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Hi there,

I have a data set of muscle volume information as well as joint kinematic data on the same subjects. I am looking to model this information into the OpenSim model to determine how the muscle volumes impact kinematics. I have been reading through some previous forums to see if anyone has done anything similar but cannot seem to figure out how I could input that muscle volume information.

Some of the research has indicated that I can change the max isometric force to account for muscle mass but just curious to see if anyone has figured this out!

Changing the maximum isometric force is one way to model changes due to differences in muscle strength. It's one of the properties in an OpenSim model, and it can be derived from other muscle properties, such as muscle volume, optimal fiber length, specific tension, and pennation angle.

A few resources that could be useful to dig into:
- OpenSim Muscle documentation
- Lectures from the Biomechanics of Movement course, and in particular 5.3 Muscle Architecture
- The Rajagopal model paper, which updated parameters of the muscles based on muscle volume data from MRI

I have a github repo that shows how to use muscle volume to scale max isometric force. My use-case was using the Handsfield regression equations that predict muscle volume from height and weight but you should be able to pretty easily adapt the code to your data!

https://github.com/johnjdavisiv/scale-muscle-strength