RT Journal Article SR Electronic T1 School-based interventions modestly increase physical activity and cardiorespiratory fitness but are least effective for youth who need them most: an individual participant pooled analysis of 20 controlled trials JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP 721 OP 729 DO 10.1136/bjsports-2020-102740 VO 55 IS 13 A1 Timothy Bryan Hartwig A1 Taren Sanders A1 Diego Vasconcellos A1 Michael Noetel A1 Philip D Parker A1 David Revalds Lubans A1 Susana Andrade A1 Manuel Ávila-García A1 John Bartholomew A1 Sarahjane Belton A1 Naomi E Brooks A1 Anna Bugge A1 Iván Cavero-Redondo A1 Lars Breum Christiansen A1 Kristen Cohen A1 Tara Coppinger A1 Sindre Dyrstad A1 Vanessa Errisuriz A1 Stuart Fairclough A1 Trish Gorely A1 Francisco Javier Huertas-Delgado A1 Johann Issartel A1 Susi Kriemler A1 Silje Eikanger Kvalø A1 Pedro Marques-Vidal A1 Vicente Martinez-Vizcaino A1 Niels Christian Møller A1 Colin Moran A1 John Morris A1 Mary Nevill A1 Angélica Ochoa-Avilés A1 Mai O'Leary A1 Louisa Peralta A1 Karin A Pfeiffer A1 Jardena Puder A1 Andrés Redondo-Tébar A1 Lorraine B Robbins A1 Mairena Sanchez-Lopez A1 Jakob Tarp A1 Sarah Taylor A1 Pablo Tercedor A1 Mette Toftager A1 Emilio Villa-González A1 Niels Wedderkopp A1 Kathryn Louise Weston A1 Zenong Yin A1 Zhou Zhixiong A1 Chris Lonsdale A1 Borja del Pozo Cruz YR 2021 UL http://bjsm.bmj.com/content/55/13/721.abstract AB 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.