Abductor Muscles

Hallo,

first of all a short questions:

The body mass of the whole gait3D model (legs + upper body part) is
64,9 kg (649 N)whereas the FreePostureMove model is 75 kg (750 N),
right?

My goal is to determin the hip resultant force and the hip muscle
forces (especially the Gluteus Minimus/Medium/Maximus, Piriformis and
Tensor Fasciae Latae etc.)for different postures and again if one
muscle will be suppressed to see the differences.

So far I have changed the FreePostureMove model to a one legged stance
model. The hip resultant force with about 2000 N is reasonable (2000
N / 750 N = ~2.7 Body weight). Unfortunately by looking at the muscle
forces especially at the abductors (Gluteus Minimus 1-3 and Medius 1-
3) they are all about zero. How can this be as the abductors are
mainly responsible to keep the pelvis in ballance? Former studies
revealed that the hip joint is charged with about 5/6 Body weigth
(body weight minus standing leg) and a lever arm depending on the
posture (position of the COM). The only possibility to withstand a
moment on the hip joint are mainly the abductors on the other side
with the lever arm from the greater trochanter to center of the hip
joint. It is impossible that they are zero as in my model…

What is wrong with my model?

I’ve attached my model in the file folder as

OneLegStand_Model1.zip

Maybe you can have a look at it to give me a judgement what could be
wrong. Do I have to change the solution algorithm to AnyMuslceModel
where all muscles have constant strength ?

Thank you for your help.

Best regards

Thomas

Hi Thomas,

To the first question: yes the body mass for the Gait3D model is 64.9
kg. The model has been scaled to fit the subject of the experiment
(in dimension as well as in mass). The standard mass of our model is
75 kg, so it is the mass of the FreePostureMove by default.

Now I have run your model and it appeared that the Gluteus muscle
forces are not zero. So my guess is that you was probably not looking
at the good output. Of course you have to look at the right side and
not at the left side. But I’m more thinking about the different
output in each muscle. There is several force output in each muscle
folder and the one you should look at are Fm, Ft and Fp.
Fm is the force in the contractile element of the muscle. Ft is the
force in the tendon. Those two forces are different when using the 3
elements model, but as you are using the simple muscle model there is
no difference between tendon or contractile element and those two
forces are equally representing the total muscle force.
Fp represents the force of the passive elasticity of the muscle and
it is only used for the 3 elements muscle model. In the simple model
there is no passive elasticity so Fp is zero.

Best regards,
Sylvain, AnyBody Support.

— In anyscript@yahoogroups.com, “knox40” <knox40@…> wrote:
>
> Hallo,
> -----------------
> first of all a short questions:
>
> The body mass of the whole gait3D model (legs + upper body part) is
> 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg (750 N),
> right?
> -----------------
>
> My goal is to determin the hip resultant force and the hip muscle
> forces (especially the Gluteus Minimus/Medium/Maximus, Piriformis
and
> Tensor Fasciae Latae etc.)for different postures and again if one
> muscle will be suppressed to see the differences.
>
> So far I have changed the FreePostureMove model to a one legged
stance
> model. The hip resultant force with about 2000 N is reasonable
(2000
> N / 750 N = ~2.7 Body weight). Unfortunately by looking at the
muscle
> forces especially at the abductors (Gluteus Minimus 1-3 and Medius
1-
> 3) they are all about zero. How can this be as the abductors are
> mainly responsible to keep the pelvis in ballance? Former studies
> revealed that the hip joint is charged with about 5/6 Body weigth
> (body weight minus standing leg) and a lever arm depending on the
> posture (position of the COM). The only possibility to withstand a
> moment on the hip joint are mainly the abductors on the other side
> with the lever arm from the greater trochanter to center of the hip
> joint. It is impossible that they are zero as in my model…
>
> What is wrong with my model?
>
> I’ve attached my model in the file folder as
>
> OneLegStand_Model1.zip
>
> Maybe you can have a look at it to give me a judgement what could
be
> wrong. Do I have to change the solution algorithm to AnyMuslceModel
> where all muscles have constant strength ?
>
>
> Thank you for your help.
>
> Best regards
>
> Thomas
>

Hi Sylvain,

first of all thank you for your answer.

You are right, the abductors are not all zero. Nevertheless the
Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor Fasciae
Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is quite low
compared with values from literature for a one legged stance.

Contrary the adductor muscles are comparative higher.

Why are the abductors so different from literature and so low? They
should contribute mainly to the stability of the standing posture by
counterbalancing the weight of the torso!

Hope you can help me as I don’t know how these results could be
explained.

Best regards

Thomas

Thomas Thielen

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…>
wrote:
>
> Hi Thomas,
>
> To the first question: yes the body mass for the Gait3D model is
64.9
> kg. The model has been scaled to fit the subject of the experiment
> (in dimension as well as in mass). The standard mass of our model
is
> 75 kg, so it is the mass of the FreePostureMove by default.
>
> Now I have run your model and it appeared that the Gluteus muscle
> forces are not zero. So my guess is that you was probably not
looking
> at the good output. Of course you have to look at the right side
and
> not at the left side. But I’m more thinking about the different
> output in each muscle. There is several force output in each muscle
> folder and the one you should look at are Fm, Ft and Fp.
> Fm is the force in the contractile element of the muscle. Ft is the
> force in the tendon. Those two forces are different when using the
3
> elements model, but as you are using the simple muscle model there
is
> no difference between tendon or contractile element and those two
> forces are equally representing the total muscle force.
> Fp represents the force of the passive elasticity of the muscle and
> it is only used for the 3 elements muscle model. In the simple
model
> there is no passive elasticity so Fp is zero.
>
> Best regards,
> Sylvain, AnyBody Support.
>
>
>
>
> — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> >
> > Hallo,
> > -----------------
> > first of all a short questions:
> >
> > The body mass of the whole gait3D model (legs + upper body part)
is
> > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg (750
N),
> > right?
> > -----------------
> >
> > My goal is to determin the hip resultant force and the hip muscle
> > forces (especially the Gluteus Minimus/Medium/Maximus, Piriformis
> and
> > Tensor Fasciae Latae etc.)for different postures and again if one
> > muscle will be suppressed to see the differences.
> >
> > So far I have changed the FreePostureMove model to a one legged
> stance
> > model. The hip resultant force with about 2000 N is reasonable
> (2000
> > N / 750 N = ~2.7 Body weight). Unfortunately by looking at the
> muscle
> > forces especially at the abductors (Gluteus Minimus 1-3 and
Medius
> 1-
> > 3) they are all about zero. How can this be as the abductors are
> > mainly responsible to keep the pelvis in ballance? Former studies
> > revealed that the hip joint is charged with about 5/6 Body weigth
> > (body weight minus standing leg) and a lever arm depending on the
> > posture (position of the COM). The only possibility to withstand
a
> > moment on the hip joint are mainly the abductors on the other
side
> > with the lever arm from the greater trochanter to center of the
hip
> > joint. It is impossible that they are zero as in my model…
> >
> > What is wrong with my model?
> >
> > I’ve attached my model in the file folder as
> >
> > OneLegStand_Model1.zip
> >
> > Maybe you can have a look at it to give me a judgement what could
> be
> > wrong. Do I have to change the solution algorithm to
AnyMuslceModel
> > where all muscles have constant strength ?
> >
> >
> > Thank you for your help.
> >
> > Best regards
> >
> > Thomas
> >
>

Hi Thomas,

I did not have time to download and debug your model but the free
posture model is similar to the gait models in the sense that it is
grounded at the pelvis rather than at the feet.

This means that the muscle actions are determined mostly by the
measured ground reaction forces you are aplying to the feet. How were
they applied in your case and are you using actual measured forces
that correspond exactly to the posture you have placed the model in?

The issue might be that because the GRFs go mostly axially through
the leg, the model becomes rather sensitive to small deviations in
force direction. If it deviates just a little in direction the force
vector can end up passing on the wrong side of a joint and create a
joint moment that has the wrong sign. This will of course change the
muscle activations completely.

I hope that might help.
John

— In anyscript@yahoogroups.com, “knox40” <knox40@…> wrote:
>
> Hi Sylvain,
>
> first of all thank you for your answer.
>
> You are right, the abductors are not all zero. Nevertheless the
> Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor Fasciae
> Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is quite low
> compared with values from literature for a one legged stance.
>
> Contrary the adductor muscles are comparative higher.
>
> Why are the abductors so different from literature and so low? They
> should contribute mainly to the stability of the standing posture
by
> counterbalancing the weight of the torso!
>
> Hope you can help me as I don’t know how these results could be
> explained.
>
> Best regards
>
> Thomas
>
> Thomas Thielen
>
>
>
>
> — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> wrote:
> >
> > Hi Thomas,
> >
> > To the first question: yes the body mass for the Gait3D model is
> 64.9
> > kg. The model has been scaled to fit the subject of the
experiment
> > (in dimension as well as in mass). The standard mass of our model
> is
> > 75 kg, so it is the mass of the FreePostureMove by default.
> >
> > Now I have run your model and it appeared that the Gluteus muscle
> > forces are not zero. So my guess is that you was probably not
> looking
> > at the good output. Of course you have to look at the right side
> and
> > not at the left side. But I’m more thinking about the different
> > output in each muscle. There is several force output in each
muscle
> > folder and the one you should look at are Fm, Ft and Fp.
> > Fm is the force in the contractile element of the muscle. Ft is
the
> > force in the tendon. Those two forces are different when using
the
> 3
> > elements model, but as you are using the simple muscle model
there
> is
> > no difference between tendon or contractile element and those two
> > forces are equally representing the total muscle force.
> > Fp represents the force of the passive elasticity of the muscle
and
> > it is only used for the 3 elements muscle model. In the simple
> model
> > there is no passive elasticity so Fp is zero.
> >
> > Best regards,
> > Sylvain, AnyBody Support.
> >
> >
> >
> >
> > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > >
> > > Hallo,
> > > -----------------
> > > first of all a short questions:
> > >
> > > The body mass of the whole gait3D model (legs + upper body
part)
> is
> > > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg (750
> N),
> > > right?
> > > -----------------
> > >
> > > My goal is to determin the hip resultant force and the hip
muscle
> > > forces (especially the Gluteus Minimus/Medium/Maximus,
Piriformis
> > and
> > > Tensor Fasciae Latae etc.)for different postures and again if
one
> > > muscle will be suppressed to see the differences.
> > >
> > > So far I have changed the FreePostureMove model to a one legged
> > stance
> > > model. The hip resultant force with about 2000 N is reasonable
> > (2000
> > > N / 750 N = ~2.7 Body weight). Unfortunately by looking at the
> > muscle
> > > forces especially at the abductors (Gluteus Minimus 1-3 and
> Medius
> > 1-
> > > 3) they are all about zero. How can this be as the abductors
are
> > > mainly responsible to keep the pelvis in ballance? Former
studies
> > > revealed that the hip joint is charged with about 5/6 Body
weigth
> > > (body weight minus standing leg) and a lever arm depending on
the
> > > posture (position of the COM). The only possibility to
withstand
> a
> > > moment on the hip joint are mainly the abductors on the other
> side
> > > with the lever arm from the greater trochanter to center of the
> hip
> > > joint. It is impossible that they are zero as in my model…
> > >
> > > What is wrong with my model?
> > >
> > > I’ve attached my model in the file folder as
> > >
> > > OneLegStand_Model1.zip
> > >
> > > Maybe you can have a look at it to give me a judgement what
could
> > be
> > > wrong. Do I have to change the solution algorithm to
> AnyMuslceModel
> > > where all muscles have constant strength ?
> > >
> > >
> > > Thank you for your help.
> > >
> > > Best regards
> > >
> > > Thomas
> > >
> >
>

