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oai:figshare.com:article/34008117 2026-09-28T04:28:03Z category_173 portal_316 item_type_3 month_year_09_2026

Supplementary file 1_Reallocating childhood physical activity and sedentary time and adolescent mental health: a compositional data analysis of the UK Millennium Cohort Study.docx Yucheng Zhu (7349678) Yingguo Hu (25119312) Yuhong Zhu (709836) Applied Psychology compositional data analysis isotemporal substitution mental health physical activity sedentary behavior Background<p>Physical activity during childhood may promote mental health, but the effects of reallocating time between intensity zones on specific mental health dimensions remain poorly understood. To address this research gap, this study examined prospective associations between the composition of device-based physical activity at age 7 and multiple mental health outcomes at age 14 using a compositional data analysis (CoDA) framework that accounts for the constrained nature of daily time use.</p>Methods<p>Data were drawn from 5,145 children (48.1% boys) in the UK Millennium Cohort Study. Physical activity was measured using waist-worn ActiGraph GT1M accelerometers at age 7 and classified into sedentary behavior (SB), light-intensity physical activity (LPA), and moderate-to-vigorous-intensity physical activity (MVPA). Mental health was assessed at age 14 using the parent-reported Strengths and Difficulties Questionnaire (SDQ). Isometric log-ratio (ILR) transformed activity compositions were entered into linear regression models adjusting for baseline SDQ at age 7 and sociodemographic covariates. Compositional isotemporal substitution models estimated the predicted change in each SDQ outcome associated with reallocating 15 min per day between activity types. All analyses were stratified by sex. Conventional linear regression was conducted as a sensitivity analysis.</p>Results<p>Reallocating 15 min per day from LPA to MVPA was associated with fewer peer problems (delta = −0.050, p = 0.008). However, reallocating time from SB to MVPA was concurrently associated with higher hyperactivity (delta = 0.050, p = 0.002) and externalizing scores. Sex-stratified analyses revealed that the associations with peer problems were more pronounced among boys (e.g., LPA to MVPA on peer problems: delta = −0.097, p < 0.001) and were absent in girls, a pattern supported by formal interaction testing (p = 0.004). Conventional regression yielded directionally consistent results.</p>Conclusion<p>Childhood physical activity composition is prospectively associated with adolescent mental health in a dimension-specific manner, with suggestive evidence of sex differences. Modeled reallocation of time to MVPA was associated with more favorable peer-relationship and internalizing outcomes, particularly in boys, while associations with externalizing outcomes likely reflect reverse causality. These findings highlight the potential relevance of physical activity intensity for future longitudinal and intervention research on youth mental health.</p> 2026-09-28T04:28:03Z Dataset Dataset 10.3389/fpsyg.2026.1932607.s004 https://figshare.com/articles/dataset/Supplementary_file_1_Reallocating_childhood_physical_activity_and_sedentary_time_and_adolescent_mental_health_a_compositional_data_analysis_of_the_UK_Millennium_Cohort_Study_docx/34008117 CC BY 4.0