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Simulated muscle forces provide crucial knowledge for rehabilitation and training exercise design. To accurately simulate the internal loading conditions, input kinematics of the skeletal structures without soft tissue artefact (STA) are required. The aim of this study was to evaluate the ability of two numerical approaches to reduce STA for squat kinematics. Squat repetitions of 6 elderly subjects were examined using skin markers and video-fluoroscopy. Kinematic analysis was performed with a segmental and musculoskeletal simulation approach and compared to fluoroscopic data. The averaged RMS errors relative to the maximum knee range of motion were 8.8%, 32% and 49% for flexion/extension, ab-/adduction, and internal/external rotation, respectively. Skin marker based underestimation of the flexion angle could be corrected with a linear factor of 1.15.