06/14/2012 at 07:00 AM EDT
Lance Armstrong left countless riders in the dust in a sparkling cycling career that included seven Tour de France victories. But he can't seem to shake the doping allegations that threaten to sully his legendary accomplishments.
The latest episode of the saga is unfolding this week, as the U.S. Anti-Doping Agency has brought formal doping charges against Armstrong, 40, in an effort to strip him of his titles, CNN
Armstrong, as he has in the past, vigorously denied the charges.
"I have never doped, and, unlike many of my accusers, I have competed as an endurance athlete for 25 years with no spike in performance, passed more than 500 drug tests and never failed one," he said on his website.
He said the USADA wants to "dredge up discredited allegations," which he called "baseless" and "motivated by spite."
Armstrong has been accused of doping before
by other disgraced U.S. riders, including Floyd Landis and Tyler Hamilton. In February, the U.S. Justice Department closed a criminal investigation after reviewing allegations against Armstrong, apparently for lack of evidence that he used performance-enhancing drugs.
"These are the very same charges and the same witnesses that the Justice Department chose not to pursue after a two-year investigation," Armstrong said of the USADA's action.