Dynamic Neuromuscular Stabilisation

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Dynamic neuromuscular stabilization (DNS) is based on principles of developmental kinesiology i.e. the maturing human locomotor system. The approach views people with certain types of pain and dysfunction having defects in neuromotor programming. It also has applications in sporting and occupational performance. DNS was developed by Professor Pavel Kolar in the Czech Republic, who was in turn influenced by three other prominent Czech professors. It is allegedly practiced widely in many parts of Europe in mainstream clinical centres, but is largely unknown in New Zealand. It is a functional approach rather than the more traditional structural biomedical approach.

Developmental Kinesiology

Ontogenesis is a term that refers to the development of motor functions postnatally. When humans are first born the neurological and locomotor systems are immature, especially when compared to other mammalian species. As the central nervous system matures, postural foundations are increasingly established, with specific motor patterns at certain developmental milestones. The development of these motor patterns are genetically programmed rather than environmentally learned. There are three levels of postnatal CNS maturation with corresponding three levels of sensory-motor control.

In the neonatal period and first few weeks of life the spinal and brain stem control systems are dominant. There is functional and structural immaturity with no balance and no postural function. There is no synergy and coordination of the deep spinal stabilising structures to create a fixed point through the pelvis and trunk. There is excessive asymmetry, i.e. if the head is moved then the whole body moves. Without deep stablisation, there is anterior pelvic tilt, flaring of the rib cage, and elevation and protraction of the shoulder girdle. Primitive reflexes such as the Moro and sucking reflexes are positive.

At three months continuing to around 18 months we see integration of the subcortical region with the establishment of postural foundations and development of synergy, coordination, and timing. There is the development of fixed stabilising points through the trunk and pelvis. With these fixed points the larger muscle groups can work through them allowing isolated movements and we see less asymmetry. We see increasing synergy and coordination of the deep stabilising system allowing the child to reach higher and more unstable positions - from prone and supine positions (stablisation in the sagittal plane), to rolling over, crawling, kneeling, squatting, and eventually walking. Gaze fixation and somatosensory input also develop allowing increasing input from the environment. Primitive reflexes are inhibited in this time period.

From two to six years and beyond we see integration of the cortical system in the central nervous system. There is motor learning with selective movement, fine motor skills, agility, and motor dexterity.

There are many different ideas about what an ideal posture is. Despite differences in body shapes, every human has a central nervous system and has gone through developmental milestones. Ontogenesis shows us genetically determined ideal posture, and is automatic with healthy central nervous system maturation. For example the squat position of a 12 month old uses the same locomotor programme as a powerlifter doing a loaded squat.

The Integrated Stabilising System of the Spine

The integrated stabilising system of the spine refers to the integration of the deep stabilising muscles with other larger muscles groups. The deep stabilising system is a combination of the diaphragm, the pelvic floor, the entire abdominal wall, multifidi, and deep neck flexors. When there is synergy, coordination and timing of this system then even before any purposeful movement the diaphragm will first descend. The deep stabilising musculature will respond to the resultant increased abdominal pressure, a fixed point is created, and other larger muscles such as rectus femoris can then work off that fixed point. This is a "feedforward mechanism."

The diaphragm is the ring leader of the deep stabilising system. The diaphragm has three functions: respiration, stabilisation, and gastro-oesophageal sphincter function. It is anatomically related to the transversus abdominis. It works in conjunction with the pelvic floor, abdominal wall, iliopsoas, and multifidus. The diaphragm and pelvic floor act as partners in respiratory and postural function, and also both have a sphincter function. They must work in coordination as one functional unit.

This is different from bracing. Bracing is concentric activation the abdominal wall from the outside in, such as when preparing to be punched. It can provide stability but it doesn't allow good support with movement. Core stabilisation on the other hand is stabilisation from the inside out by increased intra-abdominal pressure and can help safely manage different movements and loading, and helps coordination of respiration and stabilisation. Dynamic stabilisation is in contrast to static stabilisation, and allows maintenance of intra abdominal pressure with movement and changes in loading.

Postural function proceeds and follows any movement, and is a dynamic function thus the name dynamic neuromuscular stabilising. It ensures the position of the trunk, spine, and pelvis during movement. It is controlled at the subcortical level and allows anticipatory brain activity to aid efficient purposeful movement. If postural function of the deep stabilising system is not optimal, movement can still be performed, but it can limit performance, overload the passive structures of the kinetic chain, and increase the risk of injury.

