One of the girls says she tore a ligament and a leg muscle during the exercise
Police in the US are investigating after a series of videos emerged showing high school cheerleaders screaming in pain while being forced into the splits during training.
The cheerleading coach responsible has been removed from his position over the disturbing footage.
A number of other school employees - including the school principal and an assistant principal - have been placed on leave.
The video shows coach Ozell Williams forcing 13-year-old Ally Wakefield into the splits while her arms are held by teammates.
Ms Wakefield said she tore a ligament and a leg muscle during the exercise which is known as 'breaking.'
The videos were shot by members of the cheerleading team and were sent anonymously to KUSA TV in Colorado:
The channel said it had received videos showing a total of eight cheerleaders repeatedly being pushed into splits.
The videos were filmed during the first week of cheer camp in June.
It has been reported that Mr Williams was fired from a previous coaching position for using the 'breaking' exercise.
In a statement yesterday, the Denver Public Schools (DPS) department said it is supporting the police investigation and doing all it can to support the students and families involved.
DPS Superintendent Tom Boasberg said: "We have sent notification to our athletic directors emphasizing that DPS does not allow the use of “forced splits” or any other activity that puts a student’s physical or mental health at risk, or in which a student is forced to perform an exercise beyond the point at which they express their desire to stop."
"I want to reiterate that this applies not just to athletics, but throughout our school communities," he said.
Speaking to the Denver Post Mr Williams said the video has been taken out of context. He said he would love to tell his side of the story but insisted he cannot say anything further about the controversy "at this time."