Desensitization to dyspnea in COPD with specificity for exercise training mode

Christopher B CooperDavid Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USAAbstract: Patients with chronic obstructive pulmonary disease (COPD) exhibit improved exercise capacity after physical training due to reconditioning and improved ventilatory efficiency. Other possible effects are improved ventilatory muscle function and desensitization to dyspnea. We compared general physical training (GPT), consisting of walking and stair climbing exercises, with inspiratory muscle training (IMT), consisting of targeted breathing through inspiratory resistances, in two groups with severe COPD. Seven subjects; age 60 (8) years, forced expiratory volume in one second (FEV1) 0.84 (0.35) L, arterial oxygen tension (PaO2) 11.1 (0.8) kPa, arterial carbon dioxide tension (PaCO2) 4.9 (0.3) kPa, had GPT and nine subjects; age 60 (9) years, FEV1 0.83 (0.31) L, PaO2 10.4 (0.8) kPa, PaCO2 4.4 (0.5) kPa had IMT. Each group trained daily for 30 minutes for eight weeks and 70% of the sessions were supervised. Six minute walking distance increased in both groups: 32 m (6.9% P < 0.05) with GPT and 23 m (4.8%; P < 0.05) with IMT but significant improvements in symptom-limited incremental cycle exercise performance were not detected. Breathlessness by visual analog scale was reduced following 6-minute walks after GPT (P < 0.05) but not after IMT. Following maximal incremental tests, breathlessness scores were unchanged for both groups. COPD patients performing regular physical exercise report reductions in breathlessness which are specific to the exercise training mode.Keywords: COPD, exercise, ventilatory muscles, dyspnea