Stimulating Muscle Movement

So i thought i'd start with designing some rough concepts of chairs, focussing solemnly on the ways these could simulate movement of the spinal position, and straight away i realized i needed more information. The chairs shown above are just quick sketches i had a go at this morning when i realized i need to figure out first where in the chair exactly the movement is needed, i placed one rotational point underneath the seat and one in the back of the seat. In the Placentero Chair the rotation point was too low to prevent lower back issues, but where exactly is the vital point of rotation?

Online i researched the basic information about back pain to help me understand how to solve this issue, and on the websitewww.medicinenet.com they gave me a list of the most common causes of lower back pain:Number 1 is a Lumbar Strain, "this is a stretch injury to the ligaments, tendons and/or muscles of the lower back. The stretching incident results in a microscopic tear of varying degrees in these tissues. It can occur due to overuse, improper use or trauma"Number 2 is a Nerve Irritation, "The nerves of the lumber spine can be irritated by mechanical impingement or disease anywhere along their paths- from the roots at the spinal cord to the skin surface."Number 3 is Lumbar Radiculopathy, "which is a nerve irritation that is caused by damage to the discs between the vertebrae. Damage to the disc occurs because of degeneration ('wear and tear') of the outer ring of the disc, traumatic injury, or both.Number 4 is Bony Encroachment, which is basically either movement or growth of the vertebrae of the lumbar spine which can then limit the space of the adjacent spinal cord and nerves.Number 5 is Bone and Joint Conditions, "this includes conditions that lead to lower back pain existing from birth and those that result from wear and tear (degenerative) or injury, and those that are due to inflammation of the joints (arthritis). Number 6 is as a result of other problems, "Other causes of lower back pain include kidney problems, pregnancy, ovary problems and tumors."
Further on i found the most vital part of information as they went on to say that the movement of the spine is strongly influenced by the movement of the hips as the muscles in our lower back is obviously closely connected to the hipbone.Finally i realized the prime importance is not in the moving of the back rest of the chair or in the movement of the entire chair but rather in the rotational movement of the actual seating part by itself.