Interval versus continuous training in lung transplant candidates: a randomized trial.
Interval (IT) and continuous training (CT) represent well-established exercise modalities in patients with moderate to severe chronic obstructive pulmonary disease (COPD). However, their effects and feasibility in patients with end-stage COPD remain unclear.Sixty patients (53 ± 6 years, 53% women) being evaluated for lung transplantation where randomly assigned either to IT (n = 30, cycling at 100% peak work rate for 30 seconds alternating with 30 seconds of rest) or CT (n = 30, cycling at 60% of peak work rate) during a 3-week inpatient rehabilitation program. Both exercise protocols yielded an equivalent amount of total work. Patients had a mean forced expiratory volume at 1 second (FEV(1)) of 25% ± 8% of predicted value.Patients in both groups achieved similar clinically relevant improvements in 6-minute walking distance of 35 ± 29 meters for IT and 36 ± 43 meters for CT, with a between-group difference of 0.3 meters (95% confidence interval, -18.2 to 18.8). Changes in lung function parameters were not significant. Perceived intensity of dyspnea was significantly (p< 0.05) lower in IT (Borg 6.2 ± 1.8) compared with CT (Borg 7.1 ± 1.7). Patients required a median of 5 unintended breaks (interquartile range, 2-28) during IT exercise and 29 (interquartile range, 6-68) during CT (p< 0.001).IT is associated with a lower intensity of dyspnea during exercise and fewer unintended breaks but achieves similar improvements in exercise capacity compared with CT in pre-lung transplant COPD patients.