Calculation of muscle forces

system · January 31, 2007, 4:28pm

Hallo,
i simulated a static task with an armmodel, so that only three muscles
were taken into account. The task was to hold the almost 90degree
flexed lower arm against gravity. For better understandig which muscle
forces i estimate, i calculated the same task by hand with the law of
the lever. Although this method is very imprecise i could see, that
there a more muscle forces than needed to do this special task. How
could i understand this? Are there some internal tasks which increase
muscle force, tendon tension or joint friction for example?
Thank you very much, best regards, Maren.

system · February 2, 2007, 3:13pm

Hi Maren

Could I ask you to upload your model to the file section?

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “Maren” <anystarter@…> wrote:
>
> Hallo,
> i simulated a static task with an armmodel, so that only three muscles
> were taken into account. The task was to hold the almost 90degree
> flexed lower arm against gravity. For better understandig which muscle
> forces i estimate, i calculated the same task by hand with the law of
> the lever. Although this method is very imprecise i could see, that
> there a more muscle forces than needed to do this special task. How
> could i understand this? Are there some internal tasks which increase
> muscle force, tendon tension or joint friction for example?
> Thank you very much, best regards, Maren.
>

system · February 2, 2007, 4:23pm

Hi Christian, i uploaded my model in the folder “Marens Armmodell”.
Good Luck

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Maren
>
> Could I ask you to upload your model to the file section?
>
> Best regards
> Christian, AnyBody Support
>
>
>
> — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> >
> > Hallo,
> > i simulated a static task with an armmodel, so that only three muscles
> > were taken into account. The task was to hold the almost 90degree
> > flexed lower arm against gravity. For better understandig which muscle
> > forces i estimate, i calculated the same task by hand with the law of
> > the lever. Although this method is very imprecise i could see, that
> > there a more muscle forces than needed to do this special task. How
> > could i understand this? Are there some internal tasks which increase
> > muscle force, tendon tension or joint friction for example?
> > Thank you very much, best regards, Maren.
> >
>

system · February 5, 2007, 5:49am

Hi Maren

Thank you, I am looking at it.

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “Maren” <anystarter@…> wrote:
>
> Hi Christian, i uploaded my model in the folder “Marens Armmodell”.
> Good Luck
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hi Maren
> >
> > Could I ask you to upload your model to the file section?
> >
> > Best regards
> > Christian, AnyBody Support
> >
> >
> >
> > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > >
> > > Hallo,
> > > i simulated a static task with an armmodel, so that only three
muscles
> > > were taken into account. The task was to hold the almost 90degree
> > > flexed lower arm against gravity. For better understandig which
muscle
> > > forces i estimate, i calculated the same task by hand with the
law of
> > > the lever. Although this method is very imprecise i could see, that
> > > there a more muscle forces than needed to do this special task. How
> > > could i understand this? Are there some internal tasks which
increase
> > > muscle force, tendon tension or joint friction for example?
> > > Thank you very much, best regards, Maren.
> > >
> >
>

system · February 7, 2007, 4:13am

Hi Maren

Have you made any changes to
BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
If yes could you upload the file?

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Maren
>
> Thank you, I am looking at it.
>
> Best regards
> Christian, AnyBody Support
>
> — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> >
> > Hi Christian, i uploaded my model in the folder “Marens Armmodell”.
> > Good Luck
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > >
> > > Hi Maren
> > >
> > > Could I ask you to upload your model to the file section?
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > >
> > >
> > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > >
> > > > Hallo,
> > > > i simulated a static task with an armmodel, so that only three
> muscles
> > > > were taken into account. The task was to hold the almost 90degree
> > > > flexed lower arm against gravity. For better understandig which
> muscle
> > > > forces i estimate, i calculated the same task by hand with the
> law of
> > > > the lever. Although this method is very imprecise i could see,
that
> > > > there a more muscle forces than needed to do this special
task. How
> > > > could i understand this? Are there some internal tasks which
> increase
> > > > muscle force, tendon tension or joint friction for example?
> > > > Thank you very much, best regards, Maren.
> > > >
> > >
> >
>

system · February 7, 2007, 4:30pm

Hi Christian,

at this moment i am not sure wether i changed something in this file,
but i uploaded it in the folder “Marens Armmodell”. The origin model
from the repository was the gearstick model and i changed it to make a
static task: hold the lower arm against gravity with nearly maximum
supination so that as few as possible muscles were used. Best regards,
Maren

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Maren
>
> Have you made any changes to
> BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> If yes could you upload the file?
>
> Best regards
> Christian, AnyBody Support
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hi Maren
> >
> > Thank you, I am looking at it.
> >
> > Best regards
> > Christian, AnyBody Support
> >
> > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > >
> > > Hi Christian, i uploaded my model in the folder “Marens Armmodell”.
> > > Good Luck
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
wrote:
> > > >
> > > > Hi Maren
> > > >
> > > > Could I ask you to upload your model to the file section?
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > >
> > > >
> > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > >
> > > > > Hallo,
> > > > > i simulated a static task with an armmodel, so that only three
> > muscles
> > > > > were taken into account. The task was to hold the almost
90degree
> > > > > flexed lower arm against gravity. For better understandig which
> > muscle
> > > > > forces i estimate, i calculated the same task by hand with the
> > law of
> > > > > the lever. Although this method is very imprecise i could see,
> that
> > > > > there a more muscle forces than needed to do this special
> task. How
> > > > > could i understand this? Are there some internal tasks which
> > increase
> > > > > muscle force, tendon tension or joint friction for example?
> > > > > Thank you very much, best regards, Maren.
> > > > >
> > > >
> > >
> >
>

system · February 9, 2007, 3:36am

Hi Maren

Thanks for the last file, it made it work:D
I am not sure why you see bigger muscle activity in the AnyBody model
then in the other one. Are you considering the passive elastic forces
from the elbow stretching muscles? This could be one of the reasons to
the difference. Maybe you could try using the AnySimpleMuscle model,
because they have no passive elastic properties.
Let me know what you think, I think it is an exciting discussion.

