Chapter 15. The Standing Posture

At the conclusion of this chapter, the student should be able to:

• 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 of the erect posture.
• 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.

There are innumerable concepts of human posture and innumerable interpretations of its significance. Posture may well claim to be “all things to all people.” To the physical anthropologist, posture may be an indication of phylogenetic development; to the orthopedic surgeon, it may be an indication of the soundness of the skeletal framework and muscular system; to an artist, it may be an expression of the personality and the emotions; to the actor, it serves as a tool for expressing mood or character; to the physician, biologist, fashion model, employer, sculptor, dancer, therapist, psychologist—to each of these—posture has a different significance. Each sees posture within the framework of his or her own profession and interest. This is no less true of kinesiologically oriented therapists and educators. To them, posture is a gauge of mechanical efficiency, kinesthetic sense, muscle balance, and neuromuscular coordination.

For all practical purposes no individual’s posture can be described completely. Posture means position, and a multisegmented organism such as the human body cannot be said to have a single posture. It assumes many postures and seldom holds any of them for an appreciable time. Although characteristic patterns become apparent as we observe an individual over an extended period, it is difficult, if not impossible, to measure, or even record, these patterns. It would take a comprehensive series of pictures of an individual’s varied stance and movement patterns to provide an adequate sample. Perhaps this is the reason that most posture research has been related to the volitional standing position.

Another difficulty in analyzing and evaluating human posture is the varieties of human physique represented, such as those defined many years ago by Sheldon et al. (1940). The importance of considering these individual differences of build when evaluating posture was reported by Althoff et al. (1988). Each of us has had the experience of recognizing a friend from the back. It was probably, in part, that individual’s habitual posture that gave the clue for visual identification.

In view of the fact that dynamic postures should be of greater concern than static postures to those who specialize in human movement, it may be well to say a word in defense of the practice of examining the posture of subjects in the erect standing position. It is admitted that the posture in such a position is of little importance in itself, unless this posture must be maintained for long periods of time. In reality all posture is somewhat dynamic. Even when standing still, the body is in motion, undergoing postural sway. The motion of the center of gravity, and the center of pressure, is used as a measure of postural stability. The alignment of the body when maintaining the erect standing posture becomes important in controlling and maintaining the appropriate level of postural sway. It also becomes significant when taken as the point of departure for the many postural patterns assumed by the individual, both at rest and in motion. Because there is an almost endless variety of activity postures and because these are extremely difficult to judge, a convenient custom is to accept the standing posture as the individual’s basic posture from which all other postures stem. Hence, as a reflection of the individual’s characteristic postural patterns, the standing posture takes on an importance it would not otherwise have. It should be kept in mind, however, that its importance is in direct proportion to the extent to which it represents the individual’s habitual carriage.

Muscular Activity in Erect Standing

Compared with other mammals, humans have very economical antigravity mechanisms, and the muscle energy needed to maintain the erect standing position is not great. A reason for the economy of muscle effort required is the major role of the ligaments in supporting and maintaining the integrity of the joints. The muscles that are active are those that aid in keeping the weight-bearing column of bones in relative alignment and that oppose gravity’s downward-directed force.

According to electromyographic studies reported by Basmajian and DeLuca (1985), Trepman et al. (1994), and Laughton et al. (2003), the postural muscular activity in the body segments can be expected as follows.

Foot

None of the intrinsic musculature is active during normal standing but becomes active in the pushoff for walking or rising on the toes.

Leg

The posterior calf muscles are more active than the anterior ones. Any swaying forward or backward produces compensatory muscle action to bring the body back to the vertical balanced position. Rising on the toes or wearing high heels increases the activity of both the anterior and posterior muscles. The muscles of the ankle are responsible for the control of sagtittal plane (anteroposterior) postural sway.

