Secular Trend in the Physical Fitness of Xinjiang Children and Adolescents between 1985 and 2014

We assessed trends in physical fitness by age group and nutrition status among children and adolescents in Xinjiang during 1985–2014. The data of 49,357 participants aged 7–18 were extracted in 1985, 1995, 2005, and 2014. Growth and nutritional status were defined using World Health Organization definitions. A physical fitness indicator (PFI) was calculated as the sum of six components measured in every survey. The relationship between body mass index (BMI) and PFI was investigated using nonlinear regression. Taking 1985 as a reference, PFI increased to 2 in 1995 and then fell sharply to −2.8 in 2005 and −3.8 in 2014. The prevalence of normal weight increased from 87.5% in 1985 to 89.4% in 1995 and then decreased to 75.2%, consistent with the change in PFI. The relationship between BMI and PFI showed an inverted U-shaped curve. The largest increment occurred in boys aged 13–15 and girls aged 16–18 during 1985–1995; the largest decline occurred in boys and girls aged 10–12 during 1995–2005. Our research provides a reference for local governments providing nutrition subsidies and projects in southern Xinjiang, indicating that greater attention is needed for children aged 7–12.