A multidisciplinary pulmonary rehabilitation program has become an important part of the treatment of chronic obstructive pulmonary disease. It can improve both exercise tolerance and health related quality of life in these patients. Exercise training has to be included for the program to be successful. The intensity of the training is of great importance: there is more physiological benefit in high-intensity training, compared to moderate-intensity training. High-intensity training results in reduced levels of blood lactate and pulmonary ventilation at a given heavy work rate. High-intensity training is limited in COPD patients because of exercise-induced dyspnoea. Flow limitation, as a consequence of increased ventilatory demands of exercise, causes a breathing pattern with greater demands on their inspiratory muscles: this results in a pattern of low tidal volume and high-frequency breathing. Increased inspiratory muscle work causes dyspnoea and limitation in exercise intensity. Artificial ventilatory assistance could improve exercise tolerance and hence help severe COPD patients to achieve a higher level of training. It could help to unload and assist the overburdened ventilatory muscles and give a possibility for higher levels of exercise intensity. In this review article we will discuss the effectiveness and feasibility of training with ventilatory aids.