Respiratory failure is the most common cause of death in neuromuscular diseases. The aim of this research is to evaluate the thoracopulmonary recruitment by comparison of inspiratory vital capacity (VC ins)and inspiratory/expiratory vital capacity (VC ins-ex) with the vital capacity (VC) according to pathology and severity of pulmonary damage of patients with neuromuscular diseases. The methodology consists in realize VC by support of inspiratory/expiratory pressures, while the patient is passive and realizing a maximal inspiratory/expiratory effort simultaneously, with the aid of mechanical insufflation/exsufflation device (Cough Assist®). The evaluation will last for 30 minutes and the non-inclusion criteria are those for an insufflation. The study hypothesis is that long term insufflation/exsufflation device use could improve thoracopulmonary mobility.