MARINA DEL REY, Calif. (BRAIN) — As Twitter.com lit up with chatter on doping and comments from the presentation by U.S. Anti-Doping chief executive Travis Tygart at the Triathlon Business International conference Monday, Lance Armstrong chimed in.

In the keynote that kicked off the annual triathlon gathering in Marina Del Rey on Monday morning, Tygart talked about the win-at-all-costs culture of sports and USADA's investigation of Armstrong.

Chris Bohannon, a territory manager for Orbea and Orca and conference attendee, tweeted several comments Tygart made, and Armstrong responded with several tweets.

"What a joke.#Whendoesthevictorytourend?" Armstrong tweeted, later adding, "It's a one way conversation right now."

In exchanges via Twitter and emails with conference organizers, Armstrong asked to attend the conference to give his side of the story. Organizers announced late Monday night, at the conclusion of an awards ceremony recognizing top triathlon retailers, products, events and athletes, that Armstrong would be making an appearance and taking up a slot in the schedule of panels on Tuesday morning where he would talk about the investigation and answer questions from conference attendees.

"Badges for entry will be required," said Mike Reilly of Triathlon Business International.

But late Monday night Armstrong contacted organizers to say he wasn't coming.

"TBI was open to providing an opportunity to answer questions from a TBI board member and questions posed from the audience. There were no restrictions from Lance other than the ongoing legal investigation from the whistle blower case. Although we do not know the reason, in the end he chose not to come," said TBI president Jack Caress.

The Triathlon Business International conference concludes Tuesday afternoon at the Marina Del Rey Marriott. The annual gathering, now in its fourth year, drew close to 230 attendees in the triathlon market including race directors, manufacturers, retailers and service providers and vendors.