Sunday, 4 September 2011


Body mechanics has been described as the efficient use of the body as a machine and as a means of locomotion. Body mechanics are body posture and balance.The bones, joints, muscles, nerves and brain all function together to maintain posture and balance. Posture is defined as the position in which the various parts of the body are held while sitting, standing, walking and lying.

To understand the body mechanics one has to understand the effects of gravity on balance. The centre of gravity of an object may be defined as the point at which its mass is centered. In man when standing, the centre of gravity is located in the centre of the pelvis approximately mid-way between the umbilicus and the symphysis pubis. The line of gravity is a vertical line which passes through the centre of gravity. There is a constant pull exerted by the earth on every object towards its centre which helps to maintain the good posture and balance.

An object is more stable if:
  • Its centre of gravity is close to its base of support.
  • The line of gravity goes through the base of support.
  • It has a wide base of support.
  • The centre of gravity is lower and close to the base of support.

Proper body mechanics are important to the nurses in their work and they are equally beneficial to the patient.

  1. The proper body alignment and posture prevent fatigue and deformities.
  2. Poor posture causes kyphosis, lordosis, scoliosis and other deformities.
  3. Good posture promotes the physiologic functions of the body aids in circulation and digestion.
  4. It helps to reduce the expenditure of the energy.
  5. It helps to maintain the balance of the body without undue strain on the body parts.
  6. It contributes to one's beauty.


One of the primary factors of musculo-skeletal activity is that the longest and strongest muscles should be used to provide energy needs of the body.When muscles which can not provide the best support and strength are forced into exertion, strain, injury and fatigue of the body tissues.The reason is that in the area of the lower back there are no long muscles.unless the strong and long muscles of the legs are used properly during the periods of strenuous activity. It is likely that back injury will be incurred. Therefore following rules are to be maintained for the good body mechanics:

  1. Maintain good posture (anatomical position) in all activities.
  2. Use the longest and strongest muscles of the extremities to provide the energy needed in the strenuous activities.
  3. Keep the object close to the body to prevent unnecessary strain on the muscles.This brings the centre of gravity of the object close  to the centre of gravity of the body.
  4. Place the feet apart to provide a wide base of support. A broader base provide a better body balance.
  5. Flex the knees to come close to the object instead of bending the back.
  6. Keep work close to the body.
  7. Slide, roll, push or pull an object rather than lifting it in order to reduce the energy needed to lift the weight against the pull of gravity.
  8. Use the weight of the body to pull or push an object by keeping the body above the object.

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