WATCH: Ex-ski coach Bertrand Charest won't take stand at his sex assault trial

Former national ski coach Bertrand Charest, who's now on trial for sexually abusing his teenage skiers in the 1990s, will not take the stand in his own defence.

On Monday, the trial heard from Charest's younger sister Isabelle, who said when she was skiing competitively in the late 1980s and early 1990s, it was common for coaches to rub the legs and buttocks of ski students to keep them warm.

The accused is on trial on 57 charges, including sexual assault and breach of trust, in connection with 12 alleged victims between the ages of 12 and 19 during the 1990s.

His sister says she spent time with her brother's ski team between 1995 and 1997 and says the atmosphere within the group was fun and friendly.

The defence says it plans to call its final witness by Wednesday and has scheduled to start closing arguments Friday.

-Canadian Press also contributed to this report.