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “Maren” <anystarter@…> wrote:
>
> Hi Christian,
>
> at this moment i am not sure wether i changed something in this file,
> but i uploaded it in the folder “Marens Armmodell”. The origin model
> from the repository was the gearstick model and i changed it to make a
> static task: hold the lower arm against gravity with nearly maximum
> supination so that as few as possible muscles were used. Best regards,
> Maren
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hi Maren
> >
> > Have you made any changes to
> > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > If yes could you upload the file?
> >
> > Best regards
> > Christian, AnyBody Support
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > >
> > > Hi Maren
> > >
> > > Thank you, I am looking at it.
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > >
> > > > Hi Christian, i uploaded my model in the folder “Marens
Armmodell”.
> > > > Good Luck
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> > > > >
> > > > > Hi Maren
> > > > >
> > > > > Could I ask you to upload your model to the file section?
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > >
> > > > >
> > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > > >
> > > > > > Hallo,
> > > > > > i simulated a static task with an armmodel, so that only three
> > > muscles
> > > > > > were taken into account. The task was to hold the almost
> 90degree
> > > > > > flexed lower arm against gravity. For better understandig
which
> > > muscle
> > > > > > forces i estimate, i calculated the same task by hand with the
> > > law of
> > > > > > the lever. Although this method is very imprecise i could see,
> > that
> > > > > > there a more muscle forces than needed to do this special
> > task. How
> > > > > > could i understand this? Are there some internal tasks which
> > > increase
> > > > > > muscle force, tendon tension or joint friction for example?
> > > > > > Thank you very much, best regards, Maren.
> > > > > >
> > > > >
> > > >
> > >
> >
>

system · February 9, 2007, 9:01am

Hi Christian,
that is an interesting idea. I havenÂ´t looked at the passive forces of
the antagonists yet. Thank you very much, i will try it out. Is it
possible for you to send me the formula how AnyBody calculates the
muscle forces? Best regards, Maren

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
>
> Hi Maren
>
> Thanks for the last file, it made it work:D
> I am not sure why you see bigger muscle activity in the AnyBody model
> then in the other one. Are you considering the passive elastic forces
> from the elbow stretching muscles? This could be one of the reasons to
> the difference. Maybe you could try using the AnySimpleMuscle model,
> because they have no passive elastic properties.
> Let me know what you think, I think it is an exciting discussion.
>
> Best regards
> Christian, AnyBody Support
>
>
> — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> >
> > Hi Christian,
> >
> > at this moment i am not sure wether i changed something in this file,
> > but i uploaded it in the folder “Marens Armmodell”. The origin model
> > from the repository was the gearstick model and i changed it to make a
> > static task: hold the lower arm against gravity with nearly maximum
> > supination so that as few as possible muscles were used. Best regards,
> > Maren
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > >
> > > Hi Maren
> > >
> > > Have you made any changes to
> > > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > If yes could you upload the file?
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
wrote:
> > > >
> > > > Hi Maren
> > > >
> > > > Thank you, I am looking at it.
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > >
> > > > > Hi Christian, i uploaded my model in the folder “Marens
> Armmodell”.
> > > > > Good Luck
> > > > >
> > > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > wrote:
> > > > > >
> > > > > > Hi Maren
> > > > > >
> > > > > > Could I ask you to upload your model to the file section?
> > > > > >
> > > > > > Best regards
> > > > > > Christian, AnyBody Support
> > > > > >
> > > > > >
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > > > >
> > > > > > > Hallo,
> > > > > > > i simulated a static task with an armmodel, so that only
three
> > > > muscles
> > > > > > > were taken into account. The task was to hold the almost
> > 90degree
> > > > > > > flexed lower arm against gravity. For better understandig
> which
> > > > muscle
> > > > > > > forces i estimate, i calculated the same task by hand
with the
> > > > law of
> > > > > > > the lever. Although this method is very imprecise i
could see,
> > > that
> > > > > > > there a more muscle forces than needed to do this special
> > > task. How
> > > > > > > could i understand this? Are there some internal tasks which
> > > > increase
> > > > > > > muscle force, tendon tension or joint friction for example?
> > > > > > > Thank you very much, best regards, Maren.
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

system · February 9, 2007, 6:08pm

I am also very interested in this too. I as well, have created an AnyBody
simple arm-curl model to compare to long-hand calculated muscle forces. When I
start adding too many muscles to the model (calculating long-hand), I run into
the problem of indeterminancy. However, if I set for example, the biceps breve
as a function of the biceps longum, and all of the triceps (ME_1 and 2, LA_1 and
2) as a function of each other based on PCSA, I can get the same results as
AnyBody. There are two things I am still curious about however.

1.) First off, the Triceps_LH 1 & 2 always demonstrate a Fm of 0. The same
goes for both the Brachialis_1 & 2, and Brachioradialis_1 & 2. Why is it that
these muscles exert no force on the system while the biceps breve and longum
clearly do. I’m assuming it comes down to the mathematics within the software
(and I am interested, like Maren, to find out more on this) and the fact that to
minimize the maximal muscle effort, computationally it makes sense to avoid
these muscles because when calculated, their input is greater than with the
biceps alone. However does this make sense physiologically? I’m just trying to
reason this out…

2.) And along these lines, does the software perhaps group flexors and
extensors somehow based on PCSA like I did for the biceps and triceps?

