Posture

 

POSTURE

INTRODUCTION

Through evolution, human beings have assumed an upright erect or bipedal posture. The advantage

of an erect posture is that it enables the hand to be free and the eyes to be farther from the ground so that the individual can see farther ahead.

What is Posture?

Posture is defined as the attitude assumed by the body either with support during the course of muscular activity, or as a result of the coordinated action performed by a group of muscles working to maintain the stability.

 Inactive Posture

These are attitude adopted for resting  or sleeping, and they are suitable for this purpose when all the essential muscular activity required to maintain life is reduced to a minimum

Active Posture

 The integrated action of many muscles is required to maintain active posture which may be either static or dynamic.

1. Dynamic posture is how you hold yourself when you are moving, like when you are walking, running, or bending over to pick up something. This type of active posture is required to form an efficient basis for movement.

1. Static posture is how you hold yourself when you are not moving, like when you are sitting, standing, or sleeping. In the erect posture they preserve a state of equilibrium.

WHY IS POSTURE IMPORTANT?

We do not consciously maintain our posture; instead, certain muscles normally do it for us. A healthy posture helps us stand, walk, sit, and lie in positions that place the least strain on supporting muscles and ligaments during movement and weight-bearing activities. Correct posture also:

• Helps us keep bones and joints in correct alignment so that our muscles are used correctly, decreasing the abnormal wearing of joint surfaces that could result in degenerative arthritis and joint pain.
• Reduces the stress on the ligaments holding the spinal joints together, minimizing the likelihood of injury.
• Allows muscles to work more efficiently, allowing the body to use less energy and, therefore, preventing muscle fatigue.
• Helps prevent muscle strain, overuse disorders, and even back and muscular pain.

IDEAL STATIC POSTURAL ALIGNMENT

Classically, ideal static postural alignment (viewed from the side) is defined as a straight line (line of gravity) that passes through the 

• earlobe
• the bodies of the cervical vertebrae
• the tip of the shoulder 
• midway through the thorax 
• through the bodies of the lumbar vertebrae
• slightly posterior to the hip joint 
• slightly anterior to the axis of the knee joint 
• just anterior to the lateral malleolus

In sitting:

• The ears should be aligned with the shoulders and the shoulders aligned with the hips
• The shoulders should be relaxed and elbows are close to the sides of the body
• The angle of the elbows, hips and knees is approximately 90 degrees
• The feet flat on the floor
• The forearms are parallel to the floor with wrists straight
• Feet should rest comfortably on a surface

MUSCLE ACTION IN POSTURE

The balanced posture of the body reduces the work done by the muscles in maintaining it in an erect posture. It has been determined (using electromyography) that, in general:

• The intrinsic muscles of the feet are quiescent, because of the support provided by the ligaments.
• Soleus is constantly active because gravity tends to pull the body forward over the feet. 
• Gastrocnemius and the deep posterior tibial muscles are less frequently active.
• Tibialis anterior is less active (unless high heels are being worn).
• Quadriceps and the Hamstrings are generally not as active
• Iliopsoas is constantly active.
• Gluteus maximus is inactive.
• Gluteus medius and tensor fascia latae are active to counteract lateral postural sway.
• Erector Spinae is active, counteracting gravity's pull forwards.
• The abdominal muscles remain quiescent, although the lower fibres of the Internal obliques are active in order to protect the inguinal canal

REFERENCES

1. Gardiner MD. The principles of exercise therapy.
2. Levangie PK, Norkin CC. Joint structure and function: a comprehensive analysis.
3. Magee, David J. Orthopedic Physical Assessment (6Th Edition). 2008.
4. Medlineplus Good Posture Available from:https://medlineplus.gov/guidetogoodposture.html 
5. Chiba R, Takakusaki K, Ota J, Yozu A, Haga N. Human upright posture control models based on multisensory inputs; in fast and slow dynamics. Neuroscience research. 2016 Mar 1;104:96-104.
6. https://www.physio-pedia.com/Posture