Comparison of Changes in Body Composition during Puberty Development of Obese and Normal-weight Children in China

Objective To compare the changes in body composition, including fat mass index （FMI） and fat free mass index （FFMI） during puberty development of obese and normal-weight children in China, and to explore the effect of age and gender on body composition. Methods A total of 356 children at the age of 7-15 years were enrolled in this study. Body composition of 10 normal-weight and obese children in each age group was measured by dual-energy x-ray absorptiometry （DEXA）. FFMI and FMI were calculated according to the following formula： FFMI （kg·m^-2）=FFM（kg）/ height^2（m^2） and FMI（kg·m^-2）=FM （kg）/ height^2（m^2）. Results The fat mass and fat free mass of obese children were significantly higher than those of normal-weight children （P〈0.05）. The FMI and FFMI of obese children increased significantly with age and were higher than those of the same sex, gender, and age normal-weight children （P〈0.05）. Conclusion The levels of fat mass, fat free mass, FMI, and FFMI are different in obese and normal-weight children, and gender effects are significant in boys having higher levels of these indicators than in girls. FFMI and FMI can be used as monitoring indexes in weight control of obese children.

Investigation of the First Spermatorrhea Age of Males in Jiangsu Province, China

Background: The growth of adolescents is affected by economic development and education levels. We investigated the first spermatorrhea age of adolescents in urban area and in rural area of Jiangsu province, China. Methods: The data were obtained through anonymous questionnaire by using cross-sectional methods. From May 2016 to March 2017 in Jiangsu province, China, a total of 2131 Han nationality students were enrolled in cluster. The survey was contained date of birth, age, grade, age of first spermatorrhea and how long ago of the first spermatorrhea, all data were analyzed by Prism 8.0. Results: The questionnaire accounted for response was 97.3%, and the effective rate was 96.3%. The mean age of first spermatorrhea was (13.7 ± 1.5) years old, which included 13.6 ± 1.4 years in urban and 13.9 ± 1.5 years in rural. The first spermatorrhea occurred in the fifth and sixth grade primary school, and 1, 2, 3 grades of junior high school were 3.5%, 13%, 27.4%, 28.5% and 15.1%, respectively. There was 62.3% of first spermatorrhea occurred in summer. The rate of spermatorrhea with natural occurrence accounted for 95.1%, and with active accounted for 4.9%. Conclusions: Compared with rural area, the age of the first spermatorrhea of males in urban area is significant earlier. The adolescent’s first spermatozoa were mostly occurred in summer. The relevant physical and reproductive education should be started from the third grade of primary school. The reproductive health education should be carried out when the youth are 7 years old.