In principle, any of the structures within the lumbar spine that receive innervation from the nervous system can be a source of back pain. Thus back pain can arise from any of the ligaments, muscles, fascia, joints or discs of the Lumbar Spine. Read more information on low back pain. 

Mobilizations primarily consist of passive movements which can be classified as physiological or accessory. The purpose is to provide short term pain relief and to restore pain-free, functional movements by achieving full range at the joint.

Joint mobilization is a treatment technique which can be used to manage musculoskeletal dysfunction, by restoring the motion in the respective joint. The techniques are performed by physiotherapists and fall under the category of manual therapy. Spinal mobilization is described in terms of improving mobility in areas of the spine that are restricted. Such restriction may be found in joints, connective tissues or muscles. By removing the restriction by mobilization the source of pain is reduced and the patient experiences symptomatic relief. This results in gentle mobilizations being used for pain relief while more forceful, deeper mobilizations are effective for decreasing joint stiffness.  

Research has shown that mobilization used as therapy can produce significant mechanical and neurophysiological effects. The explanations of these effects – the mechanism of mobilization – is still relatively unknown, especially in regards to the spine, and is subject to further research. However, several theories have been established in accordance with the effects seen, including the effects of pain relief, increasing range of motion and the influence on the autonomic nervous system.

Mobilizations offer pain relief through hypoalgesia – decreasing the nervous system’s sensitivity to painful stimuli. There are various potential mechanisms of this neurophysiological effect:

1. Pain gating
   Pain gating refers to the theory that stimulation of the mechano-receptive peripheral afferent nerves in the muscles produce sensory input that interferes with nociceptive impulses at the spinal cord.The input from the larger sensory nerves inhibits the transmission of pain through the smaller nociceptive nerves to the brain, leading to a pain-relieving result. Therefore, the processes of stimulating mechanoreceptors via mobilisation produce short term pain relief through the mechanism of pain gating. However, the pain gate theory only explains the pain-relieving effect during the mobilisation, not any long term effects post-treatment. Therefore it is hypothesised that any longer-term pain-relieving effects are mediated by higher brain mechanisms.

2. Descending mechanisms and supraspinal regions
   Research has shown that mobilisation leads to activation of pain inhibitory pathways that originate in the midbrain and travel down the spinal cord – the descending pathways.

The pathway stimulation works to provide pain relief by suppression of pain through this inhibitory mechanism. In addition to this these descending pathways, research has shown a trend where regions of the brain responsible for central pain processing are suppressed during mobilisation.

3. Adaptation
   It has been hypothesised that mobilisation promotes adaptations of the nervous system with a decrease in the level of neural input from the painful site. Research also suggests that mobilisations increase the pain threshold levels – relative hypoalgesia. It has been suggested that this could be due to electrochemical changes in the regulation of threshold potential.

4. Increasing Range of Motion

Mobilizations are often used with the objective to increase the range of motion of the joint through stretching of fibrous tissue. This stretching may cause the tissue to ‘creep’. The phenomenon of creep relates to the ability of tissues to change shape over time as a constant load is applied. The creep deformation is not permanent and, once the load is removed, the tissue will slowly resume its original length. However, in the short term, this mechanical effect of mobilization enables an increase in range of motion at the joint.

Influence on Autonomic Nervous System

Mobilization has been found to influence sympathetic activity, affecting heart rate, blood pressure and respiratory rate. These sympathetic responses could possibly be linked to another evidenced effect of mobilization – changes in blood component levels. Teodorczyk-Injeyan et al (2006) found that mobilization effected the levels of blood components, with a reduction in inflammatory proteins. Therefore it was suggested that mobilization could be a potential therapeutic modality to reduce inflammatory response – working as an anti-inflammatory mechanism, though the exact explanation for this process is unknown.

Bialosky et al (2009) suggested that the mechanical and neurophysiological effects explored here are interlinked. They proposed that a mechanical force initiates a chain of neurological responses, which would then produce the outcomes associated with manual therapy. This proposal was illustrated in their model of the mechanisms of manual therapy.

The effects of mobilization and the mechanisms responsible are not fully understood and more research is needed to provide evidence for the theories discussed. It is also important to note that variables such as the placebo effect and psychological factors may also pertain to the effects seen.

Effects of Mobilization on Stiffness and Pain

Mobilizations involving pressure onto the vertebra can be used to increase joint range of motion, and also to produce and analgesic effect. 

Manual therapy and mobilizations can be used to treat 5 symptom groups:

• Pain
• Stiffness
• Pain associated with stiffness
• Momentary jabs of pain
• Disorders directly related to a specific diagnosis