Inspiratory muscle training (IMT) was performed using the Threshold IMT device using the threshold loading method. The IMT was administered to the patients in the training group at 30% of the MIP value, 5 days a week, twice a day, for 15 minutes for 8 weeks. The patients in the training group were called for a check-up once a week and the MIP value was re-evaluated. The training workload for that week was determined by taking 30% of the new measured MIP value.

During the training, the patients were asked to sit with their upper body (shoulders and upper chest) in a relaxed position, and after the nose was closed with the clip, the mouthpiece of the device was tightly closed with the lips. While in this position, the patient was asked to inhale and exhale 5 times into the device, then remove the device from their mouth and listen for 5 breaths, and continue this cycle for 15 minutes.

A spirometry device was used to evaluate lung functions and measurements were made according to ATS/ERS criteria. Before the test, the weight (kg), height (cm), age and gender values of the patients were recorded on the spirometry device. All measurements were made in a sitting position with the feet in full contact with the ground. A nose clip was used. At the beginning of the test, inspiration and expiration were requested within the limits of tidal volume. Then, the deepest possible inspiration was followed by rapid expiration. Care was taken to ensure that the expiration period continued uninterrupted for 6 seconds. The best of three tests that were 95% compatible with each other was selected and recorded. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), Tiffeneau ratio (FEV1/FVC) and peak expiratory volume (PEF) (L/min) values were measured and both the measured values and the percentages of expected values were recorded.

Respiratory muscle strength was measured in accordance with ATS/ERS criteria using an electronic and portable intraoral pressure measuring device.All of the measurements were made in the sitting position with the feet in full contact with the ground. Nasal breathing was blocked with a nose clip. In order to measure the maximum inspiratory pressure (MIP), maximum expiratory maneuver was performed before the patient took the mouthpiece of the device into his mouth, and then maximal inspiration (Müller maneuver) was performed at maximum speed for 1-3 seconds. For maximum expiratory pressure measurement, the maximum inspiratory maneuver was performed before the mouthpiece of the device was taken into the mouth, and then maximal expiration (Valsalva maneuver) was performed at maximum speed for 1-3 seconds. 3 measurements were repeated for each evaluation and the highest value was recorded in "cmH2O".

Functional capacity was measured with the 6-Minute Walk Test (6MWT) according to the guideline of ERS. The 6MWT to be a reliable, reproducible, and valid functional test for assessing exercise tolerance and endurance. Subjects were instructed to walk from one end to the other of a 30 m hallway at their own pace, while attempting to cover as much ground as possible in the allotted 6 min. The test was self-paced and the subject could rest if he or she so wished.