Can ventilation-feedback training augment exercise tolerance in patients with chronic obstructive pulmonary disease?

Rationale: Exercise-induced dynamic hyperinflation contributes to decreased exercise tolerance in chronic obstructive pulmonary disease (COPD). It is unknown whether respiratory retraining (ventilation-feedback [VF] training) can affect exercise-induced dynamic hyperinflation and increase exercise tolerance.
Objectives: To determine whether patients with COPD would achieve longer exercise duration if randomized to a combination of exercise training plus VF training than either form of training on its own.
Methods: A total of 64 patients randomized to 1 of 3 groups: VF plus exercise (n = 22), exercise alone (n = 20), and VF alone (n = 22).
Measurements and Main Results: Exercise duration before and after 36 training sessions and exercise-induced dynamic hyperinflation and respiratory pattern before and after training were measured. In the 49 patients who completed training, duration of constant work-rate exercise was 40.0 (+/- 20.4) minutes (mean +/- SD) with VF plus exercise, 31.5 (+/- 17.3) minutes with exercise alone, and 16.1 (+/- 19.3) minutes with VF alone. Exercise duration was longer in VF plus exercise than in VF alone (P < 0.0001), but did not reach predetermined statistical significance when VF plus exercise was compared with exercise alone (P = 0.022) (because of multiple comparisons, P </= 0.0167 was used for statistical significance). After training, exercise-induced dynamic hyperinflation, measured at isotime, in VF plus exercise was less than in exercise alone (P = 0.014 for between-group changes) and less than in VF alone (P = 0.019 for between-group changes). After training, expiratory time was longer in VF plus exercise training (P < 0.001), and it was not significantly changed in the other two groups.
Conclusions: The combination of VF plus exercise training decreases exercise-induced dynamic hyperinflation and increases exercise duration more than VF alone. An additive effect to exercise training from VF was not demonstrated by predetermined statistical criteria.