Two drugs could be on the way that would change the world as we know it. I'm not prepared to go into a philosophical discourse on the subject yet. There could be many downsides (and scary sides) to this should it work as advertised, but a primary one could be the loss of sports and competition to the world.
This is a far cry beyond what we now consider sports doping to be. At best, doping creates an advantage over like-trained individuals. In tests with mice, those that exercised while taking GW1516 increased their performance by 77%. This would mean that athletes could actually be made from scratch. What this would do is take away the current explorative nature of our beings to find out just what the limits of the human body are. That is the true nature of sport. While this has been altertered, slightly, with modern doping practices it's now where near where it could be.
I suppose it's possible that we'll roll with this and just accept medical changes as part of sport. But I'm pretty uncomfortable with that thought at the moment.
Here are a couple of articles: