The application of muscle endurance training techniques to the respiratory muscles in COPD

Standard treatments for chronic obstructive pulmonary disease (COPD) that are directed at reducing the degree of obstruction may be insufficient to relieve symptoms and improve exercise tolerance in severe cases. Many severely affected patients have reduced respiratory muscle endurance, which makes them less able to tolerate their excessive respiratory workloads. Despite the absence of a naturally-occurring endurance-training effect, the respiratory muscles of patients with COPD can be trained for increased endurance when periodic respiratory exertion is deliberately induced by isocapnic hyperventilation or added inspiratory resistance. Such training has resulted either in improved sustainable ventilatory capacity or in improved exercise tolerance. These improvements due to respiratory muscle training were better than those observed with whole body exercise training programs in some cases but not in others. Respiratory muscle training is a promising new adjunct in the management of COPD, but further investigation is required to delineate its indications and contraindications.