model states from static optimization (SO) for muscle analysis

[Israel Luis]

Hi,

I am a new Ph.D. student and try to analyze the muscle states: tendon and fiber force, in walking by performing static optimization (SO). For such a purpose, I wanted to use the MuscleAnalysis from the Analyze tool. This tool asked me to input "control" and "states" but the SO does not provide me with a state file (only force, activation and control). On the other hand, I wanted to obtain this file but using the statesReporter from the Analyze tool but it also asked me for a state file. Therefore, I would like to ask you guys:

Do you know how I can get the state file from SO so I can use it to perform the MuscleAnalysis?

I can also use CMC (which provides both files: control and states) but I just want to know if there any way to use the SO and MuscleAnalysis together.

Any comments will be appreciated. Thank you!

[Carmichael Ong]

Static optimization uses the "rigid tendon" assumption, so the tendons won't change length. On a high level, if you are trying to analyze muscle-tendon mechanics, this assumption may not be a good one depending on the motion you're studying (i.e., ones where you expect tendon length to chnage a lot). If so, you may want to stick with CMC anyways.

If you're still interested in using the static optimization results, you can use the controls file from static optimization to fill in "Controls", and instead of using "States" use "Motion" instead and use the "From file" option to input the same kinematics used for static.