PTA 130 – Fundamentals of Treatment I
Posture, Ergonomics, Stability, Balance,
Proprioception
Lesson Objectives
 Describe common postural abnormalities
 Discuss Basic Ergonomic/Body Mechanics Principles
 Define stability and how it affects function
 Describe balance training techniques
Posture
 Relative alignment of body segments with one another
 Good alignment: provides minimal stress to segments
 Poor alignment: creates imbalances   stress 
adaptations  efficiency
 Impairments in joints, muscles, or connective tissues
may lead to faulty posture?
 Can faulty posture lead to impairments?
Alignment
 The adult spine is divided into four curves:
 Two primary (posterior)
 Located in the thoracic and sacral regions
 Kyphosis denotes a posterior curve
 Two compensatory (anterior)
 Located in the cervical and lumbar regions
 Lordosis denotes an anterior curve
Gravity and Postural Alignment
 Gravity places stress on the structures responsible for
maintaining the body upright
 Provides a continual challenge to stability and efficient
movement
 A plumb line is typically used for reference when
assessing posture and represents the relationship of the
body parts with the line of gravity
Frontal Posture View
Standing: Anterior View
 Plumb line bisects the body into
symmetrical segments
 Line bisects nose, mouth, sternum,
umbilicus, and pubic bones
 Feet are equidistant from plumb
line
 Shoulders are in a neutral position
 Is this different from anatomical
position?
Standing: Anterior View
 What should the therapist look for in this posture?
 Level right to left: earlobes, shoulders, fingertips, nipples,
iliac crests, patellae, medial malleoli
 Patellae: directed forward
 Feet: directed forward or out slightly
 Knees and ankles: in line with each other
 Knees: straight
 Symmetrical muscle development
Posterior Posture View
Standing: Posterior View
 Plumb line bisects head and runs along
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spinous processes
Level left to right: earlobes, shoulders,
scapulae, hips, posterior superior iliac
spine, gluteal fold, posterior knee creases,
medial malleoli
Scapulae lie against rib cage: T2-T7
Calcaneus: straight with Achilles
perpendicular to floor
Symmetrical muscles
Weight equally distributed
Lateral Posture View
Standing: Lateral View
 In an ideal posture, the plumb line
should fall:
 Slightly anterior to the lateral
malleolus
 Slightly anterior to the axis of the
knee joint
 Through the greater trochanter
 Through the bodies of the lumbar and
cervical vertebrae
 Through the shoulder joint
 Through the lobe of the ear
Standing: Lateral View
 Horizontal line between ASIS (anterior superior iliac
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spine) and PSIS (posterior superior iliac spine)
Weight balanced between heel and toes
Knees should be straight, but not locked
Chin slightly tucked
Chest up and forward
Mild curve inward at cervical and lumbar spine
Sitting Posture
 Improper sitting posture or prolonged sitting can have
adverse affects on alignment
 Common faulty sitting posture issues:
 Rounded shoulders
 Forward head
 Tight hip flexors
 Shortened hamstring muscle length
 Increased thoracic spine kyphosis
 Decreased lumbar spine lordosis
Ideal Sitting Posture
 Seat height:
 Allows feet flat on floor—90° at hips, 90° at knees
 Seat depth:
 Front edge 1 to 2 in. from posterior knee
 Back height:
 To lower scapulae and support lumbar spine, thoracic spine
 Arms:
 Allow shoulder relaxation and permit forearms to rest
with elbows bent 90°, wrists in neutral, fingers able to rest
comfortably on keyboard
Common Faulty Postures
 Pelvic and Lumbar Region
 Increased Lordosis Posture (Lordotic)
 Relaxed or Slouched Posture
 Flat Low-Back Posture
 Cervical and Thoracic Region
 Increased Kyphosis Posture
 Round Back with Forward Head
 Flat Upper Back and Neck Posture
 Scoliosis
 Frontal Plane Deviations
 Pelvic drop or elevation
Increased Lordosis Posture
 Characterized by:
 An increase in the lumbosacral angle
 An increase in lumbar lordosis
 Increase in anterior pelvic tilt and hip flexion
 Potential Muscle Impairments
 What are they?
 Common Causes
 Pregnancy
 Obesity
 Weak abdominal muscles
Relaxed or Slouched Posture
 Also called swayback posture
 Characterized by:
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A shift of the entire pelvic region anteriorly
Increased lordosis in the lower lumbar region
Increased kyphosis in the thoracic region
Usually present with a forward head posture
 Potential Muscle Impairments
 What are they?
 Common Causes
 Fatigue
 Muscle weakness
Relaxed or Slouched Posture
Flat Low-Back Posture
 Characterized by:
 Decreased lumbosacral angle
 Decreased lumbar lordosis
 Hip Extension
 Posterior pelvic tilt
 Potential Muscle impairments:
 What are they?
