Over at the Quantified Self blog, Gary Wolf has a fascinating interview with a person calling himself "Phineus" about steroid use and performance tracking among serious athletes.
GW: How common is this sort of self-experimentation among athletes?
Phineus: Among athletes that perform in any strength-, speed-, or endurance-dependent sport at the highest levels, at least 80 percent use "drugs" of some type. I use this term very broadly, because from a training perspective a drug is a drug is a drug. The usual distinction between a nutritional supplement and a drug is not a biological distinction, but a legal distinction.
GW: The ones who get caught using banned drugs always say "I didn't know what I was taking!"
Phineus: Pro athletes who claim ignorance are using the only defense they can. "I thought I was injecting flaxseed oil to get bigger." Right. That would be like a NASCAR driver claiming he knows nothing about fuel or tires. His job requires he know the vehicle, and being a top professional athlete requires understanding exactly what you put in your body to get performance out of your organic machine. It could make the difference between a 7-figure or 8-figure income. Carl Lewis tested positive for performance enhancers – stimulants – the same year that Ben Johnson tested positive for anabolic steroids and had his gold medal revoked. How did Carl Lewis then inherit the gold by default? Lewis had a more developed defense – herbal tea consumption – and the term "inadvertent use" was used to dismiss the charges. Athletes know exactly what's banned — the lists are beaten over their heads ad nauseum because sports franchises and amateur federations dislike the labor costs, PR headache, and revenue loss that scandals can produce.