Posture,Effects Of Posture

Posture varies person to person:

To the orthopedic surgeon, it perhaps a sign of the durability of the musculoskeletal system.

To the Kinesiologist,  a part of mechanical efficiency of balance, muscles and of neuromuscular coordination.

considered as the relative arrangement of parts of the body that varies with the positions and movements of the body whole life.

It is the attitude which is adopted by body parts to maintain stability and balance with minimal effort and less strain during supportive and nonsupportive positions.


Definition of  a “ Good Posture”:

A good posture is the status of skeletal and muscular balance which shields the enduring structures of the body against injury and progressive deformity regardless of the attitude in which these structures are working or resting.
according to these conditions, the muscles will function most efficiently and the optimum positions managed for the thoracic and abdominal organs.
There is no unique best posture for all individuals. Each person must take the body one has and make the best of it. The “ good Posture” is the one that suits one’s own condition and the condition of the atmosphere.
e.g. during attention. The regular posture will be erect, while in extreme fatigue, the regular posture will be that conserves energy.
The “good posture” is the posture in which the body segments are balanced in the position of less strain and maximal support.

Factors affecting Posture:

1- Mechanical Factors:

The relationship of the line of gravity to body segments:
The line of gravity bears a definite relation to certain anatomic landmarks.

A) Pelvic Inclination:

It is measured from X-Ray of the pelvis and is determined
by measuring the angle formed between :
a line from a point in the lumbosacral junction or from posterior –superior iliac spine to the simphysis pubis.
and a horizontal line.
Its normal value is between 50 to 60 degrees and this value is affected by increased or decreased lumbar lordosis.
If the lumbar lordosis decreases its value will be decreased and if the lumbar lordosis increases the pelvic inclination will increase.
It is greater in females than in males.

B) Body physique

(Ectomorph, Mesomorph, Endomorph )

C) Flexibility

of the structure of the weight bearing segments.

D) Strength

of antigravity muscles & balance of antagonistic muscles.

Anatomical factors :

The integrity of a musculoskeletal system.
Neural control.
Visual & kinesthetic awareness.
The demand of workplace.
Social & cultural traditions.
Psychological factors.

Physiological factors.

– The human body cannot be said to have a single posture. Postural norms are appropriate only for the average figure & apply only to the static standing position.

Postural Control:

the ability to maintain the stability of the body as a whole and body segments “against gravity” or “movement of different body segments” or “changes in the supporting surface”.

Control depends on the integrity of the nervous system, musculoskeletal system, and special senses.

Types of Postures

Easy posture
Fatigue posture.
Rigid posture.

Easy Posture:

It is a good, symmetrical and balanced position in this position cannot be maintained for a long time.
The subject will, therefore, shift his weight in a swaying movement in order to prevent fatigue and to maintain good circulation in the postural muscles of the legs when standing.
By alternating the main support from one leg to another, the muscles become periodically unloaded and relaxed.
The pelvic inclination is about 60°.

Fatigue Posture:

It is asymmetrical or sagging posture. This position s relaxed and can be maintained for a long time as most of the body’s joints are in semi- flexion.
The load on the muscles will decrease and the energy expenditure is 10 % less than easy posture.
The pelvic inclination decreases due to posterior tilting of the pelvis.

Rigid Posture:

It is called normal Stellung posture or posture of attention. It doesn’t mean normal posture. This position cannot be assumed for a long time as most of the body’s joints are an extension. Therefore, the load will increase on the joints and muscles and the energy expenditure is 20% more than in the easy posture.
The pelvic inclination increases due to the anterior tilting of the pelvis.


Faulty Posture

A faulty posture results from:
Faulty relationship of the various body parts which produces increased strain on the supporting structures.
Inadequate balance over the base of support.
Postural deviations will occur with an increase or decrease of body curvatures and pelvic inclination.


Faulty posture leads to prolonged posture strain which causes:

Ligaments stretch which, if becoming permanent, will lead to joint instability
→ increased faulty posture.
Uneven pressure on joint cartilage which will cause abnormal friction,
which in turn will lead to joint damage
→ increased faulty posture.