Relationship between feet position and anteriorposterior center of pressure (COP) location - What are the determining factors in the adjustment of center of gravity? -

Abstract. [Purpose] The purpose of this study was to examine the locus of the center of pressure (COP) of standing postures with different feet positions. [Subjects] Sixty healthy young adults participated in the experiments as subjects. [Methods] The COP was measured using a force plate. Subjects stabilized themselves on the force plate, and the change of the COP trajectory was measured for 30 s. The COP was measured in three standing postures: wide-base, tandem, and one-foot standing. The relative center of anterior-posterior sway was examined as a proportion of the base of support length. [Results] Using one foot length, l, measured from the heel to the toe of the foot as a standard, the mean of the center of anterior-posterior sway was 44.5 ± 5.5% of l in the wide-base stance, 50.2 ± 4.4% of l in the one-foot dominant stance, and 50.4 ± 4.3% of l in the one-foot non-dominant stance. Since the length of the feet is 2l in the tandem posture, the mean of the center of anterior-posterior sway was 41.0 ± 7.0% of 2l with the dominant foot in front and 41.5 ± 6.0% of 2l with the non-dominant foot in front. [Conclusion] The mean of the center of anterior-posterior sway was inclined toward the anterior position in single leg standing compared to the wide base standing. In tandem standing, the COP was located on the rear foot. The results of this study might be useful in considering the mechanism of postural control of patients with hemiplegia.