Evaluate moment arms

Main Forum
1

Good morning,

I want to evaluate the muscle moment arms.
I turn on the “EVALUATE MOMENT ARMS 1” in “…\AAUHuman\BodyModels\GenericBodyModel\BodyModel.any” . Unfortunately I didn’t get any results.

Thank you for your answer.
Best regards,
Justyna

2

Dear Justyna,

I will explain this based on our ‘StandingModel’ example in the AMMR.

  1. As you could figure out, you can activate the moment arm study by declaring ‘#define EVALUATE_MOMENT_ARMS 1’ in the ‘StandingModel.Main.any’ file.

  2. Then you can see the folder ‘EvaluateMomentArms’ in the Operations tree and the Model tree.
    Main.HumanModel.EvaluateMomentArms

  3. You should go into each degree of freeom which will be related to your moment arm analysis.
    For instance, let’s try the KneeFlexion in the right leg.
    Then you can find the following study -> Main.HumanModel.EvaluateMomentArms.Right.Leg.KneeFlexion.Study
    If you can find this, just try to execute it.

  4. Let’s try to go to the Model tree.
    Then let’s find the following folder: Main.HumanModel.EvaluateMomentArms.Right.Leg.KneeFlexion.Study.Output.MomentArmCalculations
    Under this folder, you can see a lot of muscle names.
    But some of those values will just include zero values because those muscle are not related to that degree of freedom.
    For knee flexion, for instance, VastusLateralis and VastusMedialis muscles will have non-zero moment arms.

I hope this will be helpful to you.

Best regards,
Moonki

3

hi
i tried to active #define EVALUATE_MOMENT_ARMS 1 in main but if i add it before Main {…} this eror : Documentation Comment error : Prefix Documentation Comment is not followed by an object or class template is mine and if add it after :
Main {
#define EVALUATE_MOMENT_ARMS 1
…
}
i didn’t any response in software that was similar to your statements:“Then you can see the folder ‘EvaluateMomentArms’ in the Operations tree and the Model tree.
[i]Main.HumanModel.EvaluateMomentArms”

please help me with your kidness.
and if you have any example code about [/i]evaluation of moment arm in AnyBody please send me.

4

Hi,

Could you please try to use that #define statement alone like this?


Main = 
{

...

#define EVALUATE_MOMENT_ARMS 1

...

};

Best regards,
Moonki

5

Hi
thank you for reply, but unfortunately this change in code wasn’t useful,
my software version is “AnyBody version : 4. 0. 2. 697” , is it problem?? and what is solution?
Best regards,
M.D

6

Hi,

I’m sorry to say but we don’t support the models and the problems based on older version of AnyBody Modeling System.

Now the current versions are AMS 6.0.X.

I would like to recommend you to consider to upgrade your AnyBody Modeling System to its latest versions.

Best regards,
Moonki

7

Hi
This would mean my problem is my software version? in that version(4.2) i can’t evaluate moment arm?

Best Regards
M.D

8

Hi,

I’m sorry to say again, but that is not about either software or model issues.

We have our policy that we will support our users who are using relatively recent versions of AnyBody Modeling System.

I hope that you can understand the situation.

Best regards,
Moonki

9

Hi Justyna,

This error: “Documentation Comment error : Prefix Documentation Comment is not followed by an object or class template” is because you have three slashes on a comment line just before the define statement like this: ///.
The three comment lines are documentation comments that will end up in the model tree, and they require the object of the comment to follow right after them. Just delete the comments with the three /// and you will be fine.

1 Like
10

Hello Moonki,

Does the command ‘#define EVALUATE_MOMENT_ARMS 1’ make it possible to evaluate moment arms in the arm? I tried what you’ve said and it only works for the legs. Is there a way to do the same operation for the arm muscles and degrees of freedom?

Thanks,
Brandon

11

Hi Brandon,

It is not availble for the arms yet, but it can be done in the exact same way as for the legs so if you need it, please refer to the way it is done for the legs and then try to do the same.

Best regards
Søren

12

Hi all,

I am using the MoCap_LowerBody model (vers. 6.0.4.).
I was wondering if I can use this command for my model as well?
I can turn it on an dI also find the Evalute Moment Arms study. However, when I run it, the resulting output is why shorter than my usual file.
E.g. my file has 114 frames, but the moment arm seems to be only calculted for 39 frames.
Furthermore, I am wondering abput the resulting values (see Figure, example for soleus medialis 3).

I’d appreciate your help.
Thanks, Nathalie

13

Hi Nathalie

Maybe you misunderstand what the moment arm studies do. The moment-arms studies are completely independent of the trial you are analysing. The different moment-arms studies will move a joint through some range of motion (e.g. hip flexion, abduction, etc.).

If you, for example, choose the hip-flexion study, the output will be the muscles’moment arms for hip flexion as a function of the hip flexion angle.

It is also possible to set posture of other dof when running the moment-arms studies. For the hip flexion study, that is done by modifying HipAbduction, HipAbduction, KneeFlexion, etc. under

Main.HumanModel.EvaluateMomentArms.Right.Leg.HipFlexion

So you could, in fact, recreate a particular posture from you mocap trial, and then investigate different moment arms at that given pose.

14

Furthermore, I am wondering abput the resulting values (see Figure, example for soleus medialis 3).

You should plot the values as a function of the joint angle instead of time.

So change the abscissa to

Main.HumanModel.EvaluateMomentArms.Right.Leg.AnklePlantarFlexion.Study.Output.MomentArmCalculations.Abscissa.JointAngle

That should give you a better picture of what is going on. I have attached a picture. The negative moment arm indicates that soleus is shortening during the plantar flexion movement (i.e. agonistic muscle). Antagonistic muscle like tibialis ant will have positive moment arms. This may change in future releases, as it is a little unintuitive.

Also, note that there is known bug for ankle plantar flexion. It has the wrong sign :frowning: This will be fixed in the next release.

15

Great thanks. Now this makes sense.

Is it also possible to calculate the moment arms of some muscles throughout e.g. one gait cycle?

16

Hi Nathalie,

No this is not so simple, there is currently no easy way to do this

Best regards
Søren