Ana Forrest has great focus on core strengthening, when we come from a place of core strength we are able to relax the hips and lower back. It is the first step to opening the upper back and lengthening the side of the body. It is a great place to start. I have found that these core strengthening exercises given in Forrest yoga are quite advanced and difficult to execute correctly without compensating elsewhere initially. One might need to take a step back first and find a slightly less challenging way first.