Development of postural control

why start with postural control?

"The emergence of independent walking, running, climbing, eye- hand coordination and manipulation of objects requires the development of postural activity to support the primary movement. " "Simultaneous development of the postural, locomotor and manipulative systems is essential to the emergence and refinement of skills in all areas" Shumway-Cook & Woollacott p 183

postural changes in 4-6 year old children

4-6 year old children often undergo a growth spurt. Their body size and proportion changes rapidly at this time Changes in response onsets and variability of response seen in 4-6 year olds seem to be attributed to developmental changes in the maturation of the nervous system itself 4-6 year old children must develop new ways to master their own postural control within this new and changing body shape 7-10 year old children seem to use adult-like postural response patterns that carry them through the adolescent growth spurt

skip

A step-hop pattern which requires added coordination Most children are able to skip by age 6 Skipping should occur with both feet leading

earliest patterns

Alternating leg movements is seen in utero by 9 weeks PCA Stepping behavior can be elicited in newborns with trunk support and forward lean It has been suggested that supine kicking and newborn stepping is elicited by the same pattern generator Infants cannot walk independently until the postural system, musculoskeletal system, sensory systems have developed sufficiently

the effect of practice (mobility)

An infant will take 14,000 steps daily and fall 17 times an hour when learning to walk Over time they travel further and fall less They are determined!

learning to stand

As pull to stand behavior progressed (7-9 mos of age) infants begin to show directionally appropriate balance responses in their ankle muscles Later thigh muscles added in a distal to proximal sequence Trunk muscles are added to this synergy ~ 9-11 mos Vision elicits organized postural responses at an earlier age (5 mos) than the somatosensory system Sway responses pulled the infant in the direction of the visual stimulus

Classic reflex hierarchies

Assumes that the maturation of the brain controls the maturation age of the person Depended on reflex testing and motor milestones as the basis of labeling of the "age" of the child Many of our motor assessments of young children are based on the performance of motor skills by a particular age to assess if the child is developing in a typical manner or not. We assess reflex integration Tries to answer "Is there something wrong with my child?"

beginnings of postural control

Babies with intact vision as young as 60 hours old can begin to orient themselves (look with eyes) toward the visual stimulus These responses are probably present at birth but require experience and practice to become refined and strengthened. Blind babies will turn their head slightly toward a stimulus in their hand by 6 months but this behavior disappears Vision seems to guide emergence of vestibular and somatosensory inputs for control of head posture

postural sway

Children aged 1.5 to 3 yers produce well organized responses to postural perturbations when standing But the amplitude of those responses are larger and slower than adults Children aged 4-6 show even slower and more variable postural responses observed by EMG than 1.5 to 3 year old children Is this expected? Why? What is going on?

what is meant by control?

Control is the ability to move away from a steady state erect posture AND regain steady state balance without falling Control of CoG within a wider cone of stability When evaluating a patient you must note whether the client is able to achieve steady state balance as well as move away and regain balance Can the person turn, rotate, look around, pick up something and return to a steady state of balance?

Gesell and a Spiraling Hierarchy of development

Development does not proceed in a straight line, but with alternating advancement and regression as the person incorporates the new behavior into their repertoire. Mature, adaptive behavior often emerges after the person has had time, practice and solves problems with new use of skills

exploratory vs performatory sway

Exploratory sway - used to investigate sensorimotor possibilities for postural control in a new dimension Performatory sway - uses sensory information to control posture As infants transition into standing, their sitting balance control may appear to worsen for a short while as they explore new possibilities to control their posture in stance Spiral development!

what evidence do we have for the emergence of postural control?

Hedberg (2004,5) on a moving platform, found directionally specific postural responses in posterior neck muscles in infants as young as 1 month of age In typical people the neurologic postural responses seem to develop prior to observation of the postural performance Note: Responses in neck flexors were present in only 30% of trials

why does a PT need to know this?

