Although the counsel not to get involved in certain sports is listed in the awake magazine, I think it is up to a person's conscience (to a degree).
I knew many JWs that went Whitewater Rafting and scubadiving and nothing was said to them. I also know of a Witness who allows her daughter to play on the school's basketball team. I think it depends on the strictness of the congregation whether a stink is made about it or not.