Thigh and Hip

Very little activity occurs in the thigh muscles during relaxed standing. Swaying produces alternating bursts of activity in the gluteus medius and tensor fasciae latae. This is due to the fact that the abductors/adductors control frontal plane (mediolateral) postural sway. The iliopsoas is constantly active, apparently to prevent hyperextension at the hip joint.

Spine

There is very slight activity in the sacrospinalis or abdominal muscles, depending on the relation of the line of gravity to the spinal column. Activity is exhibited in one or the other of the two sets of muscles. Slight to moderate back muscle activity is more likely than abdominal muscle activity.

Upper Extremity

The integrity of the joints in the passively hanging extremity is assisted by low-grade activity in a number of muscles. The serratus anterior and the fibers of the trapezius support the shoulder girdle, and the supraspinatus resists downward dislocation of the humerus. There appears to be no activity in the muscles crossing the elbow or wrist joints when the arm hangs passively.

The Neuromuscular Mechanism for Maintaining Erect Posture

The proprioceptors are responsible for most of the reflex movements necessary for the maintenance of the erect standing position and for the adjustments that must be made to meet changing conditions. They include the receptors of the muscles, joints, and labyrinths and are accompanied by two exteroceptors, one visual and the other cutaneous. The latter serves as a proprioceptor together with the pressure receptors, especially in connection with the extensor thrust reflex. Volitional postural adjustments are made by the same mechanism that is responsible for all volitional movements (see Volitional Movement) and, of necessity, are governed by the structural limitations of the individual. Recently the role of the neuromuscular system in the maintenance of the upright standing posture has been called into question. Winter and colleagues (2001) have produced a model in which the neuromuscular system apparently controls the initial stiffness of the lower extremity (primarily the ankle joint). Postural sway is then the result of the spring action produced by this joint stiffness. More recent theories paint a picture of a much more complex system of sensorimotor control of posture, including theories of ballistic control and feed forward control. It should be of interest for the student to watch the development of these theories (Kohn 2005; Peterka and Loughlin 2004).

Postural Stability

Hellebrandt (1940) was one of the first to demonstrate that even the erect standing posture is not literally static. “Standing,” she concluded, “is, in reality, movement upon a stationary base.” Her experiments using scales and a reaction board revealed that the center of gravity did not remain motionless above the base of support, no matter how still the subject attempted to stand, but moved forward, backward, and sideward. This motion indicated that the subjects were constantly swaying. When the swaying was prevented by artificial means, there was a tendency to faint. Thus the involuntary swaying was seen to serve the purpose of a pump, aiding the venous return and ensuring the brain of adequate circulation for retaining consciousness.

Postural sway is a measure of the movement of the center of gravity within the base of support. Measures of sway have been used to quantify static balance and to distinguish the existence of neurological disorders, load-carrying demands, aging, or attentional demands. Postural sway is measured in many ways, with the most popular being computerized dynamic posturography. More recently, several researchers (Forth et al. 2006; Haddad et al. 2006) have demonstrated that the “time to contact” (TtC) method appears to provide greater clinical sensitivity. This measure includes the velocity of the center of mass in addition to center of mass location.

Postural stability is currently measured on the basis of the horizontal difference in sway motion between center of gravity and center of pressure. Center of pressure is the single resultant of the multiple forces occurring over the entire plantar surface of the foot. In balanced standing, the line of gravity should be through the center of pressure. The greater the excursion of the center of pressure in relation to the center of gravity, the more likely that there is poor segmental alignment and/or poor postural stability. However close the line of gravity is to the center of pressure, this condition does not necessarily indicate good segmental alignment. One can assume an exaggerated zigzag alignment and still stand in such a way that difference in motion between the line of gravity and the center of pressure is quite small, provided the “zags” balance the “zigs,” yet the posture may leave much to be desired. In this connection students may find Laboratory Experiences 3 and 4 of particular interest.

