AMES, Iowa — A University of Iowa investigative committee said Wednesday the school should scrap an intense workout that left 13 football players hospitalized, conceding that whatever triggered their injuries remains a mystery.

AMES, Iowa — A University of Iowa investigative committee said Wednesday the school should scrap an intense workout that left 13 football players hospitalized, conceding that whatever triggered their injuries remains a mystery.

The five-member panel's report clears the players, trainers and coaches of any wrongdoing, saying similar workouts have been done in the past without any injuries. The January workout, however, led to the 13 football players being diagnosed with rhabdomyolysis, which breaks down muscle cells and discolors urine. All the players were treated and none show any lasting effects.

"We're not able to tell you exactly why it happened," said committee member William Hines, a law professor and dean emeritus at the university's College of Law. "We can speculate ... but that's a mystery that will have to remain unsolved."

The report lists 10 recommendations, including abandoning the strenuous workout, which includes back squats with heavy weights. It also calls for everyone associated with the football program to be educated about rhabdomyolysis.

When members of a team become ill or injured after a strenuous workout, all others on the team should be tested to make sure they're not suffering from a condition, according to the report.