Hi John, Hi Sylvain,

Unfortunately I have no measured ground reaction forces to drive the
model. Instead I defined three nodes (HeelContactNode,
ToeMedialContactNode and ToeLateralContactNode) where I have the feet
connected to. This nodes should provide the ground reaction forces
similar to the PedalDemoConditional model. The foot in my changed
FreePostureMove model is driven by an interpolation driver.

I have switched of the reaction force in the y direction of the
PelvisGroundDriver to transfer the load to the feed. In my opinion
the fixed rotation of the pelvis must cause the low gluteus muscle
forces, am I right?
In principle all these reaction forces should be off, but how can I
than balance the model? Can I use a COM driver for that? Can you give
me an example how to use it and which dof’s do I have to change?

Thanks so far.

Best regards

Thomas

— In anyscript@yahoogroups.com, “John Rasmussen” <jr@…> wrote:
>
> Hi Thomas,
>
> I did not have time to download and debug your model but the free
> posture model is similar to the gait models in the sense that it is
> grounded at the pelvis rather than at the feet.
>
> This means that the muscle actions are determined mostly by the
> measured ground reaction forces you are aplying to the feet. How
were
> they applied in your case and are you using actual measured forces
> that correspond exactly to the posture you have placed the model in?
>
> The issue might be that because the GRFs go mostly axially through
> the leg, the model becomes rather sensitive to small deviations in
> force direction. If it deviates just a little in direction the
force
> vector can end up passing on the wrong side of a joint and create a
> joint moment that has the wrong sign. This will of course change
the
> muscle activations completely.
>
> I hope that might help.
> John
>
>
> — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> >
> > Hi Sylvain,
> >
> > first of all thank you for your answer.
> >
> > You are right, the abductors are not all zero. Nevertheless the
> > Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor Fasciae
> > Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is quite
low
> > compared with values from literature for a one legged stance.
> >
> > Contrary the adductor muscles are comparative higher.
> >
> > Why are the abductors so different from literature and so low?
They
> > should contribute mainly to the stability of the standing posture
> by
> > counterbalancing the weight of the torso!
> >
> > Hope you can help me as I don’t know how these results could be
> > explained.
> >
> > Best regards
> >
> > Thomas
> >
> > Thomas Thielen
> >
> >
> >
> >
> > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > wrote:
> > >
> > > Hi Thomas,
> > >
> > > To the first question: yes the body mass for the Gait3D model
is
> > 64.9
> > > kg. The model has been scaled to fit the subject of the
> experiment
> > > (in dimension as well as in mass). The standard mass of our
model
> > is
> > > 75 kg, so it is the mass of the FreePostureMove by default.
> > >
> > > Now I have run your model and it appeared that the Gluteus
muscle
> > > forces are not zero. So my guess is that you was probably not
> > looking
> > > at the good output. Of course you have to look at the right
side
> > and
> > > not at the left side. But I’m more thinking about the different
> > > output in each muscle. There is several force output in each
> muscle
> > > folder and the one you should look at are Fm, Ft and Fp.
> > > Fm is the force in the contractile element of the muscle. Ft is
> the
> > > force in the tendon. Those two forces are different when using
> the
> > 3
> > > elements model, but as you are using the simple muscle model
> there
> > is
> > > no difference between tendon or contractile element and those
two
> > > forces are equally representing the total muscle force.
> > > Fp represents the force of the passive elasticity of the muscle
> and
> > > it is only used for the 3 elements muscle model. In the simple
> > model
> > > there is no passive elasticity so Fp is zero.
> > >
> > > Best regards,
> > > Sylvain, AnyBody Support.
> > >
> > >
> > >
> > >
> > > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > > >
> > > > Hallo,
> > > > -----------------
> > > > first of all a short questions:
> > > >
> > > > The body mass of the whole gait3D model (legs + upper body
> part)
> > is
> > > > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg
(750
> > N),
> > > > right?
> > > > -----------------
> > > >
> > > > My goal is to determin the hip resultant force and the hip
> muscle
> > > > forces (especially the Gluteus Minimus/Medium/Maximus,
> Piriformis
> > > and
> > > > Tensor Fasciae Latae etc.)for different postures and again if
> one
> > > > muscle will be suppressed to see the differences.
> > > >
> > > > So far I have changed the FreePostureMove model to a one
legged
> > > stance
> > > > model. The hip resultant force with about 2000 N is
reasonable
> > > (2000
> > > > N / 750 N = ~2.7 Body weight). Unfortunately by looking at
the
> > > muscle
> > > > forces especially at the abductors (Gluteus Minimus 1-3 and
> > Medius
> > > 1-
> > > > 3) they are all about zero. How can this be as the abductors
> are
> > > > mainly responsible to keep the pelvis in ballance? Former
> studies
> > > > revealed that the hip joint is charged with about 5/6 Body
> weigth
> > > > (body weight minus standing leg) and a lever arm depending on
> the
> > > > posture (position of the COM). The only possibility to
> withstand
> > a
> > > > moment on the hip joint are mainly the abductors on the other
> > side
> > > > with the lever arm from the greater trochanter to center of
the
> > hip
> > > > joint. It is impossible that they are zero as in my model…
> > > >
> > > > What is wrong with my model?
> > > >
> > > > I’ve attached my model in the file folder as
> > > >
> > > > OneLegStand_Model1.zip
> > > >
> > > > Maybe you can have a look at it to give me a judgement what
> could
> > > be
> > > > wrong. Do I have to change the solution algorithm to
> > AnyMuslceModel
> > > > where all muscles have constant strength ?
> > > >
> > > >
> > > > Thank you for your help.
> > > >
> > > > Best regards
> > > >
> > > > Thomas
> > > >
> > >
> >
>

