Landis told ESPN.com last week that during the two or three years leading up to his 2006 Tour de France victory -- subsequently nullified after he tested positive for synthetic testosterone -- he and some of his fellow riders combined strategically timed transfusions and microdoses of EPO (erythropoietin, a red blood cell booster) in order to keep their blood values constant rather than spiking and dipping. The main difference between their methodology and that of riders in the 1990s, Landis said, was riders of his era learned to inject EPO intravenously rather than subcutaneously, as a cancer patient or someone with another grave illness would do.

When EPO is injected under the skin, it is absorbed first into soft tissue and released into the bloodstream gradually, prolonging its therapeutic effects. Injecting EPO intravenously has the same effect of boosting red blood cell count and improving oxygen processing capacity. However, the drug disperses more quickly in the bloodstream and thus becomes undetectable sooner -- especially if riders dilute their blood with an intravenous drip of saline solution or simply by drinking a lot of water after injecting it.

Roughly speaking, the biological passport is designed to catch riders who cheat based on fluctuations in their baseline blood values. One fundamental element is the ratio of their "young" or new red blood cells, called reticulocytes, compared to mature cells. When an athlete transfuses his own blood, the body responds by slowing down production of reticulocytes. Landis said riders brought the level of red blood cell production back to normal by microdosing with EPO during races on a nightly basis.According to Landis, the coup de grace that made this methodology work was that he and his U.S. Postal Service teammates routinely had advance notice of supposedly unannounced anti-doping controls. "We always knew when the blood testers were going to be there the following morning, so we would know when to have the saline solution bags so we could dilute our blood the night before," he said. He said he did not know how the team staff got wind of the schedule. "It was just nice that they did," he said.

"You can use three to four times your body's normal production of EPO if you inject it intravenously and have virtually no chance of testing positive within a matter of hours," Landis told ESPN.com. "So the biological passport is a joke, and I'm fairly certain the UCI knows about it." Landis added that he bought an expensive piece of machinery to measure his own reticulocyte count and also learned to do the analysis manually with a microscope.