:::(in response to my removal of putting Freerunning in the first sentence)... Feraess, even if you're right about Freerunning being "not relevant enough to be listed in the first sentence" ideally, you have to consider the current situation in which Freerunning redirects to this page.  If you create a separate article, that's great, but given the fact that the subject is redirected, the article can't trivialize the term, let alone the subject, both of which it currently does.  Whatever the relation between the two disciplines based on available reliable information, you can't argue that the term "Freerunning" isn't constantly paired with "Parkour".  The entire topic should just be called Parkour & Freerunning, which would nullify your point supported or not that Freerunning may not fit as a subset of Parkour.  That is, listing both would say "There are 2 topics on this page related in some manner or another".