by Dennis Zacharkow, PT
For over a century, a sway back posture is considered the most common standing postural fault (Checkley, 1890). (See Figure 1.) Also referred to as a slumped, fatigue posture, the antigravity postural musculature is required to expend a minimum of energy in this posture, with the strain falling largely on the ligaments (Kelly, 1949). McCormick's (1942) investigation confirmed this, finding the standing alignment with the minimum metabolic increase to be the sway back posture, with the hips thrust forward to the limit of extension, the thoracic curve increased to the maximum, the trunk tilted back, and a forward head posture.
Several of these sway back postural faults were described decades before McCormick's important study. Staffel (1889) referred to the forward shift of the pelvis, the prominent abdomen, sunken thorax, and the head thrust forward. Skarstrom (1909) described the hips carried excessively forward, with the thoracic curve "pronounced and long, often encroaching on the upper lumbar region."
According to Goldthwait (1915), with the slumped, fatigue posture "the chest is necessarily lowered, the lungs are much less fully expanded than normal, the diaphragm is depressed, the abdominal wall is relaxed, so that with the lessened support of the abdominal wall, together with the lowering of the diaphragm, the abdominal organs are necessarily forced downward and forward." In addition, with the slumped, fatigue posture the angulation of the ribs is more nearly vertical, with less depth and less fullness in the lower rib region.
In the sway back standing posture, Alexander (1918) described the diaphragm as being "unduly low in breathing," resulting in a forward displacement of the center of gravity, that is compensated for by the backward leaning of the trunk.
Rathbone (1934) considered the sway back standing posture to owe its origin in many cases to a poor sitting posture. "The back is curved throughout its length during the sitting; and, when the person habituated to that stretch of his spinal muscles rises, all he has to do to stand is to thrust his hips forward and not change the relationship of the spinal segments one bit" (Rathbone and Hunt, 1965).
According to Rathbone (1934), with the sway back standing posture, "the lumbar curve is not increased; instead it is obliterated or reversed. There is a sharp hyperextension at the lumbosacral juncture due to the swaying back of the upper part of the body, but this bend cannot be called an increase in the lumbar curve."
Along with Rathbone (1934), Knudsen (1947) and Schoberth (1962) characterized the sway back standing posture as involving a decreased pelvic inclination.
Howland (1936) felt the sway back standing posture was often mislabeled as involving an increased lumbar lordosis due to the presence of large hips or a protruding abdomen. (Note: See Dennis Zacharkow's article entitled "The Fallacy of Analyzing Posture Based on the Surface Contours of the Body.")
Bowen (1917) and Klausen and Rasmussen (1968) reported a change in trunk muscle activity with the backward leaning of the trunk characteristic of the sway back standing posture: activity in the erector spinae ceases and is replaced by activity in the upper rectus abdominis.
With the decreased pelvic inclination of the sway back standing posture, teaching an anterior pelvic tilt might appear to be of benefit. However, an anterior pelvic tilt will not change the forward position of the hips or backward leaning of the trunk; it will not activate the relaxed lower abdominal wall or raise the lowered position of the diaphragm; and it will have no effect on reducing the increased thoracic curve (Day et al., 1984).
These exercises are frequently advocated for correcting the protruding lower abdomen that is characteristic of a sway back standing posture. Unfortunately, crunches and sit-ups will only further overstretch the relaxed lower abdominal wall, while they strengthen the already tight upper rectus abdominis muscle. (In the sway back standing posture, the upper rectus abdominis muscle is continually active as the main antigravity muscle of the trunk.)
Sitting with the addition of sacral and lower thoracic support (The Yogaback Posture) is very effective in correcting the sway back standing posture.
Maintaining gentle pressure against the sacral support will counteract the forward migration of the pelvis characteristic of both slumped sitting postures and sway back standing postures. Sacral support will also promote activation of the deep lower abdominals, resulting in a raised position of the diaphragm, along with greater depth and expansion of the lower rib cage.
Lower thoracic support will elevate the chest and rib cage, elongate the thoracic spine, bring the upper trunk forward over the hips, facilitate proper diaphragmatic breathing, and stretch the tight upper rectus abdominis muscle.
Swaying backwards from the ankles while elongating the thoracic spine is the most effective standing exercise for correcting a sway back posture (Figure 2).
Stand with one foot placed a very short step forward in advance of the other foot, with the arms held in approximately 135 degrees of shoulder flexion. Sway backward from the ankles until the body weight is over the middle of the rear foot. The backward swaying will start at the ankles, but will also result in a backward movement of the hips and pelvis. Concentrate on holding the hips and pelvis back, but do not allow the trunk to bend forward.
Then, lower the arms to the sides with the palms facing posteriorly and the elbows turned outwards.
This exercise will help obtain the proper axial relationship of the thorax and pelvis, elongate the thoracic spine, and promote a retraction of the lower abdominal wall (Alexander, 1918; Zacharkow, 1988). This exercise is most effective if done barefoot or wearing shoes without heels.
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