The lack of stability or “instability” of the lumbar spine must be differentiated from hypermobility. In both the range of motion is greater than normal. However, instability is present when excessive movement is accompanied by a lack of “protective” muscle control (Maitly 1986). The two situations are often the cause of many lumbar pains.
Spine stability is determined by three different systems: the passive, relating to noncontractile tissue; the active, to contractile tissue (muscles); and the neural control system related to the nervous system.
One of our goals in the rehabilitation process is to acheive the restoration of active lumbar stabilization, so that the final stage is to convert the conscious control of movements (cortical pathway) to an unconscious level (subcortical pathway).
This can be achieved by an increase in sensorial stimulation, improving the activation of the subcortical systems and thus the muscle reaction speed.
Yet in many back pain prevention or treatment programs, the norm are still abdominal exercises in which torso flexion (“sit-ups”) with or without rotation, or leg elevation, mainly using the mobilizing abdominal muscles, predominate. However, one of the important functions of the abdominals is spine stabilization.
We may classify the muscles of the torso in the following way:
- Mobilizing: the rectus abdominis, the lateral fibers of the external oblique and erector spinae
- Primary stabilizers:transversus abdominis and multifidus
- Secondary stabilizers(can also move joints):internal oblique, medial fibers of the external oblique and the quadratum lumborum.