[Mathew]

The extensor action and the right elbow location are two completely seperate issues. Extensor action is the right arm always trying to straighten against the leash or checkrein of the left arm. That means the further the right hand goes towards the right shoulder it will bend. If you draw a straight line from the shoulder to the base of your right hand, the bent right arm could theoretically without regard to anatomical constraints could rotate around this line and effect the elbow location without affecting the extensor action for any given point.