Core Stability & Functional Movement

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

Technorati Tags: core, core stability, low back pain, lunges, motor learning, movement impairment syndromes, physiotherapy, single leg stance, squats, transversus abdominis, trunk control

Proprioception, Kinaesthesia & Neuro-muscular control

As clinicians we often use these terms interchangeably to describe the phenomena of altered limb sensation or control.  However, researchers classify each component separately on the basis that there are different physiological mechanisms underlying each component.

- is considered the cumulative neural input to the CNS from mechano-receptors located in the joint capsules, ligaments, muscles, tendons and the skin.  Other terms that are often used synonymously with proprioception include ‘kinaesthesia’ and ‘balance’.

- is the conscious awareness of joint position and movement resulting from proprioceptive input to the CNS.

- refers to the ability to maintain the centre of gravity over the base of support without falling.  The ability to maintain balance requires the integration of proprioceptive input from the periphery and afferent information from the eyes and vestibular apparatus in the inner ear.

Appropriate use of this terminology is important among clinicians to enhance communication and understanding in this area.

In the last decade clinicians have been increasingly interested in the use of closed chain exercises on the basis of their enhanced proprioceptive value.  This is partly on the basis of the similarity to functional loading and the presumption that the total proprioceptive input is more likely to activate the appropriate neural pathways.  Closed chain exercise results in the simultaneous motion of all joints in the extremity, which thus requires co-ordinated muscle activity to control all the segments in the limb.

Here lies the challenge for us clinicians because the attraction of such a massive sensory of bombardment is obvious, but the trade off is the inability to accurately quantify the contribution of individual muscles and the specific area of breakdown.  If we take ‘single leg squat’ as an example and look at the typical areas of breakdown as determined from observational analysis we might observe some of the following:

 

1)                  Increased pronation.

2)                  External tibial rotation (out toeing).

3)                  Valgus knee.

4)                  Medial femoral rotation.

5)                  Adducted femur.

6)                  Laterally displaced pelvis.

7)                  Pelvic drop or elevation (trendelenberg or disguised trendelenberg)

8)                  Pelvic rotation.

9)                  Trunk deviation.

10)              Balance reactions using the upper limbs.

The challenge as clinicians is to determine the zone of breakdown and the compensatory mechanisms.  The dilemma of functional loading is to stimulate proprioceptive input where the sensory feedback is usually far less distinct than isolation of a specific region in a non-functional position.  Treatment strategies therefore involve some element of “aspiration” that there will be transfer of muscle recruitment and position sense from specific exercise positions into functional situations. Therein lies the challenge – to go specific or go general.

There certainly appear to be a group of patients where any physical stimulation is sufficient to activate some level of useful muscle function and significantly impact symptoms.

There also appear to be a group of patients who are reasonable active but present with more specific muscle imbalance issues related to patterns of activation.

There are also patients who are systemically hypermobile with a pre-disposition to low tone. They are dependent on specific stimulation to maintain status.

And then there are those who are stiff, who are usually structurally more robust, appear to have better intrinsic tissue characteristics and can be less vigilant about maintaining muscle tone. They may however require more of a flexibility focus.

Such is the tapestry of life but worth remembering as it influences the nature of our patient management and the type of advice given – very important if we are to be credible messangers.

Enjoy the clinical challenge.

David.

Technorati Tags: Adducted femur, Balance reactions using the upper limbs., Body balance, closed chain exercise, External tibial rotation (out toeing), Increased pronation, kinesthesia, Laterally displaced pelvis, Medial femoral rotation, Pelvic drop or elevation (trendelenberg or disguised trendelenberg), Pelvic rotation, proprioception, single leg squat, Trunk deviation, Valgus knee

FUNCTIONAL ADAPTATIONS TO QUADRICEPS INHIBITION

The acknowledgement of quadriceps inhibition as a complicating factor in knee joint pathology is pretty much unquestioned in routine clinical practice.  This is evident by the standard  prescription of inner range quadriceps exercises as part of any post operative knee  regime and also cases of knee pathology that do not require surgical intervention.  My views on the appropriateness of inner range quadriceps as a primary strategy for quadriceps re-education are well known and have been discussed in previous posts (see Terminal Knee Extension) but suffice to say that I am not a big fan as I think there are more superior choices of exercise.

Compensatory Movement Patterns

In this discussion I want to review some of the compensatory movement patterns  observed clinically which appear to be the result of poor quadriceps functioning:

1. Impaired terminal knee extension

-  is the most obvious example and needs no further expansion here.

2. Compensatory hamstring hyperactivity

- this can be indicated by a persistence of hamstring tightness even when routinely stretched, indicative of an increased recruitment strategy.  It may appear paradoxical but the literature is full of detail on quadriceps / hamstring co-activation (particularly the ACL rehabilitation literature). Not surprisingly the reciprocal activation of hamstring / quadriceps recruitment is not an on-off mechanism but a graded degree of simultaneous tension – consistent with all joint requirements for stability. It may be that the compression produced by hamstring activity is a compensatory strategy for compromised quadriceps contribution?

