View Full Version : about definition of moment

Sae Yong Lee
02-23-2007, 02:07 AM
Dear Biomch-L subscriber

My name is Sae Yong Lee. I am doctorate student studying at University of
Virginia in Kinesiology program.
I have question related to moment. Are there anyone help me to clarify the
definition of moment related termiology?
1. Difference between joint moment, net joint moment, external moment,
muscle moment, and internal moment. I'll write down my understanding of
those terms.
Joint moment: The moment acting at the joint to overcome external moment.
net joint moment: Sum of all moment acting at the joint including internal
(active (muscle) + passive (ligament, joint capsule...), external moment.
muscle moment: Moment produced by the muscle (different to quantify using
motion analysis system).
Internal moment: Moment produced by active (muscle) + passive (ligament,
joint capsule...). part of joint moment.
external moment: Moment produced by external forces such as ground reaction
Please give me some comments whether or not my understanding is right.

2. What is general Newtonian inverse dynamics calculating? I have been
believed that it is internal moment which is moment produced by passive and
active structures crossing the joint. But I got confused these days while I
was reading articles. It seems like quite a lot of articles alternatively
use all those terms I mentioned. Even though the several articles use same
system to calculate Moment, one said it is external moment and the other
said internal moment. Is it joint moment, net joint moment, external moment,
muscle moment, or internal moment.

3. If anyone use Vicon system or Motion monitor system, what kind of moment
does this system calculating? Are there any reference article that mention
about the calculation of moment of these systems?


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