Effects of continuous aerobic exercise on lung function and quality of life with asthma: a systematic review and meta-analysis

Background Despite the obvious benefits of aerobic exercise for asthmatic patients, controversies persist. The current study evaluated the effectiveness of continuous aerobic exercise on lung function and quality of life of asthmatic patients. Methods We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials databases up to May 2019 and included randomized controlled trials (RCTs) of asthmatic patients intervened with whole body continuous aerobic exercise (moderate intensity, at least 20 minutes and two times a week, over a minimum period of four weeks), in which the endpoint measures were lung function and asthma-related quality of life. A fixed-effects model (I2≤50%) or random-effects model (I2>50%) was applied to calculate the pooled effects according to the I2-and Chi-squared (χ2) test, funnel plots were quantified to present publication bias, and a P value <0.05 was statistically significant. Results Eventually, 22 trials conformed to the selection criteria. In the aerobic exercise group, the forced expiratory volume improved in one second (FEV1) (I2=10.2%, WMD: 0.12, P=0.011), peak expiratory flow (PEF) (I2=87.3%, WMD: 0.66, P=0.002), forced vital capacity (FVC) (I2=0.0%, WMD: 0.18, P<0.001), FVC/predict (I2=3.9%, WMD: 4.3, P=0.014), forced expiratory flow between 25% and 75% of vital capacity (FEF25-75%) (I2=0.0%, WMD: 9.6, P=0.005), Asthma Quality of Life Questionnaire (AQLQ) (I2=0.0%, WMD: 0.20, P=0.002), and Pediatric Asthma Quality of life Questionnaire (PAQLQ) (I2=72.1%, WMD: 0.81, P<0.001), respectively, while no statistical significance existed in FEV1%predict (I2=36.0%, WMD: 0.68, P=0.312) and FEV1/FVC ratio (I2=0.0%, WMD: 0.27, P=0.443) compared with the control group. When the exercise mode was taken into account, we observed significant improvement in FEV1, PEF, and FVC in the swimming (P<0.05) or indoor treadmill (P<0.05) training group. Conclusions Our meta-analysis proved that regular continuous aerobic exercise benefits asthma patients on FEV1, PEF, FVC, FVC%pred, FEF25-75%, and quality of life, and was well tolerated, while there were no improvements in FEV1%pred and FEV1/FVC%. As such, swimming and treadmill training may be appropriate options.