Cardiopulmonary Rehabilitation Enhances Heart Rate Recovery in Patients With COPD

BACKGROUND: Autonomic dysfunction is present early in the course of COPD, and is associated with adverse outcomes. We utilized heart rate recovery, a simple and validated index of autonomic balance, to investigate the effects of exercise training on autonomic dysfunction in patients with COPD. METHODS: We evaluated 45 stable subjects with COPD who participated in a 36-session exercise-based cardiopulmonary rehabilitation program. Subjects underwent maximal cardiopulmonary exercise testing at baseline and after completion of the rehabilitation program. We recorded exercise testing parameters and heart rate during rest, exercise, and recovery. Heart rate recovery was calculated as heart rate at peak exercise minus heart rate at the first minute of recovery. RESULTS: Thirty-nine subjects (age 66.3 +/- 7.8 y, 90% male, body mass index 27.1 +/- 4.1 kg/m(2), FEV1 45.7 +/- 18.7%) completed the program. In these subjects, heart rate recovery increased from 16.2 +/- 8.0 beats/min to 18.4 +/- 8.4 beats/min (P = .01), resting heart rate decreased from 88.0 +/- 10.7 beats/min to 83.3 +/- 10.5 beats/min (P = .004), and heart rate at anaerobic threshold decreased from 109.0 +/- 12.5 beats/min to 105.5 +/- 11.7 beats/min (P = .040). In addition, oxygen consumption ((V) over dot(O2)) increased from 14.3 +/- 3.7 mL/kg/min to 15.2 +/- 3.8 mL/kg/min at peak exercise, and from 9.7 +/- 2.4 mL/kg/min to 10.4 +/- 2.6 mL/kg/min at anaerobic threshold (both P = .02), while the (V) over dot(O2)/t slope increased from -0.32 +/- 0.16 mL/kg/min(2) to -0.38 +/- 0.19 mL/kg/min(2) (P = .003). Parameters of ventilatory performance improved also. CONCLUSIONS: In subjects with COPD, exercise-based rehabilitation improves heart rate recovery, modestly though, which indicates a degree of attenuated autonomic dysfunction. Exercise and muscular oxidative capacity, as expressed by (V) over dot(O2)/t slope, is also improved.