Prediction of antagonistic muscle forces using inverse dynamic optimization during flexion extension of the knee

This paper examined the feasibility of using different optimization criteri a in inverse dynamic optimization to predict antagonistic muscle forces and joint reaction forces during isokinetic flexion/extension and isometric ex tension exercises of the knee. Both quadriceps and hamstrings muscle groups were included in this study. The knee joint motion included flexion/extens ion, varus/valgus, and internal/external rotations. Four linear, nonlinear, and physiological optimization criteria were utilized in the optimization procedure. All optimization criteria adopted in this paper were shown to be able to predict antagonistic muscle contraction during flexion and extensi on of the knee. The predicted muscle forces were compared in temporal patte rns with EMG activities (averaged data measured from five subjects). Joint reaction forces were predicted to be similar using all optimization criteri a. In comparison with previous studies, these results suggested that the ki nematic information involved in the inverse dynamic optimization plays an i mportant role in prediction of the recruitment of antagonistic muscles rath er than the selection of a particular optimization criterion. Therefore, it might be concluded that a properly formulated inverse dynamic optimization procedure should describe the knee joint rotation in three orthogonal plan es.