Can long-term regular physical activity improve health outcomes among adults with asthma—evidence from a systematic review and Bayesian meta-analysis

BACKGROUND: Evidence on the effects of regular physical activity (PA) on asthmatic adults is rather weak and inconsistent since previous studies were conducted based on the limited studies, various populations groups and single outcome. A systematic review (SR) and meta-analysis have a high level of evidence to comprehensively evaluate the effects of PA for adults with asthma based on the available data. Our study aims to provide an SR of available evidence regarding the effect of regular PA on asthma in adults. METHODS: A comprehensive search strategy was conducted using the PubMed, EMBASE, Cochrane Library, and Web of Science databases from their inception to October 2021. We identifying the eligible studies based on the PIOS principles, namely, populations (adults with asthma), interventions (regular PA), outcomes (quality of life or relapse-related outcomes), study design [randomized controlled trials (RCTs)]. A Bayesian-based meta-analysis was performed to pool available evidence. Quality assessment for individual studies was performed with the Cochrane risk of bias tool and the Newcastle-Ottawa Scale (NOS). RESULTS: A total of 22 publications (18 RCTs and 4 longitudinal studies) were identified, comprised of 85,392 individuals aged between 18 and 75 years old. Overall quality of the included studies was rated as low-to-moderated quality. We found that PA was effective in improving quality of life (QOL) [health related quality of life, (HRQoL) & Asthma Control Questionnaire, (ACQ): standard mean difference (SMD) =−0.80, 95% credible interval (CrI): −1.30 to −0.31; I(2)=86.9%, P(heterogeneity)<0.001], pulmonary function (FEV1/pred) [weighted mean difference (MD) =0.47, 95% CrI: 0.03 to 0.90; I(2)=74.9%, P(heterogeneity)<0.001], and maximal oxygen consumption (VO2max) (MD =1.18, 95% CrI: 0.87 to 1.48; I(2)=17.0%, P(heterogeneity)=0.31). Based on the longitudinal studies, the long-term high-level PA group had a lower risk of developing asthma compared with the low-level PA group [odds ratio (OR) =0.87, 95% CrI: 0.78 to 0.95; I(2)=27.4%, P(heterogeneity)=0.22)]. DISCUSSION: Adults with asthma need to carried out regular PA in accordance with the recommendations, which will improve their QOL and pulmonary function, and moreover, long-term PA appears to be more beneficial for asthmatic patients. The quality and quantity of included studies might affect the interpretation.