Objective: Evaluation of the effects of a integrative lifestyle intervention program on physical performance and perceived physical health, mental health and health related quality of life after ICU-admission. Study design: Randomised controlled trial Study population: Long-term ICU patients (length of stay ICU ≥48h) Intervention: The intervention group will be part of a 12-week combined lifestyle intervention encompassing group physical therapy twice a week and improvement of dietary caloric and protein intake by means of nutritional advice and, if applicable, caloric and/or protein supplementation. The control group will be subject to follow up meetings with research staff to assess physical and mental health and quality of life. Main study parameters/endpoints: Physical functioning (RAND-36 subscale-score) at the end of the 12 week intervention period. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: All participants have two additional appointments where they participate in an interview and perform physical tests (bioimpedance measurements, ultrasound of the upper thigh muscles, hand grip strength test, Morton mobility index test, and the six-minute walking test with pulse oximetry). At baseline and week 12 of the program, all participants complete a combination of questionnaires on mental health and quality of life. The intervention group will additionally be subject to supervised group training sessions twice a week for the duration of the intervention (12 weeks). Further, two meetings with a professional about their diet will be organised. If a patient has a deficit in caloric and/or protein intake, dietary supplements with daily intake instructions will be provided. The risks and disadvantages of this intervention are minimal. However, this study requires considerable time investment and physical and mental effort. The extent of this study is crucial to clarify the effect of a combined intervention program on recovery after critical illness.