Inspiratory muscle training involves inhalation against a consistent resistance to build muscles used for inspiration for increased strength and endurance. The use of inspiratory muscle training was studied for its effect on dyspnea in patients with cancer. The patients used a device for breathing with a one-way valve that provided resistance when they inhaled through the device. They did this 15 minutes twice daily, five days a week. Various approaches for respiratory muscle training have been used or examined in patients with chronic obstructive pulmonary disease and for application in sports.