A randomized controlled trial on inspiratory muscle training in pulmonary hypertension: Effects on respiratory functions, functional exercise capacity, physical activity, and quality of life

Background: Impaired respiratory muscle function may be one of the causes of increased dyspnea, reduced exercise capacity, and physical activity (PA), and poor quality of life in pulmonary hypertension (PH). Objective: To investigate the effects of threshold inspiratory muscle training (TIMT) on respiratory functions, functional exercise capacity, PA, and QoL in patients with PH. Methods: Thirty patients with PH were randomly allocated to a TIMT (n = 15) and sham group (n = 15). Three patients in the sham group could not participate in the program. The TIMT group (n = 15) trained at 30% of the maximal inspiratory pressure (MIP), and the sham group (n = 12) performed at lowest pressure without change in threshold pressure. In both groups, patients performed TIMT at home for 15 min, twice per day, with the MIP load determined by the trainer, and were supervised once weekly at the hospital for eight weeks. The primary outcomes were MIP and maximal expiratory pressure (MEP). The secondary outcome measures included spirometric measurements, six-minute walking distance (6MWD), PA (SenseWear armband and International Physical Activity Questionnaire-Short Form-IPAQ-Short Form), and QoL (Minnesota Living with Heart Failure-MLHF). Results: After the training, changes in MIP (p = 0.023) were higher in the intervention group compared with the sham group. Differences in MEP, FEV1 (%), FVC (%), FEV1/FVC (%), 6MWD, %6MWD, IPAQ-SF, MLHFQ, and armband parameters were not significantly different between the groups (p > 0.05). Conclusions: The results of the study demonstrated that TIMT could increase MIP and did not improve other parameters of respiratory functions, functional exercise capacity, PA, and QoL in patients with PH. (C) 2020 Elsevier Inc. All rights reserved.