When I used to teach exercise and aerobics classes, I always told my students that they would probably not feel much the first day. It's the second and third days that they'd want to stick pins in a Mary doll. Any time you work a muscle group that hasn't been exerted to such an extent, this will happen. The absolute best thing you can do to ease the pain and soreness is to take a hot bath w/Epsom salts. It helps to rid your body of built up lactic acid, which is the cause of your soreness. Good luck and good for you for taking a spinning class, girl!