Hi Thomas,

The fact that you have the reaction force On for the pelvis is mainly
the reason for the low muscle activity. The gluteus does not balance
the pelvis because the Reaction.Type already does it. So you have to
switch Off the reaction for the 3 rotations of the pelvis. I think
you can keep on the reaction for the translation on x and z.
This should give you much more reasonable results.

Best regards,
Sylvain, AnyBody Support.

— In anyscript@yahoogroups.com, “knox40” <knox40@…> wrote:
>
> Hi John, Hi Sylvain,
>
> Unfortunately I have no measured ground reaction forces to drive
the
> model. Instead I defined three nodes (HeelContactNode,
> ToeMedialContactNode and ToeLateralContactNode) where I have the
feet
> connected to. This nodes should provide the ground reaction forces
> similar to the PedalDemoConditional model. The foot in my changed
> FreePostureMove model is driven by an interpolation driver.
>
> I have switched of the reaction force in the y direction of the
> PelvisGroundDriver to transfer the load to the feed. In my opinion
> the fixed rotation of the pelvis must cause the low gluteus muscle
> forces, am I right?
> In principle all these reaction forces should be off, but how can I
> than balance the model? Can I use a COM driver for that? Can you
give
> me an example how to use it and which dof’s do I have to change?
>
> Thanks so far.
>
> Best regards
>
> Thomas
>
>
>
> — In anyscript@yahoogroups.com, “John Rasmussen” <jr@> wrote:
> >
> > Hi Thomas,
> >
> > I did not have time to download and debug your model but the free
> > posture model is similar to the gait models in the sense that it
is
> > grounded at the pelvis rather than at the feet.
> >
> > This means that the muscle actions are determined mostly by the
> > measured ground reaction forces you are aplying to the feet. How
> were
> > they applied in your case and are you using actual measured
forces
> > that correspond exactly to the posture you have placed the model
in?
> >
> > The issue might be that because the GRFs go mostly axially
through
> > the leg, the model becomes rather sensitive to small deviations
in
> > force direction. If it deviates just a little in direction the
> force
> > vector can end up passing on the wrong side of a joint and create
a
> > joint moment that has the wrong sign. This will of course change
> the
> > muscle activations completely.
> >
> > I hope that might help.
> > John
> >
> >
> > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > >
> > > Hi Sylvain,
> > >
> > > first of all thank you for your answer.
> > >
> > > You are right, the abductors are not all zero. Nevertheless the
> > > Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor
Fasciae
> > > Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is quite
> low
> > > compared with values from literature for a one legged stance.
> > >
> > > Contrary the adductor muscles are comparative higher.
> > >
> > > Why are the abductors so different from literature and so low?
> They
> > > should contribute mainly to the stability of the standing
posture
> > by
> > > counterbalancing the weight of the torso!
> > >
> > > Hope you can help me as I don’t know how these results could be
> > > explained.
> > >
> > > Best regards
> > >
> > > Thomas
> > >
> > > Thomas Thielen
> > >
> > >
> > >
> > >
> > > — In anyscript@yahoogroups.com, “AnyBody Support” <support@>
> > > wrote:
> > > >
> > > > Hi Thomas,
> > > >
> > > > To the first question: yes the body mass for the Gait3D model
> is
> > > 64.9
> > > > kg. The model has been scaled to fit the subject of the
> > experiment
> > > > (in dimension as well as in mass). The standard mass of our
> model
> > > is
> > > > 75 kg, so it is the mass of the FreePostureMove by default.
> > > >
> > > > Now I have run your model and it appeared that the Gluteus
> muscle
> > > > forces are not zero. So my guess is that you was probably not
> > > looking
> > > > at the good output. Of course you have to look at the right
> side
> > > and
> > > > not at the left side. But I’m more thinking about the
different
> > > > output in each muscle. There is several force output in each
> > muscle
> > > > folder and the one you should look at are Fm, Ft and Fp.
> > > > Fm is the force in the contractile element of the muscle. Ft
is
> > the
> > > > force in the tendon. Those two forces are different when
using
> > the
> > > 3
> > > > elements model, but as you are using the simple muscle model
> > there
> > > is
> > > > no difference between tendon or contractile element and those
> two
> > > > forces are equally representing the total muscle force.
> > > > Fp represents the force of the passive elasticity of the
muscle
> > and
> > > > it is only used for the 3 elements muscle model. In the
simple
> > > model
> > > > there is no passive elasticity so Fp is zero.
> > > >
> > > > Best regards,
> > > > Sylvain, AnyBody Support.
> > > >
> > > >
> > > >
> > > >
> > > > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > > > >
> > > > > Hallo,
> > > > > -----------------
> > > > > first of all a short questions:
> > > > >
> > > > > The body mass of the whole gait3D model (legs + upper body
> > part)
> > > is
> > > > > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg
> (750
> > > N),
> > > > > right?
> > > > > -----------------
> > > > >
> > > > > My goal is to determin the hip resultant force and the hip
> > muscle
> > > > > forces (especially the Gluteus Minimus/Medium/Maximus,
> > Piriformis
> > > > and
> > > > > Tensor Fasciae Latae etc.)for different postures and again
if
> > one
> > > > > muscle will be suppressed to see the differences.
> > > > >
> > > > > So far I have changed the FreePostureMove model to a one
> legged
> > > > stance
> > > > > model. The hip resultant force with about 2000 N is
> reasonable
> > > > (2000
> > > > > N / 750 N = ~2.7 Body weight). Unfortunately by looking at
> the
> > > > muscle
> > > > > forces especially at the abductors (Gluteus Minimus 1-3 and
> > > Medius
> > > > 1-
> > > > > 3) they are all about zero. How can this be as the
abductors
> > are
> > > > > mainly responsible to keep the pelvis in ballance? Former
> > studies
> > > > > revealed that the hip joint is charged with about 5/6 Body
> > weigth
> > > > > (body weight minus standing leg) and a lever arm depending
on
> > the
> > > > > posture (position of the COM). The only possibility to
> > withstand
> > > a
> > > > > moment on the hip joint are mainly the abductors on the
other
> > > side
> > > > > with the lever arm from the greater trochanter to center of
> the
> > > hip
> > > > > joint. It is impossible that they are zero as in my model…
> > > > >
> > > > > What is wrong with my model?
> > > > >
> > > > > I’ve attached my model in the file folder as
> > > > >
> > > > > OneLegStand_Model1.zip
> > > > >
> > > > > Maybe you can have a look at it to give me a judgement what
> > could
> > > > be
> > > > > wrong. Do I have to change the solution algorithm to
> > > AnyMuslceModel
> > > > > where all muscles have constant strength ?
> > > > >
> > > > >
> > > > > Thank you for your help.
> > > > >
> > > > > Best regards
> > > > >
> > > > > Thomas
> > > > >
> > > >
> > >
> >
>

Hi Sylvain,

Thank’s again for your help, this forum is quite a good institution
from ANYBODY.

Of course that was the reason why the muscle forces were so low. By
switching the reaction force OFF, the muscle forces are in good
agreement with anticipate values.

In the next step I want to change the balance point (COM) of the
upper body and chart the hip force against the changing COM position.
As I am not using the COM driver within the FreePostureMove model,
how can I record the center of mass during movement?

AnyKinMeasure Org xzmeasure ={
…?
…?

Or is it easier to use the COM Driver for this exercise? - if yes,
what dof’s should I suppress then?

