The Effect of Breathing Retraining Using Metronome-Based Acoustic Feedback on Exercise Endurance in COPD: A Randomized Trial.

BACKGROUND: During exercise-training patients with chronic obstructive pulmonary disease (COPD) can entrain their breathing pattern to visual-feedback cues as to achieve a slower respiratory rate and prolong exhalation. The result is an improvement in exercise tolerance and a reduction in dynamic hyperinflation. Acoustic stimuli, including metronome-generated acoustic stimuli, can entrain human movements. Accordingly, we hypothesized that exercise duration and dynamic hyperinflation would be less after exercise-training plus breathing-retraining using a metronome-based acoustic-feedback system than after exercise-training alone.

METHODS: Of 205 patients with COPD [FEV = 44 ± 16% predicted (± SD)] recruited, 119 were randomly assigned to exercise-training plus breathing-retraining using acoustic feedback (n = 58) or exercise-training alone (n = 61). Patients exercised on a treadmill thrice-weekly for 12 weeks. Before and at completion of training, patients underwent constant-load treadmill testing with inspiratory capacity measures every 2 min.

RESULTS: At completion of training, improvements in exercise duration in the breathing-retraining plus exercise-training and exercise-training alone groups were similar (p = 0.35). At isotime, inspiratory capacity increased (less exercise-induced dynamic hyperinflation) by 3% (p = 0.001) in the breathing-retraining plus exercise-training group and remained unchanged in the exercise-alone group. The between-group change in inspiratory capacity, however, was not significant (p = 0.08).

CONCLUSIONS: In patients with COPD, breathing-retraining using a metronome-based acoustic feedback did not result in improved exercise endurance or decreased dynamic hyperinflation when compared to exercise-training alone.

TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT NCT01009099; URL: http://www.clinicaltrials.gov.