I have a very strong client in good physical shape. However, she has a minor anterior tilt and a forward head/protracted shoulder posture. When performing the Reebok assessments, all the ones she had difficulty with kept pointing to doing the wall sit with arm raise. She finds this exercise very difficult and cannot perform it correctly. As her arms raise, she feels strain in her lower back. How do I assess whether tight lats and protracted shoulders are causing the inability to do this exercise or tightness in the lower back and core stability? What exercises can I do as a prerequisite to the wall sit arm raise?
First, it does sound like tight lats, but that is not the only issue. I could use this space to discuss how we clinically evaluate tight lats, but that will not solve your problem. Problems are rarely isolated. It is human nature to want to blame one thing, but it is never that simple. Look at it as a limited movement pattern - you must fix the pattern, not just the parts of the pattern.
The wall sit is the correct exercise choice. You just need to make some modifications. To modify the exercise until she improves, elevate her butt and leave her feet on the ground. They do this in yoga when people have tight hips. We use something that is about eight inches by eight inches with thickness ranging from two to six inches. Supporting the thighs will also help. We start them on a lift of six inches and reduce it by one or two inches as things improve. A one inch board or exercise mat cut to size works well. Only slide one arm up the wall at a time, and take note of the tightest side, if there is one. Focus on symmetry. Use a stick to create a passive traction stretch and progressively lower the butt. This stretch will help break the bad pattern, but it will take something like dead-lifts to change the posture. Stretching rarely changes posture. It requires breaking an old pattern (wall sit) and making a new pattern (dead-lifting). Most trainers don't use dead-lifting and modified dead-lifting as much as they should. We did a DVD called Secrets of the Core - The Backside that teaches this in detail if you have technical questions.
I've included two pictures below to help you visualize the move. Note, in Figure 1, the individual does not have a butt lift. I attached this picture so you can see the single arm passive traction stretch. Don't forget to do something to reduce muscle tone before you stretch. I prefer the stick over foam roll for lats (Figure 2).