Does physical activity strengthen lungs and protect against asthma in childhood? A systematic review.

BACKGROUND: Physical activity may be a potentially modifiable risk factor for asthma and driver of lung function development. This systematic review aimed to summarize the available evidence concerning the longitudinal effect of physical activity on the development of asthma, the persistence of asthma symptoms and lung function outcomes in children and adolescents. METHODS: PubMed and Embase electronic databases were searched for all original articles that investigated the longitudinal association between physical activity and asthma outcomes or lung function outcomes in children and adolescents. The search and data extraction were conducted by two independent researchers. The methodological quality of the included studies was assessed using two critical assessment tools. RESULTS: The literature search retrieved 2298 publications from the electronic databases. All articles were screened, and 2289 were subsequently excluded, resulting in nine longitudinal studies eligible for inclusion in this review. Two studies found no association with incident wheeze, and two of four found no association with various asthma outcomes. Three studies investigated the effect on lung function: one observed an association in boys only, one observed an association in girls only, and one found no associations. CONCLUSION: The evidence was highly inconsistent for the relationship between physical activity and asthma and lung function outcomes. Hence, we conclude that there is insufficient evidence to suggest that physical activity has a long-term effect on the risk of asthma development in youth. Furthermore, there is insufficient evidence to determine the longitudinal effects of physical activity on lung function in children.