Thank you for your time and help on this,
Sarah

-----Original Message-----

> Date: Fri Feb 09 03:01:04 EST 2007
> From: “Maren” <anystarter@yahoo.de>
> Subject: [anyscript] Re: Calculation of muscle forces
> To: anyscript@yahoogroups.com
>
> Hi Christian,
> that is an interesting idea. I haven?t looked at the passive forces of
> the antagonists yet. Thank you very much, i will try it out. Is it
> possible for you to send me the formula how AnyBody calculates the
> muscle forces? Best regards, Maren
>
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@…> wrote:
> >
> > Hi Maren
> >
> > Thanks for the last file, it made it work:D
> > I am not sure why you see bigger muscle activity in the AnyBody model
> > then in the other one. Are you considering the passive elastic forces
> > from the elbow stretching muscles? This could be one of the reasons to
> > the difference. Maybe you could try using the AnySimpleMuscle model,
> > because they have no passive elastic properties.
> > Let me know what you think, I think it is an exciting discussion.
> >
> > Best regards
> > Christian, AnyBody Support
> >
> >
> > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > >
> > > Hi Christian,
> > >
> > > at this moment i am not sure wether i changed something in this file,
> > > but i uploaded it in the folder “Marens Armmodell”. The origin model
> > > from the repository was the gearstick model and i changed it to make a
> > > static task: hold the lower arm against gravity with nearly maximum
> > > supination so that as few as possible muscles were used. Best regards,
> > > Maren
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> > > >
> > > > Hi Maren
> > > >
> > > > Have you made any changes to
> > > > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > If yes could you upload the file?
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> > > > >
> > > > > Hi Maren
> > > > >
> > > > > Thank you, I am looking at it.
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > > >
> > > > > > Hi Christian, i uploaded my model in the folder “Marens
> > Armmodell”.
> > > > > > Good Luck
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > > wrote:
> > > > > > >
> > > > > > > Hi Maren
> > > > > > >
> > > > > > > Could I ask you to upload your model to the file section?
> > > > > > >
> > > > > > > Best regards
> > > > > > > Christian, AnyBody Support
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > > > > >
> > > > > > > > Hallo,
> > > > > > > > i simulated a static task with an armmodel, so that only
> three
> > > > > muscles
> > > > > > > > were taken into account. The task was to hold the almost
> > > 90degree
> > > > > > > > flexed lower arm against gravity. For better understandig
> > which
> > > > > muscle
> > > > > > > > forces i estimate, i calculated the same task by hand
> with the
> > > > > law of
> > > > > > > > the lever. Although this method is very imprecise i
> could see,
> > > > that
> > > > > > > > there a more muscle forces than needed to do this special
> > > > task. How
> > > > > > > > could i understand this? Are there some internal tasks which
> > > > > increase
> > > > > > > > muscle force, tendon tension or joint friction for example?
> > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
>

system · February 12, 2007, 3:05am

Hi Maren

I don’t know if you took a look at the tutorial on muscle modeling?
You can find it here: http://www.anybodytech.com/507.0.html
A formulation of the strength and what parameters that are considered
in the three element muscle model. Is this enough info or do you need
anything more? let me know.

Best regards
Christian, AnyBody Support

— In anyscript@yahoogroups.com, “Maren” <anystarter@…> wrote:
>
> Hi Christian,
> that is an interesting idea. I havenÃ¯Â¿Â½t looked at the passive forces of
> the antagonists yet. Thank you very much, i will try it out. Is it
> possible for you to send me the formula how AnyBody calculates the
> muscle forces? Best regards, Maren
>
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@> wrote:
> >
> > Hi Maren
> >
> > Thanks for the last file, it made it work:D
> > I am not sure why you see bigger muscle activity in the AnyBody model
> > then in the other one. Are you considering the passive elastic forces
> > from the elbow stretching muscles? This could be one of the reasons to
> > the difference. Maybe you could try using the AnySimpleMuscle model,
> > because they have no passive elastic properties.
> > Let me know what you think, I think it is an exciting discussion.
> >
> > Best regards
> > Christian, AnyBody Support
> >
> >
> > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > >
> > > Hi Christian,
> > >
> > > at this moment i am not sure wether i changed something in this
file,
> > > but i uploaded it in the folder “Marens Armmodell”. The origin model
> > > from the repository was the gearstick model and i changed it to
make a
> > > static task: hold the lower arm against gravity with nearly maximum
> > > supination so that as few as possible muscles were used. Best
regards,
> > > Maren
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
wrote:
> > > >
> > > > Hi Maren
> > > >
> > > > Have you made any changes to
> > > > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > If yes could you upload the file?
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> > > > >
> > > > > Hi Maren
> > > > >
> > > > > Thank you, I am looking at it.
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > > >
> > > > > > Hi Christian, i uploaded my model in the folder “Marens
> > Armmodell”.
> > > > > > Good Luck
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > > wrote:
> > > > > > >
> > > > > > > Hi Maren
> > > > > > >
> > > > > > > Could I ask you to upload your model to the file section?
> > > > > > >
> > > > > > > Best regards
> > > > > > > Christian, AnyBody Support
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@>
wrote:
> > > > > > > >
> > > > > > > > Hallo,
> > > > > > > > i simulated a static task with an armmodel, so that only
> three
> > > > > muscles
> > > > > > > > were taken into account. The task was to hold the almost
> > > 90degree
> > > > > > > > flexed lower arm against gravity. For better understandig
> > which
> > > > > muscle
> > > > > > > > forces i estimate, i calculated the same task by hand
> with the
> > > > > law of
> > > > > > > > the lever. Although this method is very imprecise i
> could see,
> > > > that
> > > > > > > > there a more muscle forces than needed to do this special
> > > > task. How
> > > > > > > > could i understand this? Are there some internal tasks
which
> > > > > increase
> > > > > > > > muscle force, tendon tension or joint friction for
example?
> > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

system · February 12, 2007, 11:31am

Hi Sarah

I will try to give you some answers:

First of all, here are some references to papers which describes the
recruitment of the muscles, as you know the forces are distributed
among the muscles using a min/max optimization criteria.

Michael Damsgaard, John Rasmussen, SÃ¸ren TÃ¸rholm Christensen,
Egidijus Surma, and Mark de Zee (2006): Analysis of musculoskeletal
systems in the AnyBody Modeling System. Simulation Modelling Practice
and Theory. Volume 14, Issue 8 , November 2006, Pages 1100-1111.
Elsevier, ISSN: 1569-190X.

M. Damsgaard, J. Rasmussen & S.T. Christensen (2001): Inverse
dynamics of musculo-skeletal systems using an efficient min/max
muscle recruitment model. Proceedings of IDETC: 18-th Biennial
Conference on Mechanical Vibration and Noise, Pittsburgh, September 9-
13, 2001.

The algorithm do not group the muscles in any way, all muscels are
treated in the same way. The algorithm will try to lower the
activity in the maximal activated muscles of the model (provided you
do not make use of any penalties, then the explanation is longer).

I can not give a simple answer on why tricpes_longhead 1 & 2 are not
active in the given situation, the same goes for the other two
muscles you mention. The activity of Brachioradialis could be related
to the pronation of the forarm have you tried to change this?.
It is certain though, that if these muscles became active it would
increase the activity of some of the other muscles in the model. So
one thing you could do, was to add a constant force to one of the
muscles you are interested in, in order to see the effect it would
have on the other muscles, if the particular muscles became active.
In practice this can be done be creating an AnyForce and then refer
to the Line measure in the particular muscle. If you then add a force
(negative) and closely inspect which muscles then become more active
you can get an idea about which mechanisms are dominat in the model.