Alignment of Body Segments

It has been assumed by many that a standing posture in which each weight-bearing segment was balanced vertically upon the segment beneath it made less demand on the muscles than a posture in which the segments formed a zigzag alignment. Good posture, it was said, takes less muscular effort to maintain than poor. The explanation given was that when a segment is not in vertical alignment, the force of gravity is not parallel with its long axis, and hence exerts a rotary component of force. Although this reasoning may seem logical, it overlooks two facts: first, that one of the most poorly aligned postures is actually a fatigue posture in which the muscles have let go and have left it to the ligaments to prevent complete collapse (Figure 15.1); and second, that even in the most ideal posture some rotary force is present, owing to (1) the supporting column of the trunk (i.e., the spine) being situated closer to the posterior surface of the body than to the anterior, (2) the supporting base (the feet) being projected forward from the lower extremities instead of centered beneath them, (3) the spinal column being curved anteroposteriorly, and (4) the chest forming an anterior load upon which gravity is constantly exerting a rotary force (Figure 15.2). The weight of the breasts in women constitutes an additional anterior weight and thus causes an even greater rotary component of gravitational force.

There appears to be a definite relationship between the alignment of the body segments and the integrity of the joint structures. It is generally accepted that prolonged postural strain is injurious to these structures. Ligaments that are repeatedly subjected to stretch become permanently stretched, and cartilages that are subjected to uneven pressures and to abnormal friction become damaged. Adequate clinical, though not experimental, evidence exists to support the contention that prolonged postural strain is a factor in the arthritic changes that take place in the weight-bearing joints.

Lack of agreement concerning the effort required for maintaining upright posture is partly due to confusion about what is meant by “upright posture.” To some, it may mean merely the ability to stay on one’s feet and resist the downward pull of gravity. To others, it may mean good alignment as opposed to a zigzag alignment. Studies based on energy cost appear to indicate that, although it takes less energy to stand erect than to sit, minimum energy expenditure cannot be accepted as a criterion of good posture. Metabolic economy is desirable to a point, because it implies the absence of hypertonicity, but from an overall educator’s point of view, well-balanced segmental alignment should not be sacrificed for it.

The energy requirement for maintaining erect posture in reasonably good alignment would seem to bear a direct relationship to the individual’s habitual carriage. It is a matter of common observation that there is a wide range of body alignments seen in upright posture. Anyone who has had the task of evaluating the posture of large groups of individuals and of giving help to those with “poor posture” is impressed with the variation in effort it takes for a student to stand in “good posture.” Whereas one individual apparently has no difficulty in assuming this posture because it is the natural one, another cannot assume it even momentarily without the instructor’s help and without becoming overtense. It is obvious that the second individual uses more muscular energy than the first. A single interpretation of an ideal posture is neither practical nor possible when given the large individual variations that exist among human beings. Good posture, accommodating the great variety of body types and resulting in physiological and mechanical efficiency, in both static and dynamic situations, must be broadly interpreted.

Energy Cost

The increase in metabolic rate over the basal rate when standing is so small compared with the metabolic cost of moving and exercising as to be negligible. The type of posture that involves a minimum of metabolic increase over the basal rate is one in which the knees are hyperextended, the hips are pushed forward to the limit of extension, the thoracic curve is increased, the head is projected forward, and the upper trunk is inclined backward in a posterior lean (Figure 15.3b). This is a typical fatigue posture requiring a minimum of energy expenditure. A common variation is a shift of the weight to one foot with accompanying asymmetrical adjustments in the spine and lower extremities.

Age

As the human body develops from infancy to old age, several physical and neurological factors may affect posture. The infant initially lacks either the muscular strength or the neurological development to assume an upright posture. As the trunk and upper extremities develop, the infant gains the ability to assume and maintain a sitting posture. With continued muscular and neurological development, the toddler gains the ability to stand and to take the first tentative steps. Posture, at this stage, is still more erect and less stable than in the older child or mature adult. The toddler’s head is disproportionately large for the size of the body, which tends to make the toddler somewhat unstable. There is also an exaggerated lumbar curve and protruding abdomen. As the child grows and matures, the normal curvature of the spine and the growth of the body in relation to head size will produce a more upright, adult posture.

