To investigate the mechanism of short-term improvement in exercise tolerance after lung volume reduction surgery (LVRS) for severe emphysema, we performed six-minute walk tests and pulmonary-function tests, and studied their correlation before and 3-to-5 months after LVRS in 7 patients with severe emphysema who underwent bilateral lung reduction via median sternotomy. Results of the tests showed a 59% increase in the 1-second forced expiratory volume (FEV₁), a 25% reduction in the functional residual capacity (FRC), a 49% increase in the maximum voluntary ventilation (MVV), and a 20% increase in the distance walked in 6 minutes (6MD). The degree of improvement in 6 MD correlated significantly with the degree of improvement in FEV₁ (r=0.97, p< 0.01), in FRC (r=0.86, p< 0.05), and in MVV (r=0.87, p< 0.05), and did not correlate with the degree of improvement in pulmonary gas exchange. These results support the hypothesis that an increase in lung elastic recoil after targeted emphysematous resection reduces airflow limitation, and thus leads to a short-term improvement in exercise tolerance after LVRS.