I hope this answers your questions otherwise please write again.

Best regards
SÃ¸ren

— In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@…>
wrote:
>
> I am also very interested in this too. I as well, have created an
AnyBody simple arm-curl model to compare to long-hand calculated
muscle forces. When I start adding too many muscles to the model
(calculating long-hand), I run into the problem of indeterminancy.
However, if I set for example, the biceps breve as a function of the
biceps longum, and all of the triceps (ME_1 and 2, LA_1 and 2) as a
function of each other based on PCSA, I can get the same results as
AnyBody. There are two things I am still curious about however.
>
> 1.) First off, the Triceps_LH 1 & 2 always demonstrate a Fm of 0.
The same goes for both the Brachialis_1 & 2, and Brachioradialis_1 &
2. Why is it that these muscles exert no force on the system while
the biceps breve and longum clearly do. I’m assuming it comes down
to the mathematics within the software (and I am interested, like
Maren, to find out more on this) and the fact that to minimize the
maximal muscle effort, computationally it makes sense to avoid these
muscles because when calculated, their input is greater than with the
biceps alone. However does this make sense physiologically? I’m
just trying to reason this out…
>
> 2.) And along these lines, does the software perhaps group flexors
and extensors somehow based on PCSA like I did for the biceps and
triceps?
>
> Thank you for your time and help on this,
> Sarah
>
>
>
> -----Original Message-----
>
> > Date: Fri Feb 09 03:01:04 EST 2007
> > From: “Maren” <anystarter@…>
> > Subject: [anyscript] Re: Calculation of muscle forces
> > To: anyscript@yahoogroups.com
> >
> > Hi Christian,
> > that is an interesting idea. I haven?t looked at the passive
forces of
> > the antagonists yet. Thank you very much, i will try it out. Is it
> > possible for you to send me the formula how AnyBody calculates the
> > muscle forces? Best regards, Maren
> >
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
wrote:
> > >
> > > Hi Maren
> > >
> > > Thanks for the last file, it made it work:D
> > > I am not sure why you see bigger muscle activity in the AnyBody
model
> > > then in the other one. Are you considering the passive elastic
forces
> > > from the elbow stretching muscles? This could be one of the
reasons to
> > > the difference. Maybe you could try using the AnySimpleMuscle
model,
> > > because they have no passive elastic properties.
> > > Let me know what you think, I think it is an exciting
discussion.
> > >
> > > Best regards
> > > Christian, AnyBody Support
> > >
> > >
> > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > >
> > > > Hi Christian,
> > > >
> > > > at this moment i am not sure wether i changed something in
this file,
> > > > but i uploaded it in the folder “Marens Armmodell”. The
origin model
> > > > from the repository was the gearstick model and i changed it
to make a
> > > > static task: hold the lower arm against gravity with nearly
maximum
> > > > supination so that as few as possible muscles were used. Best
regards,
> > > > Maren
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support”
<support@> wrote:
> > > > >
> > > > > Hi Maren
> > > > >
> > > > > Have you made any changes to
> > > > > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > > If yes could you upload the file?
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
<support@>
> > wrote:
> > > > > >
> > > > > > Hi Maren
> > > > > >
> > > > > > Thank you, I am looking at it.
> > > > > >
> > > > > > Best regards
> > > > > > Christian, AnyBody Support
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@>
wrote:
> > > > > > >
> > > > > > > Hi Christian, i uploaded my model in the folder “Marens
> > > Armmodell”.
> > > > > > > Good Luck
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
<support@>
> > > > wrote:
> > > > > > > >
> > > > > > > > Hi Maren
> > > > > > > >
> > > > > > > > Could I ask you to upload your model to the file
section?
> > > > > > > >
> > > > > > > > Best regards
> > > > > > > > Christian, AnyBody Support
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > — In anyscript@yahoogroups.com, “Maren”
<anystarter@> wrote:
> > > > > > > > >
> > > > > > > > > Hallo,
> > > > > > > > > i simulated a static task with an armmodel, so that
only
> > three
> > > > > > muscles
> > > > > > > > > were taken into account. The task was to hold the
almost
> > > > 90degree
> > > > > > > > > flexed lower arm against gravity. For better
understandig
> > > which
> > > > > > muscle
> > > > > > > > > forces i estimate, i calculated the same task by
hand
> > with the
> > > > > > law of
> > > > > > > > > the lever. Although this method is very imprecise i
> > could see,
> > > > > that
> > > > > > > > > there a more muscle forces than needed to do this
special
> > > > > task. How
> > > > > > > > > could i understand this? Are there some internal
tasks which
> > > > > > increase
> > > > > > > > > muscle force, tendon tension or joint friction for
example?
> > > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> >
>

system · February 12, 2007, 4:29pm

Hi Soren,

The recent November 2006 article is VERY helpful - thank you for the information
on it. Is there anyway I can get a .pdf for the 2nd article - the 2001
Proceedings of IDETC article? I can’t find it anywhere and to get it I will
have to buy the entire proceedings (just for the article). Is it posted on the
AnyBody website as a publication? The proceedings here are about $150 US.

