Targeted inspiratory muscle training improves respiratory muscle function and reduces dyspnea in patients with chronic obstructive pulmonary disease.

STUDY OBJECTIVE

To examine the effects of targeted inspiratory muscle training on respiratory muscle function, clinical ratings of dyspnea, and perception of resistive loads in symptomatic patients with chronic obstructive pulmonary disease.

DESIGN

Randomized, placebo-controlled trial with an 8-week treatment period.

SETTING

Outpatient pulmonary clinic and pulmonary function laboratory.

PARTICIPANTS

We studied 19 patients with moderate to severe chronic obstructive pulmonary disease, assigning 10 patients to an experimental group and 9 to a control group.

INTERVENTIONS

Patients in both groups trained for 15 minutes twice each day using a device that provided breath-to-breath visual feedback of training intensity. Patients in the experimental group trained at six increasing levels of inspiratory resistance, whereas the patients in the control group trained at a constant, nominal level of resistance.

MEASUREMENTS AND RESULTS

Although there was no statistically discernible difference in the effects of targeted muscle training on the mean difference in maximal inspiratory pressures between the two groups (9.83 cm H2O; 95% CI, -7.37 to 27.03), patients in the experimental group did show a significant increase in inspiratory muscle strength (15.03 cm H2O; P = 0.01). Experimental subjects also had decreased dyspnea after 8 weeks of training compared with control subjects (P = 0.003). Improvements in physiologic values and in dyspnea ratings were correlated. The perception of added resistive loads was not affected by inspiratory muscle training.

CONCLUSIONS

Targeted inspiratory muscle training may enhance respiratory muscle function and reduce dyspnea in symptomatic patients with moderate to severe chronic obstructive pulmonary disease.