The Question is about sports in regards to young girls?
Answer: “Sports vary. It is a general term. So sports for young girls is through things that do not oppose the pure legislation. She can walk a lot in spaces specific for them, where there is no mixing with men and where men cannot view them. They can swim in their houses or a school specific for them where men cannot see them or reach them. There is no harm in that.
As for sports which have free-mixing between men and women or men can see them or which causes harm upon the Muslims, then this is not allowed. It is a must to have detail statement in the issue.
So the sports which are specific to the women, which there is nothing in it from what prohibited in the legislation, there is no free-mixing with men, it is in a concealed space, far from mixing, then there is no harm in that. Whether that (sport) be walking or swimming or the likes. Likewise is (the ruling) of competition between girls”.
[Taken from: https://www.binbaz.org.sa/mat/11065]
Translated by
Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan