Information Floyd Landis recently gave to the United States Anti-Doping Agency about how cyclists have and still are getting around the biological passport analysis system could have an immediate impact on the sport, according to at least two people with direct knowledge of the system.

Michael Ashenden, a Australian exercise physiologist and blood doping researcher who sits on the nine-man independent panel that reviews biological passport data for UCI (cycling's international governing body), and Dr. Don Catlin, an anti-doping researcher who pioneered methods for steroid detection, both told ESPN.com that Landis' information could be crucial in understanding how cyclists try to beat the system.

That biological passport, which monitors blood values and urine samples over time in order to build evidence of blood manipulation and is financed in large part by the sport's elite tier of teams, was put into place to supplement traditional drug testing.

Yet according to Landis, teams and riders with enough monetary resources and sophisticated medical advice knew how to circumvent the biological passport even before its official implementation in 2007.

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 with 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.