I’m not sure anyone knows the answer to this. Sports people rely on their bodies to do their jobs and be successful. There is therefore a huge temptation to help their bodies along by using drugs. Commonly we hear about steroids or EPO or testosterone as drugs that are used illegally to boost performance as there role is well understood and they can be detected during testing. If we are honest however there are a variety of drugs which could help an athlete improve their performance. Some of these are designer drugs we don’t even know about yet, some are illegal but some are everyday drugs that may help an athlete but may also be necessary for other conditions such as hayfever or ADHD… The lack of understanding of what each drug does to each person makes defining a list of “useful” drugs and ultimately defining what is illegal very difficult.