Measuring and comparing the base of support and movable range of center of gravity

Abstract

We measured the center of foot pressure (CFP) path on a center of gravity (COG) sway measuring plate in a task moving COG to its maximum limit in the standing position. We took the area encompassing the COFP path as the movable range of COG. At the same time, we traced the impression of the feet on graph paper and measured the area of the base of support. The object of this study was to investigate the possibility of using these parameters as an assessment of balance control ability. The subjects were 20 young men (13) and women (7). They stood on top of a sheet of graph paper spread on a COG sway measuring plate, and after the shape of the feet had been traced, they performed the prescribed movements. The area of the base of support was calculated from the graph of the foot trace. The area inside the perimeter of the COG sway was adopted as the movable range of COG. Two standing positions, legs together and 10 cm apart, were also employed. With legs together, the area of the base of support was 373 ± 38.5 cm2 and the movable range of COG was 105.7 ± 18.2 cm2. With legs apart, the respective values were 602.9 ± 54.2 cm2 and 187.3 ± 21.2 cm2. The ratios of movable range of COG and base of support area were 28.4 ± 4.2% with legs together, and 31.3 ± 4.3% with legs apart. Accordingly, we consider that these parameters could be used as an index for assessing balance control ability.