For many a distressful situation (that should not come!), people organize a communal recitation of parts of the book of T'hilim (Psalms). In some of these, there is a leader, who recites each verse and is copied by the assembled; he then recites the next, and so on. Almost invariably in my experience, the entire group of people (except the lame and the weak) is standing throughout. Why do they stand? I'd appreciate learning any reason for doing so or, especially, any source that says they should or that says that it's customary for them to do so.