Spirometry and Cardiopulmonary Exercise Test
CORTEX
All participants underwent spirometry testing according to standard guidelines by using the Cortex Metalyzer 3B (Cortex Biophysik GmbH) (Afterward, participants completed a peak cardiopulmonary exercise test on a seated stationary cycle ergometer (Ergoline GmbH) using a validated incremental protocol. Respiratory gases were measured breath by breath using the same Metalyzer as that used for spirometry. Continuous electrocardiogram monitoring was used to record heart rate, and blood pressure readings were taken every 4 minutes with a manual mercury sphygmomanometer (ACCOSON Freestyle). Participants maintained 60 revolutions per minute during the test, which started with one quiescent minute of resting measurements followed by 2 minutes of warm-up at 20 watts. After this, workload increased to 35 watts. To normalize test duration to 8–12 minutes, participants who reported higher activity or fitness levels had their workload increased to 75 watts after the warm-up. The workload was then increased in increments of 15 watts each minute, while participants cycled continuously until exhaustion prevented them from maintaining 50 revolutions per minute or safety termination criteria were met. The test ended with a 2-minute cool-down period at 50 watts and revolutions of the participant’s own preference.