View Full Version : Questions about center of gravity

Sun G. Chung
03-19-2000, 09:43 PM
Dear List members,

I am Sun G. Chung in Seoul, Korea.

May I have questions about center of body mass?

When we know the anthropometric parameters and position/orientation in 3D
space of all of the body segments, we can calculate the center of whole body
mass (CoM or Cog). But, when we have data only for lower body segments, such
as data from Helen Hayes marker set, how can we define the center of body

An old textbook such as, Human walking by Saunders et al, wrote that CoM of
a human body during quiet standing lied just anterior to the 2nd sacral
vertebral body. In some articles, authors regard midpoint between both ASIS
as center of body mass. And in some cases, a certain point on the line
between midASIS point and midPSIS is regarded as center of body mass.

My questions are here.

1) When one has only lower body segment position/orientation data of gait,
provided that they are not so pathologic as CP with dancing arms, can we use
that kind of simple CoG localization method?

2) Is this method accepted as scientific?

3) If yes, is there any consensus about the most appropriate localization of
center of body mass in those limited situation? Is it verified?

4) I have found an article wrote by Thirunararyan, Kerrigan and others. They
used sacral external marker for CoG and focused on vertical displacement of
CoG. Is there any article to verify the accuracy of the anteroposterior or
mediolateral displacement of CoG measured by the above simple method?

Any comments or information would be really appreciated. And I am sure to
post the summary of replies.

Thank you for your time.

Sun G. Chung M.D., Ph.D.

Full Time Instructor
Dept.Rehab medicine, Seoul National Univ Hospital
28 YeonGeon-dong, ChongRo-gu

(TEL) 82-2-760-3954 (FAX) 82-2-743-7473
email: suncg@medicine.snu.ac.kr

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