Thank you,
Sarah

-----Original Message-----

> Date: Mon Feb 12 05:31:53 EST 2007
> From: “AnyBody Support” <support@anybodytech.com>
> Subject: [anyscript] Re: Calculation of muscle forces
> To: anyscript@yahoogroups.com
>
> Hi Sarah
>
> I will try to give you some answers:
>
> First of all, here are some references to papers which describes the
> recruitment of the muscles, as you know the forces are distributed
> among the muscles using a min/max optimization criteria.
>
> Michael Damsgaard, John Rasmussen, S?ren T?rholm Christensen,
> Egidijus Surma, and Mark de Zee (2006): Analysis of musculoskeletal
> systems in the AnyBody Modeling System. Simulation Modelling Practice
> and Theory. Volume 14, Issue 8 , November 2006, Pages 1100-1111.
> Elsevier, ISSN: 1569-190X.
>
> M. Damsgaard, J. Rasmussen & S.T. Christensen (2001): Inverse
> dynamics of musculo-skeletal systems using an efficient min/max
> muscle recruitment model. Proceedings of IDETC: 18-th Biennial
> Conference on Mechanical Vibration and Noise, Pittsburgh, September 9-
> 13, 2001.
>
> The algorithm do not group the muscles in any way, all muscels are
> treated in the same way. The algorithm will try to lower the
> activity in the maximal activated muscles of the model (provided you
> do not make use of any penalties, then the explanation is longer).
>
> I can not give a simple answer on why tricpes_longhead 1 & 2 are not
> active in the given situation, the same goes for the other two
> muscles you mention. The activity of Brachioradialis could be related
> to the pronation of the forarm have you tried to change this?.
> It is certain though, that if these muscles became active it would
> increase the activity of some of the other muscles in the model. So
> one thing you could do, was to add a constant force to one of the
> muscles you are interested in, in order to see the effect it would
> have on the other muscles, if the particular muscles became active.
> In practice this can be done be creating an AnyForce and then refer
> to the Line measure in the particular muscle. If you then add a force
> (negative) and closely inspect which muscles then become more active
> you can get an idea about which mechanisms are dominat in the model.
>
> I hope this answers your questions otherwise please write again.
>
> Best regards
> S?ren
>
> — In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@…>
> wrote:
> >
> > I am also very interested in this too. I as well, have created an
> AnyBody simple arm-curl model to compare to long-hand calculated
> muscle forces. When I start adding too many muscles to the model
> (calculating long-hand), I run into the problem of indeterminancy.
> However, if I set for example, the biceps breve as a function of the
> biceps longum, and all of the triceps (ME_1 and 2, LA_1 and 2) as a
> function of each other based on PCSA, I can get the same results as
> AnyBody. There are two things I am still curious about however.
> >
> > 1.) First off, the Triceps_LH 1 & 2 always demonstrate a Fm of 0.
> The same goes for both the Brachialis_1 & 2, and Brachioradialis_1 &
> 2. Why is it that these muscles exert no force on the system while
> the biceps breve and longum clearly do. I’m assuming it comes down
> to the mathematics within the software (and I am interested, like
> Maren, to find out more on this) and the fact that to minimize the
> maximal muscle effort, computationally it makes sense to avoid these
> muscles because when calculated, their input is greater than with the
> biceps alone. However does this make sense physiologically? I’m
> just trying to reason this out…
> >
> > 2.) And along these lines, does the software perhaps group flexors
> and extensors somehow based on PCSA like I did for the biceps and
> triceps?
> >
> > Thank you for your time and help on this,
> > Sarah
> >
> >
> >
> > -----Original Message-----
> >
> > > Date: Fri Feb 09 03:01:04 EST 2007
> > > From: “Maren” <anystarter@…>
> > > Subject: [anyscript] Re: Calculation of muscle forces
> > > To: anyscript@yahoogroups.com
> > >
> > > Hi Christian,
> > > that is an interesting idea. I haven?t looked at the passive
> forces of
> > > the antagonists yet. Thank you very much, i will try it out. Is it
> > > possible for you to send me the formula how AnyBody calculates the
> > > muscle forces? Best regards, Maren
> > >
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> > > >
> > > > Hi Maren
> > > >
> > > > Thanks for the last file, it made it work:D
> > > > I am not sure why you see bigger muscle activity in the AnyBody
> model
> > > > then in the other one. Are you considering the passive elastic
> forces
> > > > from the elbow stretching muscles? This could be one of the
> reasons to
> > > > the difference. Maybe you could try using the AnySimpleMuscle
> model,
> > > > because they have no passive elastic properties.
> > > > Let me know what you think, I think it is an exciting
> discussion.
> > > >
> > > > Best regards
> > > > Christian, AnyBody Support
> > > >
> > > >
> > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@> wrote:
> > > > >
> > > > > Hi Christian,
> > > > >
> > > > > at this moment i am not sure wether i changed something in
> this file,
> > > > > but i uploaded it in the folder “Marens Armmodell”. The
> origin model
> > > > > from the repository was the gearstick model and i changed it
> to make a
> > > > > static task: hold the lower arm against gravity with nearly
> maximum
> > > > > supination so that as few as possible muscles were used. Best
> regards,
> > > > > Maren
> > > > >
> > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> <support@> wrote:
> > > > > >
> > > > > > Hi Maren
> > > > > >
> > > > > > Have you made any changes to
> > > > > > BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > > > If yes could you upload the file?
> > > > > >
> > > > > > Best regards
> > > > > > Christian, AnyBody Support
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> <support@>
> > > wrote:
> > > > > > >
> > > > > > > Hi Maren
> > > > > > >
> > > > > > > Thank you, I am looking at it.
> > > > > > >
> > > > > > > Best regards
> > > > > > > Christian, AnyBody Support
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@>
> wrote:
> > > > > > > >
> > > > > > > > Hi Christian, i uploaded my model in the folder “Marens
> > > > Armmodell”.
> > > > > > > > Good Luck
> > > > > > > >
> > > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> <support@>
> > > > > wrote:
> > > > > > > > >
> > > > > > > > > Hi Maren
> > > > > > > > >
> > > > > > > > > Could I ask you to upload your model to the file
> section?
> > > > > > > > >
> > > > > > > > > Best regards
> > > > > > > > > Christian, AnyBody Support
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > — In anyscript@yahoogroups.com, “Maren”
> <anystarter@> wrote:
> > > > > > > > > >
> > > > > > > > > > Hallo,
> > > > > > > > > > i simulated a static task with an armmodel, so that
> only
> > > three
> > > > > > > muscles
> > > > > > > > > > were taken into account. The task was to hold the
> almost
> > > > > 90degree
> > > > > > > > > > flexed lower arm against gravity. For better
> understandig
> > > > which
> > > > > > > muscle
> > > > > > > > > > forces i estimate, i calculated the same task by
> hand
> > > with the
> > > > > > > law of
> > > > > > > > > > the lever. Although this method is very imprecise i
> > > could see,
> > > > > > that
> > > > > > > > > > there a more muscle forces than needed to do this
> special
> > > > > > task. How
> > > > > > > > > > could i understand this? Are there some internal
> tasks which
> > > > > > > increase
> > > > > > > > > > muscle force, tendon tension or joint friction for
> example?
> > > > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>

system · February 13, 2007, 9:35am

Hi Sarah

If you have got the first paper i think you are ok, and will not find
much more information in the second paper. I primarily gave two
options so you had a choice.

