Objective:To observe any effect of combining high-intensity intermittent inspiratory muscle training (HII-IMT) with an external diaphragm pacer (EDP) on the respiration and exercise capacity of mechanically-ventilated (MV) patients during an acute exacerbation of chronic obstructive pulmonary disease (AECOPD).Methods:A total of 120 AECOPD patients were randomly divided into a control group, and 3 observation groups, each of 30. The control group was given conventional rehabilitation. The observation groups also received an EDP. In addition, the observation group 1 underwent HII-IMT twice a day, 6 days a week for 2 weeks, and the observation group 2 did low-to-moderate intensity sustained inspiratory muscle training (L-MIS-IMT) on the same schedule. Before and after the treatment, the functioning of the diaphragm and peripheral skeletal muscles was evaluated. Their motor functioning was measured using Medical Research Council (MRC) scoring and mobility was measured using the de Morton mobility index (DEMMI). Arterial blood gases and the durations of MV and ICU stay were recorded. Inspiratory muscle and peripheral muscle functioning were correlated with motor functioning and mobility using Spearman correlation analysis and quantile regression analysis.Results:Significant improvements were observed in the average diaphragm excursion (DE), diaphragm thickening fraction (DTF), maximum inspiratory pressure (MIP), arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), biceps thickness (BRT), quadriceps thickness (QMT), MRC scores and DEMMI values in all 4 groups. Those of observation group 1 were significantly better than the observation group 2 and 3 results, on average. The MV time of observation group 1 averaged (9.2±0.4) days and with an average ICU stay of 12 days (a range of 10.2-13.7). Both were significantly shorter than the other 3 groups′ averages. BRT, QMT, MRC score and DEMMI values were positively correlated with the increases in DE, DTF and MIP.Conclusions:HII-IMT combined with EDP can significantly improve the breathing and mobility of AECOPD patients on mechanical ventilation. The improvements in MIP, DE and DTF can better their BRT, QMT, MRC score and DEMMI values to varying degrees.