I'm not 100% sure, there would be someone who would have a better idea.. But I think the general idea is that when people get injured they feel obligated to return/are made to return to play before they are healed, especially those in sporting contracts.
So they are made to return to the game while still injured, risking further injury. They also use extensive taping and pain killers to handle the pain of the injury, which is obviously a bad thing.