On the other end of the life span, the aging adult tends to alter posture in several ways. With aging, postural sway tends to more variable. Stability is more dependent on vision as proprioception becomes less acute. Any interference with visual references tends to produce an increase in sway. In general the velocity of postural sway and the level of muscle activity both increase as stability decreases. This increase in sway velocity and variability has been linked with an increased tendency to fall. The reasons that the elderly are more susceptible to falling have been the subject of much research. Theories regarding the physical changes that contribute to decrements in postural stability include decreases in muscle strength, loss of reaction time, proprioceptive decline (as previously noted), and loss of cognitive and visual function. Another common function of aging, at least in women, is the development of a stooped posture associated with osteoporosis. It is also common to see the older person lean forward more than a younger person. This forward lean has been associated with bone mineral loss, muscular weakness, and a fear of instability (Freitas et al. 2005; Hammerberg and Wood 2003; Laughton et al. 2003).

Evolutionary and Hereditary Influences

The transformation of the human race from arboreal quadrupeds to upright bipeds is a process that is still being closely examined by anthropologists. Lovejoy (2005) proposes that this evolutionary process is directly related to the need for the male hominid to have the hands and arms available for carrying a wider variety of foods from fairly long distances. The changes that developed in human structure, he stated, were the direct result of the shift from a vertically suspended position to a vertically supported one. This shift was responsible not only for the changes in the weight-bearing parts of the musculoskeletal structure but also for changes in the upper extremities, which were now freed for the development of a great variety of manipulative skills. Although no specific principle is derived from this explanation of the role played by the force of gravity in the evolution of human structure, an awareness of it might be of help in the analysis of individual postures.

Attention has already been called to individual variations in posture. In attempting to correct a person’s posture, one must be realistic and accept the limits imposed by a possible heredity factor. Improvement can doubtless be made, but one must not expect to effect a radical change in the basic shape of the spine. In addition, certain pathological conditions, such as congenitally dislocated hips, cerebral palsy, and paralysis of trunk muscles, may cause such changes in an individual’s posture that the usual hereditary and environmental influences are obscured.

Strength and Flexibility

That strength and flexibility are factors in posture would seem to be a universally accepted thesis, judging by the preponderance of strength and flexibility exercises included in the majority of corrective programs and also by the strength and flexibility measurements included in posture tests. These exercises relate particularly to the strength of the abdominals, scapular adductors, and thoracic spinal extensors, and in the flexibility of the pectorals and the hamstrings. The results of research in which anteroposterior alignment was correlated with strength or flexibility have been somewhat contradictory. As is often the case, it is difficult to compare results because of significant differences in methodology, especially in the method for measuring the postural alignment and age and sex of the subjects.

Studies comparing anteroposterior alignment and strength have produced little definitive data. There have been some indications that fatigue or injury in the muscles of the lower extremity may contribute to decreasing stability in the upright posture. Strength, flexibility, and injury have, instead, been found to be more closely related to the ability to perform dynamic motions from an upright postural base (Kuo and Zajac 1993; Li et al. 1996; Lundin et al. 1993).

By this time the reader should understand that posture influences all we do and that it is not a static but a dynamic configuration. It should also be understood that no single ideal postural model is appropriate for all individuals. Instead, there must be an understanding of the principles that govern efficient posture. These principles must then be applied to each individual.

