Key Findings
Cardiovascular autonomic dysfunction and respiratory muscle weakness have been detected in patients with COPD. Although low-intensity inspiratory muscle training over 12 weeks increases cardiac parasympathetic (vagal) activity, eight-week programmes at the highest tolerable intensity and their effects on cardiovascular autonomic function remain untested. Thirty-nine stable COPD patients were randomized to inspiratory muscle training or control. Both received standard care, excluding pulmonary rehabilitation; the training group additionally performed 30 breaths twice daily at the highest tolerable intensity for eight weeks using a tapered flow resistive loading device. Assessments comprised pulmonary and respiratory muscle function, heart rate variability (HRV), blood pressure variability, baroreflex sensitivity, dyspnoea, 6-min walk distance and health status. Thirty-seven participants (training n = 18, control n = 19) completed the protocol. Maximal inspiratory pressure increased by 22.46 ± 15.71 cmH2O (p < 0.001), and cardiac parasympathetic activity rose (high-frequency component of HRV: 36.99 ± 17.51% to 46.84 ± 15.33%, p < 0.01). Sympathetic index decreased (low-frequency component of HRV: 54.13 ± 21.40% to 40.73 ± 17.01%, p < 0.001), as did the low-frequency/high-frequency ratio (2.30 ± 2.39 to 1.10 ± 0.83, p < 0.01). Systolic blood pressure variability decreased significantly. Baroreflex sensitivity increased from 5.36 ± 3.15 to 7.18 ± 4.58 ms/mmHg but was not significant (p = 0.05). Six-minute walk distance improved from 347.47 ± 82.72 to 378.71 ± 80.09 m (p < 0.01), and health status improved (COPD Assessment Test 7.72 ± 3.36 to 3.61 ± 2.85; Clinical COPD Questionnaire 1.07 ± 0.52 to 0.48 ± 0.31; both p < 0.001). These training-group improvements significantly exceeded control; ANCOVA confirmed group effects after baseline adjustment. Eight-week highest tolerable intensity inspiratory muscle training enhances cardiovascular autonomic function in COPD through increased parasympathetic and reduced sympathetic activity, and improves functional capacity and health status.
Why This Matters for Body-Mind Practice
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