Swimming has been considered the most appropriate activity for children with asthma for its lower asthmogenicity compared to land-based activities. However, the benefits of swimming have been hampered by reports of increased asthma risks, airway inflammation and bronchial hyper-responsiveness from exposure to chlorine by-products in swimming pools. Thus, the role of swimming for children with asthma remains unclear.
To determine the effectiveness of swimming as an intervention on lung function and asthma control in children below the age of 18 years. Any adverse effects from swimming on asthma were also examined.
Searches were performed across six databases systematically (PubMed, CINAHL, Embase, CENTRAL, Scopus, and PsycINFO). Randomized controlled trials (RCTs), quasi-experimental studies and interventional studies with at least one control/comparator group that were published in English were included. All eligible studies were screened with risk of bias examined by two independent reviewers. Meta-analyses were conducted using Review Manager 5.4 software while narrative syntheses were performed where meta-analysis was inappropriate and heterogeneity was present.
1710 records were retrieved from the search. A total of 9 studies with 387 participants were included in this review after screening. Swimming was found to have favourable effects on forced expiratory volume in one second (L) and forced vital capacity (%), but not for forced expiratory volume in one second (%) and peak expiratory flow (%). Narrative synthesis on asthma control and adverse effects were in favour of the swimming group.
Future studies that are adequately powered, involve swimming interventions of sufficient intensity, frequency and duration, examine cumulative exposures to chlorine by-products and take into account potential cofounders are warranted.

Copyright © 2021. Published by Elsevier Ltd.