(Reuters) - Lance Armstrong's assertion that he did not take performance-enhancing drugs after his seventh and final Tour de France victory in 2005 has been dismissed by the president of the World Anti-Doping Agency (WADA). Armstrong admitted years of systematic doping in an interview with chat show host Oprah Winfrey on Thursday but the American maintained he was clean when he made a comeback in 2009, 3-1/2 years after retiring. ... More...