High-intensity inspiratory muscle training in bronchiectasis: A randomized controlled trial

Abstract

Background and objective: Inspiratory muscle training (IMT) enhances velocity of inspiratory muscle contraction and modifies inspiratory and expiratory time. This study aimed to examine the impact of high-intensity IMT (H-IMT) on exercise capacity in bronchiectasis. Methods: Forty-five patients were included. Lung function, respiratory muscle strength and endurance, exercise capacity, dyspnoea, fatigue and quality of life (QOL) were evaluated. Patients were randomized into two groups: H-IMT and control groups. Twenty-three patients underwent H-IMT for 8 weeks, using threshold loading with a target workload of maximal inspiratory pressure (MIP) of at least 70%, with 3-min cycles (as 2-min training: 1-min rest intervals) for 21 min. There was a total period of 14 min of loaded breathing and 7 min of recovery. The control group (n = 22) underwent low-intensity IMT at 10% of the initial MIP and was maintained at the same intensity until the end of the training. Results: After training, both MIP and maximal expiratory pressure (MEP) and the incremental shuttle walk distance were increased in the H-IMT group compared with the control group (P < 0.05). There was a significant difference in constant threshold load, time and pressure–time units in the H-IMT group (P < 0.05) but not in the control group (P > 0.05). A significant decrease was found in fatigue in both groups (P < 0.05). The Leicester Cough Questionnaire social score for the H-IMT group decreased significantly after the treatment (P < 0.05). Conclusion: The H-IMT increased exercise capacity in patients with non-cystic fibrosis bronchiectasis. It has also positive effects on respiratory muscle strength and endurance, and social aspects of QOL.