Joint Centration

Neutral joint positions, known as "functional joint centration" in DNS terminology is a key concept in DNS. This is obtained with optimal function of the deep stabilising system. Functional joint centration has several advantages. It enables optimal loading with the most effective mechanical advantage. It provides the greatest interosseous contact allows optimal load transference across the joint. It also provides and ideal balance between agonist and antagonist muscles allowing for maximal muscle pull, and protection of passive structures.

Assessment and Treatment Approaches

The DNS approach focuses on assessing and training inefficiencies in the deep stabilising system. It aims to facilitate and reintegrate the hardwired genetic locomotor programme and utilises the positions of the developmental milestones. As adults the locomotor programme can become corrupted through postural habituation, repetitive motions, past injury, and pathological central nervous system maturation. Despite corruption, the potential for facilitation is still there.

Ideal core stabilisation corresponds to the muscular coordination of a 3 month old baby with the baby in a supine position with the hips flexed. Training instructions include maintaining a neutral (caudal) chest position, coordination of the diaphragm and pelvic floor, cylindrical activation of the abdominal wall, maintaining a neutral neck position, avoiding lordosis of the lumbar spine, actively maintaining a neutral hip position, and directing the patient's breath as far as the inguinal region and lateral dorsal aspects of the abdominal wall.

The clinician can use different methods such as manual therapy, cueing, and specific DNS active exercises to help facilitate correct activity of the deep stabilising system. Exercises are based on developmental kinesiology. They allow training of muscles during physiological function. They automatically activate ideal stabilisation function at the subcortical level.

Assessment

Sitting

This is called the diaphragm test. It involves evaluation of lateral excursion of the lower ribs during deep inspiration, evaluation of the ability to increase intraabdominal pressure following full exhalation, and evaluation of the ability to combine respiratory and postural function of the diaphragm by assessing the ability to breath normally while maintaining a slightly raised intra-abdominal pressure.

Assessment of respiratory function: The patient sits on an examination table, the thighs are supported by hanging freely with the hands relaxed. Ask the patient to breath normally while monitoring from the front the quality of the breathing, observing the movement of the ribs, the chest as a whole, the shoulder blades, and the spine. Then go behind the patient, and place your fingers along the lower intercostal spaces bilaterally. When inspiratory function is normal, the lower ribs move laterally, and the lower intercostal spaces widen, which is directly related to diaphragmatic flattening. Chest and shoulder blades should not move cranially. The spine should be upright.

When respiration is dysfunctional there is activation of the accessory muscles of respiration, especially sternocleidomastoid, scalenes, pectoralis, and upper trapezius muscles. There is minimal expansion of the lower ribs under the therapists fingers, and the clavicles and scapulae are elevated. With each inhalation the patients chest and shoulders move cranially, the clavicles are horizontal. In combination with a lack of lateral expansion of the lower ribs, there is a pathological synkinesis of the spine. Asymmetry is often observed, with abnormal excursion of the lower ribs more prominent on one side.

Then ask the patient to take a deep breath. With optimal function the diaphragm descends caudally, the lower intercostal spaces widen with intercostal muscle activity, the abdominal wall expands proportionally in all directions.

Assessment of postural function: Next palpate dorsolaterally below the ribs at the trigonum lumbale. Palpate the examine the postural function of the diaphragm, feeling for the ability of the diaphragm to lower and expand to its full extent and regulate intra-abdominal pressure.

Ask the patient to push your fingers away. Evaluate the quality of symmetry and effectiveness of expansion of the abdominal wall. The pressure corresponds to the postural function of the diaphragm. With optimal performance, the diaphragm coordinates with the pelvic floor and abdominal wall muscles.

Palpate from the front the area above the inguinal region with your thumbs. Assess the quality and symmetry of intra-abdominal pressure activation. With optimal trunk stabilisation there is concentric activation of the coordinated abdominal wall. Ask the patient to push your fingers away. In dysfunctional activation, the upper part of the rectus abdominis dominates pulling the umbilicus cranially.

Next assess combined respiratory and postural function. From behind, placing your fingers in the lower intercostal spaces, ask the patient to push into your fingers while breathing.

Supine Hips Flexed

Here the therapist examines the coordination of the diaphragm and other stabilising muscles assessing intra-abdominal pressure regulation. Place the patient in a supine position with the hips and knees at approximately 90 degrees of flexion. The knees should be abducted to the width of the pelvis. Support the patients feet. While slowly releasing support ask the patient to maintain their legs in that position. Check if the patient is able to keep their legs in the air while maintaining their spine in a static position. Raising the legs in the air should increase intra-abdominal pressure enough to stimulate coordinated activity between the anterior and posterior trunk muscles. Under this load the spine, chest, and pelvis should remain in a neutral relaxed position.

