I previously thought for a muscle cross 2 DOF or more, one DOF's changing would affect the other DOF's moment arm. For example, take muscle "rect_fem_r" in 3DGaitModel2354.osim, Y-Quantity is "hip_flexion_r moment arm", X-Quantity is "knee_angle_r", there is slight change in moment arm with the chan...

A second possible explanation is that the muscle crosses more than one degree of freedom and one or more of these other angles differ between the two models. The osim model is "MoBL_ARMS_module2_4_allmuscles.osim". I sampled 60 times in both 'elv_angle' and 'elbow_flexion' ranges. The testing muscl...