I know the following definitions of what and which.
what : asking for information specifying something
which : asking for information specifying one or more people or things from a definite set
But I can't understand why the author used both what and which in the sentence. If sports are thought of as an indefinite set, I think what is preferred. If not, which preferred.
If you ask someone to name three sports, most likely he or she will be able to answer with ease. After all, nearly everyone has an idea about what types of activities are regarded as sports and which are not. Like Supreme Court Justice Potter Stewart's famous remark about pornography ― "I know it when I see it" ― most of us think we know what sports are. However, the line drawn between examples of sports, leisure, and play is not always clear. In fact, devising a definition that establishes clear and clean parameters around what types of activities should be included and excluded is relatively difficult to do. Activities that are regarded as play today may gain the status of sport in the future. For example, many people once played badminton in their backyards but this activity was hardly considered a sport. Since 1992, however, badminton has been an Olympic sport!