Background and purpose: Previous studies have provided little information about the comparative efficacy of treatment with pressure threshold and targeted resistive inspiratory muscle training devices. This study compared the efficacy of these two types of inspiratory muscle training (IMT) devices on inspiratory muscle function, exercise capacity, and quality of life in patients with chronic obstructive pulmonary disease (COPD).
Methods: Forty two patients with moderate to severe COPD were randomly assigned to either a control group, a group receiving pressure threshold inspiratory muscle training, or a group receiving targeted resistive inspiratory muscle training. The training intensity was 50% of patients' maximal inspiratory pressure (MIP). Home-based training comprised two 15-minute sessions a day, 5 days a week for 8 weeks. Inspiratory muscle function measurement included MIP and inspiratory muscle endurance.
Results: Thirty patients completed the program, 10 from each group. Twelve patients were excluded because of changes in pharmacological regimen or admission to the hospital (n = 5), study withdrawal (n = 4), or poor compliance with the training program (n = 3). After training, a significant increase in endurance time was found for the threshold group and targeted resistive group (4.4 +/- 3.2 min and 3.0 +/- 2.9 min, respectively, both p < 0.05 vs control), with no significant difference between the 2 training groups. The 6-minute walking distance also increased significantly in both training groups (p < 0.05).
Conclusions: Targeted resistive IMT with a controlled training load has a similar efficacy to the more popularly used pressure threshold IMT and can be incorporated in the treatment of COPD patients. The targeted resistance device offers a less expensive and easily used treatment choice.