[Training of inspiratory muscles in chronic obstructive lung disease. Its impact on functional changes and exercise tolerance].

The aim of this study was to evaluate the impact of inspiratory muscle training on lung function and exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Thirty-five patients with stable COPD were enrolled. We measured lung function variables and peak inspiratory and expiratory pressures (PImax and PEmax). Tests of progressive maximal exercise tolerance and stable submaximal exercise tolerance were administered. Two study groups were formed. Group A patients (n = 20) were enrolled in a respiratory muscle training program lasting four months. Group B (n = 15) was the control group. At the end of the study period the patients underwent testing similar to the first battery of tests. All showed moderate to severe obstruction with no significant differences between groups (FEV1: group A 37.6 +/- 13%, group B 36.6 +/- 12%; FVC: group A 80.4 +/- 15%, group B 80 +/- 12%). Nor were there any significant differences between the two groups in initial results of either maximal respiratory pressures or exercise tolerance. No lung function changes were observed in either group. PImax in group A increased significantly at the end of the study (from 54 +/- 9 to 78 +/- 16 cmH2O; p < 0.001); there were no changes in group B. No changes were seen in VO2max or ventilatory response and/or gasometry during exercise in any of the groups. The trained group, on the other hand, experienced a significant decrease in dyspnea evaluated on the Borg scale exercise in maximal (5.7 +/- 1.1 versus 4.7 +/- 1.2, p < 0.005) and submaximal (5.9 +/- 0.9 versus 4.9 +/- 1.3, p < 0.005) and an increase in time of submaximal exercise tolerance (5.5 +/- 2 versus 7 +/- 3 min, p < 0.05), changes that were not observed in the control group. Based on these results, and although specific training of inspiratory muscles does not appear to improve lung function in patients with COPD, it is accompanied by a decreased sense of dyspnea during exercise and greater tolerance.