Chapter 15: The Standing Posture

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Chapter 15The Standing Posture

• KINESIOLOGY
• Scientific Basis of Human Motion, 10th edition
• Luttgens Hamilton
• Presentation Created by
• TK Koesterer, Ph.D., ATC
• Humboldt State University

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Objectives

• 1. Identify and describe the skeletomuscular and
  neuromuscular antigravity mechanisms involved in
  the volitional standing position
• 2. Summarize the similarities and differences
  that occur in the relation of the line of gravity
  to various body landmarks with good and poor
  anteroposterior segmental alignment
• 3. Discuss the factor that affect the stability
  and energy cost for the erect posture

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Objectives

• 4. Explain the effects that the variables of age,
  body build, strength, and flexibility have on the
  alignment of body segments in the standing
  posture
• 5. Name the values, if any, of good posture
• 6. Perform kinesiological analyses on the posture
  of individuals of different ages and body builds

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SIGNIFICANCE OF POSTURE

• Posture means position
• The multisegmented human body does not have a
  single posture
• Most posture research has been related to the
  volitional standing position
• A custom is to accept standing posture at a
  persons basic posture from which all other
  postures stem

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SUPPORT OF THE STANDING POSTUREMuscular
Activity in Erect Standing

• Humans have a very economical antigravity
  mechanism
• Muscle energy to maintain erect posture is not
  great
• Ligaments play a major role in supporting and
  maintain the integrity of the joints
• Muscles that are active are those that aid in
  keeping the weight-bearing column in relative
  alignment and oppose gravity

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Muscular Activity in Erect Standing

• Foot Only muscular activity is in the push-off
  phase or rising on the toes
• Leg Posterior calf muscles are more active the
  anterior
• Thigh Hip Very little activity
• Swaying produces bursts of ab/adductors
• Iliopsoas constantly active, preventing
  hyperextension of the hip joint

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Muscular Activity in Erect Standing

• Spine Very slight activity is sacrospinalis or
  abdominals
• Upper Extremity low-grade activity in a number
  of muscles
• Serratus anterior trapezius support the
  shoulder girdle
• Supraspinatus resist downward dislocation of the
  humerus
• No activity in elbow or wrist joints, when
  passively hanging

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The Neuromuscular Mechanism for Maintaining Erect
Posture

• Proprioceptors are responsible for most of the
  reflex movements to maintain posture
• Posture modification of posture depends on
• 1. Voluntary decision towards change
• 2. Experience with desired posture
• 3. Instruction resulting in different strategies
• 4. Environmental influences

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Postural Stability

• Hellebrandt (1940) Standing is, in reality,
  movement upon a stationary base
• CG does not remain motionless
• Subjects were constantly swaying
• Today, force platforms can record postural sway
  in magnitude, direction, and pattern
• Postural stability is currently measured as sway
  motion between CG and center of pressure

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Alignment of Body Segments

• Good posture
• Weight-bearing segments balanced vertically
• Rotary effect of gravitational force in minimized

Fig 15.1
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Alignment of Body Segments

• Fatigue posture
• Muscles have let go
• Ligaments prevent collapse
• Zigzag alignment of weight bearing segments
  increase rotary effect of gravitational force

Fig 15.2
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Alignment of Body Segments

• Even the most ideal posture have some rotary
  force present
• 1. Supporting column of trunk being more
  posterior
• 2. Support base (feet) being projected forward
• 3. Spinal column being curved anteroposteriorly
• 4. Chest forming an anterior load
• Females breasts are an additional anterior load

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Relationship of Alignment of Body Segments and
Integrity of Joint Structure

• Prolonged postural strain is injuries
• Ligaments can permanently stretch
• Cartilages can be damaged due to abnormal
  friction
• Arthritic changes in weight-bearing joints

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Minimum Energy Expenditure

• Cannot be accepted as the criteria of good
  posture
• Metabolic economy is desirable to a point
• Well-balanced segmental alignment should not be
  sacrificed for it
• A single interpretation of an ideal posture is
  neither practical or possible