3. Hamstring dominance in active straight  leg raise test

- the active straight leg raise test has been utilised as a measure of pelvic and groin dysfunction can also yield useful information regarding hamstrings / quadriceps activation.

I modify this test by bringing the patient into a straight leg raise position just short of hamstring tension and then request an active hold in this position.

Therapists can then observe two things:

A). A loss of terminal knee extension when under active control or

B)  Determining the site of predominant muscle activity (asking the patient to report their predominant area of perceived effort) which in this situation will often point to the hamstrings.

Because the position of the test is short of full hamstring tension one cannot deduce that this perception of increased hamstring tension is due to a lack of elasticity.

4. Compensatory trunk flexion

in an attempt to maintain the length / tension relationship of the quadriceps.  This is usefully measured in sitting with the establishment of a lumbar lordosis in an upright-seated alignment, feet off the floor.  The patient is then asked to extend the knee.  The frequent observation in this test is for the pelvis to posteriorly rotate producing trunk flexion.

In order to determine if this is a result of hamstring restriction or lack of active quadriceps control the therapist should try to passively extend the knee at the point at which the pelvis starts to posteriorly rotate.  Increased mechanical resistance indicates posterior leg tightness; greater passive range indicates inner range quadriceps inhibition compensated by posterior pelvic rotation.

5. The hamstring – gastroc paradox

- this is a concept we have touched on before and one not frequently discussed in clinical circles – although sometimes alluded to in gait analysis.  The crux of this theory is that the gastroc soleus complex acts with reversed origin /  insertion activity with the ankle as the fixed point.  Gastrocnemius contraction coupled with that of the hamstring produce a combined force, which tends to extend the knee.

In biomechanical terms this is the old ” parallelogram of forces” rule where two muscle groups crossing a joint from above and below act in a combined manner to extend the joint.  This again can be tested clinically by utilising a stance position superimposing a ¼ – ½ range squat on the front leg.  Palpation of dominant muscle activity is one way to try to determine predominant muscle activity and of course verbal feedback on dominant site of perceived effort is another.

In a previous discussion’s on extensor chain function we looked at the interaction between hip extension, knee extension and ankle plantar flexion as part of the basic propulsive mechanism.  Obviously disturbances in the synergies of these primary muscle groups will compromise the efficiency of this movement pattern.  The clinical challenge is to determine the site of increased stress and the mechanism of overload within the system. So many patients we see demonstrate an “Apropulsive (without propulsion) gait due to compromise of the extensor chain. As clinicians we need to be alert to recognise these mechanisms.

what observational gait parameters would give us clues about lack of propulsion in walking?

Enjoy the clinical challenge.

David

Technorati Tags: Biceps femoris, clinical testing, functional adaptations, functional movement, functional movement testing, hamstring / gastroc paradox, hamstring /quadriceps co-activation, Hamstring Flexibility deficits, hamstring rehabilitation, Hamstring strain, inner range quads, knee extension, knee stability, movement patterns, muscle hyperactivity, quadriceps, Semimembranosis, Semitendinosus, static quads

Manipulating Exercise Variables

Selecting variables to modify in a rehabilitation program can prove challenging. Most therapists are familiar with the obvious variables of LOAD & REPETITION but there are numerous other factors that can be manipulated.

1. Speed
2. Range of Motion
3. Base of Support
4. Plane of Motion

Combining different elements of these components allows progression or regression as required. It is essential that therapists are competent in applying these principals in a clinical setting

Click exercise variables to hear the lecture.

Technorati Tags: Exercise, rehabilitation, treatment

Functional Assessment

Many of you will be familiar with the concept of functional training in rehabilitation, so a brief review of historical aspects will suffice here.

Functional training from a rehabilitation perspective has been used for many decades with the obvious goal of returning an individual to their pre-injury functional status.

The astute reader will note that this implies a degree of individuality and specificity in rehabilitation strategies depending on the individual’s response to the injury in question and the planned functional goals to be achieved. In this discussion we are concerned with a return to playing sport, which has different functional requirements depending on the sport of choice.

Most rehabilitation specialists would agree that the fundamental measure of success is the ability to “perform at maximal function”. The issues of debate usually centre around:

1. Whether to use functional exercise as an initial priority.
2. Whether to place prerequisite criteria for progressing to functional exercise e.g. base line flexibility measures, stability measures, agility, coordination and power.
3. The use of over load / external resistance to achieve progressive increases in power output.
4. Key variables to manipulate in exercise progression e.g. load, speed, plane of motion, movement sequence.

