Even patients with milder COPD can have significant physiological abnormalities which become more pronounced during exercise, leading to intolerable breathing discomfort (dyspnea). While there is a compelling physiological rationale for the efficacy of inhaled corticosteroid/long-acting bronchodilator combination therapy [i.e., fluticasone 250μg/salmeterol 50μg (FSC250/50)] in moderate to severe COPD, little information is available on the potential impact of this therapy in milder symptomatic disease. This study will be the first to explore mechanisms of dyspnea and activity limitation in milder COPD and will determine if there is a sound physiological rationale for the use of FSC as therapy for this subpopulation.