Olympic gold medalist McKayla Maroney said on Wednesday that she was sexually abused by her USA Gymnastics doctor from the age of 13 until her retirement from the sport last year.

Maroney, now 21, detailed years of abuse by longtime team doctor Lawrence G Nassar, who is already facing criminal charges for molesting other gymnasts. She wrote a lengthy post on Twitter inspired by the #MeToo movement, the hashtag campaign that’s encouraged victims of sexual harassment or assault to step forward with their stories.

“People should know that this is not just happening in Hollywood,” Maroney wrote. “This is happening everywhere. Wherever there is a position of power, there seems to be potential for abuse. I had a dream to go to the Olympics, and the things that I had to endure to get there, were unnecessary, and disgusting.”

The Californian, who helped the US gymnastics team known as the Fierce Five to a gold medal at the London Olympics and added an individual silver in the vault, said the molestation happened under the guise of treatment.

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“It seemed whenever and wherever this man could find the chance, I was ‘treated,’” Maroney wrote. “It happened in London before my team and I won the gold medal, and it happened before I won my Silver.”

Maroney said the worst of the abuse happened during the 2011 world championships in Tokyo, where she won an individual gold in the vault and helped the United States to a gold in the team competition.

“For me, the scariest night of my life happened when I was 15 years old,” she wrote. “I had flown all day and night with the team to get to Tokyo. He’d given me a sleeping pill for the flight, and the next thing I know, I was all alone with him in his hotel room getting a ‘treatment.’ I thought I was going to die that night.”

Nassar, an osteopath who spent nearly 30 years as trainer and national medical coordinator with the USA Gymnastics program, is now in prison in Michigan after pleading guilty to possession of child pornography. He is still awaiting trial on 22 counts of first-degree criminal sexual conduct involving at least seven victims in addition to being sued by over 125 women in civil court who claim he sexually assaulted them under the guise of treatment.

Nassar has pleaded not guilty to the assault charges and the dozens of civil suits filed in Michigan are currently in mediation.

Matt Newburg, a defense attorney who has represented Nassar, declined to comment when reached on Wednesday by the Guardian.

“The Olympics is something that brings people hope, and joy,” Maroney wrote. “It inspires people to fight for their dreams, because anything is possible with hard work and dedication. I remember watching the 2004 Olympics. I was 8 years old, and I told myself that one day I would wear that red, white, and blue leotard, and compete for my country.

“Sure, from the outside looking in, it’s an amazing story. I did it. I got there, but not without a price.”

USA Gymnastics has come under fire over its handling of sexual abuse cases in the wake of the Nassar scandal and an Indianapolis Star investigation that revealed the failure to report to authorities many allegations of abuse against coaches and staff at some of its over 3,500 clubs across the country.

The intensified pressure led to the resignation of Steve Penny as president in March, but not without a reported $1m severance package that drew public criticism. One week later, Jamie Dantzscher, a 2000 Olympic bronze medalist, and three-time national champion rhythmic gymnast Jessica Howard testified before Congress that they were sexually abused by Nassar.

“USA Gymnastics failed its most basic responsibility to protect the athletes under its care,” Dantzscher said during the 90-minute hearing.

She added: “Children often don’t speak up with they’re abused. They suffer in silence. They’re taught to submit to the authority of adults. This is especially true in the hyper-competitive world of elite gymnastics. Women do speak up, and that is why I am here today.

“They failed to take action against coaches, trainers and other adults who abuse children and they allowed Dr Nassar to abuse young women and girls for more than 20 years.”

Dominique Moceanu, a 1996 gold medalist, also testified to a “culture of fear, intimidation and humiliation, established by Bela and Marta Karolyi,” the legendary coaches who are named in a civil lawsuit for physical abuse, while US Olympic Committee official Rick Adams apologized for the organization’s failure to protect the victims.

A spokesperson for the national governing body said Wednesday in a statement to the Guardian that it “admires the courage of those, like McKayla Maroney, who have come forward to share their personal experiences with sexual abuse. Because of their strength in coming forward, predators can be held accountable for their actions. We, like so many others, are outraged and disgusted by the conduct of which Larry Nassar is accused. We are sorry that any athlete has been harmed during her or his gymnastics career.

“We are strengthening and enhancing our policies and procedures regarding abuse, as well as expanding our educational efforts to increase awareness of signs to watch for and reporting suspicions of abuse, including the obligation to immediately report.”