How to develop a treatment plan for a person with neurological disorders? How to sequence that plan over time? How to develop a treatment plan if your client has never gained posture control and locomotion potential ? What if a person lost the ability to control posture or walk due to an illness or injury?

walking development

In first 6 mos of independent walking (Brenier and Bril, 1998) the vertical acceleration of the CoM was always negative Within that time step length increased and so did walking velocity By 6 mos of independent walking, the vertical acceleration of the CoM began to move toward a positive value, reaching 0 by 3-4 yrs of walking experience This marks a change in the strategy of "walking by falling" where balance is controlled to walking refinement as the other parameters of mature walking patterns emerge 1st a rhythmic stepping pattern develops with many falls and a stiff legged gait Next, postural stability during gait emerges and the pattern becomes smoother Adaptability - the ability to make adjustments to terrain, perturbations and other differences in the walking patterns shows itself to be successful

development of locomotion summary

Locomotion is possible because of development of many subsystems Postural control seems to be the most prominent rate-limiting factor Maturation of neural processes and experience contribute to the development of mature walking patterns While gait does not reach adult levels until age 7-10, most significant changes to the gait pattern occur in the first 4-5 months of independent walking

toddler strategies to walk

New walkers display significant co-activation of all muscles Automatic balance responses in gait become faster with time and practice Ability to use balance stepping strategies is absent in new walkers and do not appear until 6 mos after walking emerges Some anticipatory head movements prior to a 90 deg turn are present on EMG in 3.5 yr old children but this skill does not mature for several years. Anticipatory reactions in children are much slower than in adults

walking and balance improvement enforce each other

New walkers move slowly with very short swing durations and long periods of double limb support Balance is regained during the double limb support phase New walkers need to control the trunk and legs while moving to be successful

sensory contributions

Newly sitting infants rely on vision to control sway With increasing experience , they use somatosensory inputs When surface perturbations are used, somatosensory inputs become primary inputs to activate postural responses The manner in which research is conducted can yield different conclusions.

developmental milestones

Normed, standardized tests assess whether children and adults are functioning in a typical or atypical way at a certain age. Norms are established based on a same age population. The divisions of the ages of the population is very narrow for youngest children and becomes wider as the population ages.

implications for treatment

Offering support at decreasing levels on the trunk allows the person to practice balance with safety Where you place your hands and the height of the equipment used makes a difference With training in this manner, steady state balance can improve

righting reactions

Orients the head in space to keep head upright against gravity Optical righting, Labyrinthine righting (Without use of eyes) neck on body (turn head and body will follow) Body-on-body (Turn body and head will follow) Landau (Support in space under belly, entire torso and legs will rise up

refinement of postural control

Postural control becomes mature between ages of 10-12 years Neural mechanisms must be in place before a reaction can be seen. This is influenced by tract myelination and unaffected by training Training and experience may influence the strength of the connections between the sensory and motor systems Sway studies show that healthy active children decrease (control) the amount of sway they can balance against over time. Amplitude and frequency of postural steady state sway decreases over time

postural control development in systems theory

Postural control develops through a complex interaction between the developing CNS, the environment and the child's choice or inability to choose and act on his preferences Postural control depends on development of many interdependent body systems including - Musculoskeletal, cardiopulmonary, sensory, cognitive and neural Balance control is dependent on the organization of sensory strategies for steady- state, reactive and anticipatory control Cognitive resources are needed to control posture to provide motivation, drive, attention to task

transition to independent stance

Postural demands of steady state sitting and stance are different In what ways? Research concludes that to make this change to balance in stance requires recalibration of the sensorimotor system

reactive balance control

Postural synergies of reactive balance control appear in the trunk as early as one month of age in healthy babies They are not functional but observable by EMG recordings on a moving platform experiment Platform movements that result in a backward sway response are stronger than a forward sway response Between ages of 7-8 months, neck flexors, rectus abdominus and rectus femoris were responding 100% during platform tests and organized top to bottom by the time infants were independent sitters

generalized movement in infants (PrechtL)

