Chest
Volume 128, Issue 5, November 2005, Pages 3177-3182
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Clinical Investigations: COPD
The Effects of 1 Year of Specific Inspiratory Muscle Training in Patients With COPD

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Aim: We assessed the long-term benefits of inspiratory muscle training (IMT) on inspiratory muscle strength, exercise capacity, the perception of dyspnea, quality of life, primary care use, and hospitalizations in patients with significant COPD.

Patients: Forty-two consecutive COPD patients with FEV1< 50% of predicted were randomized into a group that received IMT for 1 year, and a control group that received training with a very low load.

Results: There was a statistically significant increase in inspiratory muscle strength (at the end of the third month of training) as assessed by maximal inspiratory pressure (from 71 ± 4.9 to 90 ± 5.1 cm H2O [± SEM], p < 0.005) and 6-min walk distance (at the end of the third month of training; from 256 ± 41 to 312 ± 54 m; p < 0.005), a decrease in the mean Borg score during breathing against resistance (at the end of the ninth month of training), improvement in the health-related quality-of-life scores (at the end of the sixth month of training) in the training group but not in the control group. At the end of the training year, these changes were maintained; in addition, a decrease in primary health-care use and hospitalization days was observed.

Conclusions: Our study shows that during IMT in patients with significant COPD, there is an increase in exercise capacity, improvement in quality of life, and decrease in dyspnea. Our study also provides evidence that long-term IMT can decrease the use of health services and hospitalization days.

Section snippets

Subjects

Forty-two consecutive patients, 32 men and 10 women, with spirometric evidence of significant chronic airflow limitation (FEV1< 50% of predicted, FEV1/FVC < 70% of predicted) with a diagnosis of COPD according to the criteria of the American Thoracic Society14 were recruited from the community. The patients were all new to an IMT program, and none were receiving additional regular exercise or dietary supplements. All were receiving regular long-acting bronchodilators, and 34 patients were

RESULTS

There were no significant differences between the two groups in age, height, weight, mean baseline FEV1and FVC, Pimax, 6MWT, and prior hospital admissions at the beginning of the study. Eleven patients dropped out of the study during the training period: 4 patients from the training group (2 of whom died) and 7 patients from the control group (4 of whom died). The attendance rate of the study was 63 ± 7% in the training group and 59 ± 8% in the control group (p = 0.082)

DISCUSSION

This study shows that in patients with significant COPD, long-term IMT results in an increase in the inspiratory muscle strength. This increase is associated with improved exercise performance, decrease in the sensation of dyspnea while breathing against resistance, improved quality of life, lower rate of primary care consultation, and fewer hospitalization days.

IMT has been extensively investigated in patients with COPD. More than a decade ago, Smith et al21 published the first meta-analysis

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