• 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. These limits are based on an erect posture of the pelvic girdle (lack of either posterior or anterior tilt) and the maintenance of normal spinal curves.
• 2. 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. Maximum postural stability usually occurs when the line of gravity is over the center of pressure.
• 3. Good standing posture is a position of extension of the weight-bearing joints. This should be an easy, balanced extension and should not be accompanied by strain or tension (Figures 15.3c and 15.4).
• 4. From 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. Excess energy expenditure indicates hypertonicity or poor neuromuscular coordination, or both.
• 5. Good posture, in repose and in activity, permits mechanically efficient function of the joints. In other words, friction in the joints is minimized, tensions of opposing ligaments are balanced, and pressures within the joints are equalized. Hence the skeletal structure is architecturally and mechanically sound and there is a minimum of wear and tear on the joints.
• 6. Good posture, both static and dynamic, requires a minimum of muscle force. This implies adequate development of the antigravity muscles to resist the pull of gravity successfully and to maintain good alignment without excessive effort or tension. It also implies a balance between antagonistic muscle groups. There is no indication, however, that “the stronger the muscles the better the posture.”
• 7. Good posture, both static and dynamic, requires sufficient flexibility in the structures of the weight-bearing joints to permit good alignment without interference or strain. Poor flexibility may be caused by tight ligaments or fasciae, short muscles, or hypertrophied muscles. The flexibility should not be so great, however, that excessive muscular effort is needed to keep the weight-bearing joints in alignment.
• 8. Good posture requires good coordination. This implies good neuromuscular control and well-developed postural reflexes.
• 9. Adjustments in posture can be made more readily by individuals who have a good kinesthetic awareness of the postures they assume and of the degree of tension in their muscles.
• 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. Young children typically have a protruding abdomen and hollow lower back. Loss of muscle strength, inactivity, and balance problems in older persons show up in a wider stance, forward head and rounded upper back, and limited flexibility in the trunk, hips, and knees.
• 12. In the last analysis, both the 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.

A number of conditions necessitate postural adjustment if one is to maintain a reasonably balanced standing position. These include standing on either an uphill or a downhill slope; standing on the level but wearing high heels; standing on a moving surface, such as bus, streetcar, subway, or train; holding a heavy bundle against the front of the body; pregnancy; and standing on one foot. In all of these the body can be relied upon to adjust automatically through the function of proprioceptors and the feedback mechanism. From the point of view of “good body mechanics,” however, the nature of the adjustment may not always be desirable. For instance, one can balance when standing on an inclined plane by bending at the knees, hips, or spine, but it would be mechanically preferable to maintain vertical segmental alignment, as well as balance. To achieve this position, one would need to stand so that the center of gravity of each weight-bearing segment was centered above the base of support. This centering can be achieved only by making the adjustment at the ankles and feet. The same is true for the person wearing high heels and for the pregnant woman, although some women lack the necessary abdominal strength for this action. It is highly desirable for them to strengthen these muscles to resist the tendency to lean back from the waist (hyperextend the spine), an adjustment that is almost sure to cause trouble in the lower back. The person carrying a heavy bundle against the front of the body may find that adjustment at the ankles is not enough, especially if the load is excessively heavy. In this case some adjustment at the knees and hips will help, but every effort should be made not to lean back at the waist (hyperextend the spine) because of the danger of lower back strain.

Maintaining postural control in various environments and under varying surface conditions requires adaptations by the body. Researchers have identified two main strategies that help negotiate specific threats to balance. The hip strategy is used to navigate slippery surfaces, and the ankle strategy is used to navigate uneven surfaces. It is probable that these strategies exist on a continuum with the hip strategy on one end and the ankle strategy on the other. The different challenges to balance lie along this continuum and usually require a combination of responses to maintain upright posture (Bardy et al. 2002).

The hip strategy is easily observable when someone is walking across a slippery surface. Adjustments made to maintain the center of gravity over the base of support are achieved through trunk flexion-extension and hip flexion-extension. Based on a review of previous literature, Blackburn et al. (2003) concluded that the hip plays a substantial role for balance in the sagittal plane.

The ankle strategy is more subtle and is observable as a person walks over gravel or moves the head suddenly. While navigating these surfaces, the ankle/foot adopts a position that allows the person walking to maintain a level gaze. The knee may bend slightly; however, the hip and knee joint angles remain relatively static when the ankle strategy is employed.

