Five rings good, four rings bad

As a family of molecules, steroids have few equals in terms of importance in their function in the human body. Their diverse properties have also made them a target for misuse, notably as performance-enhancing drugs in competitive sports.

Ben Johnson wins the 100-m sprint at 1988 olympics - but then tested positive for stanozolol

Steroids are molecules that contain four rings fused together in a cyclopentaphenanthracene system: three of the rings are six-membered, one is five-membered, see structure (1). Among this family of molecules, cholesterol (2) performs several vital roles in the body - it is involved in the production of bile acids, it is the precursor of sex hormones (also steroids), and it is needed to make vitamin D, among many other functions.  

Here we focus on the sex hormones and their derivatives, and how they have been misused by sportsmen and women to give them the advantage in world class competitions.