Introduction
MYOPIA
The beneficial effect of increased time outdoors on myopia control is widely acknowledged, and related school-based interventions have been implemented at a systemwide scale in many countries with varying levels of success.However, in real-world scenarios, children are spending more time indoors in front of screens.To investigate whether additional extracurricular physical activity time after school compromises the academic performance of schoolchildren, we conducted this noninferiority cluster randomized clinical trial (RCT), with academic performance as the primary outcome. We hypothesized that, compared with the current practice in China of free play after school, adding extracurricular physical activity after school would not compromise children’s academic performance.