Physical activity, sedentary behaviour, and childhood asthma: a European collaborative analysis

<strong>Objectives</strong> <br> To investigate the associations of physical activity (PA) and sedentary behaviour in early childhood with asthma and reduced lung function in later childhood within a large collaborative study.<br> <strong>Design</strong> <br> Pooling of longitudinal data from collaborating birth cohorts using meta-analysis of separate cohort-specific estimates and analysis of individual participant data of all cohorts combined.<br> <strong>Setting</strong> <br> Children aged 0-18 years from 26 European birth cohorts.<br> <strong>Participants</strong> <br> 136 071 individual children from 26 cohorts, with information on PA and/or sedentary behaviour in early childhood and asthma assessment in later childhood.<br> <strong>Main outcome measure</strong> <br> Questionnaire-based current asthma and lung function measured by spirometry (forced expiratory volume in 1 s (FEV₁), FEV₁/forced vital capacity) at age 6-18 years.<br> <strong>Results</strong> <br> Questionnaire-based and accelerometry-based PA and sedentary behaviour at age 3-5 years was not associated with asthma at age 6-18 years (PA in hours/day adjusted OR 1.01, 95% CI 0.98 to 1.04; sedentary behaviour in hours/day adjusted OR 1.03, 95% CI 0.99 to 1.07). PA was not associated with lung function at any age. Analyses of sedentary behaviour and lung function showed inconsistent results.<br> <strong>Conclusions</strong> <br> Reduced PA and increased sedentary behaviour before 6 years of age were not associated with the presence of asthma later in childhood.<br>