Chapter 15: The Standing Posture

1. Chapter 15:The Standing Posture KINESIOLOGY Scientific Basis of Human Motion, 10th edition Luttgens & Hamilton Presentation Created by TK Koesterer, Ph.D., ATC Humboldt State University

2. 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

3. 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

4. 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 person�s basic posture from which all other postures stem

5. 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

6. 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

7. 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

8. 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

9. 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

10. Alignment of Body Segments �Good posture� Weight-bearing segments balanced vertically Rotary effect of gravitational force in minimized

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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)

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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.