Impact of Inspiratory Muscle Training (IMT) With Intermittent Variable Resistance (IVR) Versus Constant Resistance (CR) on Functional Capacity in Lung Transplantation (LTx) Patients (I-TRAIN-LTx Study)

\- Objectives: Primary Objective: To compare Maximum Inspiratory Pressure (MIP) in lung transplant (LT) patients between the use of inspiratory muscle training (IMT) with intermittent variable resistance (IVR) or constant resistance (CR) during the first six months post-transplant. Secondary Objectives: To determine whether there are differences in the outcomes of IMT with IVR and IMT with CR in the six-minute walk test, spirometry values, and arterial blood gas analysis within the first six months post-transplant. To analyze the influence of relevant clinical conditions on dependent variables in both groups: duration of mechanical ventilation during the immediate postoperative period of LT and presence of diaphragmatic paralysis. To analyze the proportion of patients with Baseline Lung Allograft Dysfunction (BLAD) in both intervention groups. \- Methodology: Design: Open-label, two-arm, randomized clinical trial. Intervention: Random allocation into: CR Group: Will perform IMT at 30% of MIP. IVR Group: Will perform IMT at 30% and 60% of MIP. Population and Sample: Patients undergoing lung transplantation. Demographic and LT-related variables: Sex, date of birth, height, weight, body mass index, type of transplant, underlying disease leading to transplantation, phrenic paralysis, length of stay in the intensive care unit, days on mechanical ventilation, primary graft dysfunction, and acute rejection. Dependent Variables: MIP, spirometry, arterial blood gas analysis, six-minute walk test, and BLAD criteria.