Rationale: Survival rates of patients with critical illness have increased due to improved facilities and treatment methods in the intensive care unit (ICU). However, surviving critical illness does not mean these patients are cured. In general, ICU-admission is associated with decreased physical performance and perceived physical health, impaired mental health and quality of life (QoL), reflecting in an impaired long-term recovery. Long-term health problems can partly be contributed to prolonged muscle weakness and malnutrition. Improving physical performance and perceived physical health may play a key role in boosting recovery after ICU-admission. Mono-interventions focusing on improving physical performance or nutritional intake have limited effect on long term functioning and QoL. A lifestyle intervention encompassing physical therapy and optimisation of caloric and protein intake may improve wellbeing and QoL in these patients. Previous studies found that interventions focused on mobilization and physical rehabilitation are feasible within the ICU and outpatient programs. Additionally, promising results were found in personalized healthcare and lifestyle programs for other patient groups with long-term health problems, such as cancer survivors and patients with diabetes or mental health problems. Based on this, the investigators hypothesized that a lifestyle intervention program may improve wellbeing and quality of life in long-term ICU-survivors.

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.

Survival rates of critical illness have increased due to improved facilities and treatment methods in intensive care units. However, surviving critical illness does not automatically mean these patients are cured. In the past, the patients' survival was the measure of success in the treatment of critical illness. Over the past decades, the focus has been shifting towards the quality of life and care needs of these patients after critical illness. Survivors of critical illness frequently suffer from reduced quality of life. Health problems in the recovery period of survivors may predominantly be provoked by the physical consequences of longterm ICU-admission. The physical consequences of critical illness are mostly associated with skeletal muscle wasting during critical illness. This results in a decrease of muscle density up to two percent per day. Some long term physical health problems associated with this phenomenon are fatigue, neuropathy, neuromuscular dysfunction, and changes in bone mineral density. With regards to the long term psychosocial problems in survivors of critical illness there have been reports of short and long-term anxiety, depression and/or posttraumatic stress disorder (PTSD). Further, during and after critical illness, patients may experience delirium and cognitive impairments. In conclusion, survivors of critical illness suffer from long term physical and mental health problems, reflecting in a reduced HRQoL.

Critical illness survivorship is a relatively new and unknown area in research and medical health care. The term post-intensive care syndrome (PICS) has been used to describe the complex aetiology of health deficits following critical illness. A recent Dutch study (the MONITOR-IC-study) with a population of 1729 ICU-patients found that an overwhelming 70 percent of ICU-patients suffer from some form of PICS one year after discharge. Data collected from the specialized post-ICU clinic of the Medical Centre Leeuwarden (MCL) illustrated that 44% of 250 patients that visited this clinic between 2012 and 2018 were unable to sufficiently recover in physical functioning one year after ICU-discharge. Unfortunately, adequate and efficient aftercare programs for ICU survivors are still lacking and patients regularly feel abandoned and insecure after discharge. Personalised healthcare and lifestyle interventions may fulfil this discontinuity in care and improve physical performance and perceived physical health in ICU-patients, followed by improvements in mental wellbeing and HRQoL. Little is known on the effects of optimizing lifestyle on longterm recovery of these patients. Promising results were found in personalised healthcare and lifestyle programs for other patient groups with long-term health problems, such as cancer survivors and patients with diabetes or mental health problems. A Cochrane review showed several exercise rehabilitation programs after ICU-discharge to be feasible, but lacking in overall effect on functional exercise capacity, or on health-related quality of life. This paucity of effect on patient-centred outcomes may be due to inconsistencies in study protocol. However, a lack of adequate nutritional support might be an equally important pitfall. ICU-survivors may experience a number of problems that can hinder their nutritional intake, including lack of appetite, problems with taste and smell perception, and swallowing issues. Recent data from a study on post-ICU nutritional intake showed that of 12 included patients, the majority did not meet their daily caloric and protein intake. Data on nutritional intake after hospital discharge is lacking, but it is likely that patients are unable to achieve these goals without professional support.

Based on this, the investigators hypothesized that, complementary to the standard post-ICU care, a combined lifestyle intervention focussed on exercise and nutritional therapy may improve physical performance and perceived physical health alongside with an improved mental wellbeing and quality of life in long-term ICU-survivors.

Inclusion criteria Long stay post-ICU patients (length of stay ≥48h) between 6 weeks and 6 months after hospital discharge AND >18 years old AND able to visit the hospital 2 times a week AND a RAND-36 physical functioning subscale score < 67%

Exclusion criteria

• Allergy to components of ProSource® (Allergy information: gluten-free, lactose-free, NOT cow's milk free (wey-protein), produced in a factory in which soy, wheat and nuts are processed.
• Inability to understand the Dutch language
• Actively participating in a professional physical rehabilitation program during the study period.

Note: previous participation in a concluded rehabilitation program is NOT an exclusion criterion.