Respiratory muscle training in chronic obstructive pulmonary disease: inspiratory, expiratory, or both?

Inspiratory and expiratory muscles can be specifically trained yielding improvements in both strength and endurance. The improvement in inspiratory muscle performance is associated with an improvement in the sensation of dyspnea, exercise tolerance, and quality of life. When the expiratory muscles are specifically trained, a significant increase in exercise performance has also been shown. However, there is probably no additional benefit in combining SEMT with SIMT.