Depending on who you believe, Lance Armstrong, one of the greatest endurance athletes of all time, either admitted Thursday that he used banned substances during his historic seven-year reign as Tour de France champion or simply grew tired of defending himself against charges he's faced for more than a decade.

Either way, the U.S. Anti-Doping Agency said Thursday that it will strip Armstrong of his seven Tour titles after he said he wouldn't seek arbitration with the agency over the case, a move that would have been his final chance in staving off a lifetime ban and being stripped of his titles, according to the Associated Press.

Travis Tygart, USADA's chief executive, said Armstrong's decision should be interpreted as an admission of guilt.

"It is a sad day for all of us who love sport and athletes," Tygart told the AP. "It's a heartbreaking example of win at all costs overtaking the fair and safe option. There's no success in cheating to win."

But Armstrong has issued a lengthy statement that admitted nothing and said he was simply done fighting what he called an "unconstitutional witch hunt." He has consistently pointed to the hundreds of drug tests that he has passed as proof of his innocence during his 7-year run from 1999 to 2005 as Tour de France champion.

"There comes a point in every man's life when he has to say, 'Enough is enough.' For me, that time is now," Armstrong said in a statement posted on his website. "I have been dealing with claims that I cheated and had an unfair advantage in winning my seven Tours since 1999. The toll this has taken on my family and my work for our foundation and on me leads me to where I am today -- finished with this nonsense."

So who do you believe? Is Lance effectively admitting his guilt, or do you buy his claim that he's simply done fighting this battle and wants to focus on his work with his Livestrong Foundation?

Editor's Note: This article first appeared on Mill Valley Patch.