Research demonstrated that transplant recipients benefit from physical activity, but there is a gap in knowledge regarding the required intensity. In the PHOENIX-Liver study, researchers aim to investigate the adequate intensity of rehabilitation programs after liver transplantation. Patients will be randomized into one of the three PHOENIX-Liver training groups (low, moderate, moderate to high). The six months rehabilitation program is conducted from the patient's home but supervised by a PHOENIX-investigator. At baseline, after three months of rehabilitation and after six months of rehabilitation, a test moment takes place at which physical fitness, cardiovascular health, liver function, and body composition will be assessed. Questionnaires are taken monthly to survey well-being, safety, quality of life, physical activity, and cost-effectiveness. To gather information on the potential for implementation in a real-world setting, a 15-month-long physical activity phase will start after the intervention phase. This entails a maintenance physical activity program tailored to the patients' preferences. A follow-up at UZ Leuven is planned at three and at 15 months where the same clinical evaluations will be conducted as during the test moments of the intervention phase.