle tissues; this damage is a catabolic process. An anabolic process occurs when the regeneration and repair of the tissue results from new cell growth.
Hormones are the chemical messengers of the body. Hormones are produced and released by the glands that constitute the endocrine system. Each hormone is in essence a signal to an organ or a bodily process to act in a particular fashion. Examples of hormonal responses include the body's various systems being spurred into action by the production of adrenaline from the adrenal gland, and the growth of various bones and tissues being stimulated by the release of the human growth hormone from the thyroid gland.
Prohormones are chemicals that are either ingested into or created within the body. A prohormone is often described as a precursor to the formation of a hormone, without itself creating the effect of a hormone on the body. The prohormone will typically have a chemical composition that is near to that of the desired anabolic compound; enzymes produced by the liver act as catalysts in the conversion of the prohormone to anabolic hormone.
Since the refinement of anabolic steroid practices in the early 1960s, the consumption of these compounds became an approach favored by many athletes seeking to become stronger and bigger. When anabolic steroids were banned from a number of international athletic competition in the 1970s (most notably, the Olympic ban in 1976), the use of steroids by athletes evolved into a contest where the primary objective was to defeat the doping test procedures, first through sophisticated masking and diuretic techniques, and later through the use of "designer" steroids, anabolic products whose chemical composition was slightly alerted to deceive known scientific testing procedures. Nandrolone was the best known of these designer products, subsequently banned by the World Anti-Doping Agency (WADA) in 2003.
Since the mid-1990s, athletes engaged in strength training have sought to stimulate the production of the body's natural anabolic agent, the male sex hormone testosterone, as a means of building greater muscle size and strength, without ingesting a banned performance-enhancing substance. Prohormones were seen as the means to this objective. The commercial marketing of anabolic prohormones invariably makes reference to these supplements as being the closest product to testosterone that an athlete can obtain.
The most popular of the initial anabolic prohormones was androstenedione, more familiar to strength athletes as "andro," available in a number of different chemical formulations, each of which had an intended anabolic effect. Consumed as a powdered supplement, andro was effective in its role as a testosterone prohormone, as it was capable of converting, on average, between 5% and 6% of its mass into testosterone. Andro also had well-established side effects, particularly the development of enlarged breast tissue in males, a condition known as gynecomastia, as well as the risk of an enlarged prostate gland.
Boldenone, an anabolic steroid used in the equine industries (horse training and horse racing), was another chemical that has been employed by body builders and strength athletes, as it is known to convert to the hormone estrogen within the liver.
Anabolic pro-hormones are ingested in different ways: as a dietary supplement, as a transdermal (skin) patch, and as slow-release formulations through pills placed under the tongue or by way of nasal sprays. Like anabolic steroids, anabolic pro-hormones are consumed in defined cycles, a period of time within which a particular dose of the product is taken. Cycles are typically calculated to produce maximum benefit with minimum side effects. Anabolic pro-hormones are often stacked, meaning that the product is taken in conjunction with other pro-hormones or strength-directed products such as creatine or protein supplements.
Many manufacturers of dietary supplements have added prohormone mixtures into the supplements without disclosing the nature or quantity of the pro-hormone on the commercial label. The International Olympic Committee (IOC) commissioned a study in 2002 that determined as many as 15% of the products tested contained an undisclosed anabolic prohor-mone.
In 2004, WADA classed andro as an anabolic androgenic steroid (a steroid that promotes the increased growth of male features), and deemed the substance a prohibited substance.
There is significant evidence that the introduction of andro into the bloodstream through supplementation reduces the amount of high density lipoprotein (HDL) in the blood; HDLs are the proteins that contribute to the reduction of plaque within the walls to the arteries. Reduced levels of HDLs is counter to good cardiovascular health.
Dehydroepianrosterone (DHEA) is another well-known anabolic prohormone. Like andro, its advocates believe that because DHT is chemically close to testosterone, increased consumption of the product through diet will lead to similarly increased testosterone levels. There is no clear scientific evidence that DHT acts as an effective prohormone for testosterone.