Abstract

Background: Abnormalities of autonomic function have been reported in patients with chronic obstructive pulmonary disease. The effect of the exercise training in heart rate recovery (HRR) has not been established in patients with COPD. Objective: To assess the effects of 8-weeks' endurance training program on parasympathetic nervous system response measured as heart rate recovery in a sample of moderate-to-severe COPD patients. Methods: We recruited a consecutive sample of patients with COPD candidates to participate in a pulmonary rehabilitation program from respiratory outpatient clinics of a tertiary hospital. HRR was calculated, before and after training, as the difference in heart rate between end-exercise and one minute thereafter (HRR1) in a constant-work rate protocol. Results: A total of 73 COPD patients were included: mean (SD) age 66 (8) years, median (P-25-P-75) post-bronchodilator FEV1 39 (29-53)%. The prevalence of slow HRR1 (= 12 beats) at baseline was 63%, and was associated with spirometric severity (mean FEV1 35% in slow HRR1 vs 53 in normal HRR1, p 0.001). After 8-weeks training, HRR1 improved from mean (SD) 10 (7) to 12 (7) beats (p = 0.0127). Multivariate linear regression models showed that the only variable related to post-training HRR1 was pre-training HRR1 (p 0.001). Conclusions: These results suggest that training enhances HRR in patients with moderate-to-severe COPD. HRR is an easy tool to evaluate ANS such that it may be a useful clinical marker of parasympathetic nervous system response in patients with COPD.