Objective: The development status and characteristics of height and weight of Japanese, Han and Mongolian students aged 7-18 years in Inner Mongolia in 2014 were analyzed, to explore the ethnic differences in the maximum growth age of height and weight. Methods: The height and weight data of Chinese Han nationality and Mongolian students were from the "2014 survey on the physical fitness and health of students in Inner Mongolia autonomous region". Data on Japanese students were obtained from the "statistical information of the Heisei 26 annual sports survey" of Ministry of Education, Culture, Sports, Science and Technology-Japan. The total increase in height and weight, the average increase in height and weight, and the maximum age of growth were calculated, and the ethnic differences of each index were examined. Results: The average height of Han urban boys was 3.02 and 4.09 cm higher than that of Mongolian and Japanese, the height of Han urban girls was 2.34 and 3.99 cm higher respectively. The average height of boys and girls in rural areas of the Han nationality was 1.26 and 1.69 cm higher than that in Japanese (P<0.05). The average weight of urban Han boys was 2.36 and 5.92 kg higher than that of Mongolian and Japanese, Mongolian was 3.55 kg higher than Japanese. The average weight of Han and Mongolian urban girls was 4.12 and 3.99 kg higher than that of Japanese. The average weight of Han and Mongolian boys in rural areas was 2.48 and 1.55 kg higher than that in Japan. The weight of girls in the Han and Mongolian in rural was 1.53 and 2.24 kg higher than that in Japan respectively (P<0.05). Among the three ethnic groups, urban han boys(10.52 years old), urban Japanese girls (9.69 years old), rural Japanese boys (11.51 years old) and rural Japanese girls (9.71 years old) appeared earlier than other ethnic groups in the maximum growth age of height. In terms of maximum growth age of weight, Han urban boys (10.33 years old), Japanese urban girls (9.62 years old) and Japanese rural boys (11.44 years old) appeared the earliest in three nationality, and the maximum growth age of weight in the three ethnic rural girls (10.31-10.80) was basically the same. Conclusion Han and Mongolian students at the age of 7-18 years were obviously superior to Japanese students in terms of growth and development level of height and weight. The maximum growth age of height and weight of urban Han boys was 1.07 and 1.16 years earlier than that of Japanese, while that of rural Han boys was 0.90 and 0.96 years later. And maximum growth age of height and weight of rural Han girls was about 0.49-0.80 year later than that of Japanese.

Objective: To analysis the relationship between obesity types and exercise capacity among Mongolian primary school students, to provide evidence supporting the formulation of strategies to promote students physical fitness. Methods: A total of 7 941 Mongolian students aged 7-12 years in the Inner Mongolia Autonomous Region were selected, and data were collected from a field survey conducted by the National Physical Fitness and Health Survey in 2019. According to overweight and obesity screening of school aged children and adolescents, and the waist height ratio, obesity status was classified into general obesity, central obesity and complex obesity, relationships among obesity type, exercise ability and PFI. Results: The prevalence of obesity was 23.5%, 28.2%, 16.3% and 16.5% in boys and girls 7-9 and 10-12 years of age, respectively. The prevalence of obesity was higher in boys than girls( P <0.05). The detection rate of compound obesity in boys and girls was highest (15.6%, 9.2%; 18.4%, 8.2%), and the detection rate of compound obesity and central obesity in boys was higher than that in girls( P <0.05). The performance in the non obese boys and girls (on the basis of standing long jump, sit up and 50 m×8 round trip running in boys, and 50 m running, standing long jump, sit up and 50 m×8 round trip running in girls) was better than that in the obese groups( P <0.05). There were statistically significant differences in the median PFI of non obesity, general obesity, central obesity and compound obesity between boys and girls in the two groups of 7-9 and 10-12 years old (boys: H =79.23, 241.42; girls: H =61.94, 74.38, P <0.01). Conclusion The proportion of compound obesity among Inner Mongolian primary school students was relatively high, and the exercise capacity was relatively low. Specific measures should be taken to effectively control the occurrence and development of adolescent obesity.

Objective: To identify the 24-hour time allocation patterns of Mongolian junior school students, and to clarify the nature and degree of the influence of the time allocation patterns on the physical fitness of junior school students, so as to provide reference for optimizing and improving the scientific allocation of activity time of young students. Methods: In October 2022, 1 389 Mongolian junior school students aged 13-15 from four schools in Xing an League of Inner Mongolia Autonomous Region were selected with stratified cluster sampling method. The 24-hour time utilization of students were collected by using the questionnaire of "China Time Utilization Survey (CTUS) Time Log in 2017" from October 21 to 22, 2022, and physical fitness was evaluated by using the test data of the National Student Physical Health Standard from September to November 2022. Students time allocation patterns were determined by Latent Profile Analysis with Mplus software, and the correlation between the time allocation patterns and the physical fitness was analyzed by multiple linear regression. Results: The time allocation patterns of Mongolian junior school students could be classified into four types:learning type, screen type, diversity type, and sports type, and the population distribution were 24.7%, 18.3%, 9.9% and 47.1%, respectively. Among all gender and age groups, the sports type received highest total score physical fitness, followed by diversified type, learning type, and screen type ( F =72.25-154.94, P <0.01). The results of multiple regression analysis showed that gender, age, and time allocation patterns were significantly related to the total score of physical fitness ( P < 0.05 ). The total score of physical fitness in learning type, diversity type and sports type groups were all higher than that of screen type ( β =5.63, 12.86, 18.03, P <0.05). Moreover, the sports type showed highest effects on the total score of physical fitness, followed by the diversity type and learning type ( B =0.72, 0.31, 0.19, P <0.05). Conclusions There is a significant correlation between time allocation patterns and physical fitness of Mongolian junior school students, and those in sports type and diversity type of time allocation achieve better physical fitness, while those in learning type and screen type of time allocation shows relatively poorer physical fitness.In order to promote students physical fitness and healthy development, it is suggested to scientifically arrange students time allocation, increase physical activity time, and reduce sedentary activities that are detrimental to health.