Objectives To determine if subpopulations of students benefit equally from school-based physical activity interventions in terms of cardiorespiratory fitness and physical activity. To examine if physical activity intensity mediates improvements in cardiorespiratory fitness.
Design Pooled analysis of individual participant data from controlled trials that assessed the impact of school-based physical activity interventions on cardiorespiratory fitness and device-measured physical activity.
Participants Data for 6621 children and adolescents aged 4–18 years from 20 trials were included.
Main outcome measures Peak oxygen consumption (VO2Peak mL/kg/min) and minutes of moderate and vigorous physical activity.
Results Interventions modestly improved students’ cardiorespiratory fitness by 0.47 mL/kg/min (95% CI 0.33 to 0.61), but the effects were not distributed equally across subpopulations. Girls and older students benefited less than boys and younger students, respectively. Students with lower levels of initial fitness, and those with higher levels of baseline physical activity benefitted more than those who were initially fitter and less active, respectively. Interventions had a modest positive effect on physical activity with approximately one additional minute per day of both moderate and vigorous physical activity. Changes in vigorous, but not moderate intensity, physical activity explained a small amount (~5%) of the intervention effect on cardiorespiratory fitness.
Conclusions Future interventions should include targeted strategies to address the needs of girls and older students. Interventions may also be improved by promoting more vigorous intensity physical activity. Interventions could mitigate declining youth cardiorespiratory fitness, increase physical activity and promote cardiovascular health if they can be delivered equitably and their effects sustained at the population level.
- individual participant data (IPD)
- cardiorespiratory fitness
- moderate to vigorous physical activity
- school-based physical activity intervention
- peak oxygen consumption
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CL and BdPC are joint senior authors.
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Correction notice This article has been corrected since it published Online First. The third author's name has been corrected and affiliation 23 has been added.
Contributors TBH, TS, DV, MN, PP, DRL, CL and BdPC contributed to the design of this pooled study. CL, PP and BdPC conceptualised the design of the present analysis and analysed the data. TBH obtained and harmonised raw data from lead investigators of eligible studies. TBH, TS, MN, PP, CL and BdPC wrote the first draft of the manuscript. TBH, TS, MN, PP, CL and BdPC had full access to the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. TBH, CL and BdPC are the guarantors. All other authors not specifically mentioned contributed raw data (data acquisition) for the pooled analysis and made important intellectual contributions by critically revising the study protocol, manuscript drafts and the final submitted manuscript. All authors agree to being accountable for all aspects of the work related to the accuracy or integrity of any part of the work. The corresponding author (TBH) attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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