Unfortunately it is not possible to get the .pdf file for the second
paper due to copyright issues, this is also why it is not online,
sorry.

Best regards
SÃ¸ren

— In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@…>
wrote:
>
> Hi Soren,
>
> The recent November 2006 article is VERY helpful - thank you for
the information on it. Is there anyway I can get a .pdf for the 2nd
article - the 2001 Proceedings of IDETC article? I can’t find it
anywhere and to get it I will have to buy the entire proceedings
(just for the article). Is it posted on the AnyBody website as a
publication? The proceedings here are about $150 US.
>
> Thank you,
> Sarah
>
>
>
> -----Original Message-----
>
> > Date: Mon Feb 12 05:31:53 EST 2007
> > From: “AnyBody Support” <support@…>
> > Subject: [anyscript] Re: Calculation of muscle forces
> > To: anyscript@yahoogroups.com
> >
> > Hi Sarah
> >
> > I will try to give you some answers:
> >
> > First of all, here are some references to papers which describes
the
> > recruitment of the muscles, as you know the forces are
distributed
> > among the muscles using a min/max optimization criteria.
> >
> > Michael Damsgaard, John Rasmussen, S?ren T?rholm Christensen,
> > Egidijus Surma, and Mark de Zee (2006): Analysis of
musculoskeletal
> > systems in the AnyBody Modeling System. Simulation Modelling
Practice
> > and Theory. Volume 14, Issue 8 , November 2006, Pages 1100-1111.
> > Elsevier, ISSN: 1569-190X.
> >
> > M. Damsgaard, J. Rasmussen & S.T. Christensen (2001): Inverse
> > dynamics of musculo-skeletal systems using an efficient min/max
> > muscle recruitment model. Proceedings of IDETC: 18-th Biennial
> > Conference on Mechanical Vibration and Noise, Pittsburgh,
September 9-
> > 13, 2001.
> >
> > The algorithm do not group the muscles in any way, all muscels
are
> > treated in the same way. The algorithm will try to lower the
> > activity in the maximal activated muscles of the model (provided
you
> > do not make use of any penalties, then the explanation is longer).
> >
> > I can not give a simple answer on why tricpes_longhead 1 & 2 are
not
> > active in the given situation, the same goes for the other two
> > muscles you mention. The activity of Brachioradialis could be
related
> > to the pronation of the forarm have you tried to change this?.
> > It is certain though, that if these muscles became active it
would
> > increase the activity of some of the other muscles in the model.
So
> > one thing you could do, was to add a constant force to one of the
> > muscles you are interested in, in order to see the effect it
would
> > have on the other muscles, if the particular muscles became
active.
> > In practice this can be done be creating an AnyForce and then
refer
> > to the Line measure in the particular muscle. If you then add a
force
> > (negative) and closely inspect which muscles then become more
active
> > you can get an idea about which mechanisms are dominat in the
model.
> >
> > I hope this answers your questions otherwise please write again.
> >
> > Best regards
> > S?ren
> >
> > — In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@>
> > wrote:
> > >
> > > I am also very interested in this too. I as well, have created
an
> > AnyBody simple arm-curl model to compare to long-hand calculated
> > muscle forces. When I start adding too many muscles to the model
> > (calculating long-hand), I run into the problem of
indeterminancy.
> > However, if I set for example, the biceps breve as a function of
the
> > biceps longum, and all of the triceps (ME_1 and 2, LA_1 and 2) as
a
> > function of each other based on PCSA, I can get the same results
as
> > AnyBody. There are two things I am still curious about however.
> > >
> > > 1.) First off, the Triceps_LH 1 & 2 always demonstrate a Fm of
0.
> > The same goes for both the Brachialis_1 & 2, and
Brachioradialis_1 &
> > 2. Why is it that these muscles exert no force on the system
while
> > the biceps breve and longum clearly do. I’m assuming it comes
down
> > to the mathematics within the software (and I am interested, like
> > Maren, to find out more on this) and the fact that to minimize
the
> > maximal muscle effort, computationally it makes sense to avoid
these
> > muscles because when calculated, their input is greater than with
the
> > biceps alone. However does this make sense physiologically? I’m
> > just trying to reason this out…
> > >
> > > 2.) And along these lines, does the software perhaps group
flexors
> > and extensors somehow based on PCSA like I did for the biceps and
> > triceps?
> > >
> > > Thank you for your time and help on this,
> > > Sarah
> > >
> > >
> > >
> > > -----Original Message-----
> > >
> > > > Date: Fri Feb 09 03:01:04 EST 2007
> > > > From: “Maren” <anystarter@>
> > > > Subject: [anyscript] Re: Calculation of muscle forces
> > > > To: anyscript@yahoogroups.com
> > > >
> > > > Hi Christian,
> > > > that is an interesting idea. I haven?t looked at the passive
> > forces of
> > > > the antagonists yet. Thank you very much, i will try it out.
Is it
> > > > possible for you to send me the formula how AnyBody
calculates the
> > > > muscle forces? Best regards, Maren
> > > >
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support”
<support@>
> > wrote:
> > > > >
> > > > > Hi Maren
> > > > >
> > > > > Thanks for the last file, it made it work:D
> > > > > I am not sure why you see bigger muscle activity in the
AnyBody
> > model
> > > > > then in the other one. Are you considering the passive
elastic
> > forces
> > > > > from the elbow stretching muscles? This could be one of the
> > reasons to
> > > > > the difference. Maybe you could try using the
AnySimpleMuscle
> > model,
> > > > > because they have no passive elastic properties.
> > > > > Let me know what you think, I think it is an exciting
> > discussion.
> > > > >
> > > > > Best regards
> > > > > Christian, AnyBody Support
> > > > >
> > > > >
> > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@>
wrote:
> > > > > >
> > > > > > Hi Christian,
> > > > > >
> > > > > > at this moment i am not sure wether i changed something
in
> > this file,
> > > > > > but i uploaded it in the folder “Marens Armmodell”. The
> > origin model
> > > > > > from the repository was the gearstick model and i changed
it
> > to make a
> > > > > > static task: hold the lower arm against gravity with
nearly
> > maximum
> > > > > > supination so that as few as possible muscles were used.
Best
> > regards,
> > > > > > Maren
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > <support@> wrote:
> > > > > > >
> > > > > > > Hi Maren
> > > > > > >
> > > > > > > Have you made any changes to
> > > > > > >
BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > > > > If yes could you upload the file?
> > > > > > >
> > > > > > > Best regards
> > > > > > > Christian, AnyBody Support
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > <support@>
> > > > wrote:
> > > > > > > >
> > > > > > > > Hi Maren
> > > > > > > >
> > > > > > > > Thank you, I am looking at it.
> > > > > > > >
> > > > > > > > Best regards
> > > > > > > > Christian, AnyBody Support
> > > > > > > >
> > > > > > > > — In anyscript@yahoogroups.com, “Maren”
<anystarter@>
> > wrote:
> > > > > > > > >
> > > > > > > > > Hi Christian, i uploaded my model in the
folder “Marens
> > > > > Armmodell”.
> > > > > > > > > Good Luck
> > > > > > > > >
> > > > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > <support@>
> > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > Hi Maren
> > > > > > > > > >
> > > > > > > > > > Could I ask you to upload your model to the file
> > section?
> > > > > > > > > >
> > > > > > > > > > Best regards
> > > > > > > > > > Christian, AnyBody Support
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > — In anyscript@yahoogroups.com, “Maren”
> > <anystarter@> wrote:
> > > > > > > > > > >
> > > > > > > > > > > Hallo,
> > > > > > > > > > > i simulated a static task with an armmodel, so
that
> > only
> > > > three
> > > > > > > > muscles
> > > > > > > > > > > were taken into account. The task was to hold
the
> > almost
> > > > > > 90degree
> > > > > > > > > > > flexed lower arm against gravity. For better
> > understandig
> > > > > which
> > > > > > > > muscle
> > > > > > > > > > > forces i estimate, i calculated the same task
by
> > hand
> > > > with the
> > > > > > > > law of
> > > > > > > > > > > the lever. Although this method is very
imprecise i
> > > > could see,
> > > > > > > that
> > > > > > > > > > > there a more muscle forces than needed to do
this
> > special
> > > > > > > task. How
> > > > > > > > > > > could i understand this? Are there some
internal
> > tasks which
> > > > > > > > increase
> > > > > > > > > > > muscle force, tendon tension or joint friction
for
> > example?
> > > > > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>

