Vicky is right. You can't only isolate muscles but you also have to balance and INTEGRATE them. Most of our body motions are initiated in the abdomen and lower back, and any physical therapy should, in my opinion, be integrated with that power center. A good exersize regimen should be able to exersize the musculature running from the tip of the little toe, up the calf, thigh, and onto the psoas and abdomen. And that's only one of the necessary lines to integrate.