Muscle analysis and probe reporter

[suparna dey]

Hi everyone,

I am trying to analyze the effects of a passive ankle and want to use the muscle analysis and probe reporter routine of Opensim. I have data from an able-bodied subject. Now if I replace the ankle angle in the kinematics file with all zeros and keep everything else (all other joint angles, and ground reaction forces) the same and compute the muscle analysis, will it be a good estimate of how having a passive ankle would affect the subject's muscle forces?

I am aware that in reality, if the ankle becomes passive, there would be compensatory motions that would also affect the intact side kinematics and grf which would not be reflected in this simple modeling. But I just wanted to know if this can be an "ok" approximation of the goal.

Also, how should one interpret the output of the muscle analysis routine w/o external loads? I just tried running the muscle analysis w/o external loads and get some values populated in the output file. How are these computed from only IK and no force files?

Thanks and Regards