Best regards,

Thomas

— In anyscript@yahoogroups.com, “AnyBody Support” <support@…>
wrote:
>
> Hi Thomas,
>
> The fact that you have the reaction force On for the pelvis is
mainly
> the reason for the low muscle activity. The gluteus does not
balance
> the pelvis because the Reaction.Type already does it. So you have
to
> switch Off the reaction for the 3 rotations of the pelvis. I think
> you can keep on the reaction for the translation on x and z.
> This should give you much more reasonable results.
>
> Best regards,
> Sylvain, AnyBody Support.
>
>
>
> — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> >
> > Hi John, Hi Sylvain,
> >
> > Unfortunately I have no measured ground reaction forces to drive
> the
> > model. Instead I defined three nodes (HeelContactNode,
> > ToeMedialContactNode and ToeLateralContactNode) where I have the
> feet
> > connected to. This nodes should provide the ground reaction
forces
> > similar to the PedalDemoConditional model. The foot in my changed
> > FreePostureMove model is driven by an interpolation driver.
> >
> > I have switched of the reaction force in the y direction of the
> > PelvisGroundDriver to transfer the load to the feed. In my
opinion
> > the fixed rotation of the pelvis must cause the low gluteus
muscle
> > forces, am I right?
> > In principle all these reaction forces should be off, but how can
I
> > than balance the model? Can I use a COM driver for that? Can you
> give
> > me an example how to use it and which dof’s do I have to change?
> >
> > Thanks so far.
> >
> > Best regards
> >
> > Thomas
> >
> >
> >
> > — In anyscript@yahoogroups.com, “John Rasmussen” <jr@> wrote:
> > >
> > > Hi Thomas,
> > >
> > > I did not have time to download and debug your model but the
free
> > > posture model is similar to the gait models in the sense that
it
> is
> > > grounded at the pelvis rather than at the feet.
> > >
> > > This means that the muscle actions are determined mostly by the
> > > measured ground reaction forces you are aplying to the feet.
How
> > were
> > > they applied in your case and are you using actual measured
> forces
> > > that correspond exactly to the posture you have placed the
model
> in?
> > >
> > > The issue might be that because the GRFs go mostly axially
> through
> > > the leg, the model becomes rather sensitive to small deviations
> in
> > > force direction. If it deviates just a little in direction the
> > force
> > > vector can end up passing on the wrong side of a joint and
create
> a
> > > joint moment that has the wrong sign. This will of course
change
> > the
> > > muscle activations completely.
> > >
> > > I hope that might help.
> > > John
> > >
> > >
> > > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > > >
> > > > Hi Sylvain,
> > > >
> > > > first of all thank you for your answer.
> > > >
> > > > You are right, the abductors are not all zero. Nevertheless
the
> > > > Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor
> Fasciae
> > > > Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is
quite
> > low
> > > > compared with values from literature for a one legged stance.
> > > >
> > > > Contrary the adductor muscles are comparative higher.
> > > >
> > > > Why are the abductors so different from literature and so
low?
> > They
> > > > should contribute mainly to the stability of the standing
> posture
> > > by
> > > > counterbalancing the weight of the torso!
> > > >
> > > > Hope you can help me as I don’t know how these results could
be
> > > > explained.
> > > >
> > > > Best regards
> > > >
> > > > Thomas
> > > >
> > > > Thomas Thielen
> > > >
> > > >
> > > >
> > > >
> > > > — In anyscript@yahoogroups.com, “AnyBody Support”
<support@>
> > > > wrote:
> > > > >
> > > > > Hi Thomas,
> > > > >
> > > > > To the first question: yes the body mass for the Gait3D
model
> > is
> > > > 64.9
> > > > > kg. The model has been scaled to fit the subject of the
