Canadian Cohort on the Origin and Progression of Airway Disease: Physiology Platform

INCLUSION CRITERIA: Stable patients with GOLD grade 1 mild COPD will be included in the study if they have: a post-bronchodilator FEV1≥80 %predicted and an FEV1/FVC ratio \<0.7 and \<LLN; ≥40 years of age; and a cigarette smoking history ≥10 pack-years or ≥10 years of exposure to other inhaled substances (i.e., second hand smoke and/or biomass). Symptomatic (category B) subjects will have a Baseline Dyspnea Index (BDI) total score ≤9, a modified Medical Research Council (MRC) dyspnea score ≥2, or a COPD Assessment Test (CAT) score ≥10. Asymptomatic (category A) subjects will have a BDI\>9, modified MRC\<2 or CAT\<10, no history of seeking medical care for respiratory symptoms, and no history of using respiratory medications. Symptomatic current or ex-smokers (\>10 pack-year history) who do not meet criteria for COPD (e.g., post-bronchodilator FEV1\<80%predicted and FEV1/FVC\<0.7, with both measurements also \<LLN) and who are on no respiratory medication will be included. Symptomatic will be defined as: BDI≤9, modified MRC≥2 or CAT\>10. Healthy, age- and sex-matched, non-smoking (\<2 pack-year history) participants with normal spirometry will be used for comparison purposes. EXCLUSION CRITERIA: * presence of clinically significant comorbidities that could contribute to dyspnea or exercise limitation (i.e., unstable heart disease, a pulmonary disease other than COPD, uncontrolled diabetes, neuromuscular or orthopedic impairment); * history/clinical evidence of asthma; * contraindications to exercise testing; * \<40 years of age; * body mass index \<18.5 or \>=35 kg/m2.