In order to minimize the movement artifacts, the subjects were asked to sit on the dynamometer chair in a comfortable position and seat belts were used to stabilize trunk, hips and thighs. To align knee rotation axis with the dynamometer rotation axis, lateral epicondyle of the femur was set as the bone reference. Sitting position of subjects allowed free and comfortable knee flexion and extension, with a range of motion set at 80° measured from the maximum knee flexion.