system · February 13, 2007, 2:04pm

Not a problem, thank you for getting back to me. I may have more questions once
I get through the paper - sifting through the math is taking a while but it is
very helpful!

-----Original Message-----

> Date: Tue Feb 13 03:35:59 EST 2007
> From: “AnyBody Support” <support@anybodytech.com>
> Subject: [anyscript] Re: Calculation of muscle forces
> To: anyscript@yahoogroups.com
>
> Hi Sarah
>
> If you have got the first paper i think you are ok, and will not find
> much more information in the second paper. I primarily gave two
> options so you had a choice.
>
> Unfortunately it is not possible to get the .pdf file for the second
> paper due to copyright issues, this is also why it is not online,
> sorry.
>
> Best regards
> S?ren
>
>
> — In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@…>
> wrote:
> >
> > Hi Soren,
> >
> > The recent November 2006 article is VERY helpful - thank you for
> the information on it. Is there anyway I can get a .pdf for the 2nd
> article - the 2001 Proceedings of IDETC article? I can’t find it
> anywhere and to get it I will have to buy the entire proceedings
> (just for the article). Is it posted on the AnyBody website as a
> publication? The proceedings here are about $150 US.
> >
> > Thank you,
> > Sarah
> >
> >
> >
> > -----Original Message-----
> >
> > > Date: Mon Feb 12 05:31:53 EST 2007
> > > From: “AnyBody Support” <support@…>
> > > Subject: [anyscript] Re: Calculation of muscle forces
> > > To: anyscript@yahoogroups.com
> > >
> > > Hi Sarah
> > >
> > > I will try to give you some answers:
> > >
> > > First of all, here are some references to papers which describes
> the
> > > recruitment of the muscles, as you know the forces are
> distributed
> > > among the muscles using a min/max optimization criteria.
> > >
> > > Michael Damsgaard, John Rasmussen, S?ren T?rholm Christensen,
> > > Egidijus Surma, and Mark de Zee (2006): Analysis of
> musculoskeletal
> > > systems in the AnyBody Modeling System. Simulation Modelling
> Practice
> > > and Theory. Volume 14, Issue 8 , November 2006, Pages 1100-1111.
> > > Elsevier, ISSN: 1569-190X.
> > >
> > > M. Damsgaard, J. Rasmussen & S.T. Christensen (2001): Inverse
> > > dynamics of musculo-skeletal systems using an efficient min/max
> > > muscle recruitment model. Proceedings of IDETC: 18-th Biennial
> > > Conference on Mechanical Vibration and Noise, Pittsburgh,
> September 9-
> > > 13, 2001.
> > >
> > > The algorithm do not group the muscles in any way, all muscels
> are
> > > treated in the same way. The algorithm will try to lower the
> > > activity in the maximal activated muscles of the model (provided
> you
> > > do not make use of any penalties, then the explanation is longer).
> > >
> > > I can not give a simple answer on why tricpes_longhead 1 & 2 are
> not
> > > active in the given situation, the same goes for the other two
> > > muscles you mention. The activity of Brachioradialis could be
> related
> > > to the pronation of the forarm have you tried to change this?.
> > > It is certain though, that if these muscles became active it
> would
> > > increase the activity of some of the other muscles in the model.
> So
> > > one thing you could do, was to add a constant force to one of the
> > > muscles you are interested in, in order to see the effect it
> would
> > > have on the other muscles, if the particular muscles became
> active.
> > > In practice this can be done be creating an AnyForce and then
> refer
> > > to the Line measure in the particular muscle. If you then add a
> force
> > > (negative) and closely inspect which muscles then become more
> active
> > > you can get an idea about which mechanisms are dominat in the
> model.
> > >
> > > I hope this answers your questions otherwise please write again.
> > >
> > > Best regards
> > > S?ren
> > >
> > > — In anyscript@yahoogroups.com, “Sarah R. Sullivan” <sarsulli@>
> > > wrote:
> > > >
> > > > I am also very interested in this too. I as well, have created
> an
> > > AnyBody simple arm-curl model to compare to long-hand calculated
> > > muscle forces. When I start adding too many muscles to the model
> > > (calculating long-hand), I run into the problem of
> indeterminancy.
> > > However, if I set for example, the biceps breve as a function of
> the
> > > biceps longum, and all of the triceps (ME_1 and 2, LA_1 and 2) as
> a
> > > function of each other based on PCSA, I can get the same results
> as
> > > AnyBody. There are two things I am still curious about however.
> > > >
> > > > 1.) First off, the Triceps_LH 1 & 2 always demonstrate a Fm of
> 0.
> > > The same goes for both the Brachialis_1 & 2, and
> Brachioradialis_1 &
> > > 2. Why is it that these muscles exert no force on the system
> while
> > > the biceps breve and longum clearly do. I’m assuming it comes
> down
> > > to the mathematics within the software (and I am interested, like
> > > Maren, to find out more on this) and the fact that to minimize
> the
> > > maximal muscle effort, computationally it makes sense to avoid
