Apparently in cycling they all ready do and have done so since at least the eighties. In the seventies I know they did it but they did it wrong. They use stimulants like amphetamines that physiologically really don't enhance performance. Plus they are dangerous to take under certain conditions as the Tour de France competitor that dropped stone cold dead at the crest of one the steepest and most famous climbs many years ago--from memory I would say it was in the seventies.
Look at the list of world records in track and field. Notice how even today so many are from the nineties and eighties! Here in 2012 so many records still stand. Gee, I wonder why that is so?
There are many other instances in many other sports. Remember when approximately 20-30 years ago, (tapping the aging memory here again), when the Chinese women's team that in their history had all ways sucked in swimming showed up at the Olympic games with the broad sloping shoulders and their knuckles dragging on the concrete? From no where the BLEW away everyone and just about in every race broke the world record. It goes on and on.
About 20 years a large poll was taken. Olympic athletes were asked a question that went something like this:
If you could take a substance that would guarantee you a gold medal winning performance but also would guarantee that you would die from it in five years would you take it? Ninety percent said yes. (Actually I can't remember if the will die period was one year or five years but since I can't remember I will go with the five and give the athletes the benefit of the "doubt.")
If you watch NFL panels on stations like ESPN and the NFL channel or other networks you will see here and there the discussion among former players that quit not that long ago and also the sports commentators on should PEDs be allowed in the NFL and regulated or should they be banned? From what I've heard it's about 50/50 on the couple of debated I've heard. The most common agreement from both side of the argument is that the playing field should be a level one.