Young athletes in Japan have suffered physical, verbal and sexual abuse during training, a report by Human Rights Watch says.
The report, recording the experiences of more than 800 athletes in 50 sports, comes in the week that would have marked the start of the Tokyo Olympics.
"The abuses include punching, slapping and excessive or insufficient food and water," said HRW's Minky Worden.
The Japanese Olympic Committee has been contacted for a response to the report.
The Japan Sports Council, also mentioned by HRW, has also been contacted.
In 2013, the JOC promised to take steps to eradicate abuse among its sports federations after an internal survey revealed more than 10% of its athletes had been victims of bullying or harassment.
It also cut funding to its judo federation for a time after coaches were found to have physically abused female athletes.
"Human Rights Watch is calling on Japan to take decisive action and to lead in tackling this global crisis," added Worden, who is HRW's director of global initiatives.
The report is based on interviews, an online survey that drew 757 responses and meetings with eight Japanese sports organisations.
Of the 381 survey respondents aged 24 or younger, 19% indicated they had been hit, punched, slapped, kicked, knocked to the ground or beaten with an object while participating in sports.
A total of 18% reported experiencing verbal abuse, while 5% reported sexual assault or harassment while participating in sport as children.
The International Olympic Committee (IOC) said in a statement: "We acknowledge the Human Rights Watch report. Harassment and abuse is unfortunately part of society and also occurs within sport.
"The IOC stands together with all athletes, everywhere, to state that abuse of any kind is contrary to the values of Olympism, which calls for respect for everyone in sport."