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Chapter 15: The Standing Posture. KINESIOLOGY Scientific Basis of Human Motion, 11th edition Hamilton, Weimar & Luttgens Presentation Created by TK Koesterer, Ph.D., ATC Humboldt State University Revised by Hamilton & Weimar. Objectives. - PowerPoint PPT Presentation
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© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Chapter 15:Chapter 15:The Standing PostureThe Standing Posture
KINESIOLOGYScientific Basis of Human Motion, 11th edition
Hamilton, Weimar & Luttgens
Presentation Created byTK Koesterer, Ph.D., ATCHumboldt State University
Revised by Hamilton & Weimar
KINESIOLOGYScientific Basis of Human Motion, 11th edition
Hamilton, Weimar & Luttgens
Presentation Created byTK Koesterer, Ph.D., ATCHumboldt State University
Revised by Hamilton & Weimar
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
ObjectivesObjectives
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 factors that affect the stability and energy cost for the erect posture.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
ObjectivesObjectives
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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
SIGNIFICANCE OF POSTURESIGNIFICANCE 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. All posture is somewhat dynamic, including
postural sway during quiet standing. Represents a person’s habitual carriage.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
SUPPORT OF THE SUPPORT OF THE STANDING POSTURESTANDING POSTURE
Muscular Activity in Erect Standing Humans have a very economical antigravity
mechanism. Muscle energy required to maintain erect
posture is relatively small. Ligaments play a major role in supporting and
maintaining 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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Muscular Activity in Erect Muscular Activity in Erect StandingStanding
Foot: Only muscular activity is in the push-off phase or rising on the toes.
Leg: Posterior calf muscles are more active then the anterior.
Thigh & Hip: Very little activity: Swaying produces bursts of ab/adductors. Iliopsoas constantly active, preventing
hyperextension of the hip joint.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Muscular Activity in Erect Muscular Activity in Erect StandingStanding
Spine: Very slight activity in 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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
The Neuromuscular Mechanism The Neuromuscular Mechanism for Maintaining Erect Posturefor Maintaining Erect Posture
Proprioceptors are responsible for most of the reflex movements to maintain posture.
Posture modification depends on:
1. Voluntary decision towards change.
2. Experience with desired posture.
3. Instruction resulting in different strategies.
4. Environmental influences.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Postural StabilityPostural Stability
Hellebrandt (1940) “Standing is, in reality, movement upon a stationary base”.
CoG does not remain motionless. Subjects were constantly swaying. Today, computerized dynamic posturography
can record postural sway magnitude, direction, and pattern.
Postural stability is currently measured as sway motion between CoG and center of pressure as well as CoG velocity.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Alignment of Alignment of Body SegmentsBody Segments
“Good posture” Weight-bearing
segments balanced vertically.
Rotary effect of gravitational force is minimized.
Fig 15.2
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Alignment of Alignment of Body SegmentsBody Segments
“Fatigue posture” Muscles have let go. Ligaments prevent collapse. Zigzag alignment of weight
bearing segments increases rotary effect of gravitational force.
Fig 15.1
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Alignment of Body SegmentsAlignment of Body Segments
Even the most ideal posture has some rotary force present.
1. Supporting column of trunk situated more posteriorly.
2. Support base (feet) project forward.
3. Spinal column curved anteroposteriorly.
4. Chest forms an anterior load. Females breasts are an additional anterior
load.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Relationship of Alignment of Body Relationship of Alignment of Body Segments and Integrity of Joint StructureSegments and Integrity of Joint Structure
Prolonged postural strain is injurious: Ligaments can permanently stretch. Cartilages can be damaged due to
abnormal friction. Arthritic changes in weight-bearing joints.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Minimum Energy ExpenditureMinimum 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 nor possible.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
FACTORS RELATED TO THE FACTORS RELATED TO THE STANDING POSTURESTANDING POSTURE
Energy 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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AgeAge
Infant lacks muscular strength to stand upright.
Posture in toddler more erect and less stable than in older child or adult.
Postural sway becomes more variable with aging.
Stability more dependent on vision, less on proprioception in aging population.
Level of muscle activity increases as stability decreases.
Increased tendency to fall with advanced age.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Evolutionary and Evolutionary and Hereditary InfluencesHereditary Influences
As man began to walk upright there was a shift from a vertically suspended position to a vertically supported one.
Although no specific principle is derived, changes had to occur to the musculoskeletal structure.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Strength and FlexibilityStrength and Flexibility
Seem to be universally accepted factors based on the preponderance of strength and flexibility exercises: Strength of abdominals Scapula retractors Pectoral stretching Hamstring stretching
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
PRINCIPLES APPLIED PRINCIPLES APPLIED TO POSTURETO POSTURE
1. Weight-bearing segments aligned so trunk and pelvic girdle inclination is within “normal” limits.
2. Line of gravity intersects center of base of support.
3. Weight-bearing joints should be in extension, balanced, no strain or tension.
4. Good posture requires minimal energy expenditure for the maintenance of good alignment.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
PRINCIPLES APPLIED PRINCIPLES APPLIED TO POSTURETO POSTURE
5. Permits mechanically efficient function of the joints.
6. Good posture, both static and dynamic, requires a minimum of muscle force.
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 coordination. neuromuscular control & reflexes.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
PRINCIPLES APPLIED PRINCIPLES APPLIED TO POSTURETO POSTURE
9. Adjustments in posture can be made more readily with a good kinesthetic awareness of 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. Posture of any individual should be judged on the basis of how well it meets the demands made upon it throughout a lifetime.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
POSTURAL ADAPTATIONS TO EXTERNAL POSTURAL ADAPTATIONS TO EXTERNAL CONDITIONS AND SPECIAL PROBLEMSCONDITIONS AND SPECIAL PROBLEMS
Standing on an inclined plane: adjustments should be made at the ankle when possible; adjust CoG 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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
POSTURAL ADAPTATIONS TO EXTERNAL POSTURAL ADAPTATIONS TO EXTERNAL CONDITIONS AND SPECIAL PROBLEMSCONDITIONS AND SPECIAL PROBLEMS
Strategies for postural adaptation: Hip strategy:
Adjustments to maintain center of gravity over base are made through hip and trunk flexion/extension.
Ankle strategy: Adjustments to maintain center of gravity over
base are made through changes in ankle/foot motion or position.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
POSTURAL ADAPTATIONS TO EXTERNAL POSTURAL ADAPTATIONS TO EXTERNAL CONDITIONS AND SPECIAL PROBLEMSCONDITIONS 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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
POSTURE POSTURE SCREENINGSCREENING
In an optimal standing posture the 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 SCREENINGPOSTURE 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.
© 2008 McGraw-Hill Higher Education. All Rights Reserved.
Chapter 15:Chapter 15:The Standing PostureThe Standing Posture