I am thinking of going to one tomorrow (at a Virgin Active if that makes any difference) and I really have no idea what you do in one. What types of exercises is it? Is it all laying down? I am trying to lose a little weight, but mostly strengthen my core as I have an ongoing IT band injury that is totally due to weak core and glute muscles. The classes I used to do we're all cardio like BodyPump so I am entering an area I know nothing about!