Physical activity and clinical and functional status in COPD

Background: The mechanisms underlying the benefits of regular physical activity in the evolution of COPD have not been established. Our objective was to assess the relationship between regular physical activity and the clinical and functional characteristics of COPD. Methods: Three hundred forty-one patients were hospitalized for the first time because of a COPD exacerbation in nine teaching hospitals in Spain. COPD diagnosis was confirmed by spirometry under stable conditions. Physical activity before the first COPD hospitalization was measured using the Yale questionnaire. The following outcome variables were studied under stable conditions: dyspnea, nutritional status, complete lung function tests, respiratory and peripheral muscle strength, bronchial colonization, and systemic inflammation. Results: The mean age was 68 years (SD, 9 years), 93% were men, 43% were current smokers, and the mean postbronchodilator FEV₁ was 52% predicted (SD, 16% predicted). Multivariate linear regression models were built separately for each outcome variable and adjusted for potential confounders (including remaining outcomes if appropriate). When patients with the lowest quartile of physical activity were compared to patients in the other quartiles, physical activity was associated with significantly higher diffusing capacity of the lung for carbon monoxide (DLCO) [change in the second, third, and fourth quartiles of physical activity, compared with first quartile (+ 6%, + 6%, and + 9% predicted, respectively; p = 0.012 [for trend])], expiratory muscle strength (maximal expiratory pressure [PEmax]) [+ 7%, + 5%, and + 9% predicted, respectively; p = 0.081], 6-min walking distance (6MWD) [+ 40, + 41, and + 45 m, respectively; p = 0.006 (for trend)], and maximal oxygen uptake (V̇O₂peak) [+ 55, + 185, and + 81 mL/min, respectively; p = 0.110 (for trend)]. Similarly, physical activity reduced the risk of having high levels of circulating tumor necrosis factor α (odds ratio, 0.78, 0.61, and 0.36, respectively; p = 0.011) and C-reactive protein (0.70, 0.51, and 0.52, respectively; p = 0.036) in multivariate logistic regression. Conclusions: More physically active COPD patients show better functional status in terms of DLCO, PEmax, 6MWD, V̇O₂peak, and systemic inflammation.