Sport is competitive sport, Rambam said you cant hit someone Derech Nitzchon (in a way to defeat over them if its not self defense), so for example a person can learn self defense, but to compete in tournaments is Osur (Rabbi Shraga Kallus), (see Rabbi Moderchai Becher’s website where he discusses (on a Shiur on the subject) that sparring for self defense purpose is permitted).
So even playing American football or basket ball (which is a contact sport) you are hitting someone just to be ‘nitzchon’ over him, it is Osur, even according to Rabbi Moderchai Becher.
Perhaps hitting someone with a high flying ball (e.g. tennis or baseball), making him the bat back, hurts the person and qualifies as hitting someone ‘derech nitzchon’.