ABSTRACT
BACKGROUND: There are many methods for studying the somatotype of adults or children. Among them, Heath-Carter somatotype method is a comprehensive evaluation method. Using this method, 10 items of anthropometric indicators are selected and 3 factors which could be gotten to represent relative content of body fat, growth degree of skeletal muscle and relative height and thinness of body (relative line degree), are calculated, respectively.OBJECTIVE: To analyze the rules and characteristics of somatotype development in Dong students from Hunan province, so as to supplement the essential data for physical anthropology.DESIGN, TIME AND SETTING: A cross-sectional investigation was performed at the Department of Biological Engineering, Huaihua College of Hunan Province in May 2006.PARTICIPANTS: A total of 989 Dong students (boys 492, girls 497), aged 7 to 17 years, were selected from the primary schools or middle schools of Tongdao Dong Nationality Autonomous Country in Hunan province and recruited into the present study. All the selected students were verified healthy by physical examinations at school. The subjects were divided into two groups by gender, and each group was divided into 11 subgroups according to the age.METHODS: By Heath-Carter somatotype method, 10 anthropological indexes were measured. Each indicator was measured twice and the average value was selected. The above-mentioned data were input into the computer to form a database. The following indicators were calculated in turn: 3 factors on somatotype, coordinate values of X and Y on somatotype chart, mean of dimensional distances from the average somatotype to all somatotypes in the sample, difference between the two somatotypes in three-dimensional space and frequency distribution of each somatotype.MAIN OUTCOME MEASURES: Height, body mass, upper arm circumference, calf circumference, intracondylar diameters of humerus and femur, skinfold of brachial triceps, subscapular skinfold, skinfold of anterosuperior iliac spine, skinfold of gastrocnemius muscle.RESULTS: All 989 students were included in the final analysis. The dynamic range of the average value of endomorphic factor was 1.2-1.9 and 1.3-4.1, and that of mesomorphic factor was 4.2-5.1 and 1.9-3.0, and that of ectomorphic factor was 2.8-3.7 and 2.6-3.9 for the boys and the girls, respectively. Statistical analysis revealed that there was significant difference in the average value of mesomorphic factor by gender in each age (P＜0.05-0.01). The average endomorphic factor of the girls was obviously higher than that of the boys in each age (P＜0.01) except 7 to 11 years old. The average ectomorphic factor of the girls was higher than that of the boys before 13 years old and it was contrary after 13 years old. There was significant difference of average ectomorphic factor between beys and girls only in 9,11 and 15 to 17 years old (P＜0.05-0.01). The results of t-test showed that there was significant difference for the somatotypes by gender in each age (P＜0.05-0.01). The distribution of girl somatotype demonstrated a dynamic process from 7 to 17 years old, which demonstrated balanced mesomorphy-ectomorphy changed to balanced ecdomorphy, ectomorphy-ectomorphy, balanced endomorphy-ectomorphy and balanced endomorphy in turn. But distribution of boy somatotype was relatively stable, and average somatotype was mesomorphy. Cluster analysis revealed that there was obvious difference of congenital somatotype between Dong students and other 9 populations. During puberty, the somatotype feature of Dong boys was more close to that of Korean boys (SAD=0.37), but which was more far to that of Han boys in the city (SAD=2.15). The somatotype feature of Dong girls was more close to that of Zhuang girls (SAD=0.71), but which was more far to that of Korean girls (SAD=2.35) and Miao girls (SAD=2.10).CONCLUSION: The congenital somatotype of Dong students has its unique characteristics. There is obvious difference in somatotype characteristics between boys and girls.