Ask the patient to straighten and bend their lower limbs symmetrically. With ideal stabilising, the hip flexors have a stable fixed point to act through, and the trunk is stable.

With dysfunctional activation there is excessive activation of the superficial paraspinal muscles, and there is an increase in lumbar lordosis. By inspection and palpation there is a lack of activation of the lateral abdominal wall and the area above the inguinal region. There is unbalanced activation of the abdominal wall, typically manifesting as a dominance of the upper part of the rectus abdominis and poor activity of the lower abdominal wall. The umbilicus can be pulled cranially and be turned upwards. There may be an abdominal wall diastasis. With an increase in lumbar lordosis, the head may extend along with shoulder protraction and chest elevation.

Another manifestation of poor function is excessive lumbar kyphosis with a posterior pelvic tilt as the patient tries to prevent arching of the lower back. The patient pushes the lower back against the table while over activating rectus abdominis, and extending the head.

Prone

This is the trunk and head extension test. It can be performed with or without symmetrical arm support. Without arm support the patient is prone, and the upper limbs are relaxed along the body. Ask the patient to lift their head and trunk above the table, slightly extending the spine.

With optimal function the pelvis remains neutral on the mat, and there is smooth extension of the entire spine. There is balanced activity of the entire abdominal wall and appropriate intra-abdominal pressure regulation. When inspecting from above, the lateral abdominal walls are straight, with a line connecting the ribs to the pelvis. There is appropriate activity of the spine extensors. The scapulae remain in a neutral position connecting to the posterior chest.

With dysfunctional activity, spinal extension is not smooth, and the pelvis tilts anterior. The trunk remains on the mat, and extension occurs mainly in the cervical and lumbar spine. The superficial spinal muscles are overactive. There is minimal activity of the lateral abdominal wall with convex bulging observed from above. The transversus abdominis aponeurosis becomes concave inwards. There is excessive activity of the hamstring muscles, and occasionally activity of the calf muscles. There may be poor coactivation of deep neck flexors and extensors with neck hyperextension, overactivation of the upper scapula fixator muscles, and decentration of the shoulder girdle. The scapulae may adduct, elevate, and externally rotate.

Standing

This is the trunk and head extension test. Ask the patient to stand and extend backwards. Check for smooth movement and coordination of the anterior and posterior trunk muscles.

In dysfunctional activity there is anterior pelvic tilt, cervical and lumbar hyperextension, and poor thoracic spine extension. The knees may flex.

Quadruped Position

This is the quadruped test on all fours. The patient uses hands and knees for support. The knees are approximately the width of the pelvis. The thighs and arms are perpendicular to the ground. Ask the patient to slowly rock back and forth.

Observing from the side, spinal alignment should not change during movement, with movement occurring mostly in the shoulders and hips. Observing from above the scapulae should be in a neutral position connecting to the chest. The head should be align with the spine, with a neutral pelvic position, and straight spine. There should be balanced activity of all trunk muscles. Look for centration and muscle coordination of arms and legs. Hand support should be balanced.

In insufficient stabilisation there is collapse in the sagittal plane. The spine is not maintained in neutral during rocking. There are several manifestations.

• Lumbar hyperlordosis with an anterior pelvic tilt, and a cervical hyperlordosis with a posterior head tilt.
• Increased lumbar lordosis with thoracic hyperkyphosis. This is associated with neck flexion. As the body moves backwards there may be an increase in lumbar kyphosis.
• Reversal of the curve with thoracic lordosis and scapula adduction. If the scapulae are poorly stabilised the move in different positions. There is decentration of the shoulders with them protracted and internally rotated, the elbow joints hyperextend, and the hand support is on the ulnar aspect.
• Increased thoracic kyphosis with scapula abduction and external rotation of the scapulae tips. There is decentration of the lower upper limb joints with elbow flexion. In the lower extremities, anterior pelvic tilt is associated with internal hip rotation, and overloading of the lateral knees with knee adduction. Increased hamstring activity is due to efforts to maintain the pelvis in neutral. The shins lift with collapse of the pelvis. There may be hyperactivity of the paraspinal extensors, and poor activity of the abdominal muscles observing in the trigonum lumbale and above the inguinal region. There is hyperactivity of the upper trapezius and upper pectoralis major muscles, which manifests as elevation of the scapulae and internal shoulder joint rotation.

Arm Elevation Test

The patient lies supine with their arms by their sides. Ask the patient to smoothly raise their arms in the sagittal plane. During elevation the movement should be smooth occuring in centrated shoulder joints. The chest should be neutral, and the lower ribs should be fixed. Up to 120 degrees of elevation the movement is should occur purely in the glenohumeral joint. From 120 to 180 degrees there is contribution from rotation of the scapula tip and extension of the thoracic spine.

With dysfunctional activity there is an early cranial shift of the chest, pronounced lumbar lordosis, and protraction and elevation of the shoulder girdle, with thoracic hyper-kyphosis. The scapulae loses its stability during movement, resulting in early external rotation of the lower angle, and internal rotation of the glenohumeral joints. This can be observed by witnessing a decrease in distance between the head and arms. Smaller distances correspond to increasing decentration and glenohumeral joint elevation.

The test can also be performed in standing. In dysfunctional activity there is increased lumbar lordosis.

Squat Test

The patient performs a squat slowly to a 90 degree angle, maintaining this position. The arms are held in front to help with balance. The feet are positioned to the width of the pelvis.

Inspection from the side, observe the axis of the trunk and legs which should move in parallel. Ideal movement starts with hip flexion, the knees are stable above the forefeet, and the torso is in neutral with no visible decentration in the sagittal plane. Then inspect from behind. The spine should be in an upright posture with the head in neutral. Palpate the laterodorsal abdominal wall to assess intra-abdominal pressure regulation. From the front there should be joint centration and good three point loading on the feet.

In poor stabilisation, there is a loss of the parallel position of the trunk and legs, and there is compromised timing of triple flexion of the leg joints. One example is the knees driving the squat movement, with the knees moving forward of the toes, the weight is on the forefoot, and the trunk is held too vertically. Another pattern is the knees move behind the toe axis, the weight is on the heels, and the toes lift off the floor, and the torso flexes too far forward. In both of these cases, inspection from behind you can observe exaggerated spinal lordosis or kyphosis with a forward head position. The spinal extensors are overactive, and there is insufficient activation palpable at the laterodorsal abdominal wall. There is often asymmetry of pelvic movement, and a shift to one side. From the front there is often decentration of the leg joints. For example internal rotation of the femurs, with medial collapse of the knees, and foot pronation. Also frequent is overload of the lateral aspects of the feet.

Applications

Sporting Applications

Sport performance relates to power, strength, speed, and endurance. Sport technique is also required, and in order to facilitate technique, the athlete needs optimal postural foundations, optimal movement quality, coordination, and good cortical function with respect to body awareness. There is maximum demand on muscle activity, range of motion, loading of passive structures, and increased demands on the respiratory system. Training allows the body to adapt to increased loads, and aims to increase maximal performance.

Ideal locomotor strategies have a threshold, and this can come into play when pushing beyond ones limits. When this "functional threshold" is exceeded then the athlete will use more primitive stabilising strategies and there will be joint decentration. For example when doing a pull up and exceeding the capacity of the deep stabilising system the athlete will tend to hyperextend of the spine, protract the shoulders, and antevert the pelvis.

When going past this functional capacity, the athelete falls into the "functional gap". The nature of training is pushing into this functional gap, and using DNS principles in sport requires doing "threshold training," aiming to improve the athelete's functional capacity. If on the other hand the athlete frequently trains in the functional gap, then those high threshold compensatory patterns become the norm. Atheletes can be successful by working in the functional gap, but this can increase the risk of injury and prolong recovery, and reduce their true performance potential and longevity.

The following always needs to be assessed in sport:

• Centration/decentration of joints (movement segments) and deviation from neutral alignment
• Relationship between centration of distal and peripheral joints
• Timing between the function of stepping forward and support of the extremities
• Range of motion of the upper and lower extremities during stepping forward and support functions.

Occupational Applications

The same concepts used in sport can be applied to the occupational athlete. E.g. the labourer, the assembly line operator, etc. Just like the sporting athlete needs to train for their sport, so too should the occupational athlete train for their occupation.

Conclusion

In DNS assessment, the therapist compares the patients stabilising pattern to that of a healthy infant, utilising the knowledge of developmental kinesiology and what ideal deep stabilising utilisation looks like. Treatment is based on optimising the distribution of the internal muscular forces acting on each joint, taping into the hardwired genetic locomotor patterns. There is the potential for reducing the risk of injury and enhancing performance.