Objective: The aim of the study was to evaluate the short-term physiologic effects of respiratory muscle training with normocapnic hyperpnea added to standard exercise training on respiratory muscle endurance/strength and exercise tolerance in patients with chronic obstructive pulmonary disease.
Design: The study used a randomized controlled trial. Patients referred for rehabilitation were randomly assigned to 20 sessions (twice daily 5 d/wk) of either normocapnic hyperpnea (group 1, n = 12) or sham maneuvers (group 2, n = 10) in addition to individualized cycle training and abdominal, upper, and lower limb muscle exercise. At baseline and end of study, patients underwent evaluation of respiratory muscle endurance, maximum voluntary ventilation, maximal inspiratory, and expiratory pressures, and 6-min walking distance.
Results: After training, a significant improvement was found only for group 1 in respiratory muscle endurance time (by 654 [481] secs versus 149 [216] secs for group 2, P = 0.0108) and maximal inspiratory (group 1: from 81.2 [21.9] cmH2O to 107.6 [23.0] cmH2O, P = 0.018 versus group 2: from 75.4 [13.8] cmH2O to 81.3 [18.9] cmH2O, P = 0.139). The difference between groups for 6-min walking distance, maximum voluntary ventilation, and expiratory pressures was not significant.
Conclusions: Short-term normocapnic hyperpnea training added to standard exercise, compared with exercise training alone, improves respiratory muscle endurance and strength but not exercise tolerance in patients with chronic obstructive pulmonary disease.