The aim of this study was to examine the prolonged effect of procaterol, a short-acting bronchodilator, on lung function and exercise performance in patients with moderate to severe COPD. A randomized crossover trial was conducted. We recruited 19 patients with COPD aged 71.6+/-5.5 years. Patients were randomly assigned to receive either 20 mug inhaled procaterol followed by no-treatment or no-treatment followed by 20 mug inhaled procaterol separated by a washout period of 3+/-2 days. Lung function and exercise performance, using the incremental shuttle walking test (ISWT), were measured at baseline and 4 hours after receiving each treatment. Baseline forced expiratory volume in 1 second (FEV(1)) was 38.5%+/-17% predicted. There were no significant changes in FEV(1) following inhaled procaterol. However, walking distance increased by 294+/-113 meters at baseline to 331+/-119 meters after inhaled procaterol (p<0.001). These findings support the beneficial effects of inhaled procaterol on exercise performance in the absence of any change in FEV(1) when measured at 4 hours following inhalation in subjects with moderate to severe COPD. The inhaled procaterol may be useful for enhancing the effects of exercise training in patients with COPD.