Thank you for your response. Your assumptions are correct. I am trying to
simulate clinical variables; such as atropy of muscle due to surgical
intervention that I have been able to measure in vivo.
I am reducing the CSA of the paraspinal muscles that cross or have
adhesion/attachments points at the L3-4 and L4-5 disc space. I am reducing
these muscles by 10, 30 and 70% from their intact state. I am then simulating
40 and 60% of the MVC contraction for the model. I am so far looking at flexion
and torsion.
I measure the muscle force and the point of maximum movement for each individual
facicle in the trunk muscles as well as psoas, quadtratus lumb., internal and
external oblique. I am unsure of the problem because my activation patterns do
no make physiological sence. For example these are the numbers I get (N) for
the LTpt and LTpl over the entire length of the spine (60% MVC)
IL pl IL pt LT pl LT pt Multifi OE
OI Psoas QL
Intact 220.00 175.70 68.80 167.94 201.50 72.30 146.40
790.50 32.82
-10% 203.00 157.56 101.52 206.12 180.40 68.70 137.40
790.50 30.90
-30 169.60 130.67 132.50 234.60 171.30 71.90 145.50
790.50 3.30
-70 102.80 193.60 110.50 213.02 174.52 67.00 157.90
745.71 0.79
I have checked the accuracy of the 30% reduction multiple times and it appears
correct. I have reviewed what you presented on the cervical model with the
assumption of pain in the sternomastoid m.; and I think I can understand what
you’ve done. The difference is that I am assuming these subjects are absent of
pain and have been fully healed.
Your assumption of what I am looking for is correct. I would like to find a
change in both muscle force and activation between the groups. I have read many
of your papers and presentations. If you have any advice for me I would really
appreciate it. I am in a difficult situation because I don’t know anyone in my
geographical area who has familiarity with the AnyBody system.
Thank you in advance for your time.
Best Regards,
Lacey Bresnahan
Rush University Medical Center
Chicago, IL
From: Mark de Zee <mdz@hst.aau.dk>
To: anyscript@yahoogroups.com
Sent: Wednesday, January 28, 2009 2:12:31 AM
Subject: Re: [AnyScript] Muscle Force Optimization
Hej Lacey,
This is actually not an easy question to answer.
I guess that you would try to mimic some clinical observations. Could
you explain to us, what kind of observations you would like to mimic?
After that you probably have some kind of hypothesis of what the
mechanism could be. From your mail I can understand that you have
changed the cross-sectional area of the muscles or in other words you
make the muscle weaker. Basically you assume that due to the injury
muscle atrophy takes place in some muscles and afterwards you try to see
if that changes the muscle activation for a certain kind of
movement/posture.
I you then don’t see a difference does not necessarily means that the
optimization procedure is wrong. It also could mean that the
hypothetical mechanism isn’t correct.
There might be some other ways of simulating different mechanisms. But I
think that I need some more information about exactly what you would
like to do.
Regards, Mark
–
Mark de Zee, Ph.D., Research Associate Professor
Aalborg University, Department of Health Science and Technology
Center for Sensory-Motor Interaction (SMI)
lebresnahan wrote:
>
> Dear Support,
>
> I am working to alter the cross-sectional area of the paraspinal
> muscles to reflect the iatrogenic injury that occurs in vivo during
> surgery. I am trying to show there is a change in the muscle force
> activation pattern and capacity before and after the surgery. I am
> having a difficult time showing a change due to the optimization that
> is used to solve the system.
>
> Can you give me any advice on how to best measure the difference in
> force that is generated in these muscles? Thank you.
>
> Lacey Bresnahan
> Rush University Medical Center
> Chicago IL
>
>
[Non-text portions of this message have been removed]