Prechtl observed a distinct patterns of movements in typical infants Whole limb/whole body fairly slow, variable patterns that vary in intensity and seem fairly coordinated Fidgety movements of neck, trunk and limbs that are faster Impaired infants show poorly differentiated , monotonous patterns that reliably predict cerebral palsy

equilibrium reactions and protective reactions

Protective - controls the CoG in response to a tilting of the trunk Protective reactions develop in a sequence Forward, sideward then backward by 10 months of age Equilibrium - involves tri-planar movement to keep CoG under control when trunk is tilted

galloping

Requires an asymmetric pattern of legs with different timing Some tests differentiate the front gallop from the side gallop This usually emerges after running and observation

hop

Requires the body to balance on one leg and lift body weight up on one leg Additional balance requirements to land on one leg Hopping can be modified to move F, B, to the side, stay in a circle over time

development of run, gallop, hop and skip

Running most resembles walking where the limbs mimic one another but are out of phase by 50% Running requires increased strength and balance as the forces are greater, the distances of the step are longer and there is a period of flight Arm movement coordinates by age 5-6 to assist in run propulsion

anticipatory balance control

Seated infants from age 2.5 to 8 months were followed q 2 weeks on a moving platform EMG recorded trunk and arm movements as a toy was dropped in front of the infants Half infants had trunk support, other half had thoracic support Given what you already know, what were the anticipated results? Arm reaches were successful earlier with thoracic support As trunk control developed over time, arm reaches were more successful APA was present in 40% of infants at 3 months of age 300msec BEFORE the reach Compensatory postural activity was present in 80% of 3 month old infants Can conclude that reactive balance control precedes development of anticipatory control

emergence of sitting

Sitting is the ability to control spontaneous sway well enough to remain upright First both arms are used to support the upright position, then one, then the infant sits independently for longer and longer periods of time Sway distance and return to sitting enforce one another

Harbourne 3 stages of sitting

Stage 1 - Infant is able to hold up head and upper trunk but not sit Stage 2 - infant can support himself with his hands 10-30 sec Stage 3 - infant can sit but not yet crawl Harbourne and Stergiou, 2003 showed that infants showed a controlled reduction in the degrees of freedom over head and trunk as they developed independent sitting from 4-8mos of age

Early walkers have immature gait patterns

Steps are short even accounting for leg length Steps are wide Propulsion seems governed by forward trunk lean Arms are held high Body is held stiffly, leg movements are stiff Foot flat pattern

development of trunk control

The trunk is made up of many sub-units and infants seems to gain control of segments at a time In Stage 1, infants fall over and are unable to right themselves With support under arms, at 4 mos they are able to sit and maintain head control Stability and control of the head in sitting improves as control of lowered trunk segments improves

our rate limiting parameter controls our development

The weakest link in any system controls the emergence and success of the entire system Which constraint limits our ability to walk prior to 10-12 months of age? Most researchers believe it is the lack of balance (postural control) and lack of strength Functional visual, somatosensory and vestibular systems aid development of walking

which is the first balance strategy to develop in walkers?

There is a distal to proximal response so children first learn to use an ankle strategy If the balance threat is too large, they will fall Hip strategy is not used until age 7-10 when the hip strategy becomes paired with abdominal muscles At that point, the leg and trunk can be activated and hold against a larger threat

reflexes, righting reactions and protective reactions

There is little agreement by researchers on the timing, necessity of, interference by, integration of or even significance of the presence of primitive reflexes on the capabilities of a child or adult. Let's separate these stimulus/responses in primitive reflexes , righting reactions and protective reactions Primitive Reflexes - Are observed through ultrasound in the womb. Are thought to stimulate primitive movement patterns after birth when gravity and limb weight is a limiting factor in movement Rooting, Suck/Swallow, Gallant, ATNR, STNR, Tonic Labyrinthine

en bloc strategy

Until the age of about 6, children organize gait from the ground up They hold their neck stiffly "en bloc" which serves to decrease the degrees of freedom they need to control while walking Children first stabilize the ankle muscles, then the hips and trunk, shoulders and head At about age 7, children change this strategy and use an articulated , top-down mode of organizing gait which may indicate they are using more vestibular information to balance from the head down

walking progression

Within 10-15 days of independent walking, co-contraction reduces By age 2, push-off in stance begins, reciprocal arm swing begins Dorsiflexion begins in swing Duration of single leg stance increases from 32% In 1 year olds to 38% in 7 year olds

why study development of postural control and locomotion?

You know the sequence and timing of normal gross motor movement You know how the sensory , cardiopulmonary and musculoskeletal systems develop and change over time You know about gait kinetics and kinematics Now we will study how all of these systems contribute to the successful accomplishment of postural control and gait Hopefully, this will help you to prioritize your interventions for people with difficulties in these areas