The laying on the floor could be substituted by standing against a door. The floor or the door is to let you know what a straight back is. On the floor is a Pilatus excercise. Do it as often as you like. Against a door can have an added advantage. You can raise and lower through the feet and knees. In one bar, which is three beats of a Waltz, you will raise and lower twice. In one minute there are about 28 bars of music. It doesn't take much to work out how many time you will lower and rise in one minute thirty seconds in a competition. Good Luck.