Many patients who survive a critical illness suffer physical consequences that last for months, years, or even persist indefinitely and substantially reduce their quality of life. We have shown that NZ ICU patients receiving invasive mechanical ventilation (life support) are typically immobile. Immobilisation during the provision of life-support is a potentially modifiable cause of ICU-acquired weakness and may contribute to the development of long-term morbidity among ICU survivors. Over the last decade we have developed and tested a multidisciplinary intervention called targeted early activity and mobilisation demonstrating that early mobilisation of patients on life support is safe and feasible. This proposal is for the NZ component of a 750-participant RCT designed to determine if targeted early activity and mobilisation improves the outcomes of patients who were previously living at home who develop a life-threatening illness requiring prolonged life support in an ICU.