Objective: To elucidate age and sex specific characteristics in fat free mass (FFM) among middle and high school adolescents in Yinchuan City, China, and to provide a scientific basis for healthy development, chronic disease prevention and intervention in children and adolescents. Methods: Using a convenient cluster sampling method, 1 175 middle and high school adolescents, aged 10 to 20 years old, from Yinchuan, China, were selected to participate in a questionnaire survey and physical examination, which involved body composition by bioelectrical impedance analysis(BIA). Results: For adolescents aged 12 to 18 years, FFM and the fat free mass percentage (FFMP) of boys increased with age(from 39.78 to 52.63 kg; 77.51% to 83.80%, respectively), the age trends of the FFM and FFMP of body parts were in the similar pattern, and were significantly higher than those of girls(all P <0.05). In girls, the FFM reached a peak of 40.96 kg at 15 years old, and decreased slightly between the ages of 15 and 18 years, the age trends of the FFM of body parts were in the similar pattern, and the FFMP decreased with age (from 75.63% to 71.91 %). In addition, in girls, the age trends of the FFMP of left and right legs were the same as the general trend, while the FFMP of left and right arms increased with age. The FFMP of the trunk reached a minimum of 29.93% at 15 years old and increased from 15 to 18 years old(all P <0.05). Conclusion For middle and high school adolescents aged 12 to 18 years old in Yinchuan City, China, the distribution of FFM changed in accordance with age and gender differences, in accordance with the characteristics of the adolescents growth and development.

Objective To assess the prevalence of dyslipidemia among children and adolescents aged 6-18 years in Yinchuan.Methods A stratified,random cluster sampling was used to select a target samples (1 939 cases) of children from elementary schools,middle schools and high schools in different age groups,with medium economic status.The levels of serum total cholesterol (TC),high-density lipoprotein cholesterol (HDL-C),low-density lipoprotein cholesterol (LDL-C),and triglycerides (TG) were measured.Results The prevalence of total dyslipidemia was 15.5 ％ (300/1 939 cases).The prevalence of high TG,high TC,high LDL-C,low HDL-C,high non-HDL-C and hyperlipemia were 5.8％ (113/1 939 cases),0.8％ (18/1 939 cases),1.1％ (21/1 939 cases),10.6％ (205/1 939 cases),0.9％ (18/1 939 cases) and 6.4％ (124/1 939 cases),respectively.Boys were more likely to have dyslipidemia than girls (17.7％ vs.13.3％) and a low HDL-C level (13.1％ vs.8.2％),and the differences between 2 groups were statistically significant (x2 =7.178,P =0.007;x2 =12.337,P ＜ 0.001).Individuals aged 16-18 years had the highest prevalence of total dyslipidemia [19.1％ (89/466 cases)] than other age groups,and the difference was statistically significant(x2 =11.393,P ＜ 0.01).Prevalence of dyslipidemia among the obese,the overweight and the normal weight individuals were 39.7％ (69/174 cases),20.8％ (60/289 cases) and 11.6％ (171/1 469 cases),respectively.Moreover,prevalence of dyslipidemia increased significantly with gravity of obesity,and the difference was statistically significant(x2 =100.180,P ＜ 0.01).Individuals with abdominal obesity had higher prevalence rates of dyslipidemia than that of the non-abdominal obese individuals [31.5％ (92/292 cases) vs.12.6％ (207/1 064 cases)],and the difference was statistically significant (x2 =67.578,P ＜ 0.01).Approximately 39.7％ (69/174 cases) and 31.5 ％ (92/292 cases) obese individuals and abdominal obesity were candidates for taking intervention measures including nutritional counseling,school-based lifestyle as well as community fitness programs.Conclusions Screening and prevention should be regarded for dyslipidemia among children and adolescents,especially for boys and teenagers in Yinchuan.

Objective: To analyze the differences of cardiovascular(CV) risk factors between middle school students with normal weight but high body fat and students with normal weight and normal body fat in urban area of Yinchuan,to provide a theoretical basis for early detection of their invisible obesity and controlling CV metabolism disease. Methods: During 2017 to 2018, a total of 1 043 secondary school students in urban area of Yinchuan were selected through cluster sampling. Questionnaire survey, physical examination, body composition and blood lipid test were conducted among all the participants.745 middle school students with normal body mass index (BMI) were included in the analysis. Results: Nearly 31.1% students with normal BMI had high body fat, with girls significantly higher than that in boys across different age groups(χ2=10.37，106.49，P<0.01). Total cholesterol (TC) in boys with normal-weight obesity was higher than that in the normal group, while diastolic blood pressure (DBP), triglyceride (TG), TC and lowdensity lipoprotein cholesterol (LDL-C) in girls with normal-weight obesity were significantly higher than that in the normal group, with statistically significant differences (t=-2.37，-3.82，-3.48，-4.46，-4.68，P<0.01). The detection rates of high blood pressure, high TC level and high LDL-C level in normalweight obese girls were all higher than those in normal group (χ2=4.17，8.77，5.91，P<0.05). The detection rate of CV risk factors ≥2 in normal-weight obesity group was higher than that in the normal group, and the difference was statistically significant(χ2=7.05，P<0.01). Conclusion Normal-weight obesity among middle school students in urban area of Yinchuan is prevalent, which is mainly concentrated in female students. Moreover, cardiovascular risk factors are more common among those normal-weight obese students compared with normal students. Interventions for preventing and controlling normal-weight obesity should be developed and implemented as early as possible.

Objective: To analyze the interaction of fat mass (FM) and fat free mass (FFM) on the aggregation of cardiovascular disease risk factors (CVRFs) among children and adolescents in Yinchuan City, China, so as to provide scientific basis for the prevention of CVRFs and cardiovascular disease in children and adolescents. Methods: A total of 1 822 children and adolescents aged 12 to 18 years in Yinchuan City were randomly selected for questionnaire survey, physical examination, body composition assessment and laboratory tests, through a cluster sampling method from 2017 to 2020. Binary Logistic regression was used to analyze the relationship between FM, FFM and the aggregation of CVRFs, and their interaction was analyzed. Results: After adjusting for sex and age, the risk of having CVRFs aggregation ≥1 in high FM and low FFM group and high FM and high FFM group was 2.01(95% CI =1.46-2.77) and 3.64(95% CI =2.66-4.98) times higher than that in low FM and low FFM group, and the risk of having CVRFs aggregation ≥2 was 1.67(95% CI =1.06-2.63) and 4.20 (95% CI =2.76-6.38) times, respectively( P <0.05). There was a multiplicative interaction between FM and FFM, which increased the risk of CVRFs aggregration ≥1 and ≥2. The adjusted OR and 95% CI were 1.58(1.04-2.40) and 1.95(1.12-3.42), respectively( P <0.05). Conclusion The results indicated the additive and multiplicative interactions between high levels of fat mass and fat free mass on the aggregation of cardiovascular risk factors, which increased the risk of aggregation of cardiovascular risk factors.