Physical Activity and Gut Microbiota in Children (PA-Microbiome Kids)

This study evaluates the effect of a 16-week moderate-to-vigorous physical activity (MVPA) program on physical fitness and gut microbiota in healthy school-aged children. Participants will be randomly assigned to either an MVPA intervention group or an attention-control group. The primary outcome is the change in a composite physical fitness score. Secondary outcomes include changes in gut microbiota diversity and composition.

Inclusion Criteria: * Participants from a previous cross-sectional study cohort conducted in 2023 (Pan et al., Sci Rep 2025;15:21351), at which time they were 6-9 years old. * Able to complete the 16-week follow-up. * Guardian provides written informed consent, and the child provides assent. * Medically cleared by a physician or school nurse to participate in moderate-intensity physical activity (no contraindications). * No antibiotic use in the 4 weeks prior to baseline. * No fever or acute gastroenteritis in the 2 weeks prior to baseline. * Able to provide stool samples as required. Exclusion Criteria: * Diagnosed with cardiopulmonary diseases, epilepsy, severe asthma, severe musculoskeletal disorders, or congenital heart disease. * Recent acute exacerbation of chronic gastrointestinal diseases. * Planning to follow a special diet (e.g., ketogenic, vegetarian) or requiring long-term prescription of antibiotics/probiotics. * Planning to be absent for \>20% of the intervention period due to travel or other commitments. * Enrolled in other high-intensity sports training programs that cannot be cancelled. * Developmental or behavioral issues that would impede cooperation, as assessed by teachers and parents.