This argument is spiraling many a direction. Some posters believe that Houlihan did, indeed, lie. If she lied about the doping, she's a liar by definition. That's a pretty harsh statent to make of someone whose already been penalized for violating anti-doping rules. However, it does warrant a look into what might be defined as a liar.
What's a liar? I think most people would agree that it's a person who makes a believed-false statement to another person presupposing that the statement is being used to invite or influence belief, intending that that other person believe that the statement is true (or intend that the other person believe that or intend that the other person believe that the statement is believed to be true).
One can say that Houlihan implicitly assured the Athletes Integrity Unit and CAS that her statements were true and that she intended that those persons believe her statements as true (and that the statements were believed to be true) on the basis of Houlihan's implicit assurance. Houlihan was not the victim of hyperbole or irony. She made statements in a context where the following norm of conversation is in effect: Absolutely don't make any statements that you believe to be false.
It was clearly proven, based on the balance of probabilities, that Houlihan's statements were, indeed, false. Houlihan's testimony makes it sufficiently clear that she can be said to have told the AIU and CAS an untrue story -- this was not a mere assertion that this was to have been true.
Concerning the Polygraph, it may have served well to have added a couple of queries to Houlihan:
Do you “not believe” your statements to be true?"
"Do you believe that your statement is “probably false”?