Displacement of the pelvis during human walking: experimental data and model predictions

Displacements of the pelvis during treadmill walking were studied in dependence of walking speed, stride frequency and stride length. Displacement curves per stride cycle were described by means of harmonic analysis. Simple mechanical, or geometrical models of the bodyʹs center of mass (COM) tajectory during walking were used to predict amplitude and timing of pelvic displacements. As predicted by inverted pendulum models, the amplitude of pelvic displacement in vertical direction depended on stride length. Anterior-posterior displacements were predicted by assuming equal maxima of potential and forward kinetic energy of the body. Predictions for left-right displacements were based upon a model that assumed a constant stride width and a sinusoidal movement pattern. In agreement with this model, the amplitude of pelvic displacement in left-right direction depended on stride frequency. The presented models give insight into mechanical mechanisms which determine the pelvic trajectory during walking. The presented data may be useful in the clinical evaluation of gait disturbances.