Olympic medalist Tasha Schwikert and her sister, former U.S national team gymnast Jordan Schwikert, announced civil suits Monday against the U.S. Olympic Committee and USA Gymnastics for "enabling and failing to prevent" the sexual assault of athletes by team doctor Larry Nassar.

The organizations knew "or should have known of Nassar's sexual abuse and could have prevented it by taking sexual abuse allegations seriously and maintaining a culture of accountability and transparency," the two complaints said.

Both sisters say they were abused by Nassar, who was sentenced in February to up to 125 years in prison. Nassar pleaded guilty to the molestation of 10 victims, but has been accused of sexual abuse by more than 250 young women and men.

"We all know that Larry was a child predator but in order to understand how we got to Larry, and why Larry was able to abuse children for so long, we must analyze what lead up to Larry," Tasha, 33, said at a press conference Monday. "Today I want to discuss USA Gymnastics abusive culture, a culture where athletes were strictly prohibited from communicating their feelings and emotions."

USOC and USAG were not formally named as defendants in the suit due to a California law that requires plaintiffs filing childhood sex abuse claims to use Doe defendants, according to one of the sisters' lawyers.

Tasha told reporters that gymnasts participating at the elite level were often discouraged from reporting injuries for fear of not making national teams, overtrained to the point of injury, and often told to lose weight and restrict their food.

Jordan, 32, now a coach, said the culture created an environment where "anything short of perfection was highlighted and picked on." Jordan told reporters that Nassar and others encouraged her to ignore her pain and overtrained her to the point of a serious back injury which required experimental surgery.

"USA Gymnastics and USOC failed as institutions in its responsibility to protect young people participating in its programs, instead prioritizing winning and protecting themselves," Jordan said Monday.

When asked by reporters why they waited so long to file suit, the sisters responded that recent developments had prompted them to take action.

Tasha referred to the arrest of former USAG president and chief executive Steve Penny on charges of tampering with evidence in the Nassar investigation and his brief replacement by Mary Bono, who worked at a law firm which knew of Nassar's abuse. Bono resigned earlier this October, only nine months after her hiring, as a result of backlash from former Olympians.

Penny was arrested on October 18 in Tennessee after a grand jury in Walker County, Texas indicted him on felony charges of tampering with evidence. Prosecutors accuse Penny of ordering the removal of documents from Karolyi Ranch, the training facility where accusers say some of Nassar's abuse occurred. Penny then allegedly had the documents delivered to his Indianapolis home and intentionally destroyed or concealed the materials on or around Nov. 11, 2016.

Penny pleaded not guilty at a court appearance on Monday shortly after the sister's press conference. Walker County District Attorney David Weeks says a Texas judge ordered a $20,000 bond for Penny, which he posted.