At the end of this very successful conference one of my colleagues said to me, “It feels like the whole physio world is talking motor control and the CNS.”

Presented here was substantial scientific evidence supporting the motor control retraining approach to rehab. Some of it is summarised below:

Dr. Paul Hodges provided further insight into the strategies used by the central nervous system (CNS) for controlling the lumbopelvic trunk region in balance and stability challenges. For example: when perturbation of the trunk occurs, the CNS uses a feed forward strategy to move the trunk in the opposite direction to the perturbation, so that inertia can be used to decelerate trunk displacement in the direction of the perturbation force.

In trunk perturbation or in any balance - or stability - challenging situation it is normal for the CNS to employ a ‘stiffening strategy’ to co-contract trunk muscles to protect against large challenge forces (e.g. walking on ice on a windy day). However Hodges described how in motor control dysfunction the CNS inappropriately employs the same stiffening strategy to control even low load, functional movements. He aptly described this strategy as “One size fits all”, meaning the same co-contraction stiffening strategy is used to control balance and stability in all situations. This correlates with Kinetic Control’s “substitution strategies” or “co-contraction rigidity”.

Hodges also provided evidence to back up the need for recruitment specificity when retraining motor control deficits in Transversus Abdominis (Tr Ab). He showed that the more specific the isolation of Tr Ab low load recruitment the more significant the improvement in the feed forward timing of the muscle recruitment. And the less specific the isolation the more inappropriate substitution strategies are used and the less improvement in the motor control deficit.

Dr. Lorimar Moseley provided significant insight into the effect of pain perception on the CNS by focussing more on the ‘biology’ or the actual physiological changes that influence pain rather than the psychosocial aspects of pain management. He emphasised the importance of “explaining pain” to the patient to reduce their fear and adverse beliefs about their pain which in turn can improve motor control and performance.

In a joint study he carried out with Hodges he showed that in subjects with no pain, even fear or anticipation of a previously experienced pain can cause a recruitment timing delay in Tr Ab.

Moseley described how in chronic regional pain syndrome pain can actually modify the ‘virtual body’ (e.g. the sensory and motor homunculi in the cortex, there are many others) in the brain by increasing the sensory representation and decreasing, or “smudging”, the motor representation. The former has the effect of the painful body part being perceived as being bigger than it actually is. For example in one of his studies the painful hand was perceived as being 11% larger than its real size. The “motor smudging” has the effect of reducing the ability for specific recruitment in the painful region. This may partly explain why specific stabiliser muscle recruitment is so difficult for some chronic pain patients.

Low load recruitment dominance in deep stability muscles is more difficult to feel than high load co-contraction when there is a recruitment dysfunction. Patients experience a high sense of effort to achieve a dominant low threshold recruitment in deep stability muscles.This was illustrated in the study by Iain Beith, in which he showed a clear relationship between sense of effort and maximum voluntary contraction (MVC) percentiles in EMG studies on Tr Ab and the superficial abdominal muscles. He showed that the greater the level of contraction achieved in the deep muscle the harder it is to isolate the activity from the more superficial muscles. At a 60% sense of effort hollowing contraction Tr Ab contributed 25% suggesting that the other superficial muscles contributed more (substitution). At 10% sense of effort of hollowing contraction Tr Ab contributed 70% suggesting that it participates in a more dominant role. It is not possible to isolate Tr Ab from the superficial abdominals but it seems that there is a better chance of achieving a transverses dominant hollowing contraction if you don’t try so hard.

There are links advocated between posture and movement dysfunction and rehab includes postural control as part of motor control retraining. Kate Dolan presented her findings that multifidus shows a significant reduction in activity for seven hours after 20 minutes of end-range slouch sitting and after 10 minutes of repeated flexions. Also joint repositioning error (JPE) was changed after as little as 5 minutes of slump sitting.

Dr. Peter O’Sullivan showed that spinal stabiliser muscle activity was significantly less in ‘thoracic upright’ sitting than in the correct lumbopelvic upright sitting, reinforcing the need to be more specific when teaching patients the correct neutral spine sitting position. Dr. Gwen Jull stated in her pre-conference course that as well as lumbar stabilisers such as multifidus showing more activity in the correct lumbopelvic sitting position, the deep neck flexor stabilisers are also more active in the same position. O’Sullivan described how chronic pain patients use excessive co-contraction stiffening to maintain themselves in a sitting position.