The ability to remain upright, in quiet stance, is a complicated process and requires integration of the information from the visual, vestibular, and proprioceptive systems.

Consider trying to get a skeleton to remain upright just by balancing the bones one on top of another. Next, think about how the skeleton would lean if the left arm were raised and how the muscular system would have to respond to this shift (if it had a muscular system). Now, think about how unstable the skeleton would become if it were standing on one leg, which happens with each step we take. The human body must interpret threats to remaining upright, devise a plan to counteract these threats, and implement that plan in time to prevent a fall.

When standing in a moving bus, streetcar, or train, one should be prepared to make three adjustments: acceleration, deceleration, and side-to-side sway. The same principle applies to all three—namely, establishing a comfortably wide stance in the direction of motion (forward-backward for acceleration and deceleration, and sideward for a steady speed, especially if there is a pronounced sway). During sudden acceleration, especially, the person tends to be thrown toward the back of the vehicle, in keeping with Newton’s first law of motion.

The foot toward the rear, therefore, should be well braced, and more weight should be borne by the forward foot in anticipation of the jerk. The reverse is true during deceleration and stopping. In both acceleration and deceleration the body will be less likely to be thrown off balance if the knees are slightly flexed, this shortens the lever upon which the vehicle’s motion acts and also lowers the center of gravity of the body.

In a crowded vehicle that makes frequent stops it may not be possible to keep adapting the stance, and one may have to rely on a hand grasp to supplement the foot adjustment. A slightly oblique stance, favoring the forward-backward direction, serves as an acceptable compromise.

The adjustment to standing on one foot is a delicate one but is usually managed automatically by the muscle, joint, and labyrinthine proprioceptors, and by the reflex response. The adjustment consists of a shift in the body weight to the single supporting limb and in the support of the pelvis on the side of the free limb. The latter adjustment requires additional effort by the quadratus lumborum and the abductors (gluteus medius and minimis, tensor fasciae latae, and oblique abdominal muscles on the support side). The iliopsoas, which is continuously active during all standing, increases its activity in steadying the lumbar spine (Basmajian and DeLuca 1985). In addition, there is probably a continuous interplay of the deep muscles of the lumbar spine and possibly of many of the lower-extremity muscles. The alternating action of the foot and ankle muscles, especially the tarsal pronators and supinators, is quite pronounced in their effort to keep the center of gravity over the narrow base of support. This problem can be helped somewhat by turning the toes slightly outward (i.e., rotating the thigh slightly outward) before the one-legged stance is assumed.

Although human posture is of necessity dynamic in nature, in some instances it is beneficial to examine the static standing posture of individuals. Posture screening is one tool that may be used to evaluate the standing posture for signs of major misalignments, those that may eventually lead to problems in movement, deterioration of health, or tendency to injury.

An optimal standing posture might be described with reference to the line of gravity. Segments should be placed so that the line of gravity falls slightly anterior to the lateral malleolus and the midline of the knee joint when the knee is fully extended, slightly posterior to the hip joint axis when the hip is fully extended, and anterior to the sacroiliac joints (see Figure 15.1). There is some question as to whether the line should also pass through the bodies of the lumbar and cervical vertebrae or should pass through the inflection points of the three vertebral curves. For most individuals, this alignment is controlled by the ligaments and a few appropriate muscle groups, requiring a minimal effort to maintain an erect stance.

To ascertain whether an individual has a significant postural deviation, a quick posture screening might be appropriate. The following steps need to be included:

• 1. The individual to be screened should wear minimal clothing (such as a bathing suit or leotard) and no shoes.
• 2. The individual should assume a comfortable stance. The examiner must be far enough away to view the entire body at once.
• 3. Observation of the relationship of the anatomical landmarks to the line of gravity is made from the side. A hanging plumb line can help in this observation.
• 4. Observation of the alignment of the foot, ankle, and knee is made from the front.
• 5. Observation for lateral deviations of the spine and unequal levels in the pelvis and shoulders are made from the rear. If scoliosis (lateral deviation) is present, one side of the back will be more prominent than the other when the individual is asked to flex the trunk.

