Trends in physical fitness, growth, and nutritional status of Chinese children and adolescents: a retrospective analysis of 1·5 million students from six successive national surveys between 1985 and 2014

Physical fitness is strongly associated with health. Despite the extent of the nutritional transition from food scarcity to diets high in fats and refined carbohydrates that has occurred in China, to our knowledge, trends in physical fitness have not been described. We aimed to assess trends in physical fitness and its association with the nutritional transition among Chinese children and adolescents.In this retrospective analysis, data from Chinese school students aged 7-18 years were extracted from six successive national surveys undertaken between 1985 and 2014. Six components of physical fitness (forced vital capacity, standing long jump, sit-and-reach, body muscle strength, 50 m dash, and endurance running) were measured repeatedly in each survey and aggregated as a summary physical fitness indicator (PFI). Growth and nutritional status (stunting, thinness, normal weight, overweight, and obesity) were defined by use of WHO definitions, and we combined stunting and thinness as undernutrition and overweight and obesity as overnutrition. Urbanisation levels were obtained from the statistical yearbook of the National and Provincial Bureau of Statistics of China. We used fractional polynomial regression and generalised additive models to assess associations between PFI and nutritional outcomes and between PFI and levels of urbanisation.Between 1985 and 2014, 1 513 435 students participated in the Chinese National Survey on Students' Constitution and Health, and 1 494 485 were included in our study. We observed a decline of the PFI during 1985-2014 (overall PFI change -0·8), albeit with an increase from 1985 to 1995 (PFI change 1·2), coinciding with a shift in the major nutritional problems from stunting and thinness to overweight and obesity. Both undernourished (PFI -2·44 for thin and -3·42 for stunting) and overnourished (-1·49 for overweight and -3·63 for obese) students had a lower PFI than that of those with normal weight (-0·41) in 2014. Boys had a larger decline in PFI than girls in 1985-2014, especially boys with obesity (PFI change -2·7). We observed the highest PFI in 1995 (1·17), when the proportion of students with normal weight was highest. Advancing urbanisation was accompanied by declines in physical fitness, which occurred in both students in rural settings and those in urban settings in these regions.Our study supports the continuation of policies to improve physical fitness that focus on undernutrition, including economic subsidies, in poorer rural regions. However, for most of China, taxation of unhealthy foods, promotion of physical activity, reduction in academic pressures, promotion of dietary diversity, reduction of sedentary time, and engagement in formal sporting activities should be elements of policies to promote healthy weight status and prevent obesity in school students, which will also support physical fitness.National Natural Science Foundation, Humanities and Social Sciences Planning Fund Project, China Scholarship Council, and Innovation Fund for Outstanding Doctoral Candidates of Peking University Health Science Center.