Dr. Annelies Pool-Goudzwaard spoke of the pelvic floor being an important contributor to the trunk ‘stability cylinder’ and in pelvic floor dysfunction the stability of the cylinder is compromised. The pelvic floor stiffens the SIJ by 8.5% and a link has been found between pelvic floor dysfunction and headache. In dysfunction the pelvic floor can become either under-recruited at low threshold or, as emphasised by Dr. Pool, over recruited at low threshold. It can have too low a threshold of recruitment which can cause symptoms such as coccydynia.

Peter O’Sullivan described how “stability is mobility” which reiterated Paul Hodges’ claim that “stability is never static”. O’Sullivan described patients’ movement patterns presenting as ‘adaptive’ or ‘maladaptive’. ‘Adaptive’ means an antalgic or pain avoiding movement strategy appropriately used by the CNS to protect or offload acutely inflamed tissues. If such movement strategies continue after the resolution of the inflammatory healing process this can become a ‘maladaptive’ movement pattern, often perpetuated by fears and beliefs about their pain. Then their previously ‘normal movements’ have been replaced by inappropriate movement patterns. There can be various reasons why movements can become maladaptive and these patterns in themselves can become provocative and symptomatic.

On the theme of control deficits Dylan Morrisey has shown that it is possible to identify relative stiffness in different regions of the shoulder complex. His PhD studies are showing that clinically we can assess translation ‘give’ at the glenohumeral joint or ‘give’ at the scapulo-thoracic ‘joint’ and relate the ‘give’ to control deficits and pathology in the shoulder complex. This validates the Kinetic Medial Rotation Test taught on SMARTERehab Movement Dysfunction courses.

And staying with shoulders, Jui-Jeng Lin did some motion analysis studies of scapula movements during four functional tasks and found that the scapula was in an anteriorly tipped and downwardly rotated position (equivalent to the term I.A.G. - Inferior, Anterior Glenoid) in painful shoulder subjects.

SMARTERehab describes control deficits or uncontrolled movement, and repetitive movements, all as possible causes of micro trauma and tissue pathology. Micro trauma in repetitive movements was addressed by Dr. Ann Barr in a study on rats describing histological and behavioural changes in high load high repetition movements and low load high repetition movements of the rat forelimb. Tissue inflammation and damage was found in the rat paws in the involved limbs, aswell as loss of distinction of sensory cortical representation of the involved limb. Tissue and behavioural changes were found indicating possible effects of cumulative exposure to repetitive tasks

It should be noted that it is normal for tissues to be microtraumatised during movements and normal to heal. But a small percentage of people may not heal sufficiently leading to pain syndromes.

Although a lot of the spinal research appeared to be focussing around the lumbar spine, Dr. Gwen Jull and Dr. Michele Stirling held up the cervical spine corner including their pre-conference practical course. They showed that in neck pain patients there is an altered JPE and delayed feed forward recruitment timing in the deep neck flexor muscles. Two groups of patients received rehab, one involving cervico-cranial flexion (CCF) training and the other involving strength training. Symptoms resolved in both groups but the recruitment dysfunction remained in the strengthening group. The feed forward timing and the JPE were significantly improved in the CCF group. These were not improved in the strengthening group.

This reinforces two points held by trained Movement Dysfunction therapists. The first is that the recruitment dysfunction can still be present even after symptoms have resolved. The second point is that low load motor control function is only shown to be consistently improved by specific low load recruitment training and is not shown to be improved with higher load strength training.

Conclusion:

This conference suggested that contemporary physiotherapy internationally is moving towards addressing the central nervous system as the source of patient’s dysfunction. Evidence is showing that pain and performance is intricately related to changes within the CNS. There is an evolving understanding of the complex motor control strategies used by the CNS to produce and control multiple concurrent movement patterns and homeostatic functions and how these are altered with pain and disability. And there is more evidence that we as clinicians must appreciate the biological and physiological affects on the CNS of pain perception, attitudes and beliefs as well as psychosocial factors for effective management of our patients.

The 3rd International Conference on Movement Dysfunction is being held in Edinburgh, Scotland, UK in October 2009.