Introduction and Objectives Physical activity (PA) has been found to be associated with prevalent childhood asthma but evidence from cross-sectional studies is inconclusive; demonstrating both positive and negative associations of PA with asthma. The aim of this study was to systematically review and meta-analyse the literature on PA and incident or “new-onset” childhood asthma.
Methods Medline, Embase, and the Cochrane Library were searched for articles on the associations between PA and asthma, restricted to age group 0–18 years and publications 1995–2010. PA was searched by 'physical fitness, exercise, physical exertion' and asthma additionally qualified by FEV1, BHR, EIA, EIB, exercise test and wheeze. Summary ORs and 95% CIs were estimated by random and fixed effect models. The robustness was explored by subgroup (ethnicity) and sensitivity (cut-point alteration) analysis.
Results Twenty-seven articles were included in the systematic review which comprised nine longitudinal, 15 cross-sectional, one case-control, and two review studies. Five studies featured longitudinal observations and were included in the meta-analysis (total participants n=12 889; total new-onset asthma n=912). Meta-analysis of these studies showed the following associations of high PA with new-onset asthma: Random effect model: OR (95% CI) 0.854 (0.713; 1.023) (Abstract S84 Figure 1) and fixed effect model: 0.909 (0.855; 0.967). I-squared=62.7% (both models).
Conclusion The results of this review did support some inverse association between high levels of PA and asthma development in children. However, a limited number of eligible studies were identified and considerable heterogeneity was present.