Inspiratory muscle training in patients with COPD: effect on dyspnea, exercise performance, and quality of life

The aim of the study was to assess the effect of target-flow inspiratory muscle training (IMT) on respiratory muscle function, exercise performance, dyspnea, and health-related quality of life (HRQL) in patients with COPD.

Twenty patients with severe COPD were randomly assigned to a training group (group T) or to a control group (group C) following a double-blind procedure. Patients in group T (n = 10) trained with 60 to 70% maximal sustained inspiratory pressure (SIPmax) as a training load, and those in group C (n = 10) received no training. Group T trained at home for 30 min daily, 6 days a week for 6 months.

The measurements performed included spirometry, SIPmax, inspiratory muscle strength, and exercise capacity, which included maximal oxygen uptake (VO(2)), and minute ventilation (VE). Exercise performance was evaluated by the distance walked in the shuttle walking test (SWT). Changes in dyspnea and HRQL also were measured.

Results showed significant increases in SIPmax, maximal inspiratory pressure, and SWT only in group T (p < 0.003, p < 0.003, and p < 0.001, respectively), with significant differences after 6 months between the two groups (p < 0.003, p < 0.003, and p < 0.05, respectively). The levels of VO(2) and VE did not change in either group. The values for transitional dyspnea index and HRQL improved in group T at 6 months in comparison with group C (p < 0.003 and p < 0.003, respectively).

We conclude that targeted IMT relieves dyspnea, increases the capacity to walk, and improves HRQL in COPD patients.