Utilizing the conceptual scheme of Kim, this study focused on the effect of inspiratory muscle training on the strength of the respiratory muscles, exercise performance, clinical manifestations, and activities of daily living. Unlike previous studies, inspiratory muscle training was performed by the use of an ISRBD that gave alinear inspiratory resistance of 50 cm H2O/L/sec at 1 L/sec flow. Subjects used an ISRBD twice a day for 15 minutes each day for 4 weeks. Strength of respiratory muscles as measured by PImax and sputum expectoration improved significantly (P less than 0.05) but there was no significant change in exercise performance (12-minute walk distance), other clinical signs and symptoms, or activities of daily living. Visual feedback given by the bellows of the ISRBD that inflated and deflated with inspiration and expiration apparently served as a positive reinforcer and motivator for most subjects. Daily logs of clinical signs and symptoms and activities of daily living, along with weekly telephone conferences with each subject, provided comprehensive data and may have contributed to the high compliance rate (98%) in this study.