BALANCE

DEFINITION :: It is a condition in which all the forces acting on the body are balanced in such a way that the centre of mass(COM) is within the stability limits , the boundries of base of support(BOS).

The overall goals of balance is to control system stability, functions and integrated CNS control

Postural Stability Ability to maintain the COG within the

stability limits. Normal anterior/posterior sway-12

degrees from most posterior-anterior position.

Lateral sway-16 degrees from side to side.

If sway exceeds boundaries, compensation is employed to regain balance. A smaller envelope is created and tolerated.

PHYSIOLOGY OF BALANCE

Means having described about what should be the normal position in balanced state and how its imbalaced in improper adjustments of the COG line.

It can be illustrated by the foll. figure:

CONTRIBUTION OF SENSORY SYSTEM

Sensory system has a major contribution in the co-ordination of balance.

Three pairs of the sensory system have a dominating part in the same. They are

VISUAL SOMATOSENSORY VESTIBULAR

VISUAL & VESTIBULAR NEUROPHYSIOLOGY

VISUAL NEUROPHYSIOLOGY provides information regarding the position of the head, related to the environment and orients the head to maintain the gaze level.

VESTIBULAR NEUROPHYSIOLOGY provides information regarding the orientation of head in space & acceleration.

SOMATOSENSORY Free Nerve Endings Ruffini Endings Paciniform Corpuscles Golgi-Mazzoni Corpuscles Golgi Ligament Endings Muscle Spindles

PROCESSING SENSORY INFORMATION It means how all the 3 components i.e

VISUAL SOMATOSENSORY & VESTIBULAR of the sensory system processes in order and from which regions to gain proper motor output.

COMPONENTS OF BALANCE There are 3 chief components: (1) sensory system (2) musculoskeletal system (3) vestibular Sensory System: As described above MSS: Helps to maintain the normal balance by

various processes of the system such as muscle contractions, relaxations etc.

Vestibular System: It provides the info abt the orientation of head in space & acceleration.

BIOMECHANICAL COMPONENTS Here 3 main strategies used are ANKLE,

HIP & STEPPING PHENOMENA

ANKLE STRATEGY Used when displacements are small. Displaces COG by rotation abt the ankle

joint. Eg. Posterior displacement of COG-

Dorsiflexion at ankle, contraction of anterior tibialis, quadriceps, abdominalis.

Anterior COG displacement- Plantarflexion at ankle, contraction of gasterocnemius, hamstring, trunk extensors.

HIP STRATEGY Employed when ankle motion is limited,

displacement is greater, when standing on unstable surface that disallows ankle strategy.

Preferred when perturbation is rapid and near limits of stability.

Post. Displacement COG- backward sway, activation of hamstring and paraspinalis

Ant. Displacement COG- forward sway, activation abdominal and quadriceps muscles.

STEPPING STRATEGY If displacement is large enough, a

forward or backward step is used to regain postural control.

CAUSES FOR IMPAIRED BALANCE Patients may develop balance deficits

coz of impaired sensory input from joint mechanoreceptors and altered muscle spindle input. This particularly occurs in weight bearing joints.

CAUSES FOR IMPAIRED BALANCE

Injury or disease of eyes, inner ear, peripheral receptors, spinal cord, cerebellum, basal ganglia, cerebrum etc.

Injury or damage to knee, ankle, hip and back

CVAs, tumors, visual field loss Age

EXAMINATION & EVALUATION OF IMPAIRED BALANCE(3 categories)

1. Balance during functional activities with or without assistive devices.

2. Balance (static or dynamic) with or without use of assistive devices.

3. Safety during gait, locomotion or balance.

EXAMINATION & EVALUATION OF IMPAIRED BALANCE

Standing with eyes open- Fixed platform Standing blindfolded- Fixed platform Sway-refernced vision with fixed support Normal vision with sway-referenced

support Absent vision with sway-referenced

support Sway referenced vision and support

ACTIVITIES OF TREATING IMPAIRED BALANCE Impaired balance can be treated by foll

ways:

1. Gradual intervention (mode) 2. Posture for COG control 3. Movement

MODE-GRADUATED INTERVENTION Begin with weight shifts on a stable

surface. Gradually increases sway Increase surface challenges (mini-tramp)

POSTURE Often includes “core stability training” to

improve COG control and sense of trunk posture.

Begin in supine or seated position. Over sessions, use a variety of arm

positions, unstable surfaces, single leg stances etc.

MOVEMENT Adding movement patterns to acquired stable

static postures increase balance challenge. Add ant./post sway to increase stability limits. Trunk rotations and altered head positions

alter vestibular input. PNF Techniques during trunk rotation. Stepping back/forward assists in re-

stabilization exercises.

PRECAUTIONS FOR IMBALANCE Pain should not occur during exercises. Donot initiate exercises at maximum level. Avoid uncontrolled, ballistic movements as

they compromise safety & effectiveness. Avoid exercises that creates stress on back. Discontinues exercises if patient experiences

pain, dizziness or unusual shortness of breath. Eliminate obstacles or unsafe instruments from

exercise area.

CONTAINDICATONS Persons who are inheritently in balance-

challenged positions. Pain or muscle pain. Inflammatory neuromuscular disease. Severe cardio-pulmonary diseases.

TYPES OF IMPAIRMENTS Mainly 4 types- 1. Musculoskeletal 2. Neuromuscular 3. Cardiovascular or Pulmonary 4. Integumentary

MUSCULOSKLETAL- Pain, muscle weakness, Jt. Hypermobility, Faulty posture,

muscle imbalances, limited ROM etc.• NEUROMUSCULAR- Pain, impaired balance, delayed motor development,

ineffective, abnormal tone.• CARDIOVASCULAR- ↓ed aerobic capacity, impaired circulation, pain with

sustained physical activity (intermittent claudication).• INTEGUMENTARY- Skin hypomobility.

BALANCE RETRAINING Retraining the lost co-ordination of

balance to the normal stable balanced control through development of muscular activity and generation of motor output is called “BALANCE RETRAINIG”.