Concordia University Chicago in River Forest also temporarily removed coach Steve Kollar, the Chicago Tribune reported.
Athletic director Pete Gnan sent a letter to parents Thursday, explaining what happened after a late December trip to California, where the team played two games. He said the team was put through a "particularly high-intensity, collegiate-level circuit training" on Dec. 31.
"It has been alleged by some that the intensity and difficulty of Saturday's practice was a direct consequence" of players breaking curfew while in California, Gnan said.
It wasn't immediately clear whether any players were still in the hospital. An email seeking comment was sent to an athletic department spokeswoman Saturday.
"Our athletics program has zero tolerance for harassment or retaliatory actions of any kind, and reporting mechanisms are in place for students, coaches and related staff," Gnan said in his letter.
The Division III Cougars postponed games they were supposed to play Tuesday and Saturday.