powerhouse and partyboy - rubbish explanations lol .. i'm surprised at u
ok let me have a go
Anavar and many of the other drugs discussed here are 'anabolic steroids' .. that is, drugs which are chemically similar, but not identical to testosterone. Just to be confusing, the various testosterone preparations are also often referred to as anabolic steroids, because they are widely used as an anabolic when applied at supraphysiological levels (and to be fair, testosterone is both anabolic, and a steroid, just a special case).
Testosterone is a hormone responsible for controlling a number of systems within the male and female body, female levels being a lot lower than those in males (it does appear to be nonetheless important in females). Of interest to the athlete is that testosterone appears in many cases to be a limiting factor to the tendency to build and retain muscle.
The problem with applying high levels of testosterone alone to produce increase in muscle growth are well known - the russian olympic team were doing this around the 1950s. However, the athletes showed a number of side effects, and were unable to urinate without using a catheter (implying severe prostate enlargement). This was noticed by Zeigler, who then developed the first anabolic steroid, called 'dianabol', in an attempt to seperate the muscle building components (anabolic) from the unwanted virilising side effects (androgenic). This seperation of androgenic and anabolic effects is particularly important when a drug is to be used in women and children, who are very sensitive to increased androgenic effects.
Anabolic / Androgenic ratio
The anabolic / androgenic ratio is measured using a 'bioassay', where for instance rats are given high levels of the drug, then slaughtered. Then the mass of their prostate, and levator ani muscle is measured, and compared to the sizes achieved with normal testosterone levels (or perhaps supraphysiological testosterone supplementation which could be interesting). A larger prostate is taken to mean higher androgenic effects, a larger muscle is taken as higher anabolic effects.
While this classification is a huge simplification, it does help when deciding which drug is suitable for use in a particular situation, because the prostate enlargement does tend to correlate very highly with other androgenic effects (such as hair loss), and the levator enlargement with muscle building potential.
Other Anabolic Steroids
Since dianabol, a number of other anabolic steroids have been developed, some of which are used in medicine, some of which are used on animals for meat production / animal performance, and some which have proved too toxic for general use, or have been replaced by 'better' compounds for their particular job. As the androgenic / anabolic classification scheme is an approximation of the behaviour of these drugs, people have found during practical use that particular types are better suited for certain purposes than others, the exact scientific mechanism for these differences in behaviour not always being clear (or certain). Thus you will find certain drugs or combinations recommended for cutting bodyfat while retaining muscle or bulking, or lean bulking.