Joint Reaction tool with force file

[Mohammadreza Rezaie]

Dear experts,

I have a question about joint reaction analysis with force file in Analyze tool. Does this method require muscle fiber force or fiber force along tendon? I think the second one should be the case.

I followed Joint Reactions Analysis docs and its webinar and saw that the static optimization force output was explicitly used as an input to calculate joints contact force. So, does this force file contain muscles fiber force along tendon?

Thank you,
-Mohammadreza

[Carmichael Ong]

Since kinematics are also prescribed, it should be possible to calculate the force along the tendon from the fiber force. My guess is that it's likely that this is occurring under the hood.

[Mohammadreza Rezaie]

Thanks for your clarification. It's good to know how tools are working. I wonder if you could provide such information on your confluence docs; because users may use Joint Reaction tool with a force file generated by other OpenSim tools or workflows (e.g., custom static optimization practice). Thank you.