Integrating core stability into functional movement has long been one of those un-talked about subjects where the assumption is that prerequisite loading in other non-functional positions is then transferred into a loaded environment.  The model used to explain this is the classic model of motor learning described by Posner & Fitt’s in the late 1960’s, which describes three stages of motor learning:

The Cognitive phase

The Associative phase

The Autonomous phase

This model repeatedly surfaces in the physiotherapy rehabilitation literature as an framework for the sequential loading working towards functional tasks.  It should be pointed out that there are several other theories of motor learning which do not necessary follow this paradigm, but it also serves a dual purpose in the clinical environment, as interventions at the early phases using this strategy tend to be low load and therefore minimal risk / reduced likelihood of provocation.

However, there is an equally strong argument for the massive sensory bombardment, which occurs from using functional positions as a way to stimulate specific muscle activity.  Historically, the difficulty in clinical practice is to ascertain whether the target muscle groups are actually being recruited as part of a global functional movement pattern.  This undoubtedly remains the significant clinical challenge.

Some of the recent trends in athletic training involve the use of functional exercise programs, which try to replicate functional demands.  If we look at the frequent reports of symptom provocation from patients, there are some very familiar aggravating factors, which I think we would all recognise.

Sweeping & Hoovering

Carrying shopping

Walking the dog

Accessing car boots

Working in overhead positions

Twisting or reaching

It is clear from evaluating these positions that there is a change in the relationship between the thorax, the pelvis and the intervening lumbar spine and therefore some degree of mobility must accompany the necessary “stability” to counteract loading.

Because segmental rotation in the lumbar spine is very limited (estimated at 2º – 3º in each direction per segment) it would appear biomechanically that the majority of rotation must occur from the thoracic spine and the hips.  It is tempting to speculate that any impaired mobility in these areas maybe a significant driver to rotational pressures through the lumbar spine causing tissue sensitivity.

If we look at control of the lumbar spine during function from that perspective, the role of the oblique musculature (both abdominal and spinal) could be considered as “anti-rotation” muscles whose role is to minimise the stresses distributed to the Lumbar segmental structures.  In that situation the limbs and torso become the external “drivers” forcing load on the core..

Using this model to replicate function there are two key principles of loading.

1)    Asymmetrical stance

2)   Altering the loading segment (driver).

In reality this means that evaluating trunk stability needs to be assessed in conjunction with asymmetric limb loading which is more akin to normal activities of daily living.

Clinically, this means using positions such as:

Asymmetrical squat

Stride stance

Lunge

Single leg stance

as variations in the start position and combining this with variations in the loading force (driver), either using arms, torso or legs.  The degree of difficulty, hence risk of injury, is related to the magnitude of load with arms being the lowest, legs being second and torso being highest.

Whilst visual observation is how most of us rely on accessing the quality of movement there is certainly a limit to what can be achieved.  The big clinical decision is whether we can use load or speed of motion as the next level of exploration/provocation to see if we can elicit a breakdown in control.  Obviously this needs to be weighed up against the vulnerability of the pathology.
So from a practical perspective it is quicker and easier to initiate functional rehabilitation strategies as the prime intervention for low back pain patients unless their level of irritation contra-indicates or they do not tolerate the level of loading associated with function. Patients in that category may then self-select for lower loading regimes as an intermediate stage.

The alternative, and one which has become pervasive in recent years, is to work through a multitude of phases which may not particularly challenge the patient in a way that is relative to function, although appear deficient from the perspective of musculoskeletal control and ideal movement patterns. The well known phrase “Paralysis from Analysis” springs to mind.

Enjoy the clinical challenge.

David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2009. | Permalink | 2 comments | Add to del.icio.us
Post tags: core, core stability, low back pain, lunges, motor learning, movement impairment syndromes, physiotherapy, single leg stance, squats, transversus abdominis, trunk control

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