Physiological response to moderate exercise workloads in a pulmonary rehabilitation program in patients with varying degrees of airflow obstruction

Study objectives: To investigate whether a 12-week pulmonary rehabilitation program that includes moderately intensive exercise training performed twice weekly can induce a training effect in patients with a wide variation of airflow limitation. Participants: Sixty patients with COPD (38 men) with a mean ± SD FEV₁% predicted of 55.1 ± 19.8 (range, 0.51 to 2.99). All patients performed identical incremental symptom-limited cycle ergometer testing before and after a 12-week study period. Measurements and results: After 12 weeks, the patients demonstrated a significant (p < 0.05) increase in the peak values for work rate (WR; 77 ±. 30 vs 91 ± 36 W) and oxygen uptake (1.14 ± 0.45 vs 1.20 ± 0.52 L/min). Furthermore, at a given WR during incremental symptom-limited cycle ergometer testing, there were significant (p < 0.05) reductions in minute ventilation (42.4 ± 16.1 vs 37.0 ± 13.6 L/min), carbon dioxide output (1.13 ± 0.49 vs 1.03 ± 0.42 L/min), ventilatory equivalent for oxygen (37.6 ± 8.1 vs 36.0 ± 6.3), and heart rate (135 ± 15 vs 128 ± 16 beats/min). None of the observed physiologic changes correlated with FEV₁% predicted. Conclusions: A pulmonary rehabilitation program performed twice weekly with moderate exercise workloads can lead to a physiologic training response irrespective of the degree of airflow limitation.