> > > experiment
> > > > > (in dimension as well as in mass). The standard mass of our
> > model
> > > > is
> > > > > 75 kg, so it is the mass of the FreePostureMove by default.
> > > > >
> > > > > Now I have run your model and it appeared that the Gluteus
> > muscle
> > > > > forces are not zero. So my guess is that you was probably
not
> > > > looking
> > > > > at the good output. Of course you have to look at the right
> > side
> > > > and
> > > > > not at the left side. But I’m more thinking about the
> different
> > > > > output in each muscle. There is several force output in
each
> > > muscle
> > > > > folder and the one you should look at are Fm, Ft and Fp.
> > > > > Fm is the force in the contractile element of the muscle.
Ft
> is
> > > the
> > > > > force in the tendon. Those two forces are different when
> using
> > > the
> > > > 3
> > > > > elements model, but as you are using the simple muscle
model
> > > there
> > > > is
> > > > > no difference between tendon or contractile element and
those
> > two
> > > > > forces are equally representing the total muscle force.
> > > > > Fp represents the force of the passive elasticity of the
> muscle
> > > and
> > > > > it is only used for the 3 elements muscle model. In the
> simple
> > > > model
> > > > > there is no passive elasticity so Fp is zero.
> > > > >
> > > > > Best regards,
> > > > > Sylvain, AnyBody Support.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > — In anyscript@yahoogroups.com, “knox40” <knox40@> wrote:
> > > > > >
> > > > > > Hallo,
> > > > > > -----------------
> > > > > > first of all a short questions:
> > > > > >
> > > > > > The body mass of the whole gait3D model (legs + upper
body
> > > part)
> > > > is
> > > > > > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg
> > (750
> > > > N),
> > > > > > right?
> > > > > > -----------------
> > > > > >
> > > > > > My goal is to determin the hip resultant force and the
hip
> > > muscle
> > > > > > forces (especially the Gluteus Minimus/Medium/Maximus,
> > > Piriformis
> > > > > and
> > > > > > Tensor Fasciae Latae etc.)for different postures and
again
> if
> > > one
> > > > > > muscle will be suppressed to see the differences.
> > > > > >
> > > > > > So far I have changed the FreePostureMove model to a one
> > legged
> > > > > stance
> > > > > > model. The hip resultant force with about 2000 N is
> > reasonable
> > > > > (2000
> > > > > > N / 750 N = ~2.7 Body weight). Unfortunately by looking
at
> > the
> > > > > muscle
> > > > > > forces especially at the abductors (Gluteus Minimus 1-3
and
> > > > Medius
> > > > > 1-
> > > > > > 3) they are all about zero. How can this be as the
> abductors
> > > are
> > > > > > mainly responsible to keep the pelvis in ballance? Former
> > > studies
> > > > > > revealed that the hip joint is charged with about 5/6
Body
> > > weigth
> > > > > > (body weight minus standing leg) and a lever arm
depending
> on
> > > the
> > > > > > posture (position of the COM). The only possibility to
> > > withstand
> > > > a
> > > > > > moment on the hip joint are mainly the abductors on the
> other
> > > > side
> > > > > > with the lever arm from the greater trochanter to center
of
> > the
> > > > hip
> > > > > > joint. It is impossible that they are zero as in my
model…
> > > > > >
> > > > > > What is wrong with my model?
> > > > > >
> > > > > > I’ve attached my model in the file folder as
> > > > > >
> > > > > > OneLegStand_Model1.zip
> > > > > >
> > > > > > Maybe you can have a look at it to give me a judgement
what
> > > could
> > > > > be
> > > > > > wrong. Do I have to change the solution algorithm to
> > > > AnyMuslceModel
> > > > > > where all muscles have constant strength ?
> > > > > >
> > > > > >
> > > > > > Thank you for your help.
> > > > > >
> > > > > > Best regards
> > > > > >
> > > > > > Thomas
> > > > > >
> > > > >
> > > >
> > >
> >
>

