ESPN.com spoke to Dr. Gary Walder of the World Anti-Doping Agency on testosterone and testing.

Q: For a cyclist, what's the benefit of elevated levels of testosterone? Why would a cyclist use it?

A: It's certainly not one of the first-line drugs one thinks of for racing. Steroids can increase strength and improve recovery time and prevent the breakdown of muscle, maybe make him more assertive and aggressive. All of those could have some positive attribute. But most steroids are given in cycles [6-12 weeks] and in context of working out in a gym with weights. It makes no sense to me why an athlete would take testosterone the day of a race when it doesn't work that way. It doesn't make sense in terms of the pharmacology of the drug, and it really doesn't have the attributes that would be attractive to a cyclist -- particularly one running the risk of violating anti-doping regulations.

Everybody knew the spotlight was on cycling. For eight years, the world has been watching cycling particularly closely. It would be the ultimate form of denial, or the ultimate sense of invincibility, to think you're going to evade that. And when the pharmacology of the drug doesn't really, in my judgment, seem like a drug of particular note to a cyclist, it doesn't really compute.

Associated Press has a story quoting Dr. Walder as well.