儿童体力活动与肠道微生物群（PA-Microbiome Kids） (PA-Microbiome)

实验性的：MVPA计划

参与者将参加为期16周的结构化中高强度身体活动（MVPA）计划，每周3次，每次45-60分钟。 每次训练包括热身、有氧游戏、自重力量循环训练和放松环节，由经过培训的教练监督。

行为的：16周结构化中等至剧烈强度体力活动计划

一项为期16周的结构化中高强度体育锻炼计划。

其他：Attention Control + Waitlist

Participants engage in time-matched sedentary activities such as reading, science experiments, or crafts, three times per week, and are instructed to maintain their usual physical activity levels. After the 16-week trial period, they are offered a comparable MVPA program (waitlist).

行为的：注意力控制久坐活动

时间匹配的久坐活动，如阅读、科学实验或手工艺。

综合体能Z分数变化

从基线到16周的综合身体素质z分数变化。 该分数根据《国家学生体质健康标准（2014年修订）》中的年龄适宜项目和权重计算得出。 该量表是基于参考人群的标准化z分数，均值为0，标准差为1。 没有理论上的上限或下限，但数值通常在-3到+3之间。 分数越高表示整体身体素质越好。

肠道菌群α多样性变化

通过16S rRNA基因测序评估的肠道微生物群α多样性指数（Shannon和Chao1）从基线到16周的变化。 Shannon指数的最小值为0，没有理论最大值。 Chao1指数估计物种丰富度，最小值等于观察到的物种数，同样没有理论最大值。 对于这两个指数，数值越高表示多样性越大，通常被认为反映了更健康的肠道微生物组。

肠道菌群β多样性差异

MVPA组与对照组之间肠道微生物群落结构（β多样性）的差异。 将使用基于Bray-Curtis和UniFrac距离矩阵的置换多元方差分析（PERMANOVA）进行评估。 结果将以R平方值（代表组别分配解释的群落结构变异百分比）和p值的形式报告。 较大的R平方值和较小的p值表明组间差异更显著。

体重指数（BMI）Z评分变化

从基线到16周期间年龄和性别特异性BMI z评分的变化。 这是一个标准化评分，基于参考人群，平均值为0，没有理论上限或下限。 评分越高表示相对于同龄人的BMI越高。 在本研究关注健康体重的背景下，z评分的增加通常被视为较差的结果。

Heterogeneity of Treatment Effect Across Baseline PA×PF Quadrants

Heterogeneity of treatment effect (HTE) of the MVPA intervention on primary and secondary outcomes across the four pre-specified baseline phenotype groups (P1: low PA-low PF; P2: high PA-low PF; P3: low PA-high PF; P4: high PA-high PF) defined in the 2023 cross-sectional study. HTE will be assessed by including a Treatment × Baseline Quadrant interaction term in mixed-effects models. A statistically significant interaction (p < 0.05) would indicate that the intervention effect differs across baseline microbiome phenotypes. Effect sizes will be reported separately for each quadrant with 95% confidence intervals.

Baseline Microbial Taxa as Effect Modifiers of Intervention Response

Pre-specified analysis of whether baseline relative abundance (continuous, log-transformed) of Akkermansia, Faecalibacterium, Subdoligranulum, and Bacteroides coprocola modifies the MVPA intervention effect on composite physical fitness z-score and alpha diversity. Interaction terms (Treatment × Baseline Taxon Abundance) will be tested in mixed-effects models.

Change in Body Fat Percentage

Change from baseline to 16 weeks in body fat percentage. Higher values indicate greater adiposity.

Change in Waist Circumference and Waist-to-Hip Ratio

Change from baseline to 16 weeks in waist circumference (cm) and waist-to-hip ratio. Higher values indicate greater central adiposity.

Change in Resting Heart Rate

Change from baseline to 16 weeks in resting heart rate (beats per minute) measured after seated rest. Lower values generally indicate better cardiovascular fitness.

Change in Blood Pressure

Change from baseline to 16 weeks in resting systolic and diastolic blood pressure (mmHg).

Change in Vital Capacity

Change from baseline to 16 weeks in vital capacity (mL) measured by spirometry. Higher values indicate greater lung function.

Change in Stool Form and Defecation Frequency

Change from baseline to 16 weeks in stool form assessed by the Bristol Stool Form Scale (types 1 to 7) and in self-reported weekly defecation frequency.

Change in Resilience (CD-RISC-10)

Change from baseline to 16 weeks in resilience measured by the 10-item Connor-Davidson Resilience Scale. Scores range from 0 to 40; higher scores indicate greater resilience.

Change in Well-Being (WHO-5)

Change from baseline to 16 weeks in subjective well-being measured by the WHO-5 Well-Being Index. Raw scores (0 to 25) are transformed to a 0 to 100 scale; higher scores indicate better well-being.

Change in Anxiety Symptoms (SCARED)

Change from baseline to 16 weeks in anxiety symptoms measured by the child self-report Screen for Child Anxiety Related Emotional Disorders. Higher scores indicate more anxiety symptoms.

Change in Depressive Symptoms (CES-D)

Change from baseline to 16 weeks in depressive symptoms measured by the Center for Epidemiologic Studies Depression Scale. Higher scores indicate more depressive symptoms.

Change in Strengths and Difficulties (SDQ)

Change from baseline to 16 weeks measured by the Strengths and Difficulties Questionnaire. Higher total difficulties scores indicate more difficulties; higher prosocial subscale scores indicate more prosocial behaviour.

Change in Coping Style (SCSQ)

Change from baseline to 16 weeks in coping style measured by the Simplified Coping Style Questionnaire, reported as positive and negative coping subscale scores.

Change in Self-Concept

Change from baseline to 16 weeks in self-concept measured by an age-appropriate self-concept questionnaire for younger children. Higher scores indicate more positive self-concept.

Change in Emotion Regulation (ERQ-CA)

Change from baseline to 16 weeks in emotion regulation measured by the Emotion Regulation Questionnaire for Children and Adolescents, reported as cognitive reappraisal and expressive suppression subscale scores.

Change in Objective Sleep

Change from baseline to 16 weeks in accelerometer-derived sleep, including total sleep time and sleep efficiency.

Change in Physical Literacy

Change from baseline to 16 weeks in physical literacy measured by a physical literacy questionnaire. Higher scores indicate greater physical literacy.

Change in Exercise Self-Efficacy

Change from baseline to 16 weeks in exercise self-efficacy measured by an 18-item exercise self-efficacy questionnaire. Higher scores indicate greater self-efficacy.

Change in Dietary Self-Efficacy

Change from baseline to 16 weeks in dietary self-efficacy measured by a 16-item dietary self-efficacy questionnaire. Higher scores indicate greater self-efficacy.

Change in Physical Activity Enjoyment (PACES)

Change from baseline to 16 weeks in physical activity enjoyment measured by the Physical Activity Enjoyment Scale. Higher scores indicate greater enjoyment.

Change in Eating Behaviour (CEBQ)

Change from baseline to 16 weeks in eating behaviour measured by the Children's Eating Behaviour Questionnaire, reported by subscale.

Change in Executive Function and Attention

Change in Objective Physical Activity and Sedentary Time

Change from baseline to 16 weeks in accelerometer-derived moderate-to-vigorous physical activity (minutes per day) and sedentary time (minutes per day), used to verify intervention-induced change in activity.