Pulmonary rehabilitation (PR) has beneficial effects on exercise-induced dyspnea, exercise capacity and daily physical activity level in COPD.12e16 In addition, it is known in healthy subjects that exercise training can reverse the
process of deconditioning and delays the anaerobic threshold during exercise.17 Not all COPD patients benefit from PR to the same extent, as is shown in several studies.18e22 The limiting factor in exercise may play a role in the response to PR. For instance, the presence of a marked ventilatory reserve is associated with improvement in exercise capacity after PR in two studies.20,22 Besides that, the presence of cardiovascular limitation is associated with improvement in exercise capacity after PR as well.19,20
Finally, reduced muscle strength is found to be associated with improvement in exercise capacity after PR.18,20 These studies are, however, quite difficult to compare as
they show differences in patient selection, rehabilitation program, outcome measures and statistical methods used.18e22 In a well defined patient group we investigated whether a patient profile exists with a combination of variables instead of a single variable, which may predict the degree of improvement in endurance exercise capacity after PR. To reveal this profile, the cluster analysis technique was
used. We hypothesized that patients with better lung function combined with more signs of deconditioning, e.g. high lactate production during maximal exercise testing
and low peak exercise capacity show the largest improvement in endurance exercise capacity after PR.