Cardiorespiratory Fitness
CORTEX
Assessment of cardiorespiratory fitness was performed via cardiopulmonary exercise testing (CPET). Patients were seated on a stationary exercise bike (Ergoline GmbH, Bitz, Germany) for resting spirometry followed by CPET using breath-by-breath respiratory gas analysis (Metalyzer 3B, Cortex Biophysik, Leipzig, Germany). A standardized incremental exercise protocol was used, and patients were encouraged to exercise until at least a respiratory exchange ratio ≥1.1 was reached. Oxygen saturation, capillary lactate, and subjective exertion (Borg Scale) were assessed every 2 minutes, and peak oxygen consumption (V ˙ o