Hi Thomas,

If you want to record the center of mass during movement you can use the
AnyKinCoM measure, similar like this:

AnyKinCoM ComMeasure= {

    AnyFolder &Body = .Model;

 };

This should give you the position.

Best regards,

Sebastian


From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of knox40
Sent: 25. juli 2008 09:37
To: anyscript@yahoogroups.com
Subject: [AnyScript] Re: Abductor Muscles

Hi Sylvain,

Thank’s again for your help, this forum is quite a good institution
from ANYBODY.

Of course that was the reason why the muscle forces were so low. By
switching the reaction force OFF, the muscle forces are in good
agreement with anticipate values.

In the next step I want to change the balance point (COM) of the
upper body and chart the hip force against the changing COM position.
As I am not using the COM driver within the FreePostureMove model,
how can I record the center of mass during movement?

AnyKinMeasure Org xzmeasure ={
…?
…?

Or is it easier to use the COM Driver for this exercise? - if yes,
what dof’s should I suppress then?

Best regards,

Thomas

— In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“AnyBody Support” <support@…>
wrote:
>
> Hi Thomas,
>
> The fact that you have the reaction force On for the pelvis is
mainly
> the reason for the low muscle activity. The gluteus does not
balance
> the pelvis because the Reaction.Type already does it. So you have
to
> switch Off the reaction for the 3 rotations of the pelvis. I think
> you can keep on the reaction for the translation on x and z.
> This should give you much more reasonable results.
>
> Best regards,
> Sylvain, AnyBody Support.
>
>
>
> — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“knox40” <knox40@> wrote:
> >
> > Hi John, Hi Sylvain,
> >
> > Unfortunately I have no measured ground reaction forces to drive
> the
> > model. Instead I defined three nodes (HeelContactNode,
> > ToeMedialContactNode and ToeLateralContactNode) where I have the
> feet
> > connected to. This nodes should provide the ground reaction
forces
> > similar to the PedalDemoConditional model. The foot in my changed
> > FreePostureMove model is driven by an interpolation driver.
> >
> > I have switched of the reaction force in the y direction of the
> > PelvisGroundDriver to transfer the load to the feed. In my
opinion
> > the fixed rotation of the pelvis must cause the low gluteus
muscle
> > forces, am I right?
> > In principle all these reaction forces should be off, but how can
I
> > than balance the model? Can I use a COM driver for that? Can you
> give
> > me an example how to use it and which dof’s do I have to change?
> >
> > Thanks so far.
> >
> > Best regards
> >
> > Thomas
> >
> >
> >
> > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com,
“John Rasmussen” <jr@> wrote:
> > >
> > > Hi Thomas,
> > >
> > > I did not have time to download and debug your model but the
free
> > > posture model is similar to the gait models in the sense that
it
> is
> > > grounded at the pelvis rather than at the feet.
> > >
> > > This means that the muscle actions are determined mostly by the
> > > measured ground reaction forces you are aplying to the feet.
How
> > were
> > > they applied in your case and are you using actual measured
> forces
> > > that correspond exactly to the posture you have placed the
model
> in?
> > >
> > > The issue might be that because the GRFs go mostly axially
> through
> > > the leg, the model becomes rather sensitive to small deviations
> in
> > > force direction. If it deviates just a little in direction the
> > force
> > > vector can end up passing on the wrong side of a joint and
create
> a
> > > joint moment that has the wrong sign. This will of course
change
> > the
> > > muscle activations completely.
> > >
> > > I hope that might help.
> > > John
> > >
> > >
> > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “knox40” <knox40@> wrote:
> > > >
> > > > Hi Sylvain,
> > > >
> > > > first of all thank you for your answer.
> > > >
> > > > You are right, the abductors are not all zero. Nevertheless
the
> > > > Gluteus Minimus 1-3, the Gluteus Medius 1 and the Tensor
> Fasciae
> > > > Latae are zero. The Gluteus Medius 2 and 3 (70, 85 N) is
quite
> > low
> > > > compared with values from literature for a one legged stance.
> > > >
> > > > Contrary the adductor muscles are comparative higher.
> > > >
> > > > Why are the abductors so different from literature and so
low?
> > They
> > > > should contribute mainly to the stability of the standing
> posture
