US boarding schools stress both academics as well as extracurricular activities. High schools and colleges want students who are well rounded. It is important that the school will be able to cultivate in your child both excellence in academics as well as sports or arts. Unless you are competing in the Varsity level, I don’t think your child will have too much sports. And even at a varsity level, the boarding schools do know that the students have to study. They will try not to overly stress the students.
