Objective: To analyze the secular growth trends of the Chinese urban youth from 1979 to 2005, in order to make national intervention strategies and measures to improve their physical fitness and health.
Methods: Subjects were sampled from 16 provincial-capital cities in China. They were all Han primary and secondary school students aged 7 to 18 years. The increments of stature, weight and BMI, and the increments per decade of these indicators at different stages were analyzed.
Results: In recent 26 years, the overall increments were 6.5 and 4.7 cm for stature, and 8.9 and 5.2 kg for weight, for boys and girls, respectively. Swiftest rates were found in the period of 1985-1995, with the increments which were as high as 3.8 and 3.0 cm/decade for height, and 4.7 and 3.1 kg/decade for weight, for boys and girls respectively. These trends are still strong at present, without any tendency of going to the plateau. Advanced puberty plays the most contributing role in these trends, with the peak height rates being 2.4 cm/decade for girls at the age of 12 and 3.3 cm/decade for boys at the age of 14, respectively. The increments of adult height were 3.2 and 2.1 cm, while the rates were 1.2 and 0.8 cm/decade, for males and females, respectively. The distributing curves of BMI show an accelerating tendency of going to the right side, which suggests that the prevalence of childhood obesity is increasing rapidly.
Conclusion: China is now experiencing an overall and positive secular trend, which is reflected not only by the accelerating physical growth in childhood, advanced puberty, and steady increments of adult height, but also by the dramatic changes of body shape. We should not only feel proud of the achievements of these secular growth changes and the active socioeconomic influences, but also pay much attention to their negative effects, especially those that may induce the dangers of hypertension, hyperglycemia, type 2 diabetes mellitus and other adulthood diseases, as well as the disease risks of metabolic syndrome that may even occur early in childhood and adolescence.