centre of gravity


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cen·ter of grav·i·ty

(COG) (sen'tĕr grav'i-tē)
The point on a body or system where, if pressure equal to the weight of the object is applied, forces acting on the object will be in equilibrium; the point around which the mass is centered; the location of the COG in an adult human being in the anatomic position is just anterior to the second sacral vertebra.
Synonym(s): centre of gravity.

centre of gravity

; CG point within a body through which gravitational force acts; each body segment has an individual CG, but the overall CG of the static human body lies just superior to the navel, with the line of gravitational force directed downwards between the medial malleoli and just anterior to the ankle joint (through talonavicular joint); thus the erect body is stable; CG position changes continuously in relation to body movements; forward body motion is initiated when the CG is projected forward and the line of gravitational force falls beyond the body outline
  • trajectory of CG body CG follows a smooth up/down and side-to-side trajectory during gait (5 cm up/down, 5 cm side/side at normal walking speed [60 strides per minute; 1 m/second] in adults, reflects the magnitude and direction of the ground reaction forces); low point of CG trajectory coincides with double support phase; upper point of CG trajectory coincides with midpoints of single support phases; CG trajectory moves to the right from the midpoint of the single support phase of the left leg to the midpoint of the single support phase of the right leg, and vice versa, maintained by postural reflexes

References in periodicals archive ?
Performers most commonly need to attain, adjust and sometimes regain a posture that allows them to maintain the centre of gravity above the feet, the origin of support in a stationary position.
bending knees, leaning forward, moving sideways) the centre of gravity is changed in reaction to the new ecole and the new distribution of body weight.
It is crucial to note that detaching the back from the lower part of the chair can result in losing the fullness of the lower abdomen and the centre of gravity.
Given that movements are pervasive and integral parts of both musical perception and production, it is essential to consider how individual flute performers can ensure that the centre of gravity is maintained while they are involved in expressive movements during performance.
On the other hand, the other forward and backward movements, that are commonly prevalent among individuals especially younger flute performers, are generally recognized as responsible for their lack of balance as they cause individuals to go far beyond their centre of gravity and support base.
To maintain the centre of gravity while moving during playing, the pose performance method holds that constant balance and support can be efficiently maintained if the performer actively but gently pushes the little toes against the ground.
They jump up, down, sidewards and in all other directions while they maintain the centre of gravity and support through the small of the back and the forefoot (Romanov, 2002).
This also helps to bring the centre of gravity in alignment with the ball of the foot which is important in maintaining lasting support and balance.
Furthermore, pushing down the little toes helps performers to bring the body's centre of gravity to its lowest possible point on the small of the back which is essential in achieving lasting support-balance.
It has been proposed that support and balance could be improved by the efficient use of the little toes, fifth metatarsal joints, outer edges of the foot or fifth metatarsal bones, thigh muscles, attaining centre of gravity and conscious detection of the sensation of weight.

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