CHICAGO (AFP) - A US senator on Thursday (Jan 25) called for congressional hearings on sexual abuse in collegiate and amateur athletics in the aftermath of a massive scandal that has rocked the gymnastics world.

Gary Peters, a Democrat representing Michigan in the US Senate, said he wants to investigate "why there have been multiple instances of major sexual abuse scandals involving young adult and child athletes, as well as neglectful indifference by officials who should have protected them."

A judge from the Midwestern state on Wednesday sentenced former USA Gymnastics team doctor Larry Nassar to up to 175 years in prison, following seven days of powerful testimony from women and girls who were sexually assaulted by Nassar over decades, under the guise of medical treatment.

The abuse occurred at his sports medicine clinic at Michigan State University (MSU) as well as training facilities sanctioned by USA Gymnastics.

"Now that the criminal proceedings are over, it is time for us to find out who is responsible at Michigan State University and USA Gymnastics for enabling and failing to stop this criminal, who so clearly abused the patients placed in his care," Peters said.

His call came as ramifications continued to intensify in the aftermath of the marathon hearings held in a Lansing, Michigan courtroom prior to Nassar's sentencing.

The presiding judge allowed more than 160 women and their family members to testify about their abuse. Many criticised MSU, USA Gymnastics and the US Olympic Committee for not doing enough to stop Nassar.

Some of Nassar's victims have said they warned of his abuse at various times over the past two decades, but were either not believed or intimidated into silence.

The university has been implicated, having closed a 2014 internal investigation of Nassar without finding him guilty of any serious violations.

A lawsuit on Thursday sought to compel the state's governor to investigate MSU's Board of Regents, an elected group that oversees the public university.

MSU president Lou Anna Simon resigned on Wednesday and the NCAA, a body that oversees US collegiate sports, opened an investigation.

Three top officials of USA Gymnastics board also resigned and USAG severed ties with the elite training camp Karolyi Ranch.

The US Olympic Committee announced that an independent probe would examine the committee's actions and the USAG, as well.