Following the dramatic fall from grace of seven-time Tour de France winner Lance Armstrong, Sport Wales has a special investigation into the use of drugs in sport.
The US Anti-Doping Agency is set to level a series of charges against Armstrong that he used drugs to illegally enhance his performances, even though Armstrong maintains he's never failed a drugs test.
So we examine the methods being used to catch drug cheats, and examine how can athletes be sure which supplements are safe to take.
Welsh boxer Enzo Maccarinelli gives his first television interview since he was given a six-month ban for taking a banned substance.
The former world cruiserweight champion claims he took the substance inadvertently, and says he hopes to work with anti-doping authorities to stop other boxers and athletes from making the same mistake.
Plus former sprinter Darren Campbell, who now runs a sports nutrition company himself, reveals how he was once offered performance-enhancing drugs.
And, with three players currently serving bans for taking contaminated supplements, we examine the scale of any drug problems in Welsh rugby.
Catch the investigation - as well as a full preview of Saturday's Welsh derby between Wrexham and Newport County and much more - on Sport Wales on BBC Two Wales, Friday, 31 August at 21:00 BST.