 Common Causes:
 Prolonged flexed posture in sitting or standing
 Overemphasis of flexion biased exercises
Flat Lumbar Spine
Round Back (Increased Kyphosis) with
Forward Head Posture
 Characterized by:
 Increased thoracic curve
 Protracted scapula
 Forward head
 Potential Muscle impairments:
 What are they?
 Common Causes:
 Slouching
 Poor ergonomics at work station
 Occupational or functional postures
Cervical Lordosis, Thoracic Kyphosis,
and Lumbar Lordosis
Increased Thoracic Kyphosis
Flat Upper Back and Neck Posture
 Characterized by:
 Decreased thoracic curve
 Depressed scapula
 Depressed clavicles
 Decreased cervical lordosis
 Potential Muscle impairments:
 What are they?
 Common Causes:
 Not as common as other faulty postures
 May occur with exaggerated military posture
Scoliosis
 Characterized by:
 Usually involves the thoracic and lumbar regions
 May be asymmetry in the hips, pelvis, and lower
extremities
 Two types:
 Structural scoliosis
 Nonstructural scoliosis
Scoliosis
Scoliosis
 Structural Scoliosis
 An irreversible lateral curvature with fixed rotation of the
vertebrae
 Rotation of the vertebral bodies is toward the convexity of
the curve
 Nonstructural Scoliosis
 Also called functional or postural scoliosis
 It is reversible
 Through forward or side bending and with positional
changes, muscle re-education, and realignment of the pelvis
Scoliosis
 Potential Muscle Impairments
 What are they?
 Common Causes
 Structural scoliosis
 Neuromuscular disorders/diseases
 Osteopathic disorders
 Idiopathic disorders (unknown cause)
 Nonstructural scoliosis
 Leg-length discrepancy
 Muscle guarding or muscle spasm
 Asymmetrical postures
Measurement of Scoliosis
Pelvic Drop or Elevation
 Characterized by:
 Elevated ilium on the long leg
 Lowered ilium on the short leg
 Potential Muscle Impairments:
 What are they?
 Common Causes:
 Deviations at the hip, knee, ankle, or foot
 Common functional problems:
 Unilateral flat foot
 Imbalances in the flexibility of muscles
Lateral Shift
Further Postural Observations
 Knee and foot position/structure may also contribute to
postural deviations
 Knees
 Genu varus
 Genu valgus
 Genu recurvatum
 Feet
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Pronation
Supination
Hallux valgus
Hammer toes
Normal Knee Alignment
Genu Varus
Genu Valgus
Genu Recurvatum
Normal Adult Foot in WB Position
Normal Arch Position/Alignment
Pronation
Hallux Valgus
Hammer Toes
Effects of Bad Posture on Tissue
Health
 Changes in tissue occur slowly over time
 Adaptation to stresses applied
 Shortening of some structures, lengthening of opposing
structures
 Secondary weakness of both shortened and lengthened
structures
 Length–tension relationship-As a muscle shortens or
lengthens beyond optimal length, strength decreases
Results of Impaired Posture
 Efficiency of movement is impaired
 Stress on specific segments during sport activities
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increases
Pain
Muscles must work harder to maintain posture,
increasing fatigue
Individual becomes susceptible to injury
Mobility impairment
Decreased pulmonary endurance
Posture Management
 What interventions can we perform to help manage
patients with impaired posture?
 Verbal, visual and tactile reinforcement
 Cervical retraction to decrease forward head posture
 Scapular retraction to decrease rounded forward shoulder
posture
 Instruct patient on neutral pelvis position in sitting and
standing
 What other treatment options might be appropriate for
this patient population?
Proper Ergonomics
 Ergonomics is the study of designing equipment and
devices that fit the human body, its movements, and its
cognitive abilities
 Especially important for our patients who spend most of
the day sitting at a computer, performing repetitive
movements throughout the day, or are required to lift at
work
Ergonomics in Sitting
 Example of Ergonomic sitting to decrease stress on body.
Body Mechanics
 The way the body is positioned and used during activity
 Correct body mechanics makes the most effective use of
the body’s forces and levers
 Incorrect mechanics leads to inefficient use and increases
stress on the body segments
Basic Principles
 Spine should remain straight.
 Pelvis remains in neutral.
 Lowering center of gravity increases stability.
 Broadening base of support increases stability.
 Feet are placed in direction of force application or
acceptance.
 Core strength is vital for force transmission, transfer, and
body support.
Correct or Incorrect?
Correct or Incorrect?
Correct or Incorrect?
Proper lifting Techniques
 1. Keep object close to body.
 2. Do NOT bend or twist your back.
 3. Let your legs do the work.
Correct or Incorrect Lifting Technique?
Proper Pushing Technique
Other Considerations Regarding
Malalignment
 Sports increase postural deviations.
