Tyler Hamilton -- Bicyclist retires after positive doping test

Olympic champion Tyler Hamilton, once touted as the next great American cyclist and an heir to Lance Armstrong's throne atop the sport, ended his doping-tarnished career Friday by saying he tested positive for a banned substance and would retire.

Hamilton admitted taking an herbal product for two days in February to combat depression, knowing it included a steroid.

"There's nothing to fight about," the 38-year-old Hamilton told The Associated Press. "I took a banned substance. I accept the consequences. You make mistakes in your life and I accept the penalty like a man."

Hamilton will likely receive a ban from the U.S. Anti-Doping Agency that may range from eight years to life, a sentence that would have ended his racing days anyway.

"He has had a cloud over his career for a while now and the sport is better off without him," said Pat McQuaid, president of the International Cycling Union.

Hamilton's win at the 2004 Athens Games was overshadowed by a blood doping scandal. He tested positive for doping a second time later that year, served a two-year suspension and returned to racing early in 2007 — never revealing that he was fighting depression, which he said runs in his family.

Going through a spanorce and seeing his mother fight breast cancer made things worse in recent months, Hamilton said.

Seeking relief, he took something called Mitamins Advanced Formula, billed as a "natural depression treatment with vitamins, herbs and supplements."

"Obviously, that was a mistake," Hamilton said.