Sharia
The Islamic law, or Sharia, sets several bounds that indirectly impact Muslim athletes. This includes rules regarding the awrah, those parts of the body not to be exposed in public. The hijab or Burqas required by strict divisions of Islam can make it difficult for women to engage in many sports. Also, men are not allowed to have clothing that shows the area between the knees and navel, prohibiting them from engaging in, for example, Sumo wrestling. For some time, Iranian women at the Olympics only competed in shooting because it was the one area unaffected by their dress codes.
Read more about this topic: Islamic Sports