 Anterior muscles are exercised more than posterior
muscles
 Unilateral activities
 Aging tends to increase deviations
 Joint hyper- or hypo-mobility  muscle stresses.
 Scar tissue from injuries can cause imbalances.
 Site of pain may not be site of problem.
Stability
 When the line of gravity from the center of mass falls
within the base of support, a structure is stable
 Improved by lowering the center of gravity (COG) or
increasing the base of support (BOS)
 When the COG falls outside the BOS, the structure
either falls or some force must act to keep the structure
upright
 Both inert and dynamic structures provide support to
the body
Postural Stability in the Spine
 Described in three subsystems:
 Passive (inert)
 Bones and ligaments
 Active
 Muscles
 Neural control
Muscle Control in the Lumbar Spine
 Importance of the transverse abdominis (TrA) and
multifidus muscles as core stabilizers
 Provide support through attachments in the lumbar
spine
 Studies have shown that these muscles are the first ones
to become active when there is a postural disturbance
 When the TrA muscles develop tension, they act like a
girdle of support around the abdomen and the lumbar
vertebrae
Postural Stabilization
 Core stabilization is the co-contracture of abdominal and
lumbar region
 Back injuries often occur secondary to weak core
musculature
BALANCE
Balance
 Also known as postural stability
 The dynamic process by which the body’s position is
maintained in equilibrium
 Static equilibrium: the body is at rest
 Dynamic equilibrium: the body is in steady-state motion
Balance
 Biomechanical Components of Balance:
 Base of Support (BOS)- Area within the perimeter of the
contact surface between the feet and the support surface.
 Center of Gravity (COG)- Central point within the limits
of stability area
 Most adults COG is just anterior to S2 or at about 55% of a
persons height
 Limits of Stability- The sway boundaries in which an
individual can maintain equilibrium without changing his
or her BOS
Balance
 A complex motor task
 Fundamental to posture and activity
 Three-component system:
 Visual
 Vestibular
 Proprioception
Balance (Visual System)
 Provides information regarding
 Head position relative to the environment
 Orientation of the head
 Direction and speed of head movements
 Visual stimuli can be used to improve a person’s stability
Balance (Vestibular System)
 Provides information about the position and movement
of the head with respect to gravity and inertial forces
 On its’ own, the vestibular system cannot provide
information about the position of the body
 Additional information from mechanoreceptors must be
sent to the CNS in order to develop a true picture of the
orientation of the head relative to the body
Balance (Proprioception)
 Provides information about the position and motion of
the body and body parts relative to each other and the
support surface
 Muscle spindles and Golgi tendon organs play an
important role in maintaining balance when on a firm
surface
 What about when placed on a moving or unsteady
surface?
Balance
 Sensory Components of Balance
 Requires information from the Central Nervous System to
select, suppress, and combine appropriate inputs
 Musculoskeletal Components of Balance
 Provide coordination of postural stability by key muscle
groups
Motor Strategies for Balance Control
 The body must adjust its position in space in order to
maintain balance
 Three primary movement strategies to recover balance
in response to sudden perturbations:
 Ankle, hip, and stepping strategies
 CNS uses three movement systems to regain balance:
 Reflex – First response, controlled by spinal cord
 Voluntary systems – Dependent on task parameters
 Automatic – Relatively quick responses, but require
coordination of responses among body regions
Balance Strategies
 Automatic Postural Reactions (Reflexive Muscle
Contractions) are used to maintain balance
 Ankle strategy: small disturbance, slow-speeds uses ankle
dorsiflexion and plantar flexion to redistribute body
weight
 Hip strategy: rapid or large disturbances, compensatory
hip flexion and extension to redistribute body weight
 Stepping Strategy: large disturbance displaces center of
mass beyond limits of control and a step enlarges the base
of support
Balance
 Techniques to Improve Ankle Strategies Unilateral Standing – One-foot standing or unstable
surface activity.
 Techniques to Improve Hip Strategies Unilateral Standing on unstable surface with high-sway
frequencies.
 Techniques to Improve Stepping Strategies Stepping activity such as step onto stool and step-overs
Balance
 Balance Assessment Tools:
 Romberg
 Unilateral stand
 Functional Reach
 Berg Balance
 Tinetti Balance
 Timed Up and Go
 Examination of Sensory Organization
 Assessment of three sensory inputs (proprioceptive, visual,
and vestibular)
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Center of Gravity Changes With
Changes in Body Position
Line of Gravity Must Fall Within the
Base of Support
Rhomberg and Single Leg Stand
 Rhomberg The subject stands with
feet together, eyes open
and hands by the sides
 The subject closes the eyes
while the examiner
observes for a full minute
 Single leg stand (Stork
stand)
Balance Progression
QUESTIONS?