Add to ORKGMucus hypersecretion and impaired mucus clearance are well-known symptoms in patients with chronic obstructive pulmonary disease and cystic fibrosis. These symptoms should not be considered as innocent but they deserve treatment. A well known therapy to improve mucus transport is chest physiotherapy. Forced expiratory manoeuvres are probably the most effective part of chest physiotherapy. Essential in the application of forced expiratory manoeuvres to improve mucus transport is whether airway compression should be used or prevented. The variables that influence the localization and degree of airway compression are expiratory force, lung volume and possibly mouth pressure. With these variables the patient should learn the most efficient form...