Inspiratory muscle training improves autonomic modulation and exercise tolerance in chronic obstructive pulmonary disease subjects: A randomized-controlled trial

Abstract

Objectives: We aimed to evaluate the effect a regular inspiratory muscle training program on autonomic modulation measured by heart rate variability, exercise capacity and respiratory function in chronic obstructive pulmonary disease subjects (COPD).

Design: Single-center controlled study, with balanced randomization (1:1 for two arms).

Setting: A COPD reference hospital localized in Sao Luís, Brazil.

Participants: 22 COPD subjects joined the study.

Interventions: Three times a week for four weeks inspiratory muscle training (IMT) at 30% of PI_max.

Main outcome measures: Pulmonary capacities and inspiratory pressure, total six-minute walk test and, cardiac autonomic modulation.

Results: The intervention group showed improvements in the cardiac autonomic modulation, with increased vagal modulation (total variability and HF [ms²; adjusted p < 0.05]); increased expiratory and inspiratory capacities and, increased distance in the 6-min walk test.

Conclusion: 12 weeks of IMT at 30% of the maximal inspiratory pressure increased cardiac autonomic modulation, expiratory and inspiratory and exercise capacity in COPD subjects.

Keywords: Autonomic nervous system; COPD; Exercise; Heart rate variability; Inspiratory muscle exercise; Spirometry.