Respiratory Muscle Training in Patients With Chronic Obstructive Pulmonary Disease

Abstract

With advancing chronic obstructive pulmonary disease (COPD), structural and mechanical changes occur that limit minute ventilation and reduce respiratory muscle strength and endurance. Respiratory muscle fatigue may develop as a result of these physiologic changes. During exercise, patients with COPD shift their functional residual capacity upward, changing the diaphragm's length-tension relationship, making it more susceptible to fatigue. As a countermeasure to this disabling process, specific training of the respiratory muscles has been advocated. The principles of skeletal muscle training were reviewed as applied to the respiratory muscles. Respiratory muscles can be trained for gains in endurance and/or strength. Several training modalities have been investigated, including general body conditioning, voluntary isocapnic hyperpnea, resistance respiratory muscle training, inspiratory muscle threshold loading, and breathing coordination training. Each training method has demonstrated success in improving respiratory muscle performance and general exercise ability and has aided in the reduction of dyspnea. While there is sufficient evidence to conclude that the respiratory muscles respond to specific training similar to other skeletal muscles, there is still controversy regarding the role of respiratory muscle training in the management of patients with lung disease. Additional research is warranted to identify the optimal training program for patients with different disease processes and to identify those patients for whom different forms of respiratory muscle training are best suited.