Relationships among the Height of Unilateral Lower-limb Elevation, Body Movements, and the Location of Center of Pressure When Sitting

Abstract

[Purpose] To clarify the relationships among the height of unilateral lower-limb elevation, body movements represented by spinal and pelvic postures, and the location of center of pressure (COP) when sitting. [Subjects and Methods] Nine healthy males unilaterally elevated their lower limbs to heights of 10, 20 and 30 cm while sitting to analyze their location of COP and spinal/pelvic postures. [Results] The lateral pelvic tilt angle did not clearly change through 10-cm elevation, but it increased in a downward direction toward the non-elevation side through 20- and 30-cm elevation. A lateral trunk tilt toward the elevation side was also observed under the latter conditions. With an increase in the height of lower-limb elevation, the posterior pelvic tilt angle increased on both sides; the increase was more marked on the elevation side. Furthermore, on examining the location of COP in the horizontal direction, it was displaced toward the elevation side through 10-cm elevation and toward the non-elevation side through 20- and 30-cm elevation, compared with its location when sitting without elevation. In the anteroposterior direction, the COP was displaced backwards with an increase in the height of elevation, compared with its location when sitting without elevation. [Conclusion] It may be necessary to consider differences in the characteristics of postural maintenance, according to the height of unilateral lower-limb elevation.