The relationship between obstacle height and center of pressure velocity during obstacle crossing.

This study was performed to investigate the effect of obstacle height on the COP velocity when negotiating obstacles. Seven healthy female subjects were instructed to perform unobstructed level walking and to step over obstacles corresponding to 5%, 10%, and 15% of their height. The Parotec system was used to collect plantar foot pressure data. There were no significant differences in COP velocities for different obstacle height in the loading response phase. For mid-stance the COP velocity decreased as obstacle height increased. For pre-swing the COP velocity of the leading foot increased as obstacle height increased. For the trailing foot, there was a quadratic decrease in the COP velocity from 15.7 cm/s during unobstructed level walking to 12.1 cm/s when stepping over the obstacle of 15% body height. Thus, COP velocity during stance phase prior to obstacle crossing appears to be regulated for the presence of different obstacle heights.