Posture can be defined as the relationship of the parts of the body to the line of the center of gravity. The posture is a gauge of the mechanical efficiency of the neuromusculoskeletal system in the erect position.
A normal person may have different postures of standing and sitting. These unusual postures can over time lead to pain in the stressed regions. These are posture mistakes that are due to habit or lack of strength mostly in a particular region.
In other cases, there are fixed postural defects caused by different conditions or pathologies.
Development of Posture
In the uterus, the fetus is almost invariably in a position of flexion, with the convex curve of the spine lying against the curve of the uterine wall. The head, arms, and legs of the fetus are flexed on the torso.
The entire fetus lies suspended in the amniotic fluid, which has a specific gravity similar to that of the fetus. Following birth, the development of posture is affected by constant forces exerted by gravity.
The newborn holds his shoulders, elbows, hips, and knees in flexion, with his limbs slightly bowed and rotated inward. Fifteen to thirty degrees of flexion contracture of the knee is a normal physical finding.
The infant lies in a nearly horizontal position, unable to support his head or trunk. In either the prone or the supine position, gravitational force is exerted on a horizontal plane and tends to unroll the “coiling” that was previously assumed within the uterus.
The rate of development of muscle strength varies in the different parts of the body.
When the infant is in a horizontal position, the hip flexors, the anterior muscles of the neck, and the abdominal muscles are stretched and used minimally, whereas the extensors of the neck, back, and thigh are relaxed and are the first to increase their motor power.
When the child is able to support his head and begins to sit up, the weight of the head, combined with the persistent flexion attitude of the hips and the associated of the pelvis on the spine, produces a long convex curve of the entire spine.
In the prestanding stage, this total convex curve of the back is normal.
When the child begins to stand and walk, the extensor muscles of the back, neck, and hips are well developed and the spine is usually straight.
In the upright position, the force of gravity is exerted in a vertical direction, causing an exaggerated lumbar lordosis and a protuberant abdomen. With further growth and development, the child improves his stance and becomes more agile in walking and running.
What is Normal Posture?
In standing position, our posture should follow a vertical line through our ear, shoulder, hip, knee and just in front of our ankle. The line of the center of gravity of the body passes from the mastoid process to the cervicodorsal junction, crossing the bodies of the vertebrae at the dorsolumbar junction, and falling just anterior to the sacroiliac articulation and slightly posterior to the hip joint; it passes through the anterior knee joint and terminates at the front of the talus in the ankle.
The following constitute a normal posture
- The body weight is carried forward on the balls of the feet
- The lower limbs are straight with the hips and knees in neutral extension
- Pelvic inclination is about 60 degrees to the vertical
- Abdomen is retracted
- Shoulders are level and flat
- The Head is held erect
What are Bad Postures?
Technically any alteration is considered as bad posture. But in our daily life, we make use of different positions for different periods for different purposes and these are not bad postures per se.
Posture can be classified into four grades
A- Excellent or almost perfect posture
B- Good, but not ideal posture
C- Poor, but not the worst possible posture
D- Bad and very possibly symptom-producing posture
In excellent (A) posture, the head and shoulder are balanced over the pelvis, hips, and ankles, with the head erect and the chin held in. The sternum is the part of the body farthest forward, the abdomen is drawn in and flat, and the spinal curves are within normal limits.
In bad (D) posture, the head is held forward to a marked degree, the chest is depressed, the abdomen is completely relaxed and protuberant, the spinal curves are exaggerated, and the shoulders are held behind the pelvis.
But if one keeps a particular position for most of the length of time owing to habit or some condition, it becomes a bad posture.
The person may or may not be aware of the habit.
Thus following will make a posture bad
- Neck tilt or rotation
- Uneven shoulder levels
- Exaggerated spinal curves
- Change in pelvic inclination
- Unlevelled hips
- Protruding abdomen leading to spinal lordosis
- Head is bent
Most of the postural issues involve the dorsal and lumbar spine.
What are the Factors Affecting Posture?
The posture of each person has characteristics that are uniquely his. Various factors affecting posture are:
Bony Contours
The shape of the vertebrae may be modified by diseases such as tuberculosis or Scheuermann’s disease, which produce dorsal kyphosis.
Ligaments
The degree of ligamentous laxity varies in different individuals, giving rise to looseness or tautness of the joints. The spine is composed of many joints and is itself dependent upon the articulation inferior to it, such as those of the feet, knees, and hips.
Fascial and Musculotendinous Tautness
The tautness of soft-tissue structures, especially the fascia lata, hamstrings, anterior hip capsule, and pectorals, affect posture.
Muscle Strength
Particularly important is the strength of the gluteus maximus, abdominal erector spinae, and scapular adductor muscles.
Pelvic Inclination
The pelvis is the base upon which the vertebral column rests. Any change in its inclination will cause a corresponding change in the position of the fifth lumbar vertebra in relation to the sacrum, which in turn alters the posture of the entire spine. The inclination of the pelvis is ordinarily controlled by the muscles about the hip.
The pelvic inclination is increased by contraction of the extensors of the hip, i.e., the glutei, hamstrings, and the posterior portion of the hip adductors, and it is decreased by contraction of hip flexors.
The motion of the vertebral column is greatest in the lumbar region; in the thoracic spine, however, the rotation is of considerable magnitude, but flexion and extension are limited.
The muscles of respiration (the diaphragm and intercostals) produce a secondary effect on posture, as there is some extension of the dorsal spine with each inspiration.
Postural Defects of Spine
There are three common postural defects-
Kyphosis is an exaggerated curve of the thoracic region which causes the shoulders to be rounded, the neck to be shortened and the chin to poke forward. The muscles in the upper back are weakened, and the pectoralis major muscle tightens.
Lordosis is the exaggerated curve in the lumbar region and causes the pelvis to tilt forward. The abdominals and hip extensors are weakened and the trunk extensors and hip flexors tighten.
Scoliosis is a lateral curvature of the spine. Muscles on the outside of the curve become weak, and muscles on the inside of the curve become tight.
With all of these postural defects, there are measures to either avoid the condition or help correct the defect.
Treatment of bad Posture
Poor posture in children should be observed, and corrective measures are taken to increase the strength of the back and other muscles so that it will be less susceptible in adult life to fatigue, back strain, and injury.
Children rarely complain of a backache from poor posture.
Any fixed deformity needs to evaluated and corrected by surgery if needed.
For others, treatment consists of passive and active exercises. The aim is to gradually build up aerobic resistance in the postural musculature, i.e. the shoulder, back, abdominals, and hip extensors.
This, in turn, would maintain or realign a correct posture. The effects of this are:
- An improvement in neuromuscular control, postural reflexes, and muscle tone
- Reduction in the energy requirements needed to maintain correct alignment
- Reduction in wear and tear on the joints
Exercises to increase the motor strength of the key muscles affecting posture are also helpful.
The most important is the pelvic tilt. The patient is instructed to decrease the pelvic inclination by the use of the abdominal and gluteus maximus muscles. Initially, he performs the pelvic tilt exercise in a supine position, then standing against the wall.
Postural exercises should be carried out until the individual is able to maintain the correct posture naturally. The patient should continue the exercises until they become part of his normal stance and gait.
A few common suggestions for different postural issues are
- Slouching [sit in lazy drooping way]
- Exercises- Back extensions, plank
- Ergonomic sitting
- Flatback means [tucked pelvis leads to reduced normal lordosis or arch of lower spine]
- Exercises- Plank, side leg raises, seated rows, pull-ups, back extensions
- Leaning more on one leg [leads to muscle imbalance]
- Exercises to strengthen buttocks and core muscles- Plank, side leg raises, bridges
- Hunched back
- Forward leaning desk job and mobile use
- Exercises – Upper back, neck, and rear shoulder strengthening exercises
- Rounded shoulders
- Exercises for core, upper back, and chest muscles – Plank, seated rows, pull-ups, chest stretches