Perhaps the biggest source of discussion in this regard is the use of fixed weights / machine systems relative to free weights. In the non-elite athlete there are some attractive aspects to using fixed weights as the machines themselves provide some degree of stability, are relatively safe, allow max or near max loads to be utilised and can be undertaken individually.

Unfortunately the artificial stability provided by machine systems dictates that a critical aspect of functional strength is not trained and therefore of debatable relevance in functional loading. On the other hand free weights use allow mass activation of stability and mobility muscle groups, more closely approximates functional movement patterns and requires higher levels of skill and coordination particularly if technical or explosive lifts are being attempted. Most serious athletes will incorporate some degree of free weights into their training.

The gap between these two approaches can be neatly filled by incorporating batteries of functional tests which explore movement control and coordination in varying combinations of body position, primarily with body weight as the external load, but progressing with small proportional increases in resistance as control allows. It can be reasonably argued that inability to control one’s body weight through a full functional repertoire of positions which are likely to be encountered in the course of the game situation may predispose to injury.

One of the current difficulties related to repeated tests / re-tests of functional measures are the measurement systems used. These tend to be somewhat “low tech”, can sometimes rely on the individuals perception of effort to perform a desired task or require an external examiner’s observation of the quality and sequencing of movement. Needless to say there maybe many hours of debate regarding differences of opinion on these issues!!!

Nonetheless a useful concept in this regard (popularised by American Physiotherapist Gary Gray), utilises the concept of threshold training in which the extreme position which an individual can control is measured relative to that of the other side. Any further change in position produces falling or loss of balance or some compensatory adaptive mechanism – indicating failure.

Components of a total body functional profile.

1. Safety.
2. Measurability.
3. Reliability and validity.
4. Simplicity.
5. Meaningful.
6. A full spectrum functional testing.

These concepts should be borne in mind when deciding what battery of functional tests to include for an individual or as part of a team training / screening protocol. The other critical point to recognise is that loading is occurring in three planes of motion simultaneously – tri-plane motion.

In clinical practice it is often by combining three planes of motion simultaneously that one can expose weaknesses, which do not appear evident when testing an isolated plane. If one analyses the movement patterns involved in most sports we can see that they can be broken into groups of core functional activities e.g. jogging, running, decelerating, excelerating, twisting, pivoting, jumping and pushing.

Each of these complex movement patterns can be broken down into components and each can be stressed using varying combinations of challenges e.g.

1. Range of motion.
2. Sequence of motion.
3. Eyes opened / closed.
4. Corporating simultaneous trunk and limb movement.
5. External resistance e.g. elastic tubing, bungee cords or dumbbells.

All allow varying degrees of difficulty to be explored in order to be determine the functional threshold of control.

Gray groups his functional tests under the following categorisations.

1. Balance tests.
2. Balance reach tests.
3. Excursion tests.
4. Lunge tests.
5. Step up tests.
6. Step down tests.
7. Jump tests.
8. Hop tests.

Functional self-test menu

Below are listed a group of self-test movements which can be administered and the degree of difficulty noted. Please note that there can be many different reasons for an inability to perform complex patterns which could include flexibility, stability, power, endurance or coordination deficits.

1. In- line lunge with body rotation.

Stand in a long stride position with front and rear legs in one line and feet pointing forwards in the same direction. Heels must stay on the ground. Bend front knee and hold leg position still. Add alternating twists of the upper torso to left and right side.

2. Single leg stance with toe touch.

Standing on one leg bend forwards to touch toes with the hand on the same side as your standing leg. Return to upright and reach arm overhead. Focus on maximising hip and knee bend in order to increase the leg stress. Ensure that standing leg does not roll inwards.

3. Kneeling lunge with trunk side bend.

In a kneeling lunge position, with both legs in line, side bend the upper torso from left to right. If toes grip floor strongly, tap floor to prevent fixing.

4. Single leg stance forward / downward leans.

Stand facing a wall, goal post or barrier about 3ft away initially and stand on one leg. Reach forward with the index finger to touch the ground as far out in front to reach the ground if possible. Return to upright and reach with opposite hand.

5. Single leg stance reverse pivot.

Stand on one leg with back to wall or post or barrier. Reach overhead with left and right hands alternately to try and touch behind without falling over. If it is too easy move a further distance from the barrier.

6. Incline lunge with trunk rotation

Lunge at 45° from straight ahead position, holding dumbbell in opposite arm (6 to 10kgs) reach down and across to the outside of the forward foot. Return to upright. Alternate sides.

PS to initially feel the coordination for this drill try work without weights.

There are infinite numbers of variations of these types of drills which can be exciting, fun, challenging and very revealing. We will come back to some of these concepts in the future.

Technorati Tags: Balance reach tests, Balance tests, Hop tests, Jump tests, Lunge test, specific strengthening, Step down tests