Original scientific paperIn biomechanics, how the movements of living creatures are controlled by engineering methods and the effect of the force system formed on the carrier elements during a movement are examined. In addition, treatment methods are tested and developed by examining the stress conditions on the tissues. Sitting on a chair (SOC) seems like a very simple part of life, but it is actually an extremely complex chain of movements. It is the kinematic and kinetic analysis that forms the basis of the sitting on the chair analysis. Angular displacements and velocities of limbs are evaluated as kinematic analysis, joint forces, moments, energy and forces are evaluated as kinetic analysis in sitting on chair analysis. In this study, it was aimed to investigate sitting movement by making kinematic and kinetic analysis of a human lower extremity. In this direction, a solid model of the lower extremity was designed by means of the SolidWorks software. A human consists of lower extremity, hip, thigh (upper leg), knee-calf (lower leg) and foot limbs. The data obtained from this solid model has revealed what kind of stresses on which parts of the limbs and joints of the lower extremities are exposed.