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FACTORS RELATED TO THE STANDING POSTUREEnergy
Cost

• Fatigue posture
• Requires a minimum of metabolic increase
• Knees - hyperextended
• Hips forward
• Increased thoracic curve
• Head forward
• Trunk - posterior lean

Fig 15.3
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Evolutionary and Hereditary Influences

• As man began to to walk upright
• There was a shift form a vertically suspended
  position to a vertically support one
• Although no specific principle, changes had to
  occur to the musculoskeletal structure

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Strength and Flexibility

• Seem to be universally accepted relating to the
  preponderance of strength and flexibility
  exercises
• Strength of abdominals
• Scapula retractors
• Pectoral stretching
• Hamstring stretching

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Age

• Several Physical and neurological factors
• Infant initially lack muscular strength and
  neurological development
• The aging adult tends to alter posture
• Older people lean forward
• Bone mineral loss
• Muscular weakness
• Fear of instability

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Psychological Aspects

• Atypical postures may be symptoms of personality
  problems or emotions
• Emotional reaction to an abnormal posture
• Mental fatigue
• Depression, Joy, or Fear
• Evidence exist on the correlation between mood
  state and performance (Huddleston et al., 2000)

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PRINCIPLES APPLIED TO POSTURE

• 4. Form the point of view of energy expenditure,
  good posture would seem to be a position that
  requires a minimum expenditure of energy for the
  maintenance of good alignment
• 5. Good posture, in repose and in activity,
  permits mechanically efficient function of the
  joints
• 6. Good posture, both static and dynamic,
  requires a minimum of muscle force

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PRINCIPLES APPLIED TO POSTURE

• 7. Good posture, both static and dynamic,
  requires sufficient flexibility in the structure
  of the weight-bearing joints to permit good
  alignment without interference or strain
• 8. Good posture requires good condition
• neuromuscular control reflexes
• 9. Adjustments in posture can be made more
  readily by individuals who have a good
  kinesthetic awareness of postures they assume and
  of the degree of tension in their muscles

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PRINCIPLES APPLIED TO POSTURE

• 10. Good posture, both static and dynamic, is
  favorable, or at least not detrimental, to
  organic function
• 11. The characteristics of normal posture change
  with age
• 12. In the last analysis, both static and dynamic
  posture of any individual should be judged on the
  basis of how well it meets the demands made upon
  it throughout a lifetime

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POSTURAL ADAPTATIONS TO EXTERNAL CONDITIONS AND
SPECIAL PROBLEMS

• Standing on an inclined plane bending at knees,
  hips, or spine adjust CG above the base of
  support
• Same for wearing high heels, pregnancy, and
  carrying a heavy bundle in front of the body
• Standing on a moving surface be prepared to make
  adjustments to acceleration, deceleration, and
  side-to-side sway
• Comfortably wide stance in the direction of motion

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POSTURAL ADAPTATIONS TO EXTERNAL CONDITIONS AND
SPECIAL PROBLEMS

• Standing on one foot
• Usually managed automatically by the muscle,
  joint, and labyrinthine proprioceptors, and
  reflex response
• Shift body weight to supporting limb

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POSTURE SCREENING

• An optimal standing posture
• Line of gravity falls
• slightly anterior to lateral malleolus
• Midline of the knee
• Slightly posterior to hip
• Anterior to sacroiliac joints

Fig 15.3a
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POSTURE SCREENING

• 1. Subject should wear minimal clothing
• 2. Subject assumes comfortable stance
• 3. Landmarks to line of gravity from the side
• 4. Alignment of foot, ankle, knee from front
• 5. Alignment of spine pelvis from rear
• A screening matrix expedites observation of any
  deviations

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PRINCIPLES APPLIED TO POSTURE

• 1. The weight-bearing segments of the body are so
  aligned in good standing posture that angles of
  inclination in the trunk and in the pelvic girdle
  are within normal limits
• 2. In order to be stable, the intersection of the
  line of gravity with the base of support will be
  close to the geometric center of the base.
• 3. Good standing posture is a position of
  extension of the weight-bearing joints.