Screening in front of a matrix expedites observation of any deviations. Marked deviations observed during static screening may be indicative of increased risk of injury. For example, when the knees, ankles, and feet are not in line, forces transmitted during running or jumping may be directed laterally, causing knee injury. Exaggerated spinal curvatures will also result in alteration of the normal transmission of forces. A serious deviation may cause significant changes in muscle strength or usage.

All misalignments create excess tensions unless the misalignment occurs as the result of “hanging from one’s ligaments.” However, this hanging phenomenon may eventually result in stretching of the ligaments and loss of support for segmental alignment. Greater muscle force would then be required to maintain an optimum upright posture. Faulty posture involving excess tension or requiring excess muscular involvement for motion results in fatigue and inefficient movement, which may predispose the individual to injury. Therefore, postural assessment must take into account appropriate joint alignment to minimize torque and other stresses that would require constant adjustment.

With the current data indicating postural deviations in a significant segment of the population as well as a preponderance of lower back problems in adults, it would be advisable for movement specialists to attend to a simple screening procedure and to take steps to remedy postural deviations as early as possible. Care must be taken, however, to evaluate each individual as such. Minor deviations from the suggested norm may be ignored in some cases or may require a more thorough examination to determine the root cause. It is the job of the kinesiologist to look carefully into the reasons for postural deviations and to attempt to alter only those that may be detrimental. To rework a common phrase, “If it’s not broken, don’t fix it.”

• 1. To demonstrate the alignment of the body segments, take from five to seven large wooden blocks, each having a vertical line painted in the center of one side. A layer of thick felt should be glued to the top and bottom of each block and a small hook screwed into each of two opposite sides.
  • a. Arrange the blocks in a straight column with the painted lines in front. Connect the hooks on the sides with elastic bands. The elastic “ligaments” will be under equal tension and the felt “cartilages” under equal pressure when the column is in perfect alignment.
  • b. Now insert wedges between the blocks in such a way that every other block tips to the left and the alternate blocks tip to the right. The elastic ligaments will now be under unequal tension and the felt cartilages under unequal pressure. The zigzag alignment of the painted lines illustrates graphically the poor alignment of the segments.
• 2. To demonstrate good and poor alignment of a single weight-bearing joint, such as the knee, two blocks arranged like those described above may be used in a similar manner.
• 3. Take two side-view photographs of a subject standing on a reaction board. The first photograph should represent the subject’s “best” posture and the second a zigzag fatigue slump. Have another person read the scale readings at the same time the photographs are taken. Compute the distance of the line of gravity from the scale, using the method described in Finding the Center of Gravity in the Human Body. The length measurements (total length of board and distance d) are made directly on the photograph instead of on the board itself. Draw the vertical line of gravity from the point at which the line of gravity intersects the board to a point above the head. Compare the postures and the anteroposterior positions of the line of gravity in the two photographs.
• 4. Take anteroposterior line of gravity photographs of several subjects representing various postures. Determine the location of the line of gravity for each photograph using the method described in Experience 3. After drawing the line of gravity on each photograph, observe them carefully and note the relation of the line to the head, shoulders, upper trunk, lower trunk, pelvis, knees, and ankles.
• 5. Take ten anteroposterior line of gravity photographs of one subject within a period of one week. Compare these.
• 6. Take anteroposterior line of gravity photographs of several subjects representing different physique types. Can you make any generalizations about the relation of physique to posture?
• 7. Do an original posture study using a small number of subjects.
• 8. Perform a complete kinesiological analysis of a partner’s normal standing posture, taking particular note of muscle participation, neuromuscular considerations, mechanical factors, and applicable principles and violations. Conclude the analysis with a prescription for improvement, including suggested methods for change and the elimination of violations of principles.