The purpose of this study was to attain information about body proportion changes in Japanese girls. The data are collected from annual health examination surveys conducted under the supervision of school health care teachers. A longitudinal data set spanning from the first grade of elementary school (6.5 years of age) through the 3rd grade of high school (17.5 years of age) was extracted from serial surveys. A total of 306 female subjects were observed for 12 consecutive years. A body proportion chart (BPC) containing the scales for stature, sitting height, lower limb length and lower body-upper body segment ratio (LUR＝lower limb length×100/sitting height) in a single graph was developed. The sitting height and lower limb length were graphed on the chart, where the sitting height is the x-axis and the lower limb length is the y-axis.
In the chart, the growth curve transited slightly convexly, indicating that the LUR constantly increased from 6.5 years to the terminal stage of the peak height velocity. The large increment rate of the height is recognized to be between 9.5 and 11.5 years of age. After 13.5 years, the increment rate of the sitting height and leg length is diminished and the plots in the chart are clustered close together. The maximum values of the LUR were attained between 11.5 and 14.5 years of age (85.4 - 85.7).
The periods when the LUR attained peak value are coincident to the terminal stage of the peak height velocity. During two years of the peak height velocity (from 9.5 to 11.5 years of age), the sitting height and lower limb length quickly grew, suggesting that these two variables commonly contributed to the growth spurt in height although the lower limb length was slightly dominant.
After attaining the maximum value of the LUR, the growth of the lower limb length stagnated although the sitting height still increased. Consequently, the LUR starts to decrease after 13.5 years of age.
