Recently integrated in clinical practice, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification states that a mild (stage I) chronic obstructive pulmonary disease (COPD) is present, in a smoker, when the postbronchodilator forced expired volume in 1 second (FEV1) to forced vital capacity (FVC) ratio is < 0.7. A major change that was introduced by the GOLD classification system was that COPD could be diagnosed despite an FEV1 that is within normal predicted values (above 80% predicted). Because it suggests diagnosing and detecting COPD earlier than done until very recently in medical practice, the GOLD standards bring in a new reality to clinicians. In fact, this novel COPD classification comes with new research challenges because the functional impacts and systemic consequences related to COPD are mostly documented in patients with moderate to severe stages with little information specifically in GOLD stage I COPD. This information is important if the investigators are to convince physicians that GOLD stage I COPD needs to be diagnosed and eventually treated.
The investigators aimed to characterize GOLD stage I COPD patients according to activity-related dyspnea. More specifically, our objectives were to compare:
i) baseline pulmonary function ii) exercise capacity iii) quadriceps muscle function iv) levels of physical activity in daily life
between symptomatic (Sx) GOLD stage I COPD patients, asymptomatic (ASx) GOLD stage I COPD patients and healthy control subjects (CTRL). The investigators reasoned that exercise tolerance and physical activity levels would be decreased in Sx GOLD stage I COPD patients as it would be similar between ASx GOLD stage I COPD patients and CTRL.