Improving Physical Fitness and Cognitive Functions in Middle School Students: Study Protocol for the Chinese Childhood Health, Activity and Motor Performance Study (Chinese CHAMPS).

: Sedentary lifestyles and their associated harmful consequences are public health concerns that impact more than half of the world's youth population in both developed and developing countries. : The Chinese Childhood Health; Activity and Motor Performance Study (Chinese CHAMPS) was a cluster randomized controlled trial to modify school physical activity policies and the physical education (PE) curriculum; using teacher training and parent engagement to increase opportunities and support students' physical activity and healthy eating. Using a 2 × 2 factorial design, the study tested the incremental effects of increasing the amount and intensity of physical activity, alongside adding support for healthy eating, on health-related and cognitive function outcomes in Chinese middle school students. : The intervention was implemented by PE teachers in 12 middle schools in three Chinese cities, with a targeted enrollment of 650 students from August 2015⁻June 2016. The assessment of the outcomes involved a test battery of physical fitness and cognitive functioning at both baseline and at the end of the intervention. Process information on implementation was also collected. : The Chinese CHAMPS is a multi-level intervention that is designed to test the influences of policy and environmental modifications on the physical activity and eating behaviors of middle school students. It also addresses some key weaknesses in school-based physical activity interventions.