> > > by
> > > > counterbalancing the weight of the torso!
> > > >
> > > > Hope you can help me as I don’t know how these results could
be
> > > > explained.
> > > >
> > > > Best regards
> > > >
> > > > Thomas
> > > >
> > > > Thomas Thielen
> > > >
> > > >
> > > >
> > > >
> > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “AnyBody Support”
<support@>
> > > > wrote:
> > > > >
> > > > > Hi Thomas,
> > > > >
> > > > > To the first question: yes the body mass for the Gait3D
model
> > is
> > > > 64.9
> > > > > kg. The model has been scaled to fit the subject of the
> > > experiment
> > > > > (in dimension as well as in mass). The standard mass of our
> > model
> > > > is
> > > > > 75 kg, so it is the mass of the FreePostureMove by default.
> > > > >
> > > > > Now I have run your model and it appeared that the Gluteus
> > muscle
> > > > > forces are not zero. So my guess is that you was probably
not
> > > > looking
> > > > > at the good output. Of course you have to look at the right
> > side
> > > > and
> > > > > not at the left side. But I’m more thinking about the
> different
> > > > > output in each muscle. There is several force output in
each
> > > muscle
> > > > > folder and the one you should look at are Fm, Ft and Fp.
> > > > > Fm is the force in the contractile element of the muscle.
Ft
> is
> > > the
> > > > > force in the tendon. Those two forces are different when
> using
> > > the
> > > > 3
> > > > > elements model, but as you are using the simple muscle
model
> > > there
> > > > is
> > > > > no difference between tendon or contractile element and
those
> > two
> > > > > forces are equally representing the total muscle force.
> > > > > Fp represents the force of the passive elasticity of the
> muscle
> > > and
> > > > > it is only used for the 3 elements muscle model. In the
> simple
> > > > model
> > > > > there is no passive elasticity so Fp is zero.
> > > > >
> > > > > Best regards,
> > > > > Sylvain, AnyBody Support.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > — In anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com>
ps.com, “knox40” <knox40@> wrote:
> > > > > >
> > > > > > Hallo,
> > > > > > -----------------
> > > > > > first of all a short questions:
> > > > > >
> > > > > > The body mass of the whole gait3D model (legs + upper
body
> > > part)
> > > > is
> > > > > > 64,9 kg (649 N)whereas the FreePostureMove model is 75 kg
> > (750
> > > > N),
> > > > > > right?
> > > > > > -----------------
> > > > > >
> > > > > > My goal is to determin the hip resultant force and the
hip
> > > muscle
> > > > > > forces (especially the Gluteus Minimus/Medium/Maximus,
> > > Piriformis
> > > > > and
> > > > > > Tensor Fasciae Latae etc.)for different postures and
again
> if
> > > one
> > > > > > muscle will be suppressed to see the differences.
> > > > > >
> > > > > > So far I have changed the FreePostureMove model to a one
> > legged
> > > > > stance
> > > > > > model. The hip resultant force with about 2000 N is
> > reasonable
> > > > > (2000
> > > > > > N / 750 N = ~2.7 Body weight). Unfortunately by looking
at
> > the
> > > > > muscle
> > > > > > forces especially at the abductors (Gluteus Minimus 1-3
and
> > > > Medius
> > > > > 1-
> > > > > > 3) they are all about zero. How can this be as the
> abductors
> > > are
> > > > > > mainly responsible to keep the pelvis in ballance? Former
> > > studies
> > > > > > revealed that the hip joint is charged with about 5/6
Body
> > > weigth
> > > > > > (body weight minus standing leg) and a lever arm
depending
> on
> > > the
> > > > > > posture (position of the COM). The only possibility to
> > > withstand
> > > > a
> > > > > > moment on the hip joint are mainly the abductors on the
> other
> > > > side
> > > > > > with the lever arm from the greater trochanter to center
of
> > the
> > > > hip
> > > > > > joint. It is impossible that they are zero as in my
model…
> > > > > >
> > > > > > What is wrong with my model?
> > > > > >
> > > > > > I’ve attached my model in the file folder as
> > > > > >
> > > > > > OneLegStand_Model1.zip
> > > > > >
> > > > > > Maybe you can have a look at it to give me a judgement
what
> > > could
> > > > > be
> > > > > > wrong. Do I have to change the solution algorithm to
> > > > AnyMuslceModel
> > > > > > where all muscles have constant strength ?
> > > > > >
> > > > > >
> > > > > > Thank you for your help.
> > > > > >
> > > > > > Best regards
> > > > > >
> > > > > > Thomas
> > > > > >
> > > > >
> > > >
> > >
> >
>

[Non-text portions of this message have been removed]