> these
> > > muscles because when calculated, their input is greater than with
> the
> > > biceps alone. However does this make sense physiologically? I’m
> > > just trying to reason this out…
> > > >
> > > > 2.) And along these lines, does the software perhaps group
> flexors
> > > and extensors somehow based on PCSA like I did for the biceps and
> > > triceps?
> > > >
> > > > Thank you for your time and help on this,
> > > > Sarah
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > >
> > > > > Date: Fri Feb 09 03:01:04 EST 2007
> > > > > From: “Maren” <anystarter@>
> > > > > Subject: [anyscript] Re: Calculation of muscle forces
> > > > > To: anyscript@yahoogroups.com
> > > > >
> > > > > Hi Christian,
> > > > > that is an interesting idea. I haven?t looked at the passive
> > > forces of
> > > > > the antagonists yet. Thank you very much, i will try it out.
> Is it
> > > > > possible for you to send me the formula how AnyBody
> calculates the
> > > > > muscle forces? Best regards, Maren
> > > > >
> > > > >
> > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> <support@>
> > > wrote:
> > > > > >
> > > > > > Hi Maren
> > > > > >
> > > > > > Thanks for the last file, it made it work:D
> > > > > > I am not sure why you see bigger muscle activity in the
> AnyBody
> > > model
> > > > > > then in the other one. Are you considering the passive
> elastic
> > > forces
> > > > > > from the elbow stretching muscles? This could be one of the
> > > reasons to
> > > > > > the difference. Maybe you could try using the
> AnySimpleMuscle
> > > model,
> > > > > > because they have no passive elastic properties.
> > > > > > Let me know what you think, I think it is an exciting
> > > discussion.
> > > > > >
> > > > > > Best regards
> > > > > > Christian, AnyBody Support
> > > > > >
> > > > > >
> > > > > > — In anyscript@yahoogroups.com, “Maren” <anystarter@>
> wrote:
> > > > > > >
> > > > > > > Hi Christian,
> > > > > > >
> > > > > > > at this moment i am not sure wether i changed something
> in
> > > this file,
> > > > > > > but i uploaded it in the folder “Marens Armmodell”. The
> > > origin model
> > > > > > > from the repository was the gearstick model and i changed
> it
> > > to make a
> > > > > > > static task: hold the lower arm against gravity with
> nearly
> > > maximum
> > > > > > > supination so that as few as possible muscles were used.
> Best
> > > regards,
> > > > > > > Maren
> > > > > > >
> > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > > <support@> wrote:
> > > > > > > >
> > > > > > > > Hi Maren
> > > > > > > >
> > > > > > > > Have you made any changes to
> > > > > > > >
> BRep\Aalborg\BodyModels\SpineTwoArms\BodyModel_Mus3E.any?
> > > > > > > > If yes could you upload the file?
> > > > > > > >
> > > > > > > > Best regards
> > > > > > > > Christian, AnyBody Support
> > > > > > > >
> > > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > > <support@>
> > > > > wrote:
> > > > > > > > >
> > > > > > > > > Hi Maren
> > > > > > > > >
> > > > > > > > > Thank you, I am looking at it.
> > > > > > > > >
> > > > > > > > > Best regards
> > > > > > > > > Christian, AnyBody Support
> > > > > > > > >
> > > > > > > > > — In anyscript@yahoogroups.com, “Maren”
> <anystarter@>
> > > wrote:
> > > > > > > > > >
> > > > > > > > > > Hi Christian, i uploaded my model in the
> folder “Marens
> > > > > > Armmodell”.
> > > > > > > > > > Good Luck
> > > > > > > > > >
> > > > > > > > > > — In anyscript@yahoogroups.com, “AnyBody Support”
> > > <support@>
> > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > Hi Maren
> > > > > > > > > > >
> > > > > > > > > > > Could I ask you to upload your model to the file
> > > section?
> > > > > > > > > > >
> > > > > > > > > > > Best regards
> > > > > > > > > > > Christian, AnyBody Support
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > — In anyscript@yahoogroups.com, “Maren”
> > > <anystarter@> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Hallo,
> > > > > > > > > > > > i simulated a static task with an armmodel, so
> that
> > > only
> > > > > three
> > > > > > > > > muscles
> > > > > > > > > > > > were taken into account. The task was to hold
> the
> > > almost
> > > > > > > 90degree
> > > > > > > > > > > > flexed lower arm against gravity. For better
> > > understandig
> > > > > > which
> > > > > > > > > muscle
> > > > > > > > > > > > forces i estimate, i calculated the same task
> by
> > > hand
> > > > > with the
> > > > > > > > > law of
> > > > > > > > > > > > the lever. Although this method is very
> imprecise i
> > > > > could see,
> > > > > > > > that
> > > > > > > > > > > > there a more muscle forces than needed to do
> this
> > > special
> > > > > > > > task. How
> > > > > > > > > > > > could i understand this? Are there some
> internal
> > > tasks which
> > > > > > > > > increase
> > > > > > > > > > > > muscle force, tendon tension or joint friction
> for
> > > example?
> > > > > > > > > > > > Thank you very much, best regards, Maren.
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>