An American former professional road racing cyclist and triathlete. He won the Tour de France seven consecutive times (1999-2005) but was stripped of those titles by the U.S. Anti-Doping Agency (USADA) and banned from cycling in 2012.

At 16, Armstrong entered professional sport as a triathlete and became a national sprint-course triathlon champion in 1989 and 1990. In 1992 Armstrong began his career as a professional cyclist with the Motorola Cycling Team. He had numerous cycling successes in the US and Europe between 1993 and 1996 including the Clásica de San Sebastián in 1995, an overall victory in the penultimate Tour DuPontand, and a handful of stage victories in Europe, including the stage to Limoges in the Tour de France.

In October 1996 he was diagnosed as having testicular cancer that had spread to his brain and lungs. His cancer treatments included brain and testicular surgery and extensive chemotherapy. His last chemotherapy treatment was received on December 13, 1996. In February 1997 he was declared cancer-free and by January 1998 had renewed serious cycling training, having signed a new racing contract with US Postal. He was a member of the US Postal/Discovery team between 1998 and 1995.

On July 24 2005, Armstrong stated his intention to retire from racing at the end of the 2005 Tour de France but returned to competitive cycling with the Astana team in January 2009 and went on to finish third in the 2009 Tour de France. Between 2010 and 2011 he raced with the UCI ProTeam he helped found, Team Radio Shack. On February 16 2011 he finally announced his retirement from competitive cycling for good, while facing a US federal investigation into doping allegations.

In June 2012 the U.S. Anti-Doping Agency (USADA) charged Armstrong with having used illicit performance enhancing drugs, and in August they announced a lifetime ban from competition as well as the stripping of all titles since August 1998. On October 22, 2012, the Union Cycliste Internationale (UCI), the sports governing body, endorsed USADA's verdict and confirmed both the lifetime ban and the stripping of titles. These included the Tour de France titles for the years 1999 to 2005.