Department of Endocrinology and Metabolism, The First Affiliated Hospital of Ningbo University, Ningbo 315000, China.
Department of Maternal and Child Health, School of Public Health, Peking University, Beijing 100191, China.
Nutrients. 2024 Aug 21;16(16):2788. doi: 10.3390/nu16162788.
(1) Background: Although daily time-use is associated with diet quality and cardiorespiratory fitness (CRF) in children, their interdependence remains unexplored. This study first examined the associations between reallocating daily movement time and diet quality and CRF, and second the mediating role of diet quality in the relationship between daily time-use and CRF. (2) Methods: This study included 1131 Chinese children (aged 8 to 10 years; median [interquartile range]: 8.5 [8.3, 8.8]) at baseline (September 2022) and 1268 children at the 9-month follow-up (June 2023) from the OptiChild study. Daily durations of moderate-to-vigorous physical activity (MVPA), sleep, and sedentary behavior (e.g., screen time) were self-reported or proxy-reported by parents. Diet quality was assessed via the Diet Quality Questionnaire (DQQ), which uses a 24 h dietary recall and is categorized according to the Global Dietary Recommendations (GDR) score and Food Group Diversity Score (FGDS). The CRF was measured using VO after the 20 m shuttle run test. Longitudinal associations between daily time-use, diet quality, and CRF were calculated using isotemporal substitution models. Mediation analyses were used to determine whether diet quality mediated the associations between daily time-use and CRF. (3) Results: Reallocation of 30 min from screen time to MVPA resulted in significant improvements in the GDR score (β baseline = 0.11, = 0.024; β follow-up = 0.26, < 0.001), FGDS (β baseline = 0.11, = 0.006; β follow-up = 0.19, < 0.001), and CRF (β baseline = 0.40, < 0.001; β follow-up = 0.26, = 0.001). Diet quality partially mediated the associations between MVPA, screen time, and CRF. Substituting 30 min of screen time for MVPA led to diet quality mediating a proportion of the association with CRF (GDR score: 11.4%, FGDS: 6.6%). (4) Conclusions: These findings underscore the importance of optimizing daily time-use of MVPA and screen time and improving diet quality to promote physical fitness in school-aged children.
（1）背景：尽管日常时间分配与儿童的饮食质量和心肺适能（CRF）有关，但它们之间的相互关系仍未得到探索。本研究首先检验了重新分配日常运动时间与饮食质量和 CRF 的关系，其次检验了饮食质量在日常时间分配与 CRF 之间关系中的中介作用。
（2）方法：本研究纳入了来自 OptiChild 研究的 1131 名中国儿童（年龄 8 至 10 岁；中位数[四分位距]：8.5 [8.3，8.8]），他们在基线（2022 年 9 月）和 9 个月随访（2023 年 6 月）时自我报告或由家长代理报告了日常中中高强度体力活动（MVPA）、睡眠和久坐行为（如屏幕时间）的时长。饮食质量通过饮食质量问卷（DQQ）进行评估，该问卷使用 24 小时膳食回忆，并根据全球饮食建议（GDR）评分和食物组多样性评分（FGDS）进行分类。CRF 使用 20 米穿梭跑测试后的 VO 测量。使用等时替代模型计算日常时间分配、饮食质量和 CRF 之间的纵向关联。中介分析用于确定饮食质量是否介导了日常时间分配与 CRF 之间的关联。
（3）结果：将 30 分钟的屏幕时间重新分配到 MVPA 中，可显著提高 GDR 评分（基线时 β=0.11，=0.024；随访时 β=0.26， < 0.001）、FGDS（基线时 β=0.11，=0.006；随访时 β=0.19， < 0.001）和 CRF（基线时 β=0.40， < 0.001；随访时 β=0.26，=0.001）。饮食质量部分介导了 MVPA、屏幕时间与 CRF 之间的关联。用 30 分钟的屏幕时间替代 MVPA，可导致饮食质量对 CRF 的关联产生部分中介作用（GDR 评分：11.4%，FGDS：6.6%）。
（4）结论：这些发现强调了优化中高强度体力活动和屏幕时间的日常时间分配以及改善饮食质量以促进学龄儿童身体健康的重要性。
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