The impact of changes in gait speed and step frequency on the extent of the center of mass displacements.

Center of mass (COM) trajectory plays a crucial role in the analysis of human body movements. This research aimed at studying vertical and transverse COM displacements during gait on a treadmill at a given velocity and step frequency. Locomotion study was accomplished using: Vicon 250, Cardionics Treadmill 3113 and metronome Korg Ma-30. The data achieved for 12 women and 15 men aged 21-22 revealed similarity in vertical COM oscillations in both groups. Lateral COM displacements (L(COM)) were slightly higher in men than in women and they showed tendency to decrease as gait velocity increased. During natural locomotion there was an increasing trend as walking speed increased. At a given velocity of locomotion L(COM) were decreasing as step frequency increased. The only astonishing thing was that the biggest changes of vertical COM oscillations (V(COM)) were noticed at the fastest walking speed (6 km/h). It seems that so large decrease in V(COM) during walking with high velocity and increased step cadency is a consequence of considerable shortening of the movement cycles and performing time of one step.