The doping allegations against cyclist Lance Armstrong have brought a guarded response from his ex-wife Kristin.

She is accused in the USADA report of being complicit in Armstrong's doping.

Kristin implied in her latest blog for runnersworld.com that she had kept her silence for the sake of her family that includes three children by Lance.

"I know what truth is. I know my past. Not telling or selling my tales to the press is my choice - one that I made primarily for my children," she said.

"And there are many things that I am not free to discuss because I am constrained by legal principles like marital privilege, confidentiality and non-disclosure agreements.

"To the world, Lance may be a source of admiration or suspicion, but to me he is simply my wasband (former husband) and the father of my children. His choices were, and are, his. And mine are mine. And they haven't always been pretty."