 Historic sexism. There was a belief really early on in track and field that women were not able to do a lot of the events. And all of that individually has been proven wrong. Like one of the big ones was women are too weak to pole vault. They don't have the upper body strength. Women have been pole vaulting in the Olympics now since 2000. The one last event that women still are not allowed to do is the decathlon. World athletics is the governing body that could change that.