Posture is defined as the body alignment in the upright position. The Spine (vertebral column\ back bone) which forms the axial skeleton of the human body gives the body the erect and upright presentation and it forms the core to which the appendicular skeleton( shoulder girdle and pelvic girdle) is attached. It also forms the platform which is responsible of generating forces since it provides the attachment for stabilizers and force generators. The curves of the spine are maintained by strong ligaments and muscles. Any imbalance will not only affect the alignment of the spine only but also results in impaired function.
The Center Of Gravity (COG) and the Line Of Gravity (LOG).
The COG for any given object is defined as the point which is situated in the middle of the object and around which the mass is equally distributed and around which it rotates in the space.
The LOG is an imaginary line if drawn vertically it will intersect the COG.
The COG and LOG are two important elements to consider when posture and balance are evaluated. The relation between COG and LOG governs body posture.
The COG of the human body is situated in the midpelvic cavity between the Umbilicus and the Symphysis Pubis. The line of gravity that intersects the COG in the standing posture is described as the following:
A normal standing posture is when the eyes, shoulder and pelvis are leveled.
Ideal standing posture is when the LOG passes anterior to the ear lobes, passing through the junction between the spinal curves ( Cervico-Thoracic, Thoraco-Lumbar and Lumbo-Sacral), intersecting the COG in midpelvic cavity (between umbilicus and Symphysis Pubis), it falls posterior to Hip and anterior to the Knee and Ankle.
Ideal sitting posture when viewed from the lateral (side) aspect is defined as sitting erect on a seat, a vertical line passes through the shoulder and hip, the lumbar curve is preserved and hips and knees are positioned at 90 degrees angle.
“Motion is Lotion”.
Another factor to take into account is Time. Although sitting or standing ideally, sitting or standing for a long time isn’t advisable. Muscles and joints are designed for mobility and their nourishment which is provided by the blood circulation is only achieved by motion. Static tissues lack enough blood circulation and they lack enough Oxygen supply which are necessary for muscles to stay alive and produce energy and movement.
Postural mal-alignment could be either congenital (since birth) for unknown causes, acquired due to bad habits or could be Compensation (acute deformities) in response to muscle guarding.
Congenital mal-alignments include Scoliosis in which the spine loses the vertical alignment and becomes (S- shaped) when examined on x-ray or even by clinical examination of the back. Causes of congenital scoliosis isn’t fully understood but some studies relate it to genetic factors.
Another common congenital postural mal alignment is “Torticollis” which affects one side of the neck causing it to tilt to one side with some rotation to the other side.
When the nerves are put under pressure by a disc prolapsed for example, the muscles contract to help to protect the area from further damage. This contraction is asymmetrical around the spine and results in acute postural mal alignment. A well known deformity of this kind is the “Sciatic shift” which occurs in the lower back as a response of L4-L5 \ L5-S1 nerve root irritation.
Wry neck is another postural compensation as a result of nerve irritation in the neck.
But since posture is subjected to daily activities it could be altered by time with bad habits. For instance desk workers can develop a kyphotic posture ( hunch back ) and it’s also seen in the elderly, people who do lots of texting develop a Text neck ( forward head posture) , those who slouch in seats lose the lower back curvature resulting in ( flat back).
Postural alterations can result in major consequences. This muscular imbalance can result in pain, stiffness of the affected region of the spine and adjacent areas and it also affect personality and self confidence.
Correction of these faulty posture requires exercises to stretch tight tissues, mobilize stiff joints, strengthen weak muscles and lots of postural instructions. Braces are used in certain cases to help restoration of normal alignment. Posture correction is a lengthy process and requires patience and self discipline from the patient.