STUDIES ON THE SOMATOSCOPIC VALUES OF ELEMENTARY AND JUNIOR HIGH SCHOOL CHILDREN

2. Rohrer's Index and Skinfold Thickness Used as Obesity Index

Abstract

Skinfold thickness (ventral) was measured with 1461 children in total of elementary and junior high school, and Rohrer's index was also computed with them. And change by age distribution of these values were studied, and it was further inquired what significance they would have as an obesity index, with the following results :
1) The mean and the median value of skinfold thickness increased with age in both males and females, and this was especially marked in age of over 10 years. And the skinfold thickness was greater in girls than in boys, and the difference increased with age.
2) The skinfold thickness showed bimodal or trimodal distribution. Thus both in males and females, the first peak of 5-6mm tended to appear in age of 6-9 years, the second peak of 10-11mm in 12-14 years, and the third peak of 15-16mm in 13-14 years. And each distribution was positively skewed toward the higher value, and each showed extremely wide dispersion.
3) The mean and the median Rohrer's index gradually decreased in both males and females as the age advanced from 6 to 9 years. Thereafter they remaind scarcely unchanged in boys but gradually increased in girls until 14 years.
The distribution was nearly normal in 6-7 years of age, but later skewed progressively toward the higher value, thus exhibiting asymmetry. The peak always shifted to the lower value in both males and females as the age advanced from 6 to 12 years, but in 12-14 years it came to be nearly fixed or to shift rather to the higher value.
4) The skinfold thickness and body weight had high correlation, and this was the case even after the elimination of stature's influence. Also skinfold thickness and Rohrer's index had similarly high correlation, and this tendency became more prominent with age.
5) In the evaluation of obesity, it seemed necessary to take into consideration the respective features of skinfold thickness and Rohrer's index, and the author came to a conclusion that the combination of these two in obesity evaluation would remove various irrationalities, and thus offer a more adequate means.
For example, when a subject shows skinfold (ventral) of above 15mm and Rohrer's index of above 160, he can be judged as showing obesity. When, however, the skinfold is above 20mm, the judged of obesity can be formed even when Rohrer's index may be below 160. When the skinfold is below 15mm, the judgedment of obesity can be suspended even when Rohrer's index may be above 160. The details of this point must await future study for full elucidation.