A specific half squat motion is analyzed as a planar movement. Experimental data about this motion are recorded with a motion capture device and two force plates. Joint torques are estimated with-a 3D Opensim model and a sagittal Matlab model. Torque variations from the two models are consistent even if the magnitudes of the corresponding variables differ. These results are attributable to the different anthropometric tables which the two models are based on. Another strategy developed here consists in estimating joint torques without the measured ground reaction forces. In that case, global vertical reaction force is well estimated. The use of the sagittal Matlab model is an efficient way to preliminarily analyze squat trajectories. The next step in this work is the study of the influence of the load represented by the weight of a knee prosthesis.