In fact, the internal muscles may not be reached at all. The answer lies in re-educating the body to move the way it was designed. In America many people are now trying autonomous sitting for meditation. It has long been known that autonomous sitting can enhance the meditation experience. It does this by freeing circulation and breathing which in turn help induce relaxation.
Back pain can hamper or even prevent one from meditation practice.
With meditation comes body awareness. Since we are designed for constant movement, we do not fit in with our specialized, technological environment where tasks are performed over and over again, usually in a static posture. That is why we have repetitive stress injuries like carpal tunnel syndrome. Most back pain is caused by the repetitive activity of sitting. We sit at home, in the car, at work or school, in the movies.