A systematic review of associations of physical activity and sedentary time with asthma outcomes

Background: Physical inactivity and high sedentary time are associated with adverse health outcomes in several diseases. However, their impact in asthma is less clear. Objective: We aimed to synthesize the literature characterizing physical activity and sedentary time in adults with asthma, to estimate activity levels using meta-analysis, and to evaluate associations between physical activity and sedentary time and the clinical and physiological characteristics of asthma. Methods: Articles written in English and addressing the measurement of physical activity or sedentary time in adults =18 years old with asthma were identified using 4 electronic databases. Meta-analysis was used to estimate steps/day in applicable studies. Results: There were 42 studies that met the inclusion criteria. Physical activity in asthma was lower compared with controls. The pooled mean (95% confidence interval) steps/day for people with asthma was 8390 (7361, 9419). Physical activity tended to be lower in females compared with males, and in older people with asthma compared with their younger counterparts. Higher levels of physical activity were associated with better measures of lung function, disease control, health status, and health care use. Measures of sedentary time were scarce, and indicated a similar engagement in this behavior between participants with asthma and controls. High sedentary time was associated with higher health care use, and poorer lung function, asthma control, and exercise capacity. Conclusions: People with asthma engage in lower levels of physical activity compared with controls. Higher levels of physical activity may positively impact on asthma clinical outcomes. Sedentary time should be more widely assessed.