Thumb muscles

[Krishnakumar Sankar]

Hai
I would like to see the effect of FPL by cutting off the APL muscle strength and vice versa.So if I cut off a muscle strength by zeroing the isometric force of the muscle,the particular movement (say flexion ) should not happen when i adjust the flexion coordinates or instead the joint should be loosened.What should be done for this to happen because if i adjust the flexion movement of thumb after cutting off FPL strength,the movement happens normally.Could you suggest a method to achieve this.



Thank you

[Thomas Uchida]

So if I cut off a muscle strength by zeroing the isometric force of the muscle

This strategy might be problematic, depending on which OpenSim Tool you're using (e.g., an optimizer would see no difference between excitations of 0 and 1 for this muscle, which may violate an assumption that was made by the developer). Safest would be to remove the muscle entirely.

if i adjust the flexion movement of thumb after cutting off FPL strength,the movement happens normally.

How are you generating your simulation? Note that the Coordinate sliders in the GUI set the generalized coordinates (e.g., thumb joint angle) of the model directly, so you won't see a difference there. You probably want to use the Forward Tool. See, for example, the "Simulation-Based Design to Prevent Ankle Injuries" page in the Confluence documentation (https://simtk-confluence.stanford.edu:8 ... e+Injuries).

[Krishnakumar Sankar]

How are you generating your simulation?

Inverse dynamics simulation would solve the purpose ?

[Thomas Uchida]

Inverse dynamics simulation would solve the purpose ?

Based on your original post, it sounds like you wish to study how a movement will change when a muscle is disabled. The motion is an input to the Inverse Dynamics Tool, not an output. Please see the "Getting Started with Inverse Dynamics" page in the Confluence documentation for more information about the ID Tool (https://simtk-confluence.stanford.edu:8 ... e+Dynamics).

[Krishnakumar Sankar]

Static optimization of a muscle before filter and after filter produces entirely different range of muscle forces.Probably after using the filter at 6 Hz,the results are sensible.What could be the possible reason.Thanks in advance

[Thomas Uchida]

You haven't indicated what you're filtering; I will assume you're using the "Filter coordinates" box in the GUI. Without filtering, the kinematics could be noisy with large accelerations, which would require large forces to produce.