The 21-year-old was speaking during the appeals trial of ex-coach Cho Jae-beon, who was sentenced to 10 months in prison in September for assaulting Shim and three other skaters.

According to South Korean news agency Yonhap, the young skater, who helped the country defend its women's 3,000 metres relay title at their home Pyeongchang 2018 Winter Olympics, fought back tears as she described Cho's alleged beatings and the effect they had on her.

The case caused huge controversy in South Korea in the build up to the Pyeongchang Games, with Cho handed a lifetime ban by the Korea Skating Union (KSU) just weeks before the Opening Ceremony.

He is appealing his prison sentence.

The issue first arose when Shim reportedly boycotted a training programme in protest, although she did return two days later.

Shim had originally only given statements through her lawyer as she did not want to face Cho in court, but then said she felt she needed to tell her side of the story in person.

During her testimony she alleged Cho had been abusing her, both physically and verbally, since she was in elementary school.

The attacks, she said, led to injuries including broken bones and concussion.

"When I was in fourth grade, I suffered broken fingers after getting stuck by an ice hockey stick," Yonhap quoted her as saying.

"Once I got into middle school he became even more violent.

"He dragged me into confined spaces to beat me up mercilessly, and other athletes suffered ruptured eardrums and other injuries."

Cho admitted hitting Shim back in June after an interrogation by police lasting nearly eight hours.

"Before the Pyeongchang Olympics he kicked and punched me so hard that I thought I was going to die," Shim added.

"I had a concussion afterward, and I fainted and fell down during the Olympics because of that."

As well as the allegations of beatings, Shim also alleged Cho changed her skate blades without telling her for races in the build up to the Olympics, so another South Korean skater would perform better.

She also said Cho had private lessons with the skater in question during the Olympic Games, after being banned by the KSU.

Cho's lawyer dismissed the claims as "preposterous" but Shim said she hoped he will be punished "so severely so he won’t be able to do these things again".