Rationale: Epidemiological studies in older individuals have found an association between use of ACE-inhibition (ACE-I) therapy and preserved locomotor muscle mass, strength and walking speed. ACE-I therapy might therefore have a role in the context of pulmonary rehabilitation. Objectives: We investigated the hypothesis that enalapril, an ACE-inhibitor, would augment the improvement in exercise capacity seen during pulmonary rehabilitation. Methods: We performed a double-blind, placebo-controlled, parallel-group randomised controlled trial. COPD patients, with at least moderate airflow obstruction and taking part in pulmonary rehabilitation, were randomised to either 10 weeks therapy with an ACE-inhibitor (10mg enalapril) or placebo. Measurements: The primary outcome measurement was the change in peak power (assessed using cycle ergometry) from baseline. Main Results: Eighty patients were enrolled, seventy-eight randomised (age 67±8years, FEV1 48±21% predicted), and sixty-five completed the trial (34 placebo, 31 ACE-inhibitor). The ACE-inhibitor treated group demonstrated a significant reduction in systolic blood pressure (Δ-16mmHg, 95% CI -22 to -11) and serum ACE activity (Δ-18IU/L, 95% CI -23 to -12) versus placebo (between group differences p
