Physical inactivity and obesity: relation to asthma and chronic obstructive pulmonary disease?

Physical inactivity and obesity are modifiable risk factors for many chronic diseases, including cardiovascular disease, diabetes mellitus, osteoporosis, osteoarthritis, and depression. Both physical inactivity and obesity are associated with low-grade systemic inflammation that may contribute to the inflammatory processes present in many chronic diseases. In asthma, almost no studies are available in which physical inactivity has been studied using performance-based instruments. In contrast, the association between obesity and a higher prevalence of asthma has often been suggested in a large number of studies. In chronic obstructive pulmonary disease (COPD) physical inactivity has been demonstrated in a few studies that used performance-based instruments; this was associated with the higher COPD Global Initiative on Obstructive Lung Disease (GOLD) stages and a higher degree of systemic inflammation, independent of body mass index. In contrast to physical inactivity, obesity in COPD is associated with the lower GOLD stages. Additionally, obesity is associated with the chronic obstructive phenotype and features of the metabolic syndrome. To elucidate the independent relation of physical inactivity and obesity with systemic inflammation, performance-based studies of physical inactivity in asthma and COPD are highly needed.