simtk.org

Hey
Is it possible to create an isokinetic motion for a leg model?
I want to simulate an isokinetic legpress motion where i can add ankle torque and knee torqe and plot the active fiber force. Once for an isolated contraction of triceps surae and then for a combined activation of triceps surae and quadriceps femoris to watch if there is an inhibition at the combined motion.
If it helps i also got the EMG data of the muscles.

Regards
Anika

If your experimental motion is isokinetic then an inverse analysis (including static optimization) or a forward simulation that tracks those kinematics (CMC) will also reflect the isokinetic nature of the task, since these methods depend on the experimental motion.

If you wish to perform a forward simulation without experimental data with some ideal a priori knowledge of the kinematics, you can prescribe the motion of coordinates using an OpenSim Function. If you use a LinearFunction to prescribe the coordinate motion its speed will be constant.

In this case, the challenge is to control the muscle. Arnold et al. 2013 (Journal of Experimental Biology, vol 216, pp 2150-2160) used EMG to determine muscle excitations (controls) and compared muscle moments to joint moments from inverse dynamics as a validation. The goal in this case was to examine muscle-fiber operating lengths while prescribing the joint kinematics, but you could examine muscle-fiber forces and work. It may be possible to use CMC with some coordinates prescribed (but then do not have CMC track them).