Now that the horse is warmed up they go back to the shoulder in, making sure that the angle is appropriate for the horse to push into the outside rein.  They work on developing his strength by using the shoulder in.  Because this horse is tight in the back the rider sometimes rides in the posting trot.  Laura explains that the shoulder in is ridden to develop strength behind and the haunches in develops suppleness while the half pass shows both. As they ride haunches in you can see how stiff he can be and how effective this exercise is in suppling him.