The potential importance of respiratory, chiefly inspiratory-muscle, fatigue had only recently been appreciated. If inspiratory muscles fail, so does ventilation and tissue respiration. There are theoretical reasons to postulate inspiratory muscle failure in chronic obstructive pulmonary disease, and suggestions that it may occur in an acute form with exacerbations and in a chronic form during 'stability'. There are two therapeutic strategies available for prevention and treatment of inspiratory muscle fatigue: training inspiratory muscles to increase their efficiency and resting fatigued muscles. The former should work if chronic fatigue is not present, and the latter should allow recovery from chronic fatigue, so the two approaches are not necessarily mutually exclusive. This proposal was originally designed to test the efficacy of each of these therapies alone and also in combination; however, given the experience of a pretrial period, these goals were scaled back. Since there was reason to believe that VMR may be more effective than IMT, the trial focused on VMR and sham VMR only.