Effects of inspiratory muscle training (IMT) on dyspnea, respiratory muscle function and respiratory muscle activation in patients with COPD during endurance cycling

Background: It has been demonstrated that IMT reduces diaphragm activation (EMGdi) and dyspnea during exercise in COPD. Whether IMT also influences neural activation of non-diaphragmatic respiratory muscles is unknown. Methods: Patients were randomized into an IMT or sham-IMT group (30 breaths, 2 sessions daily, 8 weeks). Training load was 50% of the weekly maximal inspiratory pressure (MIP) in the IMT group and 10% of the initial MIP in the sham group. MIP measurements and constant work rate cycling tests were performed before and after the training. An esophageal catheter was used to assess EMGdi and transdiaphragmatic pressures. Non-diaphragmatic muscle activation (sEMG) was assessed using surface EMG electrodes. All parameters were compared at iso-time (time of the shortest test). Results: Table 1 shows baseline characteristics and the responses after training of 10 patients. Conclusion: These preliminary results suggest that IMT tended to improve MIP and endurance exercise performance, while EMGdi and symptoms of leg effort and dyspnea decreased. No differences in changes in activation of accessory respiratory muscles were observed between groups. Larger sample size will be necessary to confirm these trends.