Muscle Analysis showing muscle fiber lengths not changing during landing task

[Kenneth Smale]

Hello,

I am using a modified Rajagopal model that replaced the Walker knee with a 6 dof customized joint. I ran CMC on the RRA results and found that certain muscles were not being activated during a landing task. I then ran a muscle analysis and discovered that these muscles were not lengthening or shortening throughout the trial. I have attached one figure of the sagittal hip, knee, and ankle kinematics to show that since joint coordinates are changing, a change in fiber lengths would be expected. I have also included a plot of normalized fiber lengths.

Has anyone come across this issue? If so, any guidance to share?

-Kenneth