Influence of inertia on intersegment moments of the lower extremity joints.

The calculation of three-dimensional intersegment moments of the lower extremity modelled as a system of rigid bodies-during human locomotion with the help of an inverse dynamics approach is one of the main strategies to describe the local kinetics of a human motion. From the numerical point of view, the resultant intersegment moment consists of different contributions; the moment of ground reaction force, the moment dependent on the weights of the segments and two inertia dependent parts, the moment of inertia force and the rate of change of angular momentum (with respect to the segments centre of gravity). For running with a horizontal velocity of 5 m s(-1), the calculation of the moment of inertia force can be neglected for the ankle but is important for the hip. Looking at the knee, this contribution is needed if the touch down phase is of special interest. The rate of change of angular momentum-with respect to the segments centre of gravity-can be neglected for all joints of the lower extremity.