If the patient is discharged from the intensive care unit before four weeks, training will continue at the department of neurorehabilitation with a pre-specified tilt-table protocol consisting of mobilization twice a day on a similar tilt-table. Occasionally patients will be transferred to an intensive care unit at another hospital, while waiting for a further training at the department of neurorehabilitation. These patient will continue their mobilization programme on a regular tilt-table without active stepping. Patients who show functional improvement beyond the scope of tilt-table training (e.g. are able to stand from a chair) before the study period has ended, will have their final evaluation performed immediately hereafter and subsequently the standard rehabilitation regimen will be continued.