Dynamic neuromuscular stabilization (DNS) is an approach based on the principles of developmental kinesiology. Developmental kinesiology is founded on the neurophysiologic maturation of the central nervous system (CNS), linking it closely with motor control. DNS describes the development of postural-locomotor muscle function and the integration of afferent sensory inputs with the CNS maturation during postnatal ontogenesis. DNS defines ideal postural-locomotor patterns, or “postural-locomotor functional norms,” based on physiologic development. Such norms allow clinicians to identify deviations in both pediatric and adult patients with deficits in the musculoskeletal system. These norms also help to accurately diagnose neurologic and orthopedic pathologies. Therapeutically, DNS concepts utilize positions observed in the developing child (between the ages of 3 and 18 months) to activate optimal postural-locomotor functions within the patients.

In contrast to many animals, a newborn child is functionally and morphologically immature. Started in utero, after birth the child continues to develop both neurologically and physiologically; this is the process of ontogenesis. A newborn anatomy differs from the morphology of anatomical structures of an adult.^1,2,3,4 Besides genetic, metabolic, immune, and other influences, the postnatal formation of the skeleton depends largely on activation and development of the CNS, which directly influences the quality of the child’s posture as well as his locomotor functions.^5,6 Mature locomotion and function requires participation from several levels of the CNS. Through an analysis of motor behavior, movement patterns can be divided into several levels of CNS control: patterns organized primarily at the level of the spinal cord (i.e., stretch reflexes); patterns controlled at the brainstem level (primitive reflexes) (Fig. 31.1), movement patterns organized at the subcortical level (automatic postural-locomotor functions, patterns elicited during Vojta’s reflex locomotion—Fig. 31.2); and complex, purposeful and targeted movements requiring maximal volitional control that are controlled mainly at the cortical level. Of course, this categorization is, to a certain extent, artificial because an impeccable
integration of function of all parts of the CNS is required to produce smooth, spontaneous movements. However, from a developmental kinesiology perspective, this view explains how the quality of movement patterns is tied to various levels of maturation of central motor control during ontogenesis.

The knowledge and ability to analyze postural-locomotor patterns organized at individual levels of the CNS are important for clinical assessment.⁷ Evaluation of movement patterns controlled at the spinal cord or brainstem levels is used in early screening of newborns and infants.^8,9,10,11 Assessment of subcortical levels of control is done by observing the quality of the patient’s automatic stabilization function in response to mild but adequate postural demands. Cortical control is more prominent during advanced postural-locomotor situations. Observation of a patient’s motor agility and skillfulness, body awareness, and ideomotor integration represents mainly cortical level of motor control, that is, movement planning and its actual execution, or the ability to precisely carry out sensorimotor balance tasks.¹² Utilizing assessment of the different levels of CNS control is important to identify (diagnose) the source of functional deficits in the movement system.

When evaluating patients with vertebrogenic complications and other movement system pathologies, it is important to assess postural quality, that is, body posture or trunk stabilization and simultaneous execution of basic locomotor patterns that are automatic, subconscious, and subcortically controlled.^13,14,15 The highest, cortical level of control is important for the execution of common daily movements, plays a substantial role in the ability to modify volitional movements, and enables their optimal control, purposefulness, and accuracy. Cortical level of control has a major impact on the quality of athletic performances^16,17 and on the execution of other highly specialized activities such as playing musical instruments or performing artistic activities. This level of motor control is also very important for correction of flawed movement patterns, or during practice of new motor patterns during rehabilitation as well as during regular motor learning.¹⁸

The subcortical level of CNS control allows for fast, automatic movement execution and postural stabilization (or the stabilization of the thorax, spine, and pelvis), which is the main prerequisite for locomotion. Trunk stabilization is ensured through the interplay of many muscles, some of which are not completely under our volitional control. For example, the multifidus and other short spinal intersegmental muscles, some parts of the diaphragm, and the pelvic floor cannot be volitionally controlled by most individuals. For various reasons, this automatic, balanced interplay of the stabilization muscles is often disturbed and it is difficult to correct because of our limited ability to purposefully activate these muscles. It can be assumed that the reason for particular neglect of certain stabilization muscles can be found in the fact that our neurocognitive control of such muscles is primarily at the lower levels of the CNS, including the mechanism of self-sustained discharge in stabilization of muscle neurons.¹⁹ The goal of DNS rehabilitation techniques is to first bring the activation of the stabilizers under volitional control (cortical level of control dominates) and then attempt automatization of this balanced interplay of stabilization muscles (i.e., bring to the subcortical level). DNS is more than just a treatment; it’s about educating the patient. Rather than exercising, this involves hands-on guiding the patient into proper postural positions so that they will experience or “feel” these positions in an attempt to give them the ability to achieve and sustain these positions or postures in function.

The principle of sensorimotor integration also plays an important role in the concept of DNS. Deep and superficial sensation, one’s own body awareness, stereognosis and somatognosis are all prerequisites for movement. At the level of the spinal cord, proprioceptive and exteroceptive inputs lead to quick, automatic, nontargeted reactions. For example, non-painful proprioceptive and exteroceptive stimulation of the feet (by passively standing up a newborn) elicits an uprighting reaction, that is, hip and knee extension (see Fig. 31.1). This primitive motor response to feet stimulation however does not lead to balanced muscle interplay (agonists and antagonists) of the trunk and lower extremities (LEs). This lack of trunk stabilization and muscular interplay is the reason why a newborn is unable to stand independently. The integration of sensory inputs, that is, individual afferent senses such as vision, hearing, superficial tactile sensation, proprioception, or vestibular information at the subcortical level, influences the quality of the posture and locomotion. It allows for automatic spatial orientation, which enables purposeful, automatic movements. Vision is the leading sense for grasping function in sports; it determines the automatic, quick positioning of an extremity in the correct way to allow the athlete to catch a ball, hit it with a racquet, or kick it. Proprioceptive function is also incredibly important in locomotion. In hockey, it provides the player with input from the sole of the foot, informing him about his skate’s position, allowing him to avoid
possible obstructions and to orient the edge of the blade on the ice to optimize the speed and accuracy of his movements. Necessary for virtually all movements, the vestibular system is of particular importance in sports such as gymnastics where it influences the execution of a somersault or a dismount from the balance beam when visual input is limited. Even hearing will trigger automatic postural adjustments—that is, it will result in contralateral locomotion function when the starting gun is fired in the 100M dash event in track and field.

It is important to realize that the integration of all of this sensory information (tactile, visual, proprioceptive, acoustic, and vestibular, and to a certain extent even smell and taste) occurs on all three levels of the CNS. A hockey player performing a slap shot consciously focuses on the puck rather than on the position of his skate or the extent to which his lumbar spine is flexed or extended. A tennis player returning a serve watches the ball and automatically orients his body and positions his racquet so that he hits the ball to the desired location at the desired speed. Even his tongue is integrated into his postural-locomotor pattern; it moves in the direction in which he is turning as he strikes the ball (Fig. 31.3). A gymnast performing a standing back tuck integrates his spatial orientation with his proprioception and vestibular input to accurately execute this fast and precise movement. With each of these movements, the athletes are unaware of the precise and immediate corrections that are being made to their posture. Their cortex is fully focused on the execution of the task—hitting a ball, striking a puck, or performing a back tuck.

The inclusion of breathing into movement is also automatic. When a person looks up and straightens up, they automatically inhale (see Fig. 31.3). When looking down and when bent forward, exhalation occurs; this is a result of subcortical sensorimotor integration. Cortical level of sensorimotor integration enables us the deviate from the automatic synkineses and patterns enabling the practice and execution of movement variability. Through cortical control, we can look up, straighten up and at the same time exhale, or we can throw a ball to the right while looking to the left; however, we have to concentrate to carry out such activities. Initially, the altered movement will likely be difficult, slow, uncoordinated, and the athletic performance will be limited. In such a case, the cortical level of control dominates sensorimotor integration and motor control. Through repetition, the CNS will learn to integrate, balance, or organize the cortex with the subcortex. Over time, a greater percentage of the movement will be controlled at the subcortical level, enabling the movement to be smooth, precise, and quick. This will also allow the individual to perform this task while simultaneously focusing on something else (i.e., in which direction is his teammate running so he knows where to kick the ball). Cortical circuits in connection with cerebellar structures are fundamental for motor learning, acquisition of new movements, variability practice, modification, and accuracy. They allow for practicing an isolated movement within an individual segment; the ability to alternate between muscle activation and relaxation in a specific segment; execution of repetitive movements or the practice of simultaneous movements; and for execution of varied extremity movements (i.e., martial arts or tai chi).

The more we are aware of our body, the better we feel it, the greater the chances of us having good motor control over our movements. The quality of integration of sensory inputs within postural-locomotor function is fundamental for movement quality and efficiency. The DNS approach focuses not only on the training of correct stabilization function and optimal execution of movement patterns but also on integrating body awareness into the training. During DNS exercise, the patient fully concentrates on different aspects of the movement and their body such as
changes in the position of a body segment, alterations in their breathing pattern, movement execution, loading of support segments, and maintaining balance. It is therefore primarily a practice of postural-locomotor function and sensorimotor integration at the cortical level. Through repetition, the practiced pattern becomes more automatic, smooth, quick, and effortless, as control and coordination shift to the subcortical level. The greater the amount of subcortical control over these movements and patterns, the more likely the patient or athlete will be able to execute these movements correctly while focusing on other tasks (i.e., while bending down to pick up a pencil from the floor or trying to kick a soccer ball into a goal while running). One of the goals of DNS is to achieve full integration of proper movement and stabilizing strategies into subcortical levels of control.

Posture, or trunk stabilization within gravitational field, is the basic prerequisite for all movement. During ontogenetic development,^20,21 the basic postural trunk stabilization develops within the first few months of life. Muscular co-activation develops after the neonatal period as a result of CNS maturation, and simultaneous, balanced activity of agonists and antagonists allows for active body posture and stabilization of its components within the field of gravitation. A child no longer passively rests on a mat as he would during the neonatal period, but will begin to lift his head and extremities above the mat as stabilization, support, and equilibrium functions develop.

Occurring simultaneously with physiologic development of trunk stabilization and locomotor functions of the extremities is development of functional joint centration. This means that in any position or at any point within a movement, the joint is in a biomechanically optimal position because of correct neurophysiologic control. Functional centration is achieved through balanced coactivation of all the muscles surrounding the joint. As a result maximum interosseous contact between the joint surfaces (head and the joint cavity/fossa) is utilized to maximize stability. Balanced muscle interplay protects the joint during loading or force transfer and greatly protects the passive components (joint capsule, ligaments, and cartilage). This is a joint position in which the agonists (concentric activation) and the antagonists (eccentric activation) create an optimal balance between joint stability and mobility. Such precise, meticulous, and constant control over the minute positioning of the joint can only be accomplished by the subcortex.

Maintaining functional joint centration throughout the entire body is a difficult task. In addition to a high functioning CNS, it requires a stable thorax, spine, and pelvis—a prerequisite for all movement. Because of the complexity of movement and the subconscious control over stabilization, ideal stabilization is also dependent on respiration. Simultaneous, balanced co-activation of the diaphragm, abdominal muscles, spinal extensors, and pelvic floor muscles creates an interconnection between breathing, stabilization, and locomotor function.^22,23 This combined muscle function is demanding and possible only in individuals with a healthy CNS that ensures impeccable motor control.^5,24 Disturbance in CNS control not only causes alterations in the movement patterns (including breathing) but, because of chronic, improper joint loading secondary to lack of muscular balance and synergy, also leads to structural deformities.^25,26

Maturation of the CNS is the driving force behind ontogenesis. This process is manifest in the child acquiring the ability to achieve specific (landmark) positions and execute specific movements (i.e., turning from supine to prone, crawling, or walking), building a repertoire of postural-locomotion strategies. Gradually, the child learns to select the most appropriate postural strategy, depending on the ability to anticipate the consequence of the movement in order to maintain balance control and the efficiency of the task.⁵ As the CNS matures, and higher centers of the brain become active and participate in function, muscles, which were inactive at birth, start to activate and participate in movement and postural stabilization. As more muscles become active and the CNS continues to develop, the child is able to hold more demanding positions and perform more complex movements. Assessing the quality of a child’s movements and correlating them with normative time lines enables the therapist to accurately assess the quality and extent of the child’s CNS development. During ontogenesis, the child is establishing movement patterns which later become the foundation for more complex movements (i.e., turning is the foundation for hitting a baseball, crawling is the basis for sprinting, grasping is the basis for writing, and swallowing is the basis for speech). Proper development of the CNS (neurologic ontogenesis) is essential because any breakdown in this process may result in stubborn or unresolvable movement pathology and even structural pathology.

The first major functional landmark in postural ontogenesis to develop is stabilization of the thorax, spine, and pelvis in the sagittal plane (sagittal stability). Occurring at 3 months (Figs. 31.4 and 31.5), the child begins to integrate his diaphragm with the abdominal wall and pelvic floor to regulate pressure within the abdomen. Such pressure is essential because it is the chief ventral stabilizer of the spine, the foundation for uprighting of the cervical and thoracic spines, and is the keystone for all movement of the extremities. This is also a time where costal breathing begins to develop and the diaphragm starts to assist with lower esophageal sphincter function.

Once development of sagittal stabilization is completed (between 3 and 4 months of age), the child begins to acquire the ability to move his limbs independent of his trunk; this is called differentiation and is essential for normal function, sports, and optimal postural ontogenesis. Differentiation of the extremities, itself the product of optical fixation, allows the child to reach toward objects that interest him. Initially, he is only able to reach and play with a toy on the same side of the body as the extremity he is using. Gradually, as sagittal stability continues to strengthen, he is able to reach across his body. This typically occurs at 5 months of development and is a crucial moment in postural ontogenesis as it triggers rolling over, representing the first ability to switch between supine and prone positions spontaneously. The ability to reach across demonstrates that the child is more spatially aware because he is able to associate an object on one side of his body with his arm on the other side. Assuming that the quality of the child’s movement is optimal (physiologic), this indicates good maturation of the CNS and a developing connection between the two hemispheres of the brain.

The ability to reach across the body toward a desired object initiates the acquisition of the next functional landmark, turning. A physiologic child should develop the ability to turn from supine to prone by 6 months of age. Turning is an ipsilateral movement pattern in which the child’s supporting extremities are on the same side of the body and the stepping forward (reaching) extremities are on the opposite side (Fig. 31.6). Proper development of turning is
extremely important in postural ontogenesis because it is through this process that the child activates and strengthens the posterior and anterior oblique slings